AI Trajectory

null

{
  "EnableConfigs": null,
  "FocusSymbols": [
    "vfio_ap_mdev_close_device"
  ],
  "KMSANReasoning": "The patch series addresses potential use-after-free (UAF) vulnerabilities and resource management in the s390 vfio_ap driver. Specifically, it modifies the driver to intentionally leak AQIC resources (pinned NIB pages and registered guest ISCs) if the hardware fails to confirm that interrupts have been disabled or a reset has completed within a timeout. This prevents the hardware from writing to freed memory, which would cause a UAF. It also corrects the bitmap sizes used in configuration removal and addition from `AP_DEVICES` to `AP_DOMAINS` (both are 256, so this is a semantic fix).\n\nNone of these changes introduce new allocations, complex data structures, or user-space copies that could expose uninitialized memory. The `status` variable copied into `q-\u003ereset_status` is fully initialized by the `ap_tapq` inline assembly instruction reading from hardware registers.\n\nSince the primary risks addressed by this patch are use-after-free bugs and resource leaks, standard KASAN (which detects UAF) and standard debugging tools are perfectly suited for testing these changes. There is no risk of uninitialized memory usage or info-leaks that would require a dedicated KMSAN fuzzing session.",
  "NeedsKMSAN": false,
  "Reasoning": "The patch fixes an eventfd memory leak in the VFIO AP mediated device close path, which is reachable via standard VFIO mdev ioctls and device close operations even without physical AP hardware. Other changes related to AP queue resets and IRQ handling are unreachable without IBM AP crypto hardware.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit 6ff8477b285b1818ffa5b145d17d62078cd919b6\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Thu Aug 27 14:30:07 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c\nindex 940c0ff668bee..85a59730019e3 100644\n--- a/drivers/s390/crypto/vfio_ap_ops.c\n+++ b/drivers/s390/crypto/vfio_ap_ops.c\n@@ -31,6 +31,7 @@\n #define AP_QUEUE_IN_USE \"in use\"\n \n #define AP_RESET_INTERVAL\t\t20\t/* Reset sleep interval (20ms)\t\t*/\n+#define AP_RESET_MAX_WAIT\t\t2000\t/* Maximum wait for reset (2000ms)\t*/\n \n static int vfio_ap_mdev_reset_queues(struct ap_matrix_mdev *matrix_mdev);\n static int vfio_ap_mdev_reset_qlist(struct list_head *qlist);\n@@ -226,16 +227,24 @@ static struct vfio_ap_queue *vfio_ap_mdev_get_queue(\n }\n \n /**\n- * vfio_ap_wait_for_irqclear - clears the IR bit or gives up after 5 tries\n+ * vfio_ap_wait_for_irqclear:\n+ * Waits for the IR bit to clear thus indicating IRQs are disabled for a queue\n+ *\n  * @apqn: The AP Queue number\n  *\n- * Checks the IRQ bit for the status of this APQN using ap_tapq.\n- * Returns if the ap_tapq function succeeded and the bit is clear.\n- * Returns if ap_tapq function failed with invalid, deconfigured or\n- * checkstopped AP.\n- * Otherwise retries up to 5 times after waiting 20ms.\n+ * Repeatedly checks the IR bit for the status of a queue device by calling the\n+ * PQAP(TAPQ) instruction every 20ms until: the IR bit is cleared; the response\n+ * code from the PQAP instruction indicates the queue is not available or\n+ * not operational; or the loop has executed more than 5 times.\n+ *\n+ * Return:\n+ * - true if the bit is observed clear or the AP is non-operational (in which\n+ *   case no further interrupts can be generated)\n+ *\n+ * - false if the IR bit is still set after all retries are exhausted, meaning\n+ *   the hardware may still write to the NIB.\n  */\n-static void vfio_ap_wait_for_irqclear(int apqn)\n+static bool vfio_ap_wait_for_irqclear(int apqn)\n {\n \tstruct ap_queue_status status;\n \tint retry = 5;\n@@ -246,7 +255,7 @@ static void vfio_ap_wait_for_irqclear(int apqn)\n \t\tcase AP_RESPONSE_NORMAL:\n \t\tcase AP_RESPONSE_RESET_IN_PROGRESS:\n \t\t\tif (!status.irq_enabled)\n-\t\t\t\treturn;\n+\t\t\t\treturn true;\n \t\t\tfallthrough;\n \t\tcase AP_RESPONSE_BUSY:\n \t\t\tmsleep(20);\n@@ -257,12 +266,13 @@ static void vfio_ap_wait_for_irqclear(int apqn)\n \t\tdefault:\n \t\t\tWARN_ONCE(1, \"%s: tapq rc %02x: %04x\\n\", __func__,\n \t\t\t\t  status.response_code, apqn);\n-\t\t\treturn;\n+\t\t\treturn true;\n \t\t}\n \t} while (--retry);\n \n-\tWARN_ONCE(1, \"%s: tapq rc %02x: %04x could not clear IR bit\\n\",\n-\t\t  __func__, status.response_code, apqn);\n+\tWARN_ONCE(1, \"%s: tapq rc %02x: timed out verifying interrupts disabled for %02x.%04x\\n\",\n+\t\t  __func__, status.response_code, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));\n+\treturn false;\n }\n \n /**\n@@ -317,8 +327,21 @@ static struct ap_queue_status vfio_ap_irq_disable(struct vfio_ap_queue *q)\n \t\tswitch (status.response_code) {\n \t\tcase AP_RESPONSE_OTHERWISE_CHANGED:\n \t\tcase AP_RESPONSE_NORMAL:\n-\t\t\tvfio_ap_wait_for_irqclear(q-\u003eapqn);\n-\t\t\tgoto end_free;\n+\t\t\t/*\n+\t\t\t * AQIC disable was accepted (NORMAL), or the queue was\n+\t\t\t * already disabled or a prior async request is still\n+\t\t\t * completing (OTHERWISE_CHANGED).  In both cases, we must\n+\t\t\t * wait until interrupt processing has been disabled\n+\t\t\t * before proceeding.\n+\t\t\t *\n+\t\t\t * If it could not be determined whether interrupts\n+\t\t\t * have been disabled, do not free the AQIC resources: the\n+\t\t\t * hardware may still write to the NIB, so leave it pinned\n+\t\t\t * to avoid a use-after-free. The resources will be leaked.\n+\t\t\t */\n+\t\t\tif (vfio_ap_wait_for_irqclear(q-\u003eapqn))\n+\t\t\t\tgoto end_free;\n+\t\t\tgoto end_fail;\n \t\tcase AP_RESPONSE_RESET_IN_PROGRESS:\n \t\tcase AP_RESPONSE_BUSY:\n \t\t\tmsleep(20);\n@@ -326,18 +349,46 @@ static struct ap_queue_status vfio_ap_irq_disable(struct vfio_ap_queue *q)\n \t\tcase AP_RESPONSE_Q_NOT_AVAIL:\n \t\tcase AP_RESPONSE_DECONFIGURED:\n \t\tcase AP_RESPONSE_CHECKSTOPPED:\n+\t\t\t/* AP not operational; no further interrupts possible */\n+\t\t\tWARN_ONCE(1, \"%s: ap_aqic status %d\\n\", __func__,\n+\t\t\t\t  status.response_code);\n+\t\t\tgoto end_free;\n \t\tcase AP_RESPONSE_INVALID_ADDRESS:\n \t\tdefault:\n-\t\t\t/* All cases in default means AP not operational */\n+\t\t\t/*\n+\t\t\t * The AQIC disable was rejected; IRQ is still enabled\n+\t\t\t * and the hardware still holds the NIB address. Do not\n+\t\t\t * free resources.\n+\t\t\t */\n \t\t\tWARN_ONCE(1, \"%s: ap_aqic status %d\\n\", __func__,\n \t\t\t\t  status.response_code);\n-\t\t\tgoto end_free;\n+\t\t\tgoto end_fail;\n \t\t}\n \t} while (retries--);\n \n \tWARN_ONCE(1, \"%s: ap_aqic status %d\\n\", __func__,\n \t\t  status.response_code);\n+\n+end_fail:\n+\t/*\n+\t * We are here either because of a failure to verify that\n+\t * interrupts have been disabled, or because the AQIC instruction\n+\t * failed to disable them. The AQIC resources - the pinned NIB page\n+\t * and the registered guest ISC - cannot be freed here. The hardware\n+\t * may still write to the NIB; freeing the pinned page would result\n+\t * in a use-after-free kernel crash. The resources will therefore be\n+\t * leaked. This is preferable to a use-after-free.\n+\t */\n+\treturn status;\n+\n end_free:\n+\t/*\n+\t * This label is reached because the queue was successfully disabled,\n+\t * or because the queue is not operational, in which case interrupts\n+\t * can not be processed, so free the AQIC resources - the pinned NIB\n+\t * page and the registered guest ISC - used to enable interrupts\n+\t * so they will not be leaked.\n+\t */\n \tvfio_ap_free_aqic_resources(q);\n \treturn status;\n }\n@@ -495,7 +546,12 @@ static struct ap_queue_status vfio_ap_irq_enable(struct vfio_ap_queue *q,\n \t\tq-\u003esaved_isc = isc;\n \t\tbreak;\n \tcase AP_RESPONSE_OTHERWISE_CHANGED:\n-\t\t/* We could not modify IRQ settings: clear new configuration */\n+\t\t/*\n+\t\t * IRQ control is already set as requested or a prior async\n+\t\t * request has not yet completed; in either case, this response\n+\t\t * comes with CC=3 indicating the new NIB and ISC were not accepted by\n+\t\t * the hardware, so clean them up.\n+\t\t */\n \t\tret = kvm_s390_gisc_unregister(kvm, isc);\n \t\tif (ret)\n \t\t\tVFIO_AP_DBF_WARN(\"%s: kvm_s390_gisc_unregister: rc=%d isc=%d, apqn=%#04x\\n\",\n@@ -503,9 +559,12 @@ static struct ap_queue_status vfio_ap_irq_enable(struct vfio_ap_queue *q,\n \t\tvfio_unpin_pages(\u0026q-\u003ematrix_mdev-\u003evdev, nib, 1);\n \t\tbreak;\n \tdefault:\n-\t\tpr_warn(\"%s: apqn %04x: response: %02x\\n\", __func__, q-\u003eapqn,\n-\t\t\tstatus.response_code);\n-\t\tvfio_ap_irq_disable(q);\n+\t\t/* We could not modify IRQ settings: clear new configuration */\n+\t\tret = kvm_s390_gisc_unregister(kvm, isc);\n+\t\tif (ret)\n+\t\t\tVFIO_AP_DBF_WARN(\"%s: kvm_s390_gisc_unregister: rc=%d isc=%d, apqn=%#04x\\n\",\n+\t\t\t\t\t __func__, ret, isc, q-\u003eapqn);\n+\t\tvfio_unpin_pages(\u0026q-\u003ematrix_mdev-\u003evdev, nib, 1);\n \t\tbreak;\n \t}\n \n@@ -635,7 +694,6 @@ static int handle_pqap(struct kvm_vcpu *vcpu)\n \t}\n \n \tstatus = vcpu-\u003erun-\u003es.regs.gprs[1];\n-\n \t/* If IR bit(16) is set we enable the interrupt */\n \tif ((status \u003e\u003e (63 - 16)) \u0026 0x01)\n \t\tqstatus = vfio_ap_irq_enable(q, status \u0026 0x07, vcpu);\n@@ -1410,7 +1468,7 @@ static void vfio_ap_mdev_hot_unplug_domain(struct ap_matrix_mdev *matrix_mdev,\n {\n \tDECLARE_BITMAP(apqis, AP_DOMAINS);\n \n-\tbitmap_zero(apqis, AP_DEVICES);\n+\tbitmap_zero(apqis, AP_DOMAINS);\n \tset_bit_inv(apqi, apqis);\n \tvfio_ap_mdev_hot_unplug_domains(matrix_mdev, apqis);\n }\n@@ -1959,8 +2017,32 @@ static void apq_reset_check(struct work_struct *reset_work)\n \t\telapsed += AP_RESET_INTERVAL;\n \t\tstatus = ap_tapq(q-\u003eapqn, NULL);\n \t\tret = apq_status_check(q-\u003eapqn, \u0026status);\n-\t\tif (ret == -EIO)\n+\t\tif (ret == -EIO) {\n+\t\t\tmemcpy(\u0026q-\u003ereset_status, \u0026status, sizeof(status));\n+\t\t\treturn;\n+\t\t}\n+\t\tif (elapsed \u003e= AP_RESET_MAX_WAIT) {\n+\t\t/*\n+\t\t * Timed out waiting for reset to complete.\n+\t\t *\n+\t\t * The AQIC resources associated with this queue - the pinned page\n+\t\t * containing the NIB and the registered guest ISC - cannot be freed\n+\t\t * here. The NIB is the active DMA target for AP interrupt delivery\n+\t\t * until the reset completes; freeing the pinned page while the\n+\t\t * hardware may still write to it would result in a use-after-free\n+\t\t * kernel crash.\n+\t\t *\n+\t\t * If the reset eventually completes, interrupts will be terminated\n+\t\t * and the pinned NIB page and ISC registration will be leaked. This\n+\t\t * is preferable to either a use-after-free or waiting indefinitely:\n+\t\t * the caller of apq_reset_check() holds mdevs_lock while flush_work()\n+\t\t * blocks holds the matrix_dev-\u003emdevs_lock mutex, which\n+\t\t * serializes access to all mdev objects system-wide, so blocking\n+\t\t * here would stall all other guests using AP queues.\n+\t\t */\n+\t\t\tmemcpy(\u0026q-\u003ereset_status, \u0026status, sizeof(status));\n \t\t\treturn;\n+\t\t}\n \t\tif (ret == -EBUSY) {\n \t\t\tpr_notice_ratelimited(WAIT_MSG, elapsed,\n \t\t\t\t\t      AP_QID_CARD(q-\u003eapqn),\n@@ -2061,12 +2143,28 @@ static int vfio_ap_mdev_open_device(struct vfio_device *vdev)\n \treturn vfio_ap_mdev_set_kvm(matrix_mdev, vdev-\u003ekvm);\n }\n \n+static void vfio_ap_mdev_release_eventfds(struct ap_matrix_mdev *matrix_mdev)\n+{\n+\tif (matrix_mdev-\u003ereq_trigger) {\n+\t\teventfd_ctx_put(matrix_mdev-\u003ereq_trigger);\n+\t\tmatrix_mdev-\u003ereq_trigger = NULL;\n+\t}\n+\tif (matrix_mdev-\u003ecfg_chg_trigger) {\n+\t\teventfd_ctx_put(matrix_mdev-\u003ecfg_chg_trigger);\n+\t\tmatrix_mdev-\u003ecfg_chg_trigger = NULL;\n+\t}\n+}\n+\n static void vfio_ap_mdev_close_device(struct vfio_device *vdev)\n {\n \tstruct ap_matrix_mdev *matrix_mdev =\n \t\tcontainer_of(vdev, struct ap_matrix_mdev, vdev);\n \n \tvfio_ap_mdev_unset_kvm(matrix_mdev);\n+\n+\tmutex_lock(\u0026matrix_dev-\u003emdevs_lock);\n+\tvfio_ap_mdev_release_eventfds(matrix_mdev);\n+\tmutex_unlock(\u0026matrix_dev-\u003emdevs_lock);\n }\n \n static void vfio_ap_mdev_request(struct vfio_device *vdev, unsigned int count)\n@@ -2697,11 +2795,11 @@ static void vfio_ap_mdev_on_cfg_remove(struct ap_config_info *cur_config_info,\n \tdo_remove |= bitmap_andnot(aqrem,\n \t\t\t\t   (unsigned long *)prev_config_info-\u003eaqm,\n \t\t\t\t   (unsigned long *)cur_config_info-\u003eaqm,\n-\t\t\t\t   AP_DEVICES);\n+\t\t\t\t   AP_DOMAINS);\n \tdo_remove |= bitmap_andnot(cdrem,\n \t\t\t\t   (unsigned long *)prev_config_info-\u003eadm,\n \t\t\t\t   (unsigned long *)cur_config_info-\u003eadm,\n-\t\t\t\t   AP_DEVICES);\n+\t\t\t\t   AP_DOMAINS);\n \n \tif (do_remove)\n \t\tvfio_ap_mdev_cfg_remove(aprem, aqrem, cdrem);\n@@ -2812,7 +2910,7 @@ static void vfio_ap_mdev_cfg_add(unsigned long *apm_add, unsigned long *aqm_add,\n \t\tbitmap_and(matrix_mdev-\u003eaqm_add,\n \t\t\t   matrix_mdev-\u003ematrix.aqm, aqm_add, AP_DOMAINS);\n \t\tbitmap_and(matrix_mdev-\u003eadm_add,\n-\t\t\t   matrix_mdev-\u003ematrix.adm, adm_add, AP_DEVICES);\n+\t\t\t   matrix_mdev-\u003ematrix.adm, adm_add, AP_DOMAINS);\n \n \t\tmutex_unlock(\u0026matrix_dev-\u003emdevs_lock);\n \t}\n"
}

best-expensive

null

{
  "EnableConfigs": null,
  "FocusSymbols": [
    "vfio_ap_mdev_close_device"
  ],
  "Reasoning": "The patch fixes an eventfd memory leak in the VFIO AP mediated device close path, which is reachable via standard VFIO mdev ioctls and device close operations even without physical AP hardware. Other changes related to AP queue resets and IRQ handling are unreachable without IBM AP crypto hardware.",
  "WorthFuzzing": true
}

You are an expert Linux kernel maintainer.
Your job is to review a provided patch series and determine
if it makes functional changes to the kernel that should be fuzzed.

IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in
your workspace. Do NOT rely on your internal knowledge of the kernel. You must actively
use your code access tools to examine the actual source code and confirm any assumptions.

Return WorthFuzzing=false if the patch only contains:
- Modifications to Documentation/, Kconfig files, or code comments.
- Purely decorative changes, such as logging (e.g., pr_err, printk) or tracepoints.
- Changes to numeric constants or macros that do not functionally alter execution flow.
- Code paths that are impossible to reach in virtualized environments like GCE or QEMU,
  even when utilizing software-emulated hardware (e.g., usb gadget, mac80211_hwsim).
- Code in vendor-specific PCIe switch, SmartNIC, or GPU drivers (e.g., mlxsw, pds_core, qed,
  ionic, amdgpu) that require physical PCIe hardware cards not emulated in standard QEMU.
- Driver .remove, .shutdown, or pci_unregister_driver teardown callbacks (e.g., igb_remove)
  that are executed only during PCI hot-unplug or sysfs driver unbind operations.

If it modifies reachable core kernel logic, drivers, or architectures, use your code search
tools to verify the code can be executed, then return WorthFuzzing=true.

When returning WorthFuzzing=true, you MUST ALSO:
1. Extract any specific kernel functions that should be heavily fuzzed into FocusSymbols.
   Avoid listing generic hot-path functions to prevent skewed test distributions.
   Prefer non-static, non-inlined API entrypoint functions over internal static helper functions
   (which are inlined by the compiler and do not have distinct symbol addresses).
2. Identify any specific CONFIG_ options required to properly test this new/modified feature.
   Go and look into the Kconfig files and check for ifdefs around the code, do not make assumptions.
   Also check "depends on" lines in Kconfig to include any non-standard parent subsystem configs
   needed for Kbuild to compile the code statically into vmlinux. List them in the EnableConfigs
   output array, and DO NOT add a 'CONFIG_' prefix (e.g., return "NET_IPV4" instead of "CONFIG_NET_IPV4").
Prefer calling several tools at the same time to save round-trips.


Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.

For your convenience, here is the diff of the changes:
commit 6ff8477b285b1818ffa5b145d17d62078cd919b6
Author: syz-cluster <triage@syzkaller.com>
Date:   Thu Aug 27 14:30:07 2026 +0000

    syz-cluster: applied patch under review

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 940c0ff668bee..85a59730019e3 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -31,6 +31,7 @@
 #define AP_QUEUE_IN_USE "in use"
 
 #define AP_RESET_INTERVAL		20	/* Reset sleep interval (20ms)		*/
+#define AP_RESET_MAX_WAIT		2000	/* Maximum wait for reset (2000ms)	*/
 
 static int vfio_ap_mdev_reset_queues(struct ap_matrix_mdev *matrix_mdev);
 static int vfio_ap_mdev_reset_qlist(struct list_head *qlist);
@@ -226,16 +227,24 @@ static struct vfio_ap_queue *vfio_ap_mdev_get_queue(
 }
 
 /**
- * vfio_ap_wait_for_irqclear - clears the IR bit or gives up after 5 tries
+ * vfio_ap_wait_for_irqclear:
+ * Waits for the IR bit to clear thus indicating IRQs are disabled for a queue
+ *
  * @apqn: The AP Queue number
  *
- * Checks the IRQ bit for the status of this APQN using ap_tapq.
- * Returns if the ap_tapq function succeeded and the bit is clear.
- * Returns if ap_tapq function failed with invalid, deconfigured or
- * checkstopped AP.
- * Otherwise retries up to 5 times after waiting 20ms.
+ * Repeatedly checks the IR bit for the status of a queue device by calling the
+ * PQAP(TAPQ) instruction every 20ms until: the IR bit is cleared; the response
+ * code from the PQAP instruction indicates the queue is not available or
+ * not operational; or the loop has executed more than 5 times.
+ *
+ * Return:
+ * - true if the bit is observed clear or the AP is non-operational (in which
+ *   case no further interrupts can be generated)
+ *
+ * - false if the IR bit is still set after all retries are exhausted, meaning
+ *   the hardware may still write to the NIB.
  */
-static void vfio_ap_wait_for_irqclear(int apqn)
+static bool vfio_ap_wait_for_irqclear(int apqn)
 {
 	struct ap_queue_status status;
 	int retry = 5;
@@ -246,7 +255,7 @@ static void vfio_ap_wait_for_irqclear(int apqn)
 		case AP_RESPONSE_NORMAL:
 		case AP_RESPONSE_RESET_IN_PROGRESS:
 			if (!status.irq_enabled)
-				return;
+				return true;
 			fallthrough;
 		case AP_RESPONSE_BUSY:
 			msleep(20);
@@ -257,12 +266,13 @@ static void vfio_ap_wait_for_irqclear(int apqn)
 		default:
 			WARN_ONCE(1, "%s: tapq rc %02x: %04x\n", __func__,
 				  status.response_code, apqn);
-			return;
+			return true;
 		}
 	} while (--retry);
 
-	WARN_ONCE(1, "%s: tapq rc %02x: %04x could not clear IR bit\n",
-		  __func__, status.response_code, apqn);
+	WARN_ONCE(1, "%s: tapq rc %02x: timed out verifying interrupts disabled for %02x.%04x\n",
+		  __func__, status.response_code, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+	return false;
 }
 
 /**
@@ -317,8 +327,21 @@ static struct ap_queue_status vfio_ap_irq_disable(struct vfio_ap_queue *q)
 		switch (status.response_code) {
 		case AP_RESPONSE_OTHERWISE_CHANGED:
 		case AP_RESPONSE_NORMAL:
-			vfio_ap_wait_for_irqclear(q->apqn);
-			goto end_free;
+			/*
+			 * AQIC disable was accepted (NORMAL), or the queue was
+			 * already disabled or a prior async request is still
+			 * completing (OTHERWISE_CHANGED).  In both cases, we must
+			 * wait until interrupt processing has been disabled
+			 * before proceeding.
+			 *
+			 * If it could not be determined whether interrupts
+			 * have been disabled, do not free the AQIC resources: the
+			 * hardware may still write to the NIB, so leave it pinned
+			 * to avoid a use-after-free. The resources will be leaked.
+			 */
+			if (vfio_ap_wait_for_irqclear(q->apqn))
+				goto end_free;
+			goto end_fail;
 		case AP_RESPONSE_RESET_IN_PROGRESS:
 		case AP_RESPONSE_BUSY:
 			msleep(20);
@@ -326,18 +349,46 @@ static struct ap_queue_status vfio_ap_irq_disable(struct vfio_ap_queue *q)
 		case AP_RESPONSE_Q_NOT_AVAIL:
 		case AP_RESPONSE_DECONFIGURED:
 		case AP_RESPONSE_CHECKSTOPPED:
+			/* AP not operational; no further interrupts possible */
+			WARN_ONCE(1, "%s: ap_aqic status %d\n", __func__,
+				  status.response_code);
+			goto end_free;
 		case AP_RESPONSE_INVALID_ADDRESS:
 		default:
-			/* All cases in default means AP not operational */
+			/*
+			 * The AQIC disable was rejected; IRQ is still enabled
+			 * and the hardware still holds the NIB address. Do not
+			 * free resources.
+			 */
 			WARN_ONCE(1, "%s: ap_aqic status %d\n", __func__,
 				  status.response_code);
-			goto end_free;
+			goto end_fail;
 		}
 	} while (retries--);
 
 	WARN_ONCE(1, "%s: ap_aqic status %d\n", __func__,
 		  status.response_code);
+
+end_fail:
+	/*
+	 * We are here either because of a failure to verify that
+	 * interrupts have been disabled, or because the AQIC instruction
+	 * failed to disable them. The AQIC resources - the pinned NIB page
+	 * and the registered guest ISC - cannot be freed here. The hardware
+	 * may still write to the NIB; freeing the pinned page would result
+	 * in a use-after-free kernel crash. The resources will therefore be
+	 * leaked. This is preferable to a use-after-free.
+	 */
+	return status;
+
 end_free:
+	/*
+	 * This label is reached because the queue was successfully disabled,
+	 * or because the queue is not operational, in which case interrupts
+	 * can not be processed, so free the AQIC resources - the pinned NIB
+	 * page and the registered guest ISC - used to enable interrupts
+	 * so they will not be leaked.
+	 */
 	vfio_ap_free_aqic_resources(q);
 	return status;
 }
@@ -495,7 +546,12 @@ static struct ap_queue_status vfio_ap_irq_enable(struct vfio_ap_queue *q,
 		q->saved_isc = isc;
 		break;
 	case AP_RESPONSE_OTHERWISE_CHANGED:
-		/* We could not modify IRQ settings: clear new configuration */
+		/*
+		 * IRQ control is already set as requested or a prior async
+		 * request has not yet completed; in either case, this response
+		 * comes with CC=3 indicating the new NIB and ISC were not accepted by
+		 * the hardware, so clean them up.
+		 */
 		ret = kvm_s390_gisc_unregister(kvm, isc);
 		if (ret)
 			VFIO_AP_DBF_WARN("%s: kvm_s390_gisc_unregister: rc=%d isc=%d, apqn=%#04x\n",
@@ -503,9 +559,12 @@ static struct ap_queue_status vfio_ap_irq_enable(struct vfio_ap_queue *q,
 		vfio_unpin_pages(&q->matrix_mdev->vdev, nib, 1);
 		break;
 	default:
-		pr_warn("%s: apqn %04x: response: %02x\n", __func__, q->apqn,
-			status.response_code);
-		vfio_ap_irq_disable(q);
+		/* We could not modify IRQ settings: clear new configuration */
+		ret = kvm_s390_gisc_unregister(kvm, isc);
+		if (ret)
+			VFIO_AP_DBF_WARN("%s: kvm_s390_gisc_unregister: rc=%d isc=%d, apqn=%#04x\n",
+					 __func__, ret, isc, q->apqn);
+		vfio_unpin_pages(&q->matrix_mdev->vdev, nib, 1);
 		break;
 	}
 
@@ -635,7 +694,6 @@ static int handle_pqap(struct kvm_vcpu *vcpu)
 	}
 
 	status = vcpu->run->s.regs.gprs[1];
-
 	/* If IR bit(16) is set we enable the interrupt */
 	if ((status >> (63 - 16)) & 0x01)
 		qstatus = vfio_ap_irq_enable(q, status & 0x07, vcpu);
@@ -1410,7 +1468,7 @@ static void vfio_ap_mdev_hot_unplug_domain(struct ap_matrix_mdev *matrix_mdev,
 {
 	DECLARE_BITMAP(apqis, AP_DOMAINS);
 
-	bitmap_zero(apqis, AP_DEVICES);
+	bitmap_zero(apqis, AP_DOMAINS);
 	set_bit_inv(apqi, apqis);
 	vfio_ap_mdev_hot_unplug_domains(matrix_mdev, apqis);
 }
@@ -1959,8 +2017,32 @@ static void apq_reset_check(struct work_struct *reset_work)
 		elapsed += AP_RESET_INTERVAL;
 		status = ap_tapq(q->apqn, NULL);
 		ret = apq_status_check(q->apqn, &status);
-		if (ret == -EIO)
+		if (ret == -EIO) {
+			memcpy(&q->reset_status, &status, sizeof(status));
+			return;
+		}
+		if (elapsed >= AP_RESET_MAX_WAIT) {
+		/*
+		 * Timed out waiting for reset to complete.
+		 *
+		 * The AQIC resources associated with this queue - the pinned page
+		 * containing the NIB and the registered guest ISC - cannot be freed
+		 * here. The NIB is the active DMA target for AP interrupt delivery
+		 * until the reset completes; freeing the pinned page while the
+		 * hardware may still write to it would result in a use-after-free
+		 * kernel crash.
+		 *
+		 * If the reset eventually completes, interrupts will be terminated
+		 * and the pinned NIB page and ISC registration will be leaked. This
+		 * is preferable to either a use-after-free or waiting indefinitely:
+		 * the caller of apq_reset_check() holds mdevs_lock while flush_work()
+		 * blocks holds the matrix_dev->mdevs_lock mutex, which
+		 * serializes access to all mdev objects system-wide, so blocking
+		 * here would stall all other guests using AP queues.
+		 */
+			memcpy(&q->reset_status, &status, sizeof(status));
 			return;
+		}
 		if (ret == -EBUSY) {
 			pr_notice_ratelimited(WAIT_MSG, elapsed,
 					      AP_QID_CARD(q->apqn),
@@ -2061,12 +2143,28 @@ static int vfio_ap_mdev_open_device(struct vfio_device *vdev)
 	return vfio_ap_mdev_set_kvm(matrix_mdev, vdev->kvm);
 }
 
+static void vfio_ap_mdev_release_eventfds(struct ap_matrix_mdev *matrix_mdev)
+{
+	if (matrix_mdev->req_trigger) {
+		eventfd_ctx_put(matrix_mdev->req_trigger);
+		matrix_mdev->req_trigger = NULL;
+	}
+	if (matrix_mdev->cfg_chg_trigger) {
+		eventfd_ctx_put(matrix_mdev->cfg_chg_trigger);
+		matrix_mdev->cfg_chg_trigger = NULL;
+	}
+}
+
 static void vfio_ap_mdev_close_device(struct vfio_device *vdev)
 {
 	struct ap_matrix_mdev *matrix_mdev =
 		container_of(vdev, struct ap_matrix_mdev, vdev);
 
 	vfio_ap_mdev_unset_kvm(matrix_mdev);
+
+	mutex_lock(&matrix_dev->mdevs_lock);
+	vfio_ap_mdev_release_eventfds(matrix_mdev);
+	mutex_unlock(&matrix_dev->mdevs_lock);
 }
 
 static void vfio_ap_mdev_request(struct vfio_device *vdev, unsigned int count)
@@ -2697,11 +2795,11 @@ static void vfio_ap_mdev_on_cfg_remove(struct ap_config_info *cur_config_info,
 	do_remove |= bitmap_andnot(aqrem,
 				   (unsigned long *)prev_config_info->aqm,
 				   (unsigned long *)cur_config_info->aqm,
-				   AP_DEVICES);
+				   AP_DOMAINS);
 	do_remove |= bitmap_andnot(cdrem,
 				   (unsigned long *)prev_config_info->adm,
 				   (unsigned long *)cur_config_info->adm,
-				   AP_DEVICES);
+				   AP_DOMAINS);
 
 	if (do_remove)
 		vfio_ap_mdev_cfg_remove(aprem, aqrem, cdrem);
@@ -2812,7 +2910,7 @@ static void vfio_ap_mdev_cfg_add(unsigned long *apm_add, unsigned long *aqm_add,
 		bitmap_and(matrix_mdev->aqm_add,
 			   matrix_mdev->matrix.aqm, aqm_add, AP_DOMAINS);
 		bitmap_and(matrix_mdev->adm_add,
-			   matrix_mdev->matrix.adm, adm_add, AP_DEVICES);
+			   matrix_mdev->matrix.adm, adm_add, AP_DOMAINS);
 
 		mutex_unlock(&matrix_dev->mdevs_lock);
 	}

gemini-3.1-pro-preview

null

null

							input: 5755
							output: 36
							thoughts: 304
						

**Analyzing a VFIO AP Patch**

Okay, so this patch is touching `drivers/s390/crypto/vfio_ap_ops.c`. Interesting. It looks like they're reworking the interrupt handling in `vfio_ap_wait_for_irqclear`, making it return a boolean instead of void, which is a common pattern for indicating success or failure. They're also adding a timeout to `apq_reset_check`, always a good idea. The bitmap size fix, changing `AP_DEVICES` to `AP_DOMAINS`, seems like a straightforward bug fix. Finally, adding `vfio_ap_mdev_release_eventfds` and calling it in `vfio_ap_mdev_close_device` suggests some cleanup on device close, which likely means better resource management.

Now, this is s390-specific VFIO code for AP crypto devices. The real question is: is this even relevant to my typical work? Does standard QEMU even reach this code? I know s390x architecture can be emulated, but does that emulation include AP crypto devices? That's the crux of it. I need to figure out if this code is actually reachable in a standard setup.

Let's see… the driver is `drivers/s390/crypto/vfio_ap_ops.c`, and the relevant config option should be `CONFIG_VFIO_AP`. Ah, right, s390x is an architecture. I know Syzkaller does fuzz s390x if configured, but typically it runs on x86_64 or arm64. Wait, I do remember it supports s390x. So it's technically *fuzzable*, but does QEMU, in a typical setup, emulate the AP matrix device? That's the key question. I need to dig into the `drivers/s390/crypto/Kconfig` to see what options control AP device emulation. I need to determine if this code path is even active.

no matches

{
  "Expression": "config VFIO_AP",
  "PathPrefix": "drivers/s390/crypto/Kconfig"
}

{
  "error": "no matches"
}

gemini-3.1-pro-preview

null

null

							input: 6551
							output: 25
							thoughts: 29
						

Okay, here's my interpretation of those thoughts, tailored for an expert audience, presented in the first person:

**Kernel Configuration Hunt**

Alright, let me think. Where would the configuration options for this thing *actually* reside? My gut feeling is leading me towards the more specialized areas. It's probably *not* in a generic top-level crypto or VFIO section. I'm leaning towards, specifically, the s390 architecture's crypto implementation. So, my initial thought is, check `drivers/s390/crypto/Kconfig`. It's a prime candidate given the specific nature of what I'm looking for. Alternatively, it *could* be tucked away in a place related to VFIO, especially if there's some kind of hardware offloading or special VFIO-related acceleration going on. Therefore, I should also check `drivers/vfio/Kconfig`. I'll start with those two spots and see what I can turn up.

{
  "Expression": "config VFIO_AP",
  "PathPrefix": ""
}

{
  "Output": "arch/s390/Kconfig=823=config VFIO_CCW\n--\narch/s390/Kconfig-833-\narch/s390/Kconfig:834:config VFIO_AP\narch/s390/Kconfig-835-\tdef_tristate n\n"
}

gemini-3.1-pro-preview

null

null

							input: 6905
							output: 37
							thoughts: 22
						

Here's my thought process, summarized as if I were considering this myself:

**Investigating VFIO_AP Configuration on s390 Architecture**

Alright, let's dive into this. I need to understand how `VFIO_AP` is configured for the s390 architecture. My go-to location for this kind of information is, of course, the `arch/s390/Kconfig` file. That's where all the architecture-specific kernel configuration options related to drivers and features would be defined, so let's start there. I'll need to go find that file and examine its contents to see how `VFIO_AP` is handled. It's time to check what's going on in that Kconfig file.

{
  "File": "arch/s390/Kconfig",
  "FirstLine": 830,
  "LineCount": 20
}

{
  "Contents": " 830:\t\n 831:\t\t  To compile this driver as a module, choose M here: the\n 832:\t\t  module will be called vfio_ccw.\n 833:\t\n 834:\tconfig VFIO_AP\n 835:\t\tdef_tristate n\n 836:\t\tprompt \"VFIO support for AP devices\"\n 837:\t\tdepends on KVM\n 838:\t\tdepends on VFIO\n 839:\t\tdepends on AP\n 840:\t\tselect VFIO_MDEV\n 841:\t\thelp\n 842:\t\t  This driver grants access to Adjunct Processor (AP) devices\n 843:\t\t  via the VFIO mediated device interface.\n 844:\t\n 845:\t\t  To compile this driver as a module, choose M here: the module\n 846:\t\t  will be called vfio_ap.\n 847:\t\n 848:\tendmenu\n 849:\t\n"
}

gemini-3.1-pro-preview

null

null

							input: 7391
							output: 35
							thoughts: 278
						

**My Initial Assessment**

Okay, so this is tied to KVM, which immediately flags it as something related to s390x virtualization. We're talking about running KVM on s390x specifically, right? The big question here is, can we even fuzz this in a standard QEMU environment? If KVM is involved, that screams for hardware virtualization support on the s390x architecture. Syzkaller, in general, uses QEMU, either with TCG for emulation or KVM for near-native performance. If we're using KVM on s390x, we're going to *need* an s390x host.

Now, does syzkaller actually run on s390x hosts? Ah yes, it does! Syzkaller has s390x support. Good.

But here's a wrinkle... does this AP device, whatever it is, *require* physical hardware? "Adjunct Processor (AP) devices" – right, these are those IBM crypto cards. Does QEMU/KVM emulate these AP devices, or do we have to physically pass them through? The driver is `vfio_ap`, which points to VFIO mediated device interface access.

The VFIO mediated devices (mdev) typically need a parent device to exist, so that's the key. What is that parent device for `vfio_ap`? Oh, it's the AP matrix device. Right, that makes sense. So, we need to understand how the AP matrix device is registered to understand if emulation is possible. Let's see how that works...

{
  "Expression": "ap_matrix_mdev",
  "PathPrefix": "drivers/s390/crypto/"
}

{
  "Output": "drivers/s390/crypto/vfio_ap_ops.c-35-\ndrivers/s390/crypto/vfio_ap_ops.c:36:static int vfio_ap_mdev_reset_queues(struct ap_matrix_mdev *matrix_mdev);\ndrivers/s390/crypto/vfio_ap_ops.c-37-static int vfio_ap_mdev_reset_qlist(struct list_head *qlist);\n--\ndrivers/s390/crypto/vfio_ap_ops.c=82=static inline void release_update_locks_for_kvm(struct kvm *kvm)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-95- *\ndrivers/s390/crypto/vfio_ap_ops.c:96: * @matrix_mdev: a pointer to a struct ap_matrix_mdev object containing the AP\ndrivers/s390/crypto/vfio_ap_ops.c-97- *\t\t configuration data to use to update a KVM guest's APCB.\n--\ndrivers/s390/crypto/vfio_ap_ops.c-107- */\ndrivers/s390/crypto/vfio_ap_ops.c:108:static inline void get_update_locks_for_mdev(struct ap_matrix_mdev *matrix_mdev)\ndrivers/s390/crypto/vfio_ap_ops.c-109-{\n--\ndrivers/s390/crypto/vfio_ap_ops.c-119- *\ndrivers/s390/crypto/vfio_ap_ops.c:120: * @matrix_mdev: a pointer to a struct ap_matrix_mdev object containing the AP\ndrivers/s390/crypto/vfio_ap_ops.c-121- *\t\t configuration data to use to update a KVM guest's APCB.\n--\ndrivers/s390/crypto/vfio_ap_ops.c-130- */\ndrivers/s390/crypto/vfio_ap_ops.c:131:static inline void release_update_locks_for_mdev(struct ap_matrix_mdev *matrix_mdev)\ndrivers/s390/crypto/vfio_ap_ops.c-132-{\n--\ndrivers/s390/crypto/vfio_ap_ops.c-154- *\ndrivers/s390/crypto/vfio_ap_ops.c:155: * Return: the ap_matrix_mdev object to which @apqn is assigned or NULL if @apqn\ndrivers/s390/crypto/vfio_ap_ops.c:156: *\t   is not assigned to an ap_matrix_mdev.\ndrivers/s390/crypto/vfio_ap_ops.c-157- */\ndrivers/s390/crypto/vfio_ap_ops.c:158:static struct ap_matrix_mdev *get_update_locks_by_apqn(int apqn)\ndrivers/s390/crypto/vfio_ap_ops.c-159-{\ndrivers/s390/crypto/vfio_ap_ops.c:160:\tstruct ap_matrix_mdev *matrix_mdev;\ndrivers/s390/crypto/vfio_ap_ops.c-161-\n--\ndrivers/s390/crypto/vfio_ap_ops.c-193- *\ndrivers/s390/crypto/vfio_ap_ops.c:194: * Note: if @queue is not linked to an ap_matrix_mdev object, the KVM lock\ndrivers/s390/crypto/vfio_ap_ops.c-195- *\t  will not be taken.\n--\ndrivers/s390/crypto/vfio_ap_ops.c=214=static struct vfio_ap_queue *vfio_ap_mdev_get_queue(\ndrivers/s390/crypto/vfio_ap_ops.c:215:\t\t\t\t\tstruct ap_matrix_mdev *matrix_mdev,\ndrivers/s390/crypto/vfio_ap_ops.c-216-\t\t\t\t\tint apqn)\n--\ndrivers/s390/crypto/vfio_ap_ops.c=647=static int handle_pqap(struct kvm_vcpu *vcpu)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-654-\t\t\t       .response_code = AP_RESPONSE_Q_NOT_AVAIL, };\ndrivers/s390/crypto/vfio_ap_ops.c:655:\tstruct ap_matrix_mdev *matrix_mdev;\ndrivers/s390/crypto/vfio_ap_ops.c-656-\n--\ndrivers/s390/crypto/vfio_ap_ops.c-676-\tmatrix_mdev = container_of(vcpu-\u003ekvm-\u003earch.crypto.pqap_hook,\ndrivers/s390/crypto/vfio_ap_ops.c:677:\t\t\t\t   struct ap_matrix_mdev, pqap_hook);\ndrivers/s390/crypto/vfio_ap_ops.c-678-\n--\ndrivers/s390/crypto/vfio_ap_ops.c=710=static void vfio_ap_matrix_init(struct ap_config_info *info,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-717-\ndrivers/s390/crypto/vfio_ap_ops.c:718:static void signal_guest_ap_cfg_changed(struct ap_matrix_mdev *matrix_mdev)\ndrivers/s390/crypto/vfio_ap_ops.c-719-{\n--\ndrivers/s390/crypto/vfio_ap_ops.c-723-\ndrivers/s390/crypto/vfio_ap_ops.c:724:static void vfio_ap_mdev_update_guest_apcb(struct ap_matrix_mdev *matrix_mdev)\ndrivers/s390/crypto/vfio_ap_ops.c-725-{\n--\ndrivers/s390/crypto/vfio_ap_ops.c-735-\ndrivers/s390/crypto/vfio_ap_ops.c:736:static bool vfio_ap_mdev_filter_cdoms(struct ap_matrix_mdev *matrix_mdev)\ndrivers/s390/crypto/vfio_ap_ops.c-737-{\n--\ndrivers/s390/crypto/vfio_ap_ops.c=748=static bool _queue_passable(struct vfio_ap_queue *q)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-784- */\ndrivers/s390/crypto/vfio_ap_ops.c:785:static bool vfio_ap_mdev_filter_matrix(struct ap_matrix_mdev *matrix_mdev,\ndrivers/s390/crypto/vfio_ap_ops.c-786-\t\t\t\t       unsigned long *apm_filtered)\n--\ndrivers/s390/crypto/vfio_ap_ops.c=841=static int vfio_ap_mdev_init_dev(struct vfio_device *vdev)\ndrivers/s390/crypto/vfio_ap_ops.c-842-{\ndrivers/s390/crypto/vfio_ap_ops.c:843:\tstruct ap_matrix_mdev *matrix_mdev =\ndrivers/s390/crypto/vfio_ap_ops.c:844:\t\tcontainer_of(vdev, struct ap_matrix_mdev, vdev);\ndrivers/s390/crypto/vfio_ap_ops.c-845-\n--\ndrivers/s390/crypto/vfio_ap_ops.c=855=static int vfio_ap_mdev_probe(struct mdev_device *mdev)\ndrivers/s390/crypto/vfio_ap_ops.c-856-{\ndrivers/s390/crypto/vfio_ap_ops.c:857:\tstruct ap_matrix_mdev *matrix_mdev;\ndrivers/s390/crypto/vfio_ap_ops.c-858-\tint ret;\ndrivers/s390/crypto/vfio_ap_ops.c-859-\ndrivers/s390/crypto/vfio_ap_ops.c:860:\tmatrix_mdev = vfio_alloc_device(ap_matrix_mdev, vdev, \u0026mdev-\u003edev,\ndrivers/s390/crypto/vfio_ap_ops.c-861-\t\t\t\t\t\u0026vfio_ap_matrix_dev_ops);\n--\ndrivers/s390/crypto/vfio_ap_ops.c-885-\ndrivers/s390/crypto/vfio_ap_ops.c:886:static void vfio_ap_mdev_link_queue(struct ap_matrix_mdev *matrix_mdev,\ndrivers/s390/crypto/vfio_ap_ops.c-887-\t\t\t\t    struct vfio_ap_queue *q)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-895-\ndrivers/s390/crypto/vfio_ap_ops.c:896:static void vfio_ap_mdev_link_apqn(struct ap_matrix_mdev *matrix_mdev, int apqn)\ndrivers/s390/crypto/vfio_ap_ops.c-897-{\n--\ndrivers/s390/crypto/vfio_ap_ops.c=909=static void vfio_ap_unlink_mdev_fr_queue(struct vfio_ap_queue *q)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-913-\ndrivers/s390/crypto/vfio_ap_ops.c:914:static void vfio_ap_mdev_unlink_fr_queues(struct ap_matrix_mdev *matrix_mdev)\ndrivers/s390/crypto/vfio_ap_ops.c-915-{\n--\ndrivers/s390/crypto/vfio_ap_ops.c=930=static void vfio_ap_mdev_remove(struct mdev_device *mdev)\ndrivers/s390/crypto/vfio_ap_ops.c-931-{\ndrivers/s390/crypto/vfio_ap_ops.c:932:\tstruct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(\u0026mdev-\u003edev);\ndrivers/s390/crypto/vfio_ap_ops.c-933-\n--\ndrivers/s390/crypto/vfio_ap_ops.c-949-\ndrivers/s390/crypto/vfio_ap_ops.c:950:static void vfio_ap_mdev_log_sharing_err(struct ap_matrix_mdev *assignee,\ndrivers/s390/crypto/vfio_ap_ops.c:951:\t\t\t\t\t struct ap_matrix_mdev *assigned_to,\ndrivers/s390/crypto/vfio_ap_ops.c-952-\t\t\t\t\t unsigned long *apm, unsigned long *aqm)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-963-\ndrivers/s390/crypto/vfio_ap_ops.c:964:static void vfio_ap_mdev_log_in_use_err(struct ap_matrix_mdev *assignee,\ndrivers/s390/crypto/vfio_ap_ops.c-965-\t\t\t\t\tunsigned long *apm, unsigned long *aqm)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-991- */\ndrivers/s390/crypto/vfio_ap_ops.c:992:static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *assignee,\ndrivers/s390/crypto/vfio_ap_ops.c-993-\t\t\t\t\t  unsigned long *mdev_apm,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-995-{\ndrivers/s390/crypto/vfio_ap_ops.c:996:\tstruct ap_matrix_mdev *assigned_to;\ndrivers/s390/crypto/vfio_ap_ops.c-997-\tDECLARE_BITMAP(apm, AP_DEVICES);\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1046- */\ndrivers/s390/crypto/vfio_ap_ops.c:1047:static int vfio_ap_mdev_validate_masks(struct ap_matrix_mdev *matrix_mdev)\ndrivers/s390/crypto/vfio_ap_ops.c-1048-{\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1057-\ndrivers/s390/crypto/vfio_ap_ops.c:1058:static void vfio_ap_mdev_link_adapter(struct ap_matrix_mdev *matrix_mdev,\ndrivers/s390/crypto/vfio_ap_ops.c-1059-\t\t\t\t      unsigned long apid)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1067-\ndrivers/s390/crypto/vfio_ap_ops.c:1068:static void collect_queues_to_reset(struct ap_matrix_mdev *matrix_mdev,\ndrivers/s390/crypto/vfio_ap_ops.c-1069-\t\t\t\t    unsigned long apid,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1081-\ndrivers/s390/crypto/vfio_ap_ops.c:1082:static void reset_queues_for_apid(struct ap_matrix_mdev *matrix_mdev,\ndrivers/s390/crypto/vfio_ap_ops.c-1083-\t\t\t\t  unsigned long apid)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1091-\ndrivers/s390/crypto/vfio_ap_ops.c:1092:static int reset_queues_for_apids(struct ap_matrix_mdev *matrix_mdev,\ndrivers/s390/crypto/vfio_ap_ops.c-1093-\t\t\t\t  unsigned long *apm_reset)\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1143=static ssize_t assign_adapter_store(struct device *dev,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1149-\tDECLARE_BITMAP(apm_filtered, AP_DEVICES);\ndrivers/s390/crypto/vfio_ap_ops.c:1150:\tstruct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);\ndrivers/s390/crypto/vfio_ap_ops.c-1151-\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1193=static struct vfio_ap_queue\ndrivers/s390/crypto/vfio_ap_ops.c:1194:*vfio_ap_unlink_apqn_fr_mdev(struct ap_matrix_mdev *matrix_mdev,\ndrivers/s390/crypto/vfio_ap_ops.c-1195-\t\t\t     unsigned long apid, unsigned long apqi)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1215- */\ndrivers/s390/crypto/vfio_ap_ops.c:1216:static void vfio_ap_mdev_unlink_adapter(struct ap_matrix_mdev *matrix_mdev,\ndrivers/s390/crypto/vfio_ap_ops.c-1217-\t\t\t\t\tunsigned long apid,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1233-\ndrivers/s390/crypto/vfio_ap_ops.c:1234:static void vfio_ap_mdev_hot_unplug_adapters(struct ap_matrix_mdev *matrix_mdev,\ndrivers/s390/crypto/vfio_ap_ops.c-1235-\t\t\t\t\t     unsigned long *apids)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1264-\ndrivers/s390/crypto/vfio_ap_ops.c:1265:static void vfio_ap_mdev_hot_unplug_adapter(struct ap_matrix_mdev *matrix_mdev,\ndrivers/s390/crypto/vfio_ap_ops.c-1266-\t\t\t\t\t    unsigned long apid)\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1290=static ssize_t unassign_adapter_store(struct device *dev,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1295-\tunsigned long apid;\ndrivers/s390/crypto/vfio_ap_ops.c:1296:\tstruct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);\ndrivers/s390/crypto/vfio_ap_ops.c-1297-\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1321=static DEVICE_ATTR_WO(unassign_adapter);\ndrivers/s390/crypto/vfio_ap_ops.c-1322-\ndrivers/s390/crypto/vfio_ap_ops.c:1323:static void vfio_ap_mdev_link_domain(struct ap_matrix_mdev *matrix_mdev,\ndrivers/s390/crypto/vfio_ap_ops.c-1324-\t\t\t\t     unsigned long apqi)\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1367=static ssize_t assign_domain_store(struct device *dev,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1373-\tDECLARE_BITMAP(apm_filtered, AP_DEVICES);\ndrivers/s390/crypto/vfio_ap_ops.c:1374:\tstruct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);\ndrivers/s390/crypto/vfio_ap_ops.c-1375-\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1415=static DEVICE_ATTR_WO(assign_domain);\ndrivers/s390/crypto/vfio_ap_ops.c-1416-\ndrivers/s390/crypto/vfio_ap_ops.c:1417:static void vfio_ap_mdev_unlink_domain(struct ap_matrix_mdev *matrix_mdev,\ndrivers/s390/crypto/vfio_ap_ops.c-1418-\t\t\t\t       unsigned long apqi,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1434-\ndrivers/s390/crypto/vfio_ap_ops.c:1435:static void vfio_ap_mdev_hot_unplug_domains(struct ap_matrix_mdev *matrix_mdev,\ndrivers/s390/crypto/vfio_ap_ops.c-1436-\t\t\t\t\t    unsigned long *apqis)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1465-\ndrivers/s390/crypto/vfio_ap_ops.c:1466:static void vfio_ap_mdev_hot_unplug_domain(struct ap_matrix_mdev *matrix_mdev,\ndrivers/s390/crypto/vfio_ap_ops.c-1467-\t\t\t\t\t   unsigned long apqi)\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1491=static ssize_t unassign_domain_store(struct device *dev,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1496-\tunsigned long apqi;\ndrivers/s390/crypto/vfio_ap_ops.c:1497:\tstruct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);\ndrivers/s390/crypto/vfio_ap_ops.c-1498-\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1539=static ssize_t assign_control_domain_store(struct device *dev,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1544-\tunsigned long id;\ndrivers/s390/crypto/vfio_ap_ops.c:1545:\tstruct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);\ndrivers/s390/crypto/vfio_ap_ops.c-1546-\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1593=static ssize_t unassign_control_domain_store(struct device *dev,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1598-\tunsigned long domid;\ndrivers/s390/crypto/vfio_ap_ops.c:1599:\tstruct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);\ndrivers/s390/crypto/vfio_ap_ops.c-1600-\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1631=static ssize_t control_domains_show(struct device *dev,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1635-\tunsigned long id;\ndrivers/s390/crypto/vfio_ap_ops.c:1636:\tstruct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);\ndrivers/s390/crypto/vfio_ap_ops.c-1637-\tunsigned long max_domid = matrix_mdev-\u003ematrix.adm_max;\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1678=static ssize_t matrix_show(struct device *dev, struct device_attribute *attr,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1681-\tssize_t nchars;\ndrivers/s390/crypto/vfio_ap_ops.c:1682:\tstruct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);\ndrivers/s390/crypto/vfio_ap_ops.c-1683-\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1692=static ssize_t guest_matrix_show(struct device *dev,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1695-\tssize_t nchars;\ndrivers/s390/crypto/vfio_ap_ops.c:1696:\tstruct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);\ndrivers/s390/crypto/vfio_ap_ops.c-1697-\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1712=static ssize_t ap_config_show(struct device *dev, struct device_attribute *attr,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1714-{\ndrivers/s390/crypto/vfio_ap_ops.c:1715:\tstruct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);\ndrivers/s390/crypto/vfio_ap_ops.c-1716-\tint idx = 0;\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1730=static int parse_bitmap(char **strbufptr, unsigned long *bitmap, int nbits)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1741-\ndrivers/s390/crypto/vfio_ap_ops.c:1742:static int ap_matrix_overflow_check(struct ap_matrix_mdev *matrix_mdev)\ndrivers/s390/crypto/vfio_ap_ops.c-1743-{\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1775=static ssize_t ap_config_store(struct device *dev, struct device_attribute *attr,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1777-{\ndrivers/s390/crypto/vfio_ap_ops.c:1778:\tstruct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);\ndrivers/s390/crypto/vfio_ap_ops.c-1779-\tstruct ap_matrix m_new, m_old, m_added, m_removed;\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1876=static const struct attribute_group *vfio_ap_mdev_attr_groups[] = {\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1890- */\ndrivers/s390/crypto/vfio_ap_ops.c:1891:static int vfio_ap_mdev_set_kvm(struct ap_matrix_mdev *matrix_mdev,\ndrivers/s390/crypto/vfio_ap_ops.c-1892-\t\t\t\tstruct kvm *kvm)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1910-\ndrivers/s390/crypto/vfio_ap_ops.c:1911:static void unmap_iova(struct ap_matrix_mdev *matrix_mdev, u64 iova, u64 length)\ndrivers/s390/crypto/vfio_ap_ops.c-1912-{\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1923=static void vfio_ap_mdev_dma_unmap(struct vfio_device *vdev, u64 iova,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1925-{\ndrivers/s390/crypto/vfio_ap_ops.c:1926:\tstruct ap_matrix_mdev *matrix_mdev =\ndrivers/s390/crypto/vfio_ap_ops.c:1927:\t\tcontainer_of(vdev, struct ap_matrix_mdev, vdev);\ndrivers/s390/crypto/vfio_ap_ops.c-1928-\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1941- */\ndrivers/s390/crypto/vfio_ap_ops.c:1942:static void vfio_ap_mdev_unset_kvm(struct ap_matrix_mdev *matrix_mdev)\ndrivers/s390/crypto/vfio_ap_ops.c-1943-{\n--\ndrivers/s390/crypto/vfio_ap_ops.c=2069=static void vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2098-\ndrivers/s390/crypto/vfio_ap_ops.c:2099:static int vfio_ap_mdev_reset_queues(struct ap_matrix_mdev *matrix_mdev)\ndrivers/s390/crypto/vfio_ap_ops.c-2100-{\n--\ndrivers/s390/crypto/vfio_ap_ops.c=2135=static int vfio_ap_mdev_open_device(struct vfio_device *vdev)\ndrivers/s390/crypto/vfio_ap_ops.c-2136-{\ndrivers/s390/crypto/vfio_ap_ops.c:2137:\tstruct ap_matrix_mdev *matrix_mdev =\ndrivers/s390/crypto/vfio_ap_ops.c:2138:\t\tcontainer_of(vdev, struct ap_matrix_mdev, vdev);\ndrivers/s390/crypto/vfio_ap_ops.c-2139-\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2145-\ndrivers/s390/crypto/vfio_ap_ops.c:2146:static void vfio_ap_mdev_release_eventfds(struct ap_matrix_mdev *matrix_mdev)\ndrivers/s390/crypto/vfio_ap_ops.c-2147-{\n--\ndrivers/s390/crypto/vfio_ap_ops.c=2158=static void vfio_ap_mdev_close_device(struct vfio_device *vdev)\ndrivers/s390/crypto/vfio_ap_ops.c-2159-{\ndrivers/s390/crypto/vfio_ap_ops.c:2160:\tstruct ap_matrix_mdev *matrix_mdev =\ndrivers/s390/crypto/vfio_ap_ops.c:2161:\t\tcontainer_of(vdev, struct ap_matrix_mdev, vdev);\ndrivers/s390/crypto/vfio_ap_ops.c-2162-\n--\ndrivers/s390/crypto/vfio_ap_ops.c=2170=static void vfio_ap_mdev_request(struct vfio_device *vdev, unsigned int count)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2172-\tstruct device *dev = vdev-\u003edev;\ndrivers/s390/crypto/vfio_ap_ops.c:2173:\tstruct ap_matrix_mdev *matrix_mdev;\ndrivers/s390/crypto/vfio_ap_ops.c-2174-\ndrivers/s390/crypto/vfio_ap_ops.c:2175:\tmatrix_mdev = container_of(vdev, struct ap_matrix_mdev, vdev);\ndrivers/s390/crypto/vfio_ap_ops.c-2176-\n--\ndrivers/s390/crypto/vfio_ap_ops.c=2248=static int vfio_ap_irq_set_init(struct vfio_irq_set *irq_set, unsigned long arg)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2269-\ndrivers/s390/crypto/vfio_ap_ops.c:2270:static int vfio_ap_set_request_irq(struct ap_matrix_mdev *matrix_mdev,\ndrivers/s390/crypto/vfio_ap_ops.c-2271-\t\t\t\t   unsigned long arg)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2303-\ndrivers/s390/crypto/vfio_ap_ops.c:2304:static int vfio_ap_set_cfg_change_irq(struct ap_matrix_mdev *matrix_mdev, unsigned long arg)\ndrivers/s390/crypto/vfio_ap_ops.c-2305-{\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2336-\ndrivers/s390/crypto/vfio_ap_ops.c:2337:static int vfio_ap_set_irqs(struct ap_matrix_mdev *matrix_mdev,\ndrivers/s390/crypto/vfio_ap_ops.c-2338-\t\t\t    unsigned long arg)\n--\ndrivers/s390/crypto/vfio_ap_ops.c=2362=static ssize_t vfio_ap_mdev_ioctl(struct vfio_device *vdev,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2364-{\ndrivers/s390/crypto/vfio_ap_ops.c:2365:\tstruct ap_matrix_mdev *matrix_mdev =\ndrivers/s390/crypto/vfio_ap_ops.c:2366:\t\tcontainer_of(vdev, struct ap_matrix_mdev, vdev);\ndrivers/s390/crypto/vfio_ap_ops.c-2367-\tint ret;\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2391-\ndrivers/s390/crypto/vfio_ap_ops.c:2392:static struct ap_matrix_mdev *vfio_ap_mdev_for_queue(struct vfio_ap_queue *q)\ndrivers/s390/crypto/vfio_ap_ops.c-2393-{\ndrivers/s390/crypto/vfio_ap_ops.c:2394:\tstruct ap_matrix_mdev *matrix_mdev;\ndrivers/s390/crypto/vfio_ap_ops.c-2395-\tunsigned long apid = AP_QID_CARD(q-\u003eapqn);\n--\ndrivers/s390/crypto/vfio_ap_ops.c=2409=static ssize_t status_show(struct device *dev,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2415-\tunsigned long apid, apqi;\ndrivers/s390/crypto/vfio_ap_ops.c:2416:\tstruct ap_matrix_mdev *matrix_mdev;\ndrivers/s390/crypto/vfio_ap_ops.c-2417-\tstruct ap_device *apdev = to_ap_dev(dev);\n--\ndrivers/s390/crypto/vfio_ap_ops.c=2536=int vfio_ap_mdev_probe_queue(struct ap_device *apdev)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2540-\tDECLARE_BITMAP(apm_filtered, AP_DEVICES);\ndrivers/s390/crypto/vfio_ap_ops.c:2541:\tstruct ap_matrix_mdev *matrix_mdev;\ndrivers/s390/crypto/vfio_ap_ops.c-2542-\n--\ndrivers/s390/crypto/vfio_ap_ops.c=2597=void vfio_ap_mdev_remove_queue(struct ap_device *apdev)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2600-\tstruct vfio_ap_queue *q;\ndrivers/s390/crypto/vfio_ap_ops.c:2601:\tstruct ap_matrix_mdev *matrix_mdev;\ndrivers/s390/crypto/vfio_ap_ops.c-2602-\n--\ndrivers/s390/crypto/vfio_ap_ops.c=2660=int vfio_ap_mdev_resource_in_use(unsigned long *apm, unsigned long *aqm)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2677- *\ndrivers/s390/crypto/vfio_ap_ops.c:2678: * @matrix_mdev: an ap_matrix_mdev object attached to a KVM guest.\ndrivers/s390/crypto/vfio_ap_ops.c-2679- * @aprem: the adapters that have been removed from the host's AP configuration\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2683- */\ndrivers/s390/crypto/vfio_ap_ops.c:2684:static void vfio_ap_mdev_hot_unplug_cfg(struct ap_matrix_mdev *matrix_mdev,\ndrivers/s390/crypto/vfio_ap_ops.c-2685-\t\t\t\t\tunsigned long *aprem,\n--\ndrivers/s390/crypto/vfio_ap_ops.c=2729=static void vfio_ap_mdev_cfg_remove(unsigned long *ap_remove,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2732-{\ndrivers/s390/crypto/vfio_ap_ops.c:2733:\tstruct ap_matrix_mdev *matrix_mdev;\ndrivers/s390/crypto/vfio_ap_ops.c-2734-\tDECLARE_BITMAP(aprem, AP_DEVICES);\n--\ndrivers/s390/crypto/vfio_ap_ops.c=2885=static void vfio_ap_mdev_cfg_add(unsigned long *apm_add, unsigned long *aqm_add,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2887-{\ndrivers/s390/crypto/vfio_ap_ops.c:2888:\tstruct ap_matrix_mdev *matrix_mdev;\ndrivers/s390/crypto/vfio_ap_ops.c-2889-\n--\ndrivers/s390/crypto/vfio_ap_ops.c=2962=void vfio_ap_on_cfg_changed(struct ap_config_info *cur_cfg_info,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2980-\ndrivers/s390/crypto/vfio_ap_ops.c:2981:static void vfio_ap_mdev_hot_plug_cfg(struct ap_matrix_mdev *matrix_mdev)\ndrivers/s390/crypto/vfio_ap_ops.c-2982-{\n--\ndrivers/s390/crypto/vfio_ap_ops.c=3014=void vfio_ap_on_scan_complete(struct ap_config_info *new_config_info,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-3016-{\ndrivers/s390/crypto/vfio_ap_ops.c:3017:\tstruct ap_matrix_mdev *matrix_mdev;\ndrivers/s390/crypto/vfio_ap_ops.c-3018-\n--\ndrivers/s390/crypto/vfio_ap_private.h-37- *\t\tdriver, be it using @mdev_list or writing the state of a\ndrivers/s390/crypto/vfio_ap_private.h:38: *\t\tsingle ap_matrix_mdev device. It's quite coarse but we don't\ndrivers/s390/crypto/vfio_ap_private.h-39- *\t\texpect much contention.\n--\ndrivers/s390/crypto/vfio_ap_private.h-43- *\t\t will be taken when the AP devices are plugged into or unplugged\ndrivers/s390/crypto/vfio_ap_private.h:44: *\t\t from a guest, and when an ap_matrix_mdev device is added to or\ndrivers/s390/crypto/vfio_ap_private.h-45- *\t\t removed from @mdev_list or the list is iterated.\n--\ndrivers/s390/crypto/vfio_ap_private.h=47=struct ap_matrix_dev {\n--\ndrivers/s390/crypto/vfio_ap_private.h-50-\tstruct list_head mdev_list;\ndrivers/s390/crypto/vfio_ap_private.h:51:\tstruct mutex mdevs_lock; /* serializes access to each ap_matrix_mdev */\ndrivers/s390/crypto/vfio_ap_private.h-52-\tstruct ap_driver  *vfio_ap_drv;\n--\ndrivers/s390/crypto/vfio_ap_private.h=90=struct ap_queue_table {\n--\ndrivers/s390/crypto/vfio_ap_private.h-94-/**\ndrivers/s390/crypto/vfio_ap_private.h:95: * struct ap_matrix_mdev - Contains the data associated with a matrix mediated\ndrivers/s390/crypto/vfio_ap_private.h-96- *\t\t\t   device.\ndrivers/s390/crypto/vfio_ap_private.h-97- * @vdev:\tthe vfio device\ndrivers/s390/crypto/vfio_ap_private.h:98: * @node:\tallows the ap_matrix_mdev struct to be added to a list\ndrivers/s390/crypto/vfio_ap_private.h-99- * @matrix:\tthe adapters, usage domains and control domains assigned to the\n--\ndrivers/s390/crypto/vfio_ap_private.h-113- */\ndrivers/s390/crypto/vfio_ap_private.h:114:struct ap_matrix_mdev {\ndrivers/s390/crypto/vfio_ap_private.h-115-\tstruct vfio_device vdev;\n--\ndrivers/s390/crypto/vfio_ap_private.h=143=struct vfio_ap_queue {\ndrivers/s390/crypto/vfio_ap_private.h:144:\tstruct ap_matrix_mdev *matrix_mdev;\ndrivers/s390/crypto/vfio_ap_private.h-145-\tdma_addr_t saved_iova;\n"
}

gemini-3.1-pro-preview

null

null

							input: 18805
							output: 35
							thoughts: 87
						

**Investigating the Virtualization of the `ap_matrix_mdev`**

Okay, so the `ap_matrix_mdev` is, as I understand it, a mediated device. My immediate thought is, like other mediated devices, it's going to be brought into existence through sysfs. The real question is: can I instantiate an `ap_matrix_mdev` without having actual physical AP hardware present? That's the core of what I need to figure out.

To do this, I need to dig into the driver code. Let me check `drivers/s390/crypto/vfio_ap_drv.c`. I need to understand whether this driver is designed to register the mdev driver specifically on a physical AP device, or if it has the capability to handle a virtualized device as well. Knowing this will give me a clear answer on the possibility of a hardware-less instantiation. This driver logic is the key to determining the virtualizability.

{
  "Expression": "mdev_register_driver",
  "PathPrefix": "drivers/s390/crypto/"
}

{
  "Output": "drivers/s390/crypto/vfio_ap_ops.c=2507=int vfio_ap_mdev_register(void)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2510-\ndrivers/s390/crypto/vfio_ap_ops.c:2511:\tret = mdev_register_driver(\u0026vfio_ap_matrix_driver);\ndrivers/s390/crypto/vfio_ap_ops.c-2512-\tif (ret)\n"
}

gemini-3.1-pro-preview

null

null

							input: 19280
							output: 37
							thoughts: 18
						

Here's my attempt at summarizing the thought process, tailored for an expert audience:

**Tracing the Registration of `vfio_ap_matrix_driver`**

Okay, so I'm trying to figure out the initialization path of `vfio_ap_matrix_driver`. Let me start by tracing its registration. I need to quickly identify where this driver is actually bound to the system. I'm going to look for the typical module registration calls. Specifically, I'll be searching for the kernel functions associated with driver initialization, like `module_init` (or perhaps a more modern variant) or the specific registration function within the vfio subsystem, if it exists. My knowledge of the vfio framework should allow me to narrow this search down, and the relevant include files should make the driver registration details easier to find. I suspect this will involve digging through the core vfio code and associated device driver interfaces. Let's see... the journey begins.

{
  "Expression": "vfio_ap_matrix_driver",
  "PathPrefix": "drivers/s390/crypto/"
}

{
  "Output": "drivers/s390/crypto/vfio_ap_ops.c=2481=static const struct vfio_device_ops vfio_ap_matrix_dev_ops = {\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2493-\ndrivers/s390/crypto/vfio_ap_ops.c:2494:static struct mdev_driver vfio_ap_matrix_driver = {\ndrivers/s390/crypto/vfio_ap_ops.c-2495-\t.device_api = VFIO_DEVICE_API_AP_STRING,\n--\ndrivers/s390/crypto/vfio_ap_ops.c=2507=int vfio_ap_mdev_register(void)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2510-\ndrivers/s390/crypto/vfio_ap_ops.c:2511:\tret = mdev_register_driver(\u0026vfio_ap_matrix_driver);\ndrivers/s390/crypto/vfio_ap_ops.c-2512-\tif (ret)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2518-\tret = mdev_register_parent(\u0026matrix_dev-\u003eparent, \u0026matrix_dev-\u003edevice,\ndrivers/s390/crypto/vfio_ap_ops.c:2519:\t\t\t\t   \u0026vfio_ap_matrix_driver,\ndrivers/s390/crypto/vfio_ap_ops.c-2520-\t\t\t\t   \u0026matrix_dev-\u003emdev_types, 1);\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2525-err_driver:\ndrivers/s390/crypto/vfio_ap_ops.c:2526:\tmdev_unregister_driver(\u0026vfio_ap_matrix_driver);\ndrivers/s390/crypto/vfio_ap_ops.c-2527-\treturn ret;\n--\ndrivers/s390/crypto/vfio_ap_ops.c=2530=void vfio_ap_mdev_unregister(void)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2532-\tmdev_unregister_parent(\u0026matrix_dev-\u003eparent);\ndrivers/s390/crypto/vfio_ap_ops.c:2533:\tmdev_unregister_driver(\u0026vfio_ap_matrix_driver);\ndrivers/s390/crypto/vfio_ap_ops.c-2534-}\n"
}

gemini-3.1-pro-preview

null

null

							input: 20202
							output: 33
							thoughts: 31
						

Here's my thought process, as if I were analyzing that code snippet:

**Debugging a Device Registration**

Okay, let me break this down. I see `mdev_register_parent` being called, and it's operating on `matrix_dev->device`. That's the crux of this function, at least the part I'm focused on. My brain immediately asks: where the heck does `matrix_dev` originate? I know `mdev_register_parent` is crucial for hierarchical device management, and it points towards an expected parent/child relationship. I need to trace back from that call to understand the context and how `matrix_dev` is initialized and populated. This will tell me what the expectation for the parent/child device setup is.

{
  "Expression": "matrix_dev =",
  "PathPrefix": "drivers/s390/crypto/"
}

{
  "Output": "drivers/s390/crypto/vfio_ap_drv.c=67=static void vfio_ap_matrix_dev_release(struct device *dev)\n--\ndrivers/s390/crypto/vfio_ap_drv.c-70-\ndrivers/s390/crypto/vfio_ap_drv.c:71:\tmatrix_dev = container_of(dev, struct ap_matrix_dev, device);\ndrivers/s390/crypto/vfio_ap_drv.c-72-\tkfree(matrix_dev);\n--\ndrivers/s390/crypto/vfio_ap_drv.c=86=static int vfio_ap_matrix_dev_create(void)\n--\ndrivers/s390/crypto/vfio_ap_drv.c-98-\ndrivers/s390/crypto/vfio_ap_drv.c:99:\tmatrix_dev = kzalloc_obj(*matrix_dev);\ndrivers/s390/crypto/vfio_ap_drv.c-100-\tif (!matrix_dev) {\n"
}

gemini-3.1-pro-preview

null

null

							input: 20706
							output: 44
							thoughts: 16
						

Okay, let's dive into this. Here's my take on those thoughts, as if they're my own:

**Analyzing `vfio_ap_matrix_dev_create`**

Alright, `vfio_ap_matrix_dev_create`. Let's break this down. My initial thought is, this likely involves the creation of a device within the context of the VFIO (Virtual Function I/O) framework, specifically tied to some kind of AP (probably Access Path or Attribute Partitioning) matrix. This suggests we're dealing with a device representation that's more than just a simple passthrough; it's likely manipulating access rights or partitioning capabilities in a fine-grained manner. We're looking at something beyond the standard "give the VM direct access to the whole device" paradigm.

My next step would be to consider: What are the specific parameters involved? The function signature is key. What data structures are being passed? Are we dealing with some sort of descriptor that defines the AP matrix itself (perhaps a list of access permissions, memory regions, or interrupt mappings)? Is it a flat matrix or something more complex with nested structures?

I'd want to understand how this function integrates with the overall VFIO device management lifecycle. Does it allocate resources? Register the device? Initialize it? And, critically, what are the implications for security and isolation? If we're manipulating access paths, we need to ensure that the guest VM cannot escape its bounds and tamper with resources it's not authorized to use.

I would need to consider the context: is this related to creating a virtual function? Or perhaps, the AP matrix is an abstraction on top of a single VF or physical device? And I'd need to consider the error handling. How does this handle failures? What types of error conditions are possible and how are they signaled back to the caller? Does it return a standard error code or something more specific to VFIO? What does it log to help debug?

Ultimately, this function seems critical for enabling advanced I/O virtualization capabilities within VFIO. Understanding its internals is going to be key to grasping the full scope of how this system works. I'm keen to examine the source code and the surrounding documentation.

{
  "File": "drivers/s390/crypto/vfio_ap_drv.c",
  "FirstLine": 80,
  "LineCount": 40
}

{
  "Contents": "  80:\t\t.name = \"vfio_ap\",\n  81:\t\t.bus = \u0026matrix_bus,\n  82:\t\t.suppress_bind_attrs = true,\n  83:\t\t.dev_groups = matrix_dev_groups,\n  84:\t};\n  85:\t\n  86:\tstatic int vfio_ap_matrix_dev_create(void)\n  87:\t{\n  88:\t\tint ret;\n  89:\t\tstruct device *root_device;\n  90:\t\n  91:\t\troot_device = root_device_register(VFIO_AP_ROOT_NAME);\n  92:\t\tif (IS_ERR(root_device))\n  93:\t\t\treturn PTR_ERR(root_device);\n  94:\t\n  95:\t\tret = bus_register(\u0026matrix_bus);\n  96:\t\tif (ret)\n  97:\t\t\tgoto bus_register_err;\n  98:\t\n  99:\t\tmatrix_dev = kzalloc_obj(*matrix_dev);\n 100:\t\tif (!matrix_dev) {\n 101:\t\t\tret = -ENOMEM;\n 102:\t\t\tgoto matrix_alloc_err;\n 103:\t\t}\n 104:\t\n 105:\t\t/* Fill in config info via PQAP(QCI), if available */\n 106:\t\tif (test_facility(12)) {\n 107:\t\t\tret = ap_qci(\u0026matrix_dev-\u003einfo);\n 108:\t\t\tif (ret)\n 109:\t\t\t\tgoto matrix_alloc_err;\n 110:\t\t}\n 111:\t\n 112:\t\tmutex_init(\u0026matrix_dev-\u003emdevs_lock);\n 113:\t\tINIT_LIST_HEAD(\u0026matrix_dev-\u003emdev_list);\n 114:\t\tmutex_init(\u0026matrix_dev-\u003eguests_lock);\n 115:\t\n 116:\t\tdev_set_name(\u0026matrix_dev-\u003edevice, \"%s\", VFIO_AP_DEV_NAME);\n 117:\t\tmatrix_dev-\u003edevice.parent = root_device;\n 118:\t\tmatrix_dev-\u003edevice.bus = \u0026matrix_bus;\n 119:\t\tmatrix_dev-\u003edevice.release = vfio_ap_matrix_dev_release;\n"
}

gemini-3.1-pro-preview

null

null

							input: 21823
							output: 45
							thoughts: 60
						

**My Initial Analysis of the Driver Initialization**

Okay, so I'm seeing this driver first register a root device and a bus, pretty standard stuff. Then it's creating this `matrix_dev` structure. That part is straightforward. Now, it's making a call to `ap_qci(&matrix_dev->info)` if facility 12 is available. That makes sense, but I need to quickly determine whether this whole driver is being initialized automatically, or if something else is triggering it. The call to the function based on a facility check leads me to the assumption that this is not initiated on its own. Now, I need to check `vfio_ap_init`. That should give me the answer. Let's see what's happening there to confirm my thinking.

{
  "File": "drivers/s390/crypto/vfio_ap_drv.c",
  "FirstLine": 180,
  "LineCount": 40
}

{
  "Contents": " 180:\t\tif (ret)\n 181:\t\t\treturn ret;\n 182:\t\n 183:\t\tret = ap_driver_register(\u0026vfio_ap_drv, THIS_MODULE, VFIO_AP_DRV_NAME);\n 184:\t\tif (ret) {\n 185:\t\t\tvfio_ap_matrix_dev_destroy();\n 186:\t\t\treturn ret;\n 187:\t\t}\n 188:\t\n 189:\t\tret = vfio_ap_mdev_register();\n 190:\t\tif (ret) {\n 191:\t\t\tap_driver_unregister(\u0026vfio_ap_drv);\n 192:\t\t\tvfio_ap_matrix_dev_destroy();\n 193:\t\n 194:\t\t\treturn ret;\n 195:\t\t}\n 196:\t\n 197:\t\treturn 0;\n 198:\t}\n 199:\t\n 200:\tstatic void __exit vfio_ap_exit(void)\n 201:\t{\n 202:\t\tvfio_ap_mdev_unregister();\n 203:\t\tap_driver_unregister(\u0026vfio_ap_drv);\n 204:\t\tvfio_ap_matrix_dev_destroy();\n 205:\t\tdebug_unregister(vfio_ap_dbf_info);\n 206:\t}\n 207:\t\n 208:\tmodule_init(vfio_ap_init);\n 209:\tmodule_exit(vfio_ap_exit);\n"
}

gemini-3.1-pro-preview

null

null

							input: 22508
							output: 45
							thoughts: 141
						

**My Initial Thoughts on VFIO-AP Module Loading and mdev Creation**

Okay, let's break this down. From what I'm seeing, `vfio_ap_init` gets called as the VFIO-AP module loads. This seems to be the entry point. Inside that, it's calling `vfio_ap_matrix_dev_create`, then `ap_driver_register`, and finally `vfio_ap_mdev_register`. So, it's setting up the base foundation.

This implies that the *parent* device for mdev is created unconditionally, as soon as the module loads. The user-space tools can then start building their mdev instances on top of this pre-existing infrastructure. That's a sensible design – a solid foundation to manage the virtual AP devices.

I know Syzkaller has a setup for mdev devices, and I believe it creates them through the sysfs interface. But...a key question just hit me: Does it *require* actual hardware AP devices to be present on the system for this to work? Or can this be purely software-defined? I need to clarify that.

Let's dig into the `vfio_ap_mdev_probe` function. That's where the rubber meets the road, as it's triggered when an mdev is actually created. That should provide the answer. I'll focus there.

{
  "File": "drivers/s390/crypto/vfio_ap_ops.c",
  "FirstLine": 850,
  "LineCount": 40
}

{
  "Contents": " 850:\t\thash_init(matrix_mdev-\u003eqtable.queues);\n 851:\t\n 852:\t\treturn 0;\n 853:\t}\n 854:\t\n 855:\tstatic int vfio_ap_mdev_probe(struct mdev_device *mdev)\n 856:\t{\n 857:\t\tstruct ap_matrix_mdev *matrix_mdev;\n 858:\t\tint ret;\n 859:\t\n 860:\t\tmatrix_mdev = vfio_alloc_device(ap_matrix_mdev, vdev, \u0026mdev-\u003edev,\n 861:\t\t\t\t\t\t\u0026vfio_ap_matrix_dev_ops);\n 862:\t\tif (IS_ERR(matrix_mdev))\n 863:\t\t\treturn PTR_ERR(matrix_mdev);\n 864:\t\n 865:\t\tret = vfio_register_emulated_iommu_dev(\u0026matrix_mdev-\u003evdev);\n 866:\t\tif (ret)\n 867:\t\t\tgoto err_put_vdev;\n 868:\t\n 869:\t\t/*\n 870:\t\t * Take the matrix_dev-\u003eguests_lock mutex before adding the matrix_mdev\n 871:\t\t * to the mdev_list. All functions that traverse the list must also hold\n 872:\t\t * this lock to guard against additions to or removals from the list\n 873:\t\t * while it is being traversed.\n 874:\t\t */\n 875:\t\tmutex_lock(\u0026matrix_dev-\u003eguests_lock);\n 876:\t\tdev_set_drvdata(\u0026mdev-\u003edev, matrix_mdev);\n 877:\t\tlist_add(\u0026matrix_mdev-\u003enode, \u0026matrix_dev-\u003emdev_list);\n 878:\t\tmutex_unlock(\u0026matrix_dev-\u003eguests_lock);\n 879:\t\treturn 0;\n 880:\t\n 881:\terr_put_vdev:\n 882:\t\tvfio_put_device(\u0026matrix_mdev-\u003evdev);\n 883:\t\treturn ret;\n 884:\t}\n 885:\t\n 886:\tstatic void vfio_ap_mdev_link_queue(struct ap_matrix_mdev *matrix_mdev,\n 887:\t\t\t\t\t    struct vfio_ap_queue *q)\n 888:\t{\n 889:\t\tif (!q || vfio_ap_mdev_get_queue(matrix_mdev, q-\u003eapqn))\n"
}

gemini-3.1-pro-preview

null

null

							input: 23655
							output: 46
							thoughts: 71
						

Here's my summary, as though I'm thinking through this process:

**VFIO-AP Device Probing and Configuration**

Okay, so looking at this, `vfio_ap_mdev_probe` appears to be the function that handles the initial device allocation and addition to the device list. That makes sense; it's the "discovery" step. The driver is setting up the device, but not configuring it yet. It seems to be simply making it known to the system.

Then, the configuration itself happens through userspace interaction via sysfs entries, like `assign_adapter_store` and `assign_domain_store`. That's a pretty standard VFIO approach, giving userspace flexibility. I need to keep in mind that userspace is the one assigning resources and setting up the device, and the kernel is simply managing it. But... hang on a minute... does `assign_adapter_store` validate that the adapter ID actually corresponds to an existing, valid adapter? I really hope it does! Security and resource allocation are paramount. I need to double-check the code there, because a hole in that check could be exploited.

{
  "File": "drivers/s390/crypto/vfio_ap_ops.c",
  "FirstLine": 1140,
  "LineCount": 40
}

{
  "Contents": "1140:\t *\t   A lock required to validate the mdev's AP configuration could not\n1141:\t *\t   be obtained.\n1142:\t */\n1143:\tstatic ssize_t assign_adapter_store(struct device *dev,\n1144:\t\t\t\t\t    struct device_attribute *attr,\n1145:\t\t\t\t\t    const char *buf, size_t count)\n1146:\t{\n1147:\t\tint ret;\n1148:\t\tunsigned long apid;\n1149:\t\tDECLARE_BITMAP(apm_filtered, AP_DEVICES);\n1150:\t\tstruct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);\n1151:\t\n1152:\t\tmutex_lock(\u0026ap_attr_mutex);\n1153:\t\tget_update_locks_for_mdev(matrix_mdev);\n1154:\t\n1155:\t\tret = kstrtoul(buf, 0, \u0026apid);\n1156:\t\tif (ret)\n1157:\t\t\tgoto done;\n1158:\t\n1159:\t\tif (apid \u003e matrix_mdev-\u003ematrix.apm_max) {\n1160:\t\t\tret = -ENODEV;\n1161:\t\t\tgoto done;\n1162:\t\t}\n1163:\t\n1164:\t\tif (test_bit_inv(apid, matrix_mdev-\u003ematrix.apm)) {\n1165:\t\t\tret = count;\n1166:\t\t\tgoto done;\n1167:\t\t}\n1168:\t\n1169:\t\tset_bit_inv(apid, matrix_mdev-\u003ematrix.apm);\n1170:\t\n1171:\t\tret = vfio_ap_mdev_validate_masks(matrix_mdev);\n1172:\t\tif (ret) {\n1173:\t\t\tclear_bit_inv(apid, matrix_mdev-\u003ematrix.apm);\n1174:\t\t\tgoto done;\n1175:\t\t}\n1176:\t\n1177:\t\tvfio_ap_mdev_link_adapter(matrix_mdev, apid);\n1178:\t\n1179:\t\tif (vfio_ap_mdev_filter_matrix(matrix_mdev, apm_filtered)) {\n"
}

gemini-3.1-pro-preview

null

null

							input: 24624
							output: 32
							thoughts: 27
						

Okay, here's my interpretation of those thoughts, framed as if they're my own:

**Debugging an API Threshold**

Right, let's see. This code snippet is checking something like `apid` against `matrix_mdev->matrix.apm_max`. Seems straightforward enough, it's probably comparing an active process id to a defined maximum value for the matrix. My immediate thought is, "Okay, that's the comparison. But why?" I need to understand the logic behind this limit.

My brain jumps to: "Where the heck is `apm_max` *defined*?" I need to trace this back. Is it a compile-time constant? Is it read from a configuration file? Is it calculated dynamically based on system resources or user settings? Knowing the source of `apm_max` is key. That will give me context. What can affect `apm_max`? What can affect `apid`? Is this a hard limit, a soft warning, or something else entirely? Without that background, I can't even begin to troubleshoot the comparison logic itself. I need the origin of that variable. Let's see if I can find where it gets set first.

{
  "Expression": "apm_max",
  "PathPrefix": "drivers/s390/crypto/"
}

{
  "Output": "drivers/s390/crypto/vfio_ap_ops.c=710=static void vfio_ap_matrix_init(struct ap_config_info *info,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-712-{\ndrivers/s390/crypto/vfio_ap_ops.c:713:\tmatrix-\u003eapm_max = info-\u003eapxa ? info-\u003ena : 63;\ndrivers/s390/crypto/vfio_ap_ops.c-714-\tmatrix-\u003eaqm_max = info-\u003eapxa ? info-\u003end : 15;\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1143=static ssize_t assign_adapter_store(struct device *dev,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1158-\ndrivers/s390/crypto/vfio_ap_ops.c:1159:\tif (apid \u003e matrix_mdev-\u003ematrix.apm_max) {\ndrivers/s390/crypto/vfio_ap_ops.c-1160-\t\tret = -ENODEV;\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1290=static ssize_t unassign_adapter_store(struct device *dev,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1303-\ndrivers/s390/crypto/vfio_ap_ops.c:1304:\tif (apid \u003e matrix_mdev-\u003ematrix.apm_max) {\ndrivers/s390/crypto/vfio_ap_ops.c-1305-\t\tret = -ENODEV;\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1649=static ssize_t vfio_ap_mdev_matrix_show(struct ap_matrix *matrix, char *buf)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1654-\tunsigned long apqi1;\ndrivers/s390/crypto/vfio_ap_ops.c:1655:\tunsigned long napm_bits = matrix-\u003eapm_max + 1;\ndrivers/s390/crypto/vfio_ap_ops.c-1656-\tunsigned long naqm_bits = matrix-\u003eaqm_max + 1;\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1742=static int ap_matrix_overflow_check(struct ap_matrix_mdev *matrix_mdev)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1746-\tfor_each_set_bit_inv(bit, matrix_mdev-\u003ematrix.apm, AP_DEVICES) {\ndrivers/s390/crypto/vfio_ap_ops.c:1747:\t\tif (bit \u003e matrix_mdev-\u003ematrix.apm_max)\ndrivers/s390/crypto/vfio_ap_ops.c-1748-\t\t\treturn -ENODEV;\n--\ndrivers/s390/crypto/vfio_ap_private.h=59=extern struct ap_matrix_dev *matrix_dev;\n--\ndrivers/s390/crypto/vfio_ap_private.h-63- *\ndrivers/s390/crypto/vfio_ap_private.h:64: * @apm_max: max adapter number in @apm\ndrivers/s390/crypto/vfio_ap_private.h-65- * @apm: identifies the AP adapters in the matrix\n--\ndrivers/s390/crypto/vfio_ap_private.h=76=struct ap_matrix {\ndrivers/s390/crypto/vfio_ap_private.h:77:\tunsigned long apm_max;\ndrivers/s390/crypto/vfio_ap_private.h-78-\tDECLARE_BITMAP(apm, AP_DEVICES);\n"
}

gemini-3.1-pro-preview

null

null

							input: 25950
							output: 46
							thoughts: 37
						

Okay, here's my interpretation of those thoughts, summarized from my perspective as someone well-versed in this domain:

**My Line of Reasoning**

Alright, let's break this down. It seems I'm currently dealing with some kind of hardware abstraction. I see `apm_max` and immediately my brain jumps to thinking about Address Port Mapping (APM) and potentially maximum resources allocated. The value is either explicitly set to 63 or it's being assigned from `info->na`, which likely represents "no adapter" or "not applicable" depending on the context. If it's the latter, that's an important signal.

Then there's `vfio_ap_mdev_validate_masks`. Right, that's a key function in VFIO, the Virtual Function I/O framework. It's meant to ensure the device is actually available for assignment. This validation step is absolutely critical. I know from experience that blindly assuming a device is present and functional can lead to all sorts of nasty errors down the line, including crashes or security vulnerabilities. So, this check likely involves verifying the adapter's PCI configuration space, interrupts, MMIO regions, or potentially other hardware characteristics to ensure it's in a good state. The masks it validates would be related to which resources are allowed to be mapped. Seems like there's some device validation happening, that's important to keep the system stable and reliable.

{
  "File": "drivers/s390/crypto/vfio_ap_ops.c",
  "FirstLine": 1040,
  "LineCount": 40
}

{
  "Contents": "1040:\t * o the error returned from the ap_apqn_in_matrix_owned_by_def_drv() function,\n1041:\t *   most likely -EBUSY indicating the ap_attr_mutex lock is already held.\n1042:\t * o EADDRNOTAVAIL if an APQN assigned to @matrix_mdev is reserved for the\n1043:\t *\t\t   zcrypt default driver.\n1044:\t * o EADDRINUSE if an APQN assigned to @matrix_mdev is assigned to another mdev\n1045:\t * o A zero indicating validation succeeded.\n1046:\t */\n1047:\tstatic int vfio_ap_mdev_validate_masks(struct ap_matrix_mdev *matrix_mdev)\n1048:\t{\n1049:\t\tif (ap_apqn_in_matrix_owned_by_def_drv(matrix_mdev-\u003ematrix.apm,\n1050:\t\t\t\t\t\t       matrix_mdev-\u003ematrix.aqm))\n1051:\t\t\treturn -EADDRNOTAVAIL;\n1052:\t\n1053:\t\treturn vfio_ap_mdev_verify_no_sharing(matrix_mdev,\n1054:\t\t\t\t\t\t      matrix_mdev-\u003ematrix.apm,\n1055:\t\t\t\t\t\t      matrix_mdev-\u003ematrix.aqm);\n1056:\t}\n1057:\t\n1058:\tstatic void vfio_ap_mdev_link_adapter(struct ap_matrix_mdev *matrix_mdev,\n1059:\t\t\t\t\t      unsigned long apid)\n1060:\t{\n1061:\t\tunsigned long apqi;\n1062:\t\n1063:\t\tfor_each_set_bit_inv(apqi, matrix_mdev-\u003ematrix.aqm, AP_DOMAINS)\n1064:\t\t\tvfio_ap_mdev_link_apqn(matrix_mdev,\n1065:\t\t\t\t\t       AP_MKQID(apid, apqi));\n1066:\t}\n1067:\t\n1068:\tstatic void collect_queues_to_reset(struct ap_matrix_mdev *matrix_mdev,\n1069:\t\t\t\t\t    unsigned long apid,\n1070:\t\t\t\t\t    struct list_head *qlist)\n1071:\t{\n1072:\t\tstruct vfio_ap_queue *q;\n1073:\t\tunsigned long  apqi;\n1074:\t\n1075:\t\tfor_each_set_bit_inv(apqi, matrix_mdev-\u003eshadow_apcb.aqm, AP_DOMAINS) {\n1076:\t\t\tq = vfio_ap_mdev_get_queue(matrix_mdev, AP_MKQID(apid, apqi));\n1077:\t\t\tif (q)\n1078:\t\t\t\tlist_add_tail(\u0026q-\u003ereset_qnode, qlist);\n1079:\t\t}\n"
}

gemini-3.1-pro-preview

null

null

							input: 27093
							output: 45
							thoughts: 109
						

**My Analysis of the AP Device Validation Flow**

Okay, so I'm diving into this AP device validation code. My initial thought is to trace the execution path. The first check, `ap_apqn_in_matrix_owned_by_def_drv`, catches my attention. I'm immediately considering edge cases, specifically the scenario where there are *no* physical AP devices present. In that situation, I'm expecting `ap_apqn_in_matrix_owned_by_def_drv` could legitimately return `false`. That's an important condition to keep in mind, because it could cause the subsequent logic to be skipped.

Next, I see `vfio_ap_mdev_verify_no_sharing` is called. This is the stage that's intended to verify no other mdev is currently using the resource. So that check is important to enforce the expected behaviour.

Finally, `vfio_ap_mdev_link_adapter` calls `vfio_ap_mdev_link_apqn`. This sequence of calls is key to linking the adapter. I'll need to double check the details of that API call to be sure the function is correctly calling the appropriate lower level logic.

{
  "File": "drivers/s390/crypto/vfio_ap_ops.c",
  "FirstLine": 890,
  "LineCount": 40
}

{
  "Contents": " 890:\t\t\treturn;\n 891:\t\n 892:\t\tq-\u003ematrix_mdev = matrix_mdev;\n 893:\t\thash_add(matrix_mdev-\u003eqtable.queues, \u0026q-\u003emdev_qnode, q-\u003eapqn);\n 894:\t}\n 895:\t\n 896:\tstatic void vfio_ap_mdev_link_apqn(struct ap_matrix_mdev *matrix_mdev, int apqn)\n 897:\t{\n 898:\t\tstruct vfio_ap_queue *q;\n 899:\t\n 900:\t\tq = vfio_ap_find_queue(apqn);\n 901:\t\tvfio_ap_mdev_link_queue(matrix_mdev, q);\n 902:\t}\n 903:\t\n 904:\tstatic void vfio_ap_unlink_queue_fr_mdev(struct vfio_ap_queue *q)\n 905:\t{\n 906:\t\thash_del(\u0026q-\u003emdev_qnode);\n 907:\t}\n 908:\t\n 909:\tstatic void vfio_ap_unlink_mdev_fr_queue(struct vfio_ap_queue *q)\n 910:\t{\n 911:\t\tq-\u003ematrix_mdev = NULL;\n 912:\t}\n 913:\t\n 914:\tstatic void vfio_ap_mdev_unlink_fr_queues(struct ap_matrix_mdev *matrix_mdev)\n 915:\t{\n 916:\t\tstruct vfio_ap_queue *q;\n 917:\t\tunsigned long apid, apqi;\n 918:\t\n 919:\t\tfor_each_set_bit_inv(apid, matrix_mdev-\u003ematrix.apm, AP_DEVICES) {\n 920:\t\t\tfor_each_set_bit_inv(apqi, matrix_mdev-\u003ematrix.aqm,\n 921:\t\t\t\t\t     AP_DOMAINS) {\n 922:\t\t\t\tq = vfio_ap_mdev_get_queue(matrix_mdev,\n 923:\t\t\t\t\t\t\t   AP_MKQID(apid, apqi));\n 924:\t\t\t\tif (q)\n 925:\t\t\t\t\tq-\u003ematrix_mdev = NULL;\n 926:\t\t\t}\n 927:\t\t}\n 928:\t}\n 929:\t\n"
}

gemini-3.1-pro-preview

null

null

							input: 28155
							output: 37
							thoughts: 20
						

Here's my attempt at summarizing those thoughts, speaking as an expert in the field:

**Queue Discovery in VFIO**

Okay, so `vfio_ap_find_queue` is the function that's responsible for, well, *finding* the correct queue. That's straightforward enough. The immediate question that pops into my head, though, is: where are these queues *created* in the first place? `vfio_ap_find_queue` can't magically conjure them out of thin air. I need to trace back the initialization and setup of these queues. I need to understand the relationship between the VFIO driver, the specific device, and the user space application managing the device. Is it the driver's responsibility? Is it triggered by user space? Are the queues dynamically allocated based on device capabilities, or are they statically configured? This is crucial to grasp. I need to know the allocation strategy to understand the overall architecture.

{
  "Expression": "vfio_ap_find_queue",
  "PathPrefix": "drivers/s390/crypto/"
}

{
  "Output": "drivers/s390/crypto/vfio_ap_ops.c=37=static int vfio_ap_mdev_reset_qlist(struct list_head *qlist);\ndrivers/s390/crypto/vfio_ap_ops.c:38:static struct vfio_ap_queue *vfio_ap_find_queue(int apqn);\ndrivers/s390/crypto/vfio_ap_ops.c-39-static const struct vfio_device_ops vfio_ap_matrix_dev_ops;\n--\ndrivers/s390/crypto/vfio_ap_ops.c=896=static void vfio_ap_mdev_link_apqn(struct ap_matrix_mdev *matrix_mdev, int apqn)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-899-\ndrivers/s390/crypto/vfio_ap_ops.c:900:\tq = vfio_ap_find_queue(apqn);\ndrivers/s390/crypto/vfio_ap_ops.c-901-\tvfio_ap_mdev_link_queue(matrix_mdev, q);\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1942=static void vfio_ap_mdev_unset_kvm(struct ap_matrix_mdev *matrix_mdev)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1958-\ndrivers/s390/crypto/vfio_ap_ops.c:1959:static struct vfio_ap_queue *vfio_ap_find_queue(int apqn)\ndrivers/s390/crypto/vfio_ap_ops.c-1960-{\n"
}

gemini-3.1-pro-preview

null

null

							input: 28867
							output: 46
							thoughts: 14
						

Here's my attempt at summarizing the thought process, tailored for an expert audience and written in the first person:

**Analyzing `vfio_ap_find_queue`**

Okay, let's dive into `vfio_ap_find_queue`. My immediate thought is, given its name, this function is responsible for, at some level, locating the appropriate queue structure within a VFIO environment. It's likely involved in the asynchronous path, considering "AP" in the name. It could be triggered by an interrupt or a completion notification.

I'm thinking about the data structures involved. Specifically, I need to consider how VFIO represents its devices and their associated queues. Is this working with a global structure, per-device context, or something else? I need to quickly recall the VFIO core's architecture. There's probably a device object, then possibly a container, group, or a bus driver's internal representation. The queuing model could be based on MSI-X vectors, doorbell registers, or other mechanisms. It is likely the queues are represented somehow within the VFIO container, either per device, or abstracted.

My immediate questions are: What are the input parameters? What's the search criteria? Does it take a device object, a queue ID, or some other key? What does it return? A pointer to a `vfio_queue` structure, maybe? Or an error code if the queue isn't found? I expect error handling to be robust, considering the implications of misrouting I/O requests.

I wonder if it’s designed to handle multiple VMs sharing the same device, or if there's a unique queue identifier for a VM. If the latter, where does the association of the VM queue ID to the device queue exist? That’s where the context or container would be critical.

I'm also curious about its performance implications. Is this a lock-free operation, or are there spinlocks or mutexes involved? If so, what are the lock domains and potential contention points? Performance here is going to be key, especially in high-throughput workloads. A slow or blocked function here is going to be extremely impactful for performance. The code must be lean.

Finally, I'll pay close attention to the error handling. I hope to see good error codes and logging in place. It will be really important in debugging and tracking down I/O issues.

{
  "File": "drivers/s390/crypto/vfio_ap_ops.c",
  "FirstLine": 1950,
  "LineCount": 40
}

{
  "Contents": "1950:\t\t\tkvm_arch_crypto_clear_masks(kvm);\n1951:\t\t\tvfio_ap_mdev_reset_queues(matrix_mdev);\n1952:\t\t\tmatrix_mdev-\u003ekvm = NULL;\n1953:\t\n1954:\t\t\trelease_update_locks_for_kvm(kvm);\n1955:\t\t\tkvm_put_kvm(kvm);\n1956:\t\t}\n1957:\t}\n1958:\t\n1959:\tstatic struct vfio_ap_queue *vfio_ap_find_queue(int apqn)\n1960:\t{\n1961:\t\tstruct ap_queue *queue;\n1962:\t\tstruct vfio_ap_queue *q = NULL;\n1963:\t\n1964:\t\tqueue = ap_get_qdev(apqn);\n1965:\t\tif (!queue)\n1966:\t\t\treturn NULL;\n1967:\t\n1968:\t\tif (queue-\u003eap_dev.device.driver == \u0026matrix_dev-\u003evfio_ap_drv-\u003edriver)\n1969:\t\t\tq = dev_get_drvdata(\u0026queue-\u003eap_dev.device);\n1970:\t\n1971:\t\tput_device(\u0026queue-\u003eap_dev.device);\n1972:\t\n1973:\t\treturn q;\n1974:\t}\n1975:\t\n1976:\tstatic int apq_status_check(int apqn, struct ap_queue_status *status)\n1977:\t{\n1978:\t\tswitch (status-\u003eresponse_code) {\n1979:\t\tcase AP_RESPONSE_NORMAL:\n1980:\t\tcase AP_RESPONSE_DECONFIGURED:\n1981:\t\tcase AP_RESPONSE_CHECKSTOPPED:\n1982:\t\t\treturn 0;\n1983:\t\tcase AP_RESPONSE_RESET_IN_PROGRESS:\n1984:\t\tcase AP_RESPONSE_BUSY:\n1985:\t\t\treturn -EBUSY;\n1986:\t\tcase AP_RESPONSE_ASSOC_SECRET_NOT_UNIQUE:\n1987:\t\tcase AP_RESPONSE_ASSOC_FAILED:\n1988:\t\t\t/*\n1989:\t\t\t * These asynchronous response codes indicate a PQAP(AAPQ)\n"
}

gemini-3.1-pro-preview

null

null

							input: 30034
							output: 46
							thoughts: 237
						

**My Analysis of AP Device Queue Linking**

Okay, so I'm digging into this code and trying to understand how the AP device queues are linked, or *aren't* linked, as the case may be. The process starts with `ap_get_qdev(apqn)`. Clearly, if this returns something, it means the queue device *actually exists* on the system. That's the baseline.

Now, the interesting bit. If there are *no* physical AP devices present – a scenario I need to consider for certain configurations – `ap_get_qdev` returns `NULL`. That's where things get potentially tricky. If `q` is `NULL`, then `vfio_ap_mdev_link_queue` is called. But, and this is crucial, it just returns immediately if `q` is NULL.

So, what does this imply? An mdev *can* be created and configured, even if no AP queues are available! It just won't have any queues linked to it. The question then becomes: can we even reach the code that needs the queues if they don't exist?

I need to trace the paths and check the functions where I made modifications. These include, specifically, `vfio_ap_wait_for_irqclear`, `vfio_ap_irq_disable`, `vfio_ap_irq_enable`, `handle_pqap`, `apq_reset_check`, `vfio_ap_mdev_close_device`, `vfio_ap_mdev_on_cfg_remove`, and `vfio_ap_mdev_cfg_add`. Each of these functions is suspect in that it depends on the queues, and if the queues aren't linked, then I'm concerned that a code path may be taken which results in unexpected results.

Let's begin by taking a closer look at `vfio_ap_mdev_close_device`. That seems like a logical starting point to understand how we are cleaning up the resources.

{
  "File": "drivers/s390/crypto/vfio_ap_ops.c",
  "FirstLine": 2140,
  "LineCount": 40
}

{
  "Contents": "2140:\t\tif (!vdev-\u003ekvm)\n2141:\t\t\treturn -EINVAL;\n2142:\t\n2143:\t\treturn vfio_ap_mdev_set_kvm(matrix_mdev, vdev-\u003ekvm);\n2144:\t}\n2145:\t\n2146:\tstatic void vfio_ap_mdev_release_eventfds(struct ap_matrix_mdev *matrix_mdev)\n2147:\t{\n2148:\t\tif (matrix_mdev-\u003ereq_trigger) {\n2149:\t\t\teventfd_ctx_put(matrix_mdev-\u003ereq_trigger);\n2150:\t\t\tmatrix_mdev-\u003ereq_trigger = NULL;\n2151:\t\t}\n2152:\t\tif (matrix_mdev-\u003ecfg_chg_trigger) {\n2153:\t\t\teventfd_ctx_put(matrix_mdev-\u003ecfg_chg_trigger);\n2154:\t\t\tmatrix_mdev-\u003ecfg_chg_trigger = NULL;\n2155:\t\t}\n2156:\t}\n2157:\t\n2158:\tstatic void vfio_ap_mdev_close_device(struct vfio_device *vdev)\n2159:\t{\n2160:\t\tstruct ap_matrix_mdev *matrix_mdev =\n2161:\t\t\tcontainer_of(vdev, struct ap_matrix_mdev, vdev);\n2162:\t\n2163:\t\tvfio_ap_mdev_unset_kvm(matrix_mdev);\n2164:\t\n2165:\t\tmutex_lock(\u0026matrix_dev-\u003emdevs_lock);\n2166:\t\tvfio_ap_mdev_release_eventfds(matrix_mdev);\n2167:\t\tmutex_unlock(\u0026matrix_dev-\u003emdevs_lock);\n2168:\t}\n2169:\t\n2170:\tstatic void vfio_ap_mdev_request(struct vfio_device *vdev, unsigned int count)\n2171:\t{\n2172:\t\tstruct device *dev = vdev-\u003edev;\n2173:\t\tstruct ap_matrix_mdev *matrix_mdev;\n2174:\t\n2175:\t\tmatrix_mdev = container_of(vdev, struct ap_matrix_mdev, vdev);\n2176:\t\n2177:\t\tget_update_locks_for_mdev(matrix_mdev);\n2178:\t\n2179:\t\tif (matrix_mdev-\u003ekvm) {\n"
}

gemini-3.1-pro-preview

null

null

							input: 31424
							output: 39
							thoughts: 93
						

**My Reasoning on VFIO Device Closure**

Okay, so `vfio_ap_mdev_close_device` gets called when a VFIO device closes. That makes sense. I can see how that would work, even without any physical AP devices present. Userspace can open and close the mdev device directly, right? Wait a second... can userspace *actually* open the mdev device if there's no corresponding physical hardware? Yes, that's right, mdev devices are accessible through VFIO, regardless. Right, got it. Now, what about `apq_reset_check`? I need to remember that that's a work function.

{
  "Expression": "INIT_WORK.*apq_reset_check",
  "PathPrefix": "drivers/s390/crypto/"
}

{
  "Output": "drivers/s390/crypto/vfio_ap_ops.c=2536=int vfio_ap_mdev_probe_queue(struct ap_device *apdev)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2558-\tmemset(\u0026q-\u003ereset_status, 0, sizeof(q-\u003ereset_status));\ndrivers/s390/crypto/vfio_ap_ops.c:2559:\tINIT_WORK(\u0026q-\u003ereset_work, apq_reset_check);\ndrivers/s390/crypto/vfio_ap_ops.c-2560-\n"
}

gemini-3.1-pro-preview

null

null

							input: 31867
							output: 42
							thoughts: 72
						

**My Line of Inquiry: AP Queue Device Probing**

Okay, so `vfio_ap_mdev_probe_queue` is triggered, as the name suggests, when the driver is probing an AP queue device. Makes sense. But the important thing here is the prerequisite: a *physical* AP queue device has to be present for this function to even be called. Got it. No physical hardware, no probing, no problem. I'm visualizing the hardware topology in my head, making sure I understand the interaction. Now, this raises a question... what's the behavior, the relationship, with `vfio_ap_mdev_on_cfg_remove`? That's the next piece of this puzzle I need to explore. I need to understand how the driver handles the removal of a configuration. How does that interface with the device probing and presence?

{
  "Expression": "vfio_ap_mdev_on_cfg_remove",
  "PathPrefix": "drivers/s390/crypto/"
}

{
  "Output": "drivers/s390/crypto/vfio_ap_ops.c=2729=static void vfio_ap_mdev_cfg_remove(unsigned long *ap_remove,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2775-/**\ndrivers/s390/crypto/vfio_ap_ops.c:2776: * vfio_ap_mdev_on_cfg_remove - responds to the removal of adapters, domains and\ndrivers/s390/crypto/vfio_ap_ops.c-2777- *\t\t\t\tcontrol domains from the host AP configuration\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2782- */\ndrivers/s390/crypto/vfio_ap_ops.c:2783:static void vfio_ap_mdev_on_cfg_remove(struct ap_config_info *cur_config_info,\ndrivers/s390/crypto/vfio_ap_ops.c-2784-\t\t\t\t       struct ap_config_info *prev_config_info)\n--\ndrivers/s390/crypto/vfio_ap_ops.c=2962=void vfio_ap_on_cfg_changed(struct ap_config_info *cur_cfg_info,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2973-\ndrivers/s390/crypto/vfio_ap_ops.c:2974:\tvfio_ap_mdev_on_cfg_remove(cur_cfg_info, prev_cfg_info);\ndrivers/s390/crypto/vfio_ap_ops.c-2975-\tvfio_ap_mdev_on_cfg_add(cur_cfg_info, prev_cfg_info);\n"
}

gemini-3.1-pro-preview

null

null

							input: 32626
							output: 26
							thoughts: 290
						

**Analyzing AP Configuration Changes in VFIO-AP**

Okay, so `vfio_ap_on_cfg_changed` is triggered when the AP configuration shifts, which `ap_bus` notifies us about. A quick question arises: if no physical AP devices exist, can this configuration actually change? I should double-check the `ap_bus` implementation to understand its trigger conditions.

But hold on, there's a fix related to `vfio_ap_mdev_on_cfg_remove` in the patch. The code snippet shows a fix for bitmap sizes, specifically replacing `AP_DEVICES` with `AP_DOMAINS` in a couple of places. Hmm, they both are 256. This looks like a bug fix related to the size of the bitmaps used for tracking AP configuration. The fix seems logical, given both are defined to be the same. Still, I should confirm the values of both `AP_DEVICES` and `AP_DOMAINS` to be sure.

{
  "Expression": "#define AP_DEVICES",
  "PathPrefix": ""
}

{
  "Output": "drivers/s390/crypto/ap_bus.h-21-\ndrivers/s390/crypto/ap_bus.h:22:#define AP_DEVICES 256\t\t/* Number of AP devices. */\ndrivers/s390/crypto/ap_bus.h-23-#define AP_DOMAINS 256\t\t/* Number of AP domains. */\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1712=static ssize_t ap_config_show(struct device *dev, struct device_attribute *attr,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1725-/* Number of characters needed for a complete hex mask representing the bits in ..  */\ndrivers/s390/crypto/vfio_ap_ops.c:1726:#define AP_DEVICES_STRLEN\t(AP_DEVICES / 4 + 3)\ndrivers/s390/crypto/vfio_ap_ops.c-1727-#define AP_DOMAINS_STRLEN\t(AP_DOMAINS / 4 + 3)\n"
}

gemini-3.1-pro-preview

null

null

							input: 33446
							output: 46
							thoughts: 509
						

**Analyzing the Code Changes**

Okay, so the change from `AP_DEVICES` to `AP_DOMAINS` is purely a cosmetic or correctness update. Both are defined as 256, so the actual execution flow remains unchanged, and this doesn't fix a real bug. I see no impact there, but I need to make sure I am seeing the full picture.

Now, let's look at `vfio_ap_mdev_release_eventfds`. Aha, this is interesting. It looks like we have a potential resource leak issue here with `req_trigger` and `cfg_chg_trigger` eventfds. The code is structured to release these eventfds within `vfio_ap_mdev_close_device` when the VFIO device is closed. This is a good sign that they were aware of a leak, and are addressing it, because it is good practice to explicitly free acquired resources.

The key question is, *can* we hit this code path and thus, the leak, without having actual physical AP devices? We know these eventfds are set via the `VFIO_DEVICE_SET_IRQS` ioctl, so can we reach the code in question, `VFIO_DEVICE_SET_IRQS` and `vfio_ap_mdev_close_device`, through just the mdev device creation, and opening, then ioctl calls?

Yes, we absolutely can. Mdev can be created and opened, and ioctls can be called on it, so we can hit this code path. I will check `vfio_ap_mdev_ioctl` to confirm that `VFIO_DEVICE_SET_IRQS` is indeed supported there, which I fully expect it is. This is important to verify, as it determines whether or not the fix is fully functional.

{
  "File": "drivers/s390/crypto/vfio_ap_ops.c",
  "FirstLine": 2350,
  "LineCount": 40
}

{
  "Contents": "2350:\t\t\tcase VFIO_AP_REQ_IRQ_INDEX:\n2351:\t\t\t\treturn vfio_ap_set_request_irq(matrix_mdev, arg);\n2352:\t\t\tcase VFIO_AP_CFG_CHG_IRQ_INDEX:\n2353:\t\t\t\treturn vfio_ap_set_cfg_change_irq(matrix_mdev, arg);\n2354:\t\t\tdefault:\n2355:\t\t\t\treturn -EINVAL;\n2356:\t\t\t}\n2357:\t\tdefault:\n2358:\t\t\treturn -EINVAL;\n2359:\t\t}\n2360:\t}\n2361:\t\n2362:\tstatic ssize_t vfio_ap_mdev_ioctl(struct vfio_device *vdev,\n2363:\t\t\t\t\t    unsigned int cmd, unsigned long arg)\n2364:\t{\n2365:\t\tstruct ap_matrix_mdev *matrix_mdev =\n2366:\t\t\tcontainer_of(vdev, struct ap_matrix_mdev, vdev);\n2367:\t\tint ret;\n2368:\t\n2369:\t\tmutex_lock(\u0026matrix_dev-\u003emdevs_lock);\n2370:\t\tswitch (cmd) {\n2371:\t\tcase VFIO_DEVICE_GET_INFO:\n2372:\t\t\tret = vfio_ap_mdev_get_device_info(arg);\n2373:\t\t\tbreak;\n2374:\t\tcase VFIO_DEVICE_RESET:\n2375:\t\t\tret = vfio_ap_mdev_reset_queues(matrix_mdev);\n2376:\t\t\tbreak;\n2377:\t\tcase VFIO_DEVICE_GET_IRQ_INFO:\n2378:\t\t\tret = vfio_ap_get_irq_info(arg);\n2379:\t\t\tbreak;\n2380:\t\tcase VFIO_DEVICE_SET_IRQS:\n2381:\t\t\tret = vfio_ap_set_irqs(matrix_mdev, arg);\n2382:\t\t\tbreak;\n2383:\t\tdefault:\n2384:\t\t\tret = -EOPNOTSUPP;\n2385:\t\t\tbreak;\n2386:\t\t}\n2387:\t\tmutex_unlock(\u0026matrix_dev-\u003emdevs_lock);\n2388:\t\n2389:\t\treturn ret;\n"
}

gemini-3.1-pro-preview

null

null

							input: 35010
							output: 46
							thoughts: 77
						

Okay, here's my take on those thoughts, framed as my own mental processing:

**Checking VFIO Interrupt Handling**

Right, so `VFIO_DEVICE_SET_IRQS` is definitely supported, that's good. Now, let's see, `vfio_ap_set_irqs` – I remember that function. Ah yes, it calls `vfio_ap_set_request_irq` and `vfio_ap_set_cfg_change_irq`. Given the context, I think I should drill down on `vfio_ap_set_request_irq` specifically. Need to understand how the request interrupts are being managed.

{
  "File": "drivers/s390/crypto/vfio_ap_ops.c",
  "FirstLine": 2260,
  "LineCount": 40
}

{
  "Contents": "2260:\t\t\t\t\t\t\t \u0026data_size);\n2261:\t\tif (ret)\n2262:\t\t\treturn ret;\n2263:\t\n2264:\t\tif (!(irq_set-\u003eflags \u0026 VFIO_IRQ_SET_ACTION_TRIGGER))\n2265:\t\t\treturn -EINVAL;\n2266:\t\n2267:\t\treturn 0;\n2268:\t}\n2269:\t\n2270:\tstatic int vfio_ap_set_request_irq(struct ap_matrix_mdev *matrix_mdev,\n2271:\t\t\t\t\t   unsigned long arg)\n2272:\t{\n2273:\t\ts32 fd;\n2274:\t\tvoid __user *data;\n2275:\t\tunsigned long minsz;\n2276:\t\tstruct eventfd_ctx *req_trigger;\n2277:\t\n2278:\t\tminsz = offsetofend(struct vfio_irq_set, count);\n2279:\t\tdata = (void __user *)(arg + minsz);\n2280:\t\n2281:\t\tif (get_user(fd, (s32 __user *)data))\n2282:\t\t\treturn -EFAULT;\n2283:\t\n2284:\t\tif (fd == -1) {\n2285:\t\t\tif (matrix_mdev-\u003ereq_trigger)\n2286:\t\t\t\teventfd_ctx_put(matrix_mdev-\u003ereq_trigger);\n2287:\t\t\tmatrix_mdev-\u003ereq_trigger = NULL;\n2288:\t\t} else if (fd \u003e= 0) {\n2289:\t\t\treq_trigger = eventfd_ctx_fdget(fd);\n2290:\t\t\tif (IS_ERR(req_trigger))\n2291:\t\t\t\treturn PTR_ERR(req_trigger);\n2292:\t\n2293:\t\t\tif (matrix_mdev-\u003ereq_trigger)\n2294:\t\t\t\teventfd_ctx_put(matrix_mdev-\u003ereq_trigger);\n2295:\t\n2296:\t\t\tmatrix_mdev-\u003ereq_trigger = req_trigger;\n2297:\t\t} else {\n2298:\t\t\treturn -EINVAL;\n2299:\t\t}\n"
}

gemini-3.1-pro-preview

null

null

							input: 35863
							output: 45
							thoughts: 243
						

**My Assessment of the Code Change**

Okay, so this is pretty interesting. I've been looking at this code, and I'm seeing that this particular path is actually *fully* reachable in standard QEMU without needing any physical AP devices! That's a huge win in terms of testability. I can create the mdev device, open it, call `VFIO_DEVICE_SET_IRQS` to set up those `req_trigger` and `cfg_chg_trigger` signals, and then closing the device triggers the `vfio_ap_mdev_close_device` function. That function *finally* frees those `eventfd_ctx` elements by calling `vfio_ap_mdev_release_eventfds`, so it's a legitimate memory leak fix. Definitely a functional change, and definitely worth some serious fuzzing.

But hold on... What about the other changes I saw? The ones involving `vfio_ap_wait_for_irqclear`, `vfio_ap_irq_disable`, `vfio_ap_irq_enable`, `handle_pqap`, and `apq_reset_check`? Those all seem related to AP queue interrupts and resets, which usually implies some hardware dependency. The question is, are *those* functions reachable without real AP devices? Let's dig in and see. Ah, looks like `handle_pqap` is actually called from KVM when the guest executes the PQAP instruction. Right, so that's a key entry point. Let's start there.

{
  "File": "drivers/s390/crypto/vfio_ap_ops.c",
  "FirstLine": 640,
  "LineCount": 40
}

{
  "Contents": " 640:\t *   Check vfio_ap_setirq() and vfio_ap_clrirq() for other possible RC.\n 641:\t * We take the matrix_dev lock to ensure serialization on queues and\n 642:\t * mediated device access.\n 643:\t *\n 644:\t * Return: 0 if we could handle the request inside KVM.\n 645:\t * Otherwise, returns -EOPNOTSUPP to let QEMU handle the fault.\n 646:\t */\n 647:\tstatic int handle_pqap(struct kvm_vcpu *vcpu)\n 648:\t{\n 649:\t\tuint64_t status;\n 650:\t\tuint16_t apqn;\n 651:\t\tunsigned long uuid[6];\n 652:\t\tstruct vfio_ap_queue *q;\n 653:\t\tstruct ap_queue_status qstatus = {\n 654:\t\t\t\t       .response_code = AP_RESPONSE_Q_NOT_AVAIL, };\n 655:\t\tstruct ap_matrix_mdev *matrix_mdev;\n 656:\t\n 657:\t\tapqn = vcpu-\u003erun-\u003es.regs.gprs[0] \u0026 0xffff;\n 658:\t\n 659:\t\t/* If we do not use the AIV facility just go to userland */\n 660:\t\tif (!(vcpu-\u003earch.sie_block-\u003eeca \u0026 ECA_AIV)) {\n 661:\t\t\tVFIO_AP_DBF_WARN(\"%s: AIV facility not installed: apqn=0x%04x, eca=0x%04x\\n\",\n 662:\t\t\t\t\t __func__, apqn, vcpu-\u003earch.sie_block-\u003eeca);\n 663:\t\n 664:\t\t\treturn -EOPNOTSUPP;\n 665:\t\t}\n 666:\t\n 667:\t\tmutex_lock(\u0026matrix_dev-\u003emdevs_lock);\n 668:\t\n 669:\t\tif (!vcpu-\u003ekvm-\u003earch.crypto.pqap_hook) {\n 670:\t\t\tVFIO_AP_DBF_WARN(\"%s: PQAP(AQIC) hook not registered with the vfio_ap driver: apqn=0x%04x\\n\",\n 671:\t\t\t\t\t __func__, apqn);\n 672:\t\n 673:\t\t\tgoto out_unlock;\n 674:\t\t}\n 675:\t\n 676:\t\tmatrix_mdev = container_of(vcpu-\u003ekvm-\u003earch.crypto.pqap_hook,\n 677:\t\t\t\t\t   struct ap_matrix_mdev, pqap_hook);\n 678:\t\n 679:\t\t/* If the there is no guest using the mdev, there is nothing to do */\n"
}

gemini-3.1-pro-preview

null

null

							input: 37215
							output: 45
							thoughts: 114
						

**Analyzing the PQAP Execution Flow in KVM**

Okay, so here's what's happening. I see that `handle_pqap` is set up as a KVM hook. That's the entry point. When the guest runs the PQAP instruction, KVM calls this function. Simple enough. From there, it grabs the `apqn` value from GPR0, which makes sense; that's where the guest would pass it. Now comes the interesting part. It calls `vfio_ap_mdev_get_queue` using that `apqn`. I immediately recognize that as the likely gateway to accessing the AP devices if they are present. Now, if `vfio_ap_mdev_get_queue` returns NULL, that means there are no physical AP devices mapped for this particular `apqn`, likely implying something went wrong during the VFIO setup or there aren't any AP devices to use. I need to dig into `vfio_ap_mdev_get_queue` now to understand the exact conditions that cause it to return NULL. This is where I'll find the root cause.

{
  "File": "drivers/s390/crypto/vfio_ap_ops.c",
  "FirstLine": 210,
  "LineCount": 40
}

{
  "Contents": " 210:\t *\n 211:\t * Return: the pointer to the vfio_ap_queue struct representing the queue or\n 212:\t *\t   NULL if the queue is not assigned to @matrix_mdev\n 213:\t */\n 214:\tstatic struct vfio_ap_queue *vfio_ap_mdev_get_queue(\n 215:\t\t\t\t\t\tstruct ap_matrix_mdev *matrix_mdev,\n 216:\t\t\t\t\t\tint apqn)\n 217:\t{\n 218:\t\tstruct vfio_ap_queue *q;\n 219:\t\n 220:\t\thash_for_each_possible(matrix_mdev-\u003eqtable.queues, q, mdev_qnode,\n 221:\t\t\t\t       apqn) {\n 222:\t\t\tif (q \u0026\u0026 q-\u003eapqn == apqn)\n 223:\t\t\t\treturn q;\n 224:\t\t}\n 225:\t\n 226:\t\treturn NULL;\n 227:\t}\n 228:\t\n 229:\t/**\n 230:\t * vfio_ap_wait_for_irqclear:\n 231:\t * Waits for the IR bit to clear thus indicating IRQs are disabled for a queue\n 232:\t *\n 233:\t * @apqn: The AP Queue number\n 234:\t *\n 235:\t * Repeatedly checks the IR bit for the status of a queue device by calling the\n 236:\t * PQAP(TAPQ) instruction every 20ms until: the IR bit is cleared; the response\n 237:\t * code from the PQAP instruction indicates the queue is not available or\n 238:\t * not operational; or the loop has executed more than 5 times.\n 239:\t *\n 240:\t * Return:\n 241:\t * - true if the bit is observed clear or the AP is non-operational (in which\n 242:\t *   case no further interrupts can be generated)\n 243:\t *\n 244:\t * - false if the IR bit is still set after all retries are exhausted, meaning\n 245:\t *   the hardware may still write to the NIB.\n 246:\t */\n 247:\tstatic bool vfio_ap_wait_for_irqclear(int apqn)\n 248:\t{\n 249:\t\tstruct ap_queue_status status;\n"
}

gemini-3.1-pro-preview

null

null

							input: 38249
							output: 45
							thoughts: 15
						

Okay, here's my summary, presented as a first-person account, focusing on the core logic:

**My Line of Reasoning with `q`'s Nullity**

Alright, let's break this down. My internal state is currently focused on the condition where `q` is NULL. When I encounter this, I know I need to invoke `handle_pqap`. Now, the important question is *why*? Why this specific function? What's the context here?

Typically, a NULL pointer, `q`, often signifies an empty queue or a lack of valid data to process. Therefore, `handle_pqap` is being called to gracefully manage this "empty" or "undefined" state. It’s the designated handler for this specific, and critical, condition.

My goal in this situation is likely to ensure the system doesn't crash, enter an unexpected state, or make invalid calculations when encountering this `NULL` condition. `handle_pqap` is probably designed to:

*   **Initialize**: Establish the data structure, create the queue itself if it’s currently empty
*   **Handle Errors**: Alert about the issue if the situation demands reporting, logging the problem.
*   **Take Default Action**: The likely scenario: ensure that the program runs correctly or sets an internal flag indicating an empty state. Perhaps an alternate path is taken.

In summary, I am designed to use `handle_pqap` as a key safeguard against operating on uninitialized or missing data.

{
  "File": "drivers/s390/crypto/vfio_ap_ops.c",
  "FirstLine": 680,
  "LineCount": 40
}

{
  "Contents": " 680:\t\tif (!matrix_mdev-\u003ekvm) {\n 681:\t\t\tvfio_ap_le_guid_to_be_uuid(\u0026matrix_mdev-\u003emdev-\u003euuid, uuid);\n 682:\t\t\tVFIO_AP_DBF_WARN(\"%s: mdev %08lx-%04lx-%04lx-%04lx-%04lx%08lx not in use: apqn=0x%04x\\n\",\n 683:\t\t\t\t\t __func__, uuid[0],  uuid[1], uuid[2],\n 684:\t\t\t\t\t uuid[3], uuid[4], uuid[5], apqn);\n 685:\t\t\tgoto out_unlock;\n 686:\t\t}\n 687:\t\n 688:\t\tq = vfio_ap_mdev_get_queue(matrix_mdev, apqn);\n 689:\t\tif (!q) {\n 690:\t\t\tVFIO_AP_DBF_WARN(\"%s: Queue %02x.%04x not bound to the vfio_ap driver\\n\",\n 691:\t\t\t\t\t __func__, AP_QID_CARD(apqn),\n 692:\t\t\t\t\t AP_QID_QUEUE(apqn));\n 693:\t\t\tgoto out_unlock;\n 694:\t\t}\n 695:\t\n 696:\t\tstatus = vcpu-\u003erun-\u003es.regs.gprs[1];\n 697:\t\t/* If IR bit(16) is set we enable the interrupt */\n 698:\t\tif ((status \u003e\u003e (63 - 16)) \u0026 0x01)\n 699:\t\t\tqstatus = vfio_ap_irq_enable(q, status \u0026 0x07, vcpu);\n 700:\t\telse\n 701:\t\t\tqstatus = vfio_ap_irq_disable(q);\n 702:\t\n 703:\tout_unlock:\n 704:\t\tmemcpy(\u0026vcpu-\u003erun-\u003es.regs.gprs[1], \u0026qstatus, sizeof(qstatus));\n 705:\t\tvcpu-\u003erun-\u003es.regs.gprs[1] \u003e\u003e= 32;\n 706:\t\tmutex_unlock(\u0026matrix_dev-\u003emdevs_lock);\n 707:\t\treturn 0;\n 708:\t}\n 709:\t\n 710:\tstatic void vfio_ap_matrix_init(struct ap_config_info *info,\n 711:\t\t\t\t\tstruct ap_matrix *matrix)\n 712:\t{\n 713:\t\tmatrix-\u003eapm_max = info-\u003eapxa ? info-\u003ena : 63;\n 714:\t\tmatrix-\u003eaqm_max = info-\u003eapxa ? info-\u003end : 15;\n 715:\t\tmatrix-\u003eadm_max = info-\u003eapxa ? info-\u003end : 15;\n 716:\t}\n 717:\t\n 718:\tstatic void signal_guest_ap_cfg_changed(struct ap_matrix_mdev *matrix_mdev)\n 719:\t{\n"
}

gemini-3.1-pro-preview

null

null

							input: 39408
							output: 32
							thoughts: 179
						

**My Analysis of the VFIO AP Interrupt Handling**

Okay, so I'm looking at this code and trying to figure out how `vfio_ap_irq_enable` and `vfio_ap_irq_disable` are actually reached. The logic is pretty straightforward: if `q` is NULL, it immediately jumps to `out_unlock` and returns 0. That tells me these functions *aren't* accessible unless we're dealing with a legitimate, physical AP device. The crucial piece is that `q` is only ever added to the hash table within `vfio_ap_mdev_link_queue`, and that function's only called when a physical queue is discovered. That seems to indicate that this whole mechanism is intrinsically tied to real hardware.

But then my mind immediately jumps to the "what if?" scenario. Can we somehow *fake* an AP queue device? Could we potentially craft something that fools the system into thinking there's a device there when there isn't? The `ap_bus` is, after all, a physical bus. Syzkaller, in my experience, can't just spawn devices on physical buses unless there's a software emulation present. Think `mac80211_hwsim` or even `vhci`.

So, the next obvious question is, does `ap_bus` itself have any kind of software emulation? It's time to dig into the kernel source, specifically `drivers/s390/crypto/ap_bus.c`. I need to see if there's anything there that would allow for a software-based representation of these AP devices. Time to dive into the code...

{
  "Expression": "ap_bus",
  "PathPrefix": "drivers/s390/crypto/"
}

{
  "Output": "drivers/s390/crypto/Makefile-5-\ndrivers/s390/crypto/Makefile:6:ap-objs := ap_bus.o ap_card.o ap_queue.o\ndrivers/s390/crypto/Makefile-7-obj-$(CONFIG_AP) += ap.o\n--\ndrivers/s390/crypto/ap_bus.c-46-\ndrivers/s390/crypto/ap_bus.c:47:#include \"ap_bus.h\"\ndrivers/s390/crypto/ap_bus.c-48-#include \"ap_debug.h\"\n--\ndrivers/s390/crypto/ap_bus.c=175=static int ap_max_adapter_id = 63;\ndrivers/s390/crypto/ap_bus.c-176-\ndrivers/s390/crypto/ap_bus.c:177:static const struct bus_type ap_bus_type;\ndrivers/s390/crypto/ap_bus.c-178-\n--\ndrivers/s390/crypto/ap_bus.c=622=EXPORT_SYMBOL(ap_release_apmsg);\n--\ndrivers/s390/crypto/ap_bus.c-624-/**\ndrivers/s390/crypto/ap_bus.c:625: * ap_bus_match()\ndrivers/s390/crypto/ap_bus.c-626- * @dev: Pointer to device\n--\ndrivers/s390/crypto/ap_bus.c-630- */\ndrivers/s390/crypto/ap_bus.c:631:static int ap_bus_match(struct device *dev, const struct device_driver *drv)\ndrivers/s390/crypto/ap_bus.c-632-{\n--\ndrivers/s390/crypto/ap_bus.c=804=static void ap_calc_bound_apqns(unsigned int *apqns, unsigned int *bound)\n--\ndrivers/s390/crypto/ap_bus.c-808-\tmemset(\u0026ctrs, 0, sizeof(ctrs));\ndrivers/s390/crypto/ap_bus.c:809:\tbus_for_each_dev(\u0026ap_bus_type, NULL, (void *)\u0026ctrs, __ap_calc_helper);\ndrivers/s390/crypto/ap_bus.c-810-\n--\ndrivers/s390/crypto/ap_bus.c=877=static int __ap_revise_reserved(struct device *dev, void *dummy)\n--\ndrivers/s390/crypto/ap_bus.c-918-\ndrivers/s390/crypto/ap_bus.c:919:static void ap_bus_revise_bindings(void)\ndrivers/s390/crypto/ap_bus.c-920-{\ndrivers/s390/crypto/ap_bus.c:921:\tbus_for_each_dev(\u0026ap_bus_type, NULL, NULL, __ap_revise_reserved);\ndrivers/s390/crypto/ap_bus.c-922-}\n--\ndrivers/s390/crypto/ap_bus.c=1108=int ap_driver_register(struct ap_driver *ap_drv, struct module *owner,\n--\ndrivers/s390/crypto/ap_bus.c-1113-\ndrivers/s390/crypto/ap_bus.c:1114:\tdrv-\u003ebus = \u0026ap_bus_type;\ndrivers/s390/crypto/ap_bus.c-1115-\tdrv-\u003eowner = owner;\n--\ndrivers/s390/crypto/ap_bus.c=1129=EXPORT_SYMBOL(ap_driver_unregister);\n--\ndrivers/s390/crypto/ap_bus.c-1135- */\ndrivers/s390/crypto/ap_bus.c:1136:bool ap_bus_force_rescan(void)\ndrivers/s390/crypto/ap_bus.c-1137-{\n--\ndrivers/s390/crypto/ap_bus.c-1150-\t * all cards are offline so a rescan is triggered which causes\ndrivers/s390/crypto/ap_bus.c:1151:\t * a recursive call of ap_bus_force_rescan(). A simple return if\ndrivers/s390/crypto/ap_bus.c-1152-\t * the mutex is already locked by this thread solves this.\n--\ndrivers/s390/crypto/ap_bus.c-1186-}\ndrivers/s390/crypto/ap_bus.c:1187:EXPORT_SYMBOL(ap_bus_force_rescan);\ndrivers/s390/crypto/ap_bus.c-1188-\n--\ndrivers/s390/crypto/ap_bus.c-1191- */\ndrivers/s390/crypto/ap_bus.c:1192:static int ap_bus_cfg_chg(struct notifier_block *nb,\ndrivers/s390/crypto/ap_bus.c-1193-\t\t\t  unsigned long action, void *data)\n--\ndrivers/s390/crypto/ap_bus.c-1199-\ndrivers/s390/crypto/ap_bus.c:1200:\tap_bus_force_rescan();\ndrivers/s390/crypto/ap_bus.c-1201-\n--\ndrivers/s390/crypto/ap_bus.c-1204-\ndrivers/s390/crypto/ap_bus.c:1205:static struct notifier_block ap_bus_nb = {\ndrivers/s390/crypto/ap_bus.c:1206:\t.notifier_call = ap_bus_cfg_chg,\ndrivers/s390/crypto/ap_bus.c-1207-};\n--\ndrivers/s390/crypto/ap_bus.c=1549=static int apmask_commit(unsigned long *newapm)\n--\ndrivers/s390/crypto/ap_bus.c-1558-\tif (bitmap_andnot(reserved, newapm, ap_perms.apm, AP_DEVICES)) {\ndrivers/s390/crypto/ap_bus.c:1559:\t\trc = bus_for_each_drv(\u0026ap_bus_type, NULL, reserved,\ndrivers/s390/crypto/ap_bus.c-1560-\t\t\t\t      __verify_card_reservations);\n--\ndrivers/s390/crypto/ap_bus.c=1579=static ssize_t apmask_store(const struct bus_type *bus, const char *buf,\n--\ndrivers/s390/crypto/ap_bus.c-1605-\tif (changes) {\ndrivers/s390/crypto/ap_bus.c:1606:\t\tap_bus_revise_bindings();\ndrivers/s390/crypto/ap_bus.c-1607-\t\tap_send_mask_changed_uevent(newapm, NULL);\n--\ndrivers/s390/crypto/ap_bus.c=1656=static int aqmask_commit(unsigned long *newaqm)\n--\ndrivers/s390/crypto/ap_bus.c-1665-\tif (bitmap_andnot(reserved, newaqm, ap_perms.aqm, AP_DOMAINS)) {\ndrivers/s390/crypto/ap_bus.c:1666:\t\trc = bus_for_each_drv(\u0026ap_bus_type, NULL, reserved,\ndrivers/s390/crypto/ap_bus.c-1667-\t\t\t\t      __verify_queue_reservations);\n--\ndrivers/s390/crypto/ap_bus.c=1686=static ssize_t aqmask_store(const struct bus_type *bus, const char *buf,\n--\ndrivers/s390/crypto/ap_bus.c-1712-\tif (changes) {\ndrivers/s390/crypto/ap_bus.c:1713:\t\tap_bus_revise_bindings();\ndrivers/s390/crypto/ap_bus.c-1714-\t\tap_send_mask_changed_uevent(NULL, newaqm);\n--\ndrivers/s390/crypto/ap_bus.c=1727=static ssize_t scans_store(const struct bus_type *bus, const char *buf,\n--\ndrivers/s390/crypto/ap_bus.c-1731-\ndrivers/s390/crypto/ap_bus.c:1732:\tap_bus_force_rescan();\ndrivers/s390/crypto/ap_bus.c-1733-\n--\ndrivers/s390/crypto/ap_bus.c=1787=static BUS_ATTR_RO(features);\ndrivers/s390/crypto/ap_bus.c-1788-\ndrivers/s390/crypto/ap_bus.c:1789:static struct attribute *ap_bus_attrs[] = {\ndrivers/s390/crypto/ap_bus.c-1790-\t\u0026bus_attr_ap_domain.attr,\n--\ndrivers/s390/crypto/ap_bus.c-1807-};\ndrivers/s390/crypto/ap_bus.c:1808:ATTRIBUTE_GROUPS(ap_bus);\ndrivers/s390/crypto/ap_bus.c-1809-\ndrivers/s390/crypto/ap_bus.c:1810:static const struct bus_type ap_bus_type = {\ndrivers/s390/crypto/ap_bus.c-1811-\t.name = \"ap\",\ndrivers/s390/crypto/ap_bus.c:1812:\t.bus_groups = ap_bus_groups,\ndrivers/s390/crypto/ap_bus.c:1813:\t.match = \u0026ap_bus_match,\ndrivers/s390/crypto/ap_bus.c-1814-\t.uevent = \u0026ap_uevent,\n--\ndrivers/s390/crypto/ap_bus.c=1954=static inline void notify_config_changed(void)\ndrivers/s390/crypto/ap_bus.c-1955-{\ndrivers/s390/crypto/ap_bus.c:1956:\tbus_for_each_drv(\u0026ap_bus_type, NULL, NULL,\ndrivers/s390/crypto/ap_bus.c-1957-\t\t\t __drv_notify_config_changed);\n--\ndrivers/s390/crypto/ap_bus.c=1976=static inline void notify_scan_complete(void)\ndrivers/s390/crypto/ap_bus.c-1977-{\ndrivers/s390/crypto/ap_bus.c:1978:\tbus_for_each_drv(\u0026ap_bus_type, NULL, NULL,\ndrivers/s390/crypto/ap_bus.c-1979-\t\t\t __drv_notify_scan_complete);\n--\ndrivers/s390/crypto/ap_bus.c=1986=static inline void ap_scan_rm_card_dev_and_queue_devs(struct ap_card *ac)\ndrivers/s390/crypto/ap_bus.c-1987-{\ndrivers/s390/crypto/ap_bus.c:1988:\tbus_for_each_dev(\u0026ap_bus_type, NULL,\ndrivers/s390/crypto/ap_bus.c-1989-\t\t\t (void *)(long)ac-\u003eid,\n--\ndrivers/s390/crypto/ap_bus.c=1999=static inline void ap_scan_domains(struct ap_card *ac)\n--\ndrivers/s390/crypto/ap_bus.c-2015-\t\tqid = AP_MKQID(ac-\u003eid, dom);\ndrivers/s390/crypto/ap_bus.c:2016:\t\tdev = bus_find_device(\u0026ap_bus_type, NULL,\ndrivers/s390/crypto/ap_bus.c-2017-\t\t\t\t      (void *)(long)qid,\n--\ndrivers/s390/crypto/ap_bus.c-2054-\t\t\tdev = \u0026aq-\u003eap_dev.device;\ndrivers/s390/crypto/ap_bus.c:2055:\t\t\tdev-\u003ebus = \u0026ap_bus_type;\ndrivers/s390/crypto/ap_bus.c-2056-\t\t\tdev-\u003eparent = \u0026ac-\u003eap_dev.device;\n--\ndrivers/s390/crypto/ap_bus.c=2156=static inline void ap_scan_adapter(int ap)\n--\ndrivers/s390/crypto/ap_bus.c-2165-\t/* Is there currently a card device for this adapter ? */\ndrivers/s390/crypto/ap_bus.c:2166:\tdev = bus_find_device(\u0026ap_bus_type, NULL,\ndrivers/s390/crypto/ap_bus.c-2167-\t\t\t      (void *)(long)ap,\n--\ndrivers/s390/crypto/ap_bus.c-2279-\t\tdev = \u0026ac-\u003eap_dev.device;\ndrivers/s390/crypto/ap_bus.c:2280:\t\tdev-\u003ebus = \u0026ap_bus_type;\ndrivers/s390/crypto/ap_bus.c-2281-\t\tdev-\u003eparent = ap_root_device;\n--\ndrivers/s390/crypto/ap_bus.c=2390=static bool ap_scan_bus(void)\n--\ndrivers/s390/crypto/ap_bus.c-2424-\t\tstruct device *dev =\ndrivers/s390/crypto/ap_bus.c:2425:\t\t\tbus_find_device(\u0026ap_bus_type, NULL,\ndrivers/s390/crypto/ap_bus.c-2426-\t\t\t\t\t(void *)(long)ap_domain_index,\n--\ndrivers/s390/crypto/ap_bus.c=2484=static inline void __exit ap_async_exit(void)\n--\ndrivers/s390/crypto/ap_bus.c-2487-\t\tap_poll_thread_stop();\ndrivers/s390/crypto/ap_bus.c:2488:\tchsc_notifier_unregister(\u0026ap_bus_nb);\ndrivers/s390/crypto/ap_bus.c-2489-\tcancel_work(\u0026ap_scan_bus_work);\n--\ndrivers/s390/crypto/ap_bus.c=2494=static inline int __init ap_async_init(void)\n--\ndrivers/s390/crypto/ap_bus.c-2510-\ndrivers/s390/crypto/ap_bus.c:2511:\trc = chsc_notifier_register(\u0026ap_bus_nb);\ndrivers/s390/crypto/ap_bus.c-2512-\tif (rc)\n--\ndrivers/s390/crypto/ap_bus.c-2525-out_notifier:\ndrivers/s390/crypto/ap_bus.c:2526:\tchsc_notifier_unregister(\u0026ap_bus_nb);\ndrivers/s390/crypto/ap_bus.c-2527-out:\n--\ndrivers/s390/crypto/ap_bus.c=2595=static int __init ap_module_init(void)\n--\ndrivers/s390/crypto/ap_bus.c-2634-\t/* Create /sys/bus/ap. */\ndrivers/s390/crypto/ap_bus.c:2635:\trc = bus_register(\u0026ap_bus_type);\ndrivers/s390/crypto/ap_bus.c-2636-\tif (rc)\n--\ndrivers/s390/crypto/ap_bus.c-2643-\t\tgoto out_bus;\ndrivers/s390/crypto/ap_bus.c:2644:\tap_root_device-\u003ebus = \u0026ap_bus_type;\ndrivers/s390/crypto/ap_bus.c-2645-\n--\ndrivers/s390/crypto/ap_bus.c-2662-out_bus:\ndrivers/s390/crypto/ap_bus.c:2663:\tbus_unregister(\u0026ap_bus_type);\ndrivers/s390/crypto/ap_bus.c-2664-out:\n--\ndrivers/s390/crypto/ap_bus.c=2670=static void __exit ap_module_exit(void)\n--\ndrivers/s390/crypto/ap_bus.c-2674-\troot_device_unregister(ap_root_device);\ndrivers/s390/crypto/ap_bus.c:2675:\tbus_unregister(\u0026ap_bus_type);\ndrivers/s390/crypto/ap_bus.c-2676-\tmempool_destroy(ap_msg_pool);\n--\ndrivers/s390/crypto/ap_bus.h=257=void ap_request_timeout(struct timer_list *t);\ndrivers/s390/crypto/ap_bus.h:258:bool ap_bus_force_rescan(void);\ndrivers/s390/crypto/ap_bus.h-259-\n--\ndrivers/s390/crypto/ap_card.c-15-\ndrivers/s390/crypto/ap_card.c:16:#include \"ap_bus.h\"\ndrivers/s390/crypto/ap_card.c-17-\n--\ndrivers/s390/crypto/ap_queue.c-18-\ndrivers/s390/crypto/ap_queue.c:19:#include \"ap_bus.h\"\ndrivers/s390/crypto/ap_queue.c-20-#include \"ap_debug.h\"\n--\ndrivers/s390/crypto/vfio_ap_private.h-23-\ndrivers/s390/crypto/vfio_ap_private.h:24:#include \"ap_bus.h\"\ndrivers/s390/crypto/vfio_ap_private.h-25-\n--\ndrivers/s390/crypto/zcrypt_api.c=80=static inline bool zcrypt_process_rescan(void)\ndrivers/s390/crypto/zcrypt_api.c-81-{\ndrivers/s390/crypto/zcrypt_api.c:82:\treturn ap_bus_force_rescan();\ndrivers/s390/crypto/zcrypt_api.c-83-}\n--\ndrivers/s390/crypto/zcrypt_api.h-19-#include \u003casm/zcrypt.h\u003e\ndrivers/s390/crypto/zcrypt_api.h:20:#include \"ap_bus.h\"\ndrivers/s390/crypto/zcrypt_api.h-21-\n--\ndrivers/s390/crypto/zcrypt_ccamisc.c-21-\ndrivers/s390/crypto/zcrypt_ccamisc.c:22:#include \"ap_bus.h\"\ndrivers/s390/crypto/zcrypt_ccamisc.c-23-#include \"zcrypt_api.h\"\n--\ndrivers/s390/crypto/zcrypt_cex4.c-15-\ndrivers/s390/crypto/zcrypt_cex4.c:16:#include \"ap_bus.h\"\ndrivers/s390/crypto/zcrypt_cex4.c-17-#include \"zcrypt_api.h\"\n--\ndrivers/s390/crypto/zcrypt_ep11misc.c-21-\ndrivers/s390/crypto/zcrypt_ep11misc.c:22:#include \"ap_bus.h\"\ndrivers/s390/crypto/zcrypt_ep11misc.c-23-#include \"zcrypt_api.h\"\n--\ndrivers/s390/crypto/zcrypt_msgtype50.c-21-\ndrivers/s390/crypto/zcrypt_msgtype50.c:22:#include \"ap_bus.h\"\ndrivers/s390/crypto/zcrypt_msgtype50.c-23-#include \"zcrypt_api.h\"\n--\ndrivers/s390/crypto/zcrypt_msgtype6.c-23-\ndrivers/s390/crypto/zcrypt_msgtype6.c:24:#include \"ap_bus.h\"\ndrivers/s390/crypto/zcrypt_msgtype6.c-25-#include \"zcrypt_api.h\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 45262
							output: 32
							thoughts: 990
						

**Reaching a Fuzzing Decision**

Okay, let's break this down. My initial thought is that the primary logic in this patch related to the `ap_bus` and AP hardware is largely unreachable in a standard QEMU environment. The `ap_bus` relies on specific hardware instructions (`ap_qci`) and doesn't have any software emulation, meaning without physical AP hardware, it's a dead end. Therefore, most of the changes, particularly those involving IRQ handling (`vfio_ap_wait_for_irqclear`, `vfio_ap_irq_disable`, `vfio_ap_irq_enable`) and reset checks (`apq_reset_check`), will never be triggered.

However, the `vfio_ap_mdev_close_device` path seems accessible. Userspace can open the mdev device, use `VFIO_DEVICE_SET_IRQS` to set triggers (like `req_trigger` and `cfg_chg_trigger`), and then close the device. This *should* trigger `vfio_ap_mdev_close_device`, which in turn calls `vfio_ap_mdev_release_eventfds`. That's the key. This function releases eventfds, specifically addressing a memory leak.

The core question now is, is this leak fix significant enough to warrant fuzzing, given that it's the *only* reachable part of the patch? It's a simple function: just `eventfd_ctx_put` on a couple of eventfd contexts. The prompt guidance is to avoid fuzzing unreachable code or vendor-specific drivers (like PCIe switch, SmartNIC, or GPU) that rely on hardware not emulated by QEMU. While AP is a hardware-specific crypto device, the leak fix is within the `vfio_ap` driver which is part of the `vfio` framework and *is* reachable via syskaller.

I'm checking that the `req_trigger` is only freed at `vfio_ap_mdev_close_device`. Okay, the struct fields are set to NULL there.

While the prompt asks if it makes "functional changes to the kernel that should be fuzzed", it doesn't explicitly *exclude* memory leak fixes. The code is *reachable* via syzkaller, which can create the mdev and trigger the ioctl. In addition, there is no similar logic in the Linux kernel. Therefore, this is the only code to be tested. It is technically a functional change, fixing a leak.

Considering all of this, even though the bulk of the patch is unreachable, the reachable part *does* address a functional change by fixing a memory leak. It's not a major feature, but it's a measurable bug fix. Therefore, yes, I'm leaning towards fuzzing this code path.

{
  "Expression": "req_trigger",
  "PathPrefix": "drivers/s390/crypto/"
}

{
  "Output": "drivers/s390/crypto/vfio_ap_ops.c=2146=static void vfio_ap_mdev_release_eventfds(struct ap_matrix_mdev *matrix_mdev)\ndrivers/s390/crypto/vfio_ap_ops.c-2147-{\ndrivers/s390/crypto/vfio_ap_ops.c:2148:\tif (matrix_mdev-\u003ereq_trigger) {\ndrivers/s390/crypto/vfio_ap_ops.c:2149:\t\teventfd_ctx_put(matrix_mdev-\u003ereq_trigger);\ndrivers/s390/crypto/vfio_ap_ops.c:2150:\t\tmatrix_mdev-\u003ereq_trigger = NULL;\ndrivers/s390/crypto/vfio_ap_ops.c-2151-\t}\n--\ndrivers/s390/crypto/vfio_ap_ops.c=2170=static void vfio_ap_mdev_request(struct vfio_device *vdev, unsigned int count)\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2183-\ndrivers/s390/crypto/vfio_ap_ops.c:2184:\tif (matrix_mdev-\u003ereq_trigger) {\ndrivers/s390/crypto/vfio_ap_ops.c-2185-\t\tif (!(count % 10))\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2189-\ndrivers/s390/crypto/vfio_ap_ops.c:2190:\t\teventfd_signal(matrix_mdev-\u003ereq_trigger);\ndrivers/s390/crypto/vfio_ap_ops.c-2191-\t} else if (count == 0) {\n--\ndrivers/s390/crypto/vfio_ap_ops.c=2270=static int vfio_ap_set_request_irq(struct ap_matrix_mdev *matrix_mdev,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2275-\tunsigned long minsz;\ndrivers/s390/crypto/vfio_ap_ops.c:2276:\tstruct eventfd_ctx *req_trigger;\ndrivers/s390/crypto/vfio_ap_ops.c-2277-\n--\ndrivers/s390/crypto/vfio_ap_ops.c-2284-\tif (fd == -1) {\ndrivers/s390/crypto/vfio_ap_ops.c:2285:\t\tif (matrix_mdev-\u003ereq_trigger)\ndrivers/s390/crypto/vfio_ap_ops.c:2286:\t\t\teventfd_ctx_put(matrix_mdev-\u003ereq_trigger);\ndrivers/s390/crypto/vfio_ap_ops.c:2287:\t\tmatrix_mdev-\u003ereq_trigger = NULL;\ndrivers/s390/crypto/vfio_ap_ops.c-2288-\t} else if (fd \u003e= 0) {\ndrivers/s390/crypto/vfio_ap_ops.c:2289:\t\treq_trigger = eventfd_ctx_fdget(fd);\ndrivers/s390/crypto/vfio_ap_ops.c:2290:\t\tif (IS_ERR(req_trigger))\ndrivers/s390/crypto/vfio_ap_ops.c:2291:\t\t\treturn PTR_ERR(req_trigger);\ndrivers/s390/crypto/vfio_ap_ops.c-2292-\ndrivers/s390/crypto/vfio_ap_ops.c:2293:\t\tif (matrix_mdev-\u003ereq_trigger)\ndrivers/s390/crypto/vfio_ap_ops.c:2294:\t\t\teventfd_ctx_put(matrix_mdev-\u003ereq_trigger);\ndrivers/s390/crypto/vfio_ap_ops.c-2295-\ndrivers/s390/crypto/vfio_ap_ops.c:2296:\t\tmatrix_mdev-\u003ereq_trigger = req_trigger;\ndrivers/s390/crypto/vfio_ap_ops.c-2297-\t} else {\n--\ndrivers/s390/crypto/vfio_ap_private.h=90=struct ap_queue_table {\n--\ndrivers/s390/crypto/vfio_ap_private.h-106- * @qtable:\ttable of queues (struct vfio_ap_queue) assigned to the mdev\ndrivers/s390/crypto/vfio_ap_private.h:107: * @req_trigger eventfd ctx for signaling userspace to return a device\ndrivers/s390/crypto/vfio_ap_private.h-108- * @cfg_chg_trigger eventfd ctx to signal AP config changed to userspace\n--\ndrivers/s390/crypto/vfio_ap_private.h=114=struct ap_matrix_mdev {\n--\ndrivers/s390/crypto/vfio_ap_private.h-122-\tstruct ap_queue_table qtable;\ndrivers/s390/crypto/vfio_ap_private.h:123:\tstruct eventfd_ctx *req_trigger;\ndrivers/s390/crypto/vfio_ap_private.h-124-\tstruct eventfd_ctx *cfg_chg_trigger;\n"
}

gemini-3.1-pro-preview

null

null

							input: 48295
							output: 33
							thoughts: 1597
						

**My Assessment of the Patch's Fuzzing Worth**

Okay, let me think this through. This patch primarily addresses AP queue reset timeouts and IRQ disabling, specifically for s390x hardware. The eventfd leak fix is a side concern, but potentially relevant. The core logic hinges on physical s390x AP hardware, which, as far as I understand, is not emulated in QEMU. That is a major point. The central parts of the patch are fundamentally unreachable in typical virtualization scenarios.

The only genuinely reachable part seems to be the `vfio_ap_mdev_close_device` function and the release function it calls, which includes the eventfd leak fix, `vfio_ap_mdev_release_eventfds`. The `eventfd` fix, however, is trivial. We're effectively just fuzzing `eventfd_ctx_put` in a very specific scenario, which is not ideal from a coverage perspective. My initial instinct is that it's probably not worth fuzzing, but I need to be precise.

The prompt specifically says to return `WorthFuzzing=false` if the patch *only* contains unreachable code paths. The prompt is important because of this specificity. It doesn't *only* contain unreachable code, it also includes the eventfd fix reachable through `vfio_ap_mdev_close_device`. That is the defining factor.

Let's quickly check `vfio_ap_mdev_close_device`. It's called when closing a VFIO device. I can confirm userspace needs to create the mdev, add it to a VFIO group, open the group, get the FD, and close the FD. Syzkaller definitely has VFIO and mdev descriptions, so I think that is a reachable path. Now, the question is, is `VFIO_AP` enabled in syzkaller. Since syzkaller does test s390x, I believe that it should be, and if it's not, it's something I could easily add.

Therefore, because `vfio_ap_mdev_close_device` *is* reachable, I have to say `WorthFuzzing=true`. My focus should be `vfio_ap_mdev_close_device` and also, as part of it, `vfio_ap_mdev_release_eventfds`, although I'll keep in mind that the `release` function is a candidate for inlining.

Also, I see it's modifying `vfio_ap_mdev_on_cfg_remove` and `vfio_ap_mdev_cfg_add` to use `AP_DOMAINS` instead of `AP_DEVICES`, but as far as I can see, both are 256, so that's a no-op, not important. The rest of the patch, including `apq_reset_check`, `vfio_ap_wait_for_irqclear`, `vfio_ap_irq_disable`, `vfio_ap_irq_enable`, and `handle_pqap`, are still unreachable without that physical AP hardware.

So, although it feels like we're just fuzzing a trivial memory leak fix, the fact that `vfio_ap_mdev_close_device` is a VFIO device callback, and thus, an API entry point, means I have to return `WorthFuzzing=true`. We can definitely reach this with Syzkaller. It's time to check what's needed to add these new device closes. Also, there is an `AP` config, which depends on `ZCRYPT`. I'll have to investigate that.

no matches

{
  "Expression": "config AP",
  "PathPrefix": "drivers/s390/crypto/Kconfig"
}

{
  "error": "no matches"
}

gemini-3.1-pro-preview

null

null

							input: 50734
							output: 34
							thoughts: 22
						

Here's my thought process, summarized as you requested:

**Kconfig Dive for ZCRYPT**

Okay, so I need to quickly refresh my memory on where the configuration options for ZCRYPT are located within the kernel build system. I'm pretty sure it's under the `drivers/s390/crypto/` directory, but I want to be absolutely certain. The Kconfig files are the heart of how these options are presented to the build system, so that's the logical place to start digging. Let me go ahead and take a look at `drivers/s390/crypto/Kconfig` right away to confirm and pinpoint the relevant definitions. This will give me the ground truth of what's going on.

no matches

{
  "Expression": "config ZCRYPT",
  "PathPrefix": "drivers/s390/crypto/Kconfig"
}

{
  "error": "no matches"
}

gemini-3.1-pro-preview

null

null

							input: 50959
							output: 22
							thoughts: 7
						

Here's my attempt at summarizing the thought process, tailored for an expert audience:

**Tracing the Definition of `AP`**

Okay, so the text simply says "Where is `AP` defined?". My immediate thought process goes like this: I need to quickly establish the context. `AP` is clearly a variable, constant, macro, or perhaps a function, and I'm assuming it's within the current scope of whatever code or system I'm working with. The question itself is pretty broad. I need more information to really pinpoint things. 

My first step would be a rapid scan of the immediate environment. If this is a programming context, I'd mentally start looking for declarations or assignments. Is it a global variable? Is it part of a specific class or structure? Am I looking at a header file or source code? If it's a configuration setting, where are the configuration files? The goal is to quickly narrow down the possibilities.

If this is related to some kind of documentation or a research paper, I would start by going back to the beginning to see if there is any definition or introduction for the variable. I would search for acronyms or abbreviations to find out the full meaning of the variable, to see where the variable is defined. 

Essentially, this is a basic debugging or investigative process. Where's the source? What's the context? And then, where do I start looking to trace the definition to its origin?

{
  "Expression": "config AP",
  "PathPrefix": ""
}

{
  "Output": "Documentation/admin-guide/bootconfig.rst=287=to initrd image, user can notice it before boot.\n--\nDocumentation/admin-guide/bootconfig.rst-289-\nDocumentation/admin-guide/bootconfig.rst:290:Bootconfig APIs\nDocumentation/admin-guide/bootconfig.rst-291-===============\n--\narch/m68k/Kconfig.machine=29=config MAC\n--\narch/m68k/Kconfig.machine-40-\narch/m68k/Kconfig.machine:41:config APOLLO\narch/m68k/Kconfig.machine-42-\tbool \"Apollo support\"\n--\narch/powerpc/platforms/44x/Kconfig=291=config 476FPE\n--\narch/powerpc/platforms/44x/Kconfig-294-\narch/powerpc/platforms/44x/Kconfig:295:config APM821xx\narch/powerpc/platforms/44x/Kconfig-296-\tbool\n--\narch/s390/Kconfig=785=config EADM_SCH\n--\narch/s390/Kconfig-795-\narch/s390/Kconfig:796:config AP\narch/s390/Kconfig-797-\tdef_tristate y\n--\narch/s390/Kconfig-808-\narch/s390/Kconfig:809:config AP_DEBUG\narch/s390/Kconfig-810-\tdef_bool n\n--\narch/s390/Kconfig=885=config CMM_IUCV\n--\narch/s390/Kconfig-892-\narch/s390/Kconfig:893:config APPLDATA_BASE\narch/s390/Kconfig-894-\tdef_bool n\n--\narch/s390/Kconfig-908-\narch/s390/Kconfig:909:config APPLDATA_MEM\narch/s390/Kconfig-910-\tdef_tristate m\n--\narch/s390/Kconfig-925-\narch/s390/Kconfig:926:config APPLDATA_OS\narch/s390/Kconfig-927-\tdef_tristate m\n--\narch/s390/Kconfig-940-\narch/s390/Kconfig:941:config APPLDATA_NET_SUM\narch/s390/Kconfig-942-\tdef_tristate m\n--\narch/x86/Kconfig=2697=config X86_APM_BOOT\n--\narch/x86/Kconfig-2700-\narch/x86/Kconfig:2701:menuconfig APM\narch/x86/Kconfig-2702-\ttristate \"APM (Advanced Power Management) BIOS support\"\n--\narch/x86/Kconfig=2753=if APM\narch/x86/Kconfig-2754-\narch/x86/Kconfig:2755:config APM_IGNORE_USER_SUSPEND\narch/x86/Kconfig-2756-\tbool \"Ignore USER SUSPEND\"\n--\narch/x86/Kconfig-2761-\narch/x86/Kconfig:2762:config APM_DO_ENABLE\narch/x86/Kconfig-2763-\tbool \"Enable PM at boot time\"\n--\narch/x86/Kconfig-2778-\narch/x86/Kconfig:2779:config APM_CPU_IDLE\narch/x86/Kconfig-2780-\tdepends on CPU_IDLE\n--\narch/x86/Kconfig-2790-\narch/x86/Kconfig:2791:config APM_DISPLAY_BLANK\narch/x86/Kconfig-2792-\tbool \"Enable console blanking using APM\"\n--\narch/x86/Kconfig-2803-\narch/x86/Kconfig:2804:config APM_ALLOW_INTS\narch/x86/Kconfig-2805-\tbool \"Allow interrupts during APM BIOS calls\"\n--\ndrivers/clk/qcom/Kconfig=330=config CLK_HAWI_TCSRCC\n--\ndrivers/clk/qcom/Kconfig-336-\ndrivers/clk/qcom/Kconfig:337:config APQ_GCC_8084\ndrivers/clk/qcom/Kconfig-338-\ttristate \"APQ8084 Global Clock Controller\"\n--\ndrivers/clk/qcom/Kconfig-345-\ndrivers/clk/qcom/Kconfig:346:config APQ_MMCC_8084\ndrivers/clk/qcom/Kconfig-347-\ttristate \"APQ8084 Multimedia Clock Controller\"\n--\ndrivers/dma/Kconfig=78=config AMCC_PPC440SPE_ADMA\n--\ndrivers/dma/Kconfig-87-\ndrivers/dma/Kconfig:88:config APPLE_ADMAC\ndrivers/dma/Kconfig-89-\ttristate \"Apple ADMAC support\"\n--\ndrivers/firmware/efi/Kconfig=154=config EFI_DEV_PATH_PARSER\n--\ndrivers/firmware/efi/Kconfig-156-\ndrivers/firmware/efi/Kconfig:157:config APPLE_PROPERTIES\ndrivers/firmware/efi/Kconfig-158-\tbool \"Apple Device Properties\"\n--\ndrivers/iio/light/Kconfig=68=config AL3320A\n--\ndrivers/iio/light/Kconfig-78-\ndrivers/iio/light/Kconfig:79:config APDS9160\ndrivers/iio/light/Kconfig-80-\ttristate \"APDS9160 combined als and proximity sensor\"\n--\ndrivers/iio/light/Kconfig-89-\ndrivers/iio/light/Kconfig:90:config APDS9300\ndrivers/iio/light/Kconfig-91-\ttristate \"APDS9300 ambient light sensor\"\n--\ndrivers/iio/light/Kconfig-99-\ndrivers/iio/light/Kconfig:100:config APDS9306\ndrivers/iio/light/Kconfig-101-\ttristate \"Avago APDS9306 Ambient Light Sensor\"\n--\ndrivers/iio/light/Kconfig-111-\ndrivers/iio/light/Kconfig:112:config APDS9960\ndrivers/iio/light/Kconfig-113-\ttristate \"Avago APDS9960 gesture/RGB/ALS/proximity sensor\"\n--\ndrivers/iio/light/Kconfig-124-\ndrivers/iio/light/Kconfig:125:config APDS9999\ndrivers/iio/light/Kconfig-126-\ttristate \"Broadcom APDS9999 ALS, RGB and proximity sensor\"\n--\ndrivers/iommu/Kconfig=296=config SPAPR_TCE_IOMMU\n--\ndrivers/iommu/Kconfig-303-\ndrivers/iommu/Kconfig:304:config APPLE_DART\ndrivers/iommu/Kconfig-305-\ttristate \"Apple DART IOMMU Support\"\n--\ndrivers/irqchip/Kconfig=805=config IRQ_IDT3243X\n--\ndrivers/irqchip/Kconfig-809-\ndrivers/irqchip/Kconfig:810:config APPLE_AIC\ndrivers/irqchip/Kconfig-811-\tbool \"Apple Interrupt Controller (AIC)\"\n--\ndrivers/misc/Kconfig=327=config SGI_GRU_DEBUG\n--\ndrivers/misc/Kconfig-333-\ndrivers/misc/Kconfig:334:config APDS9802ALS\ndrivers/misc/Kconfig-335-\ttristate \"Medfield Avago APDS9802 ALS Sensor module\"\n--\ndrivers/net/ethernet/8390/Kconfig=105=config NE2K_PCI\n--\ndrivers/net/ethernet/8390/Kconfig-122-\ndrivers/net/ethernet/8390/Kconfig:123:config APNE\ndrivers/net/ethernet/8390/Kconfig-124-\ttristate \"PCMCIA NE2000 support\"\n--\ndrivers/net/wireless/realtek/rtw89/pci.c=3334=static int rtw89_pci_cfg_dac(struct rtw89_dev *rtwdev, bool force)\n--\ndrivers/net/wireless/realtek/rtw89/pci.c-3346-\ndrivers/net/wireless/realtek/rtw89/pci.c:3347:\t/* Configure DAC only via PCI config API, not DBI interfaces */\ndrivers/net/wireless/realtek/rtw89/pci.c-3348-\tret = pci_read_config_byte(pdev, RTW89_PCIE_L1_CTRL, \u0026val);\n--\ndrivers/perf/Kconfig=253=config MARVELL_CN10K_TAD_PMU\n--\ndrivers/perf/Kconfig-259-\ndrivers/perf/Kconfig:260:config APPLE_M1_CPU_PMU\ndrivers/perf/Kconfig-261-\tbool \"Apple M1 CPU PMU support\"\n--\ndrivers/platform/x86/Kconfig=194=config ADV_SWBUTTON\n--\ndrivers/platform/x86/Kconfig-204-\ndrivers/platform/x86/Kconfig:205:config APPLE_GMUX\ndrivers/platform/x86/Kconfig-206-\ttristate \"Apple Gmux Driver\"\n--\ndrivers/pmdomain/apple/Kconfig=3=if ARCH_APPLE || COMPILE_TEST\ndrivers/pmdomain/apple/Kconfig-4-\ndrivers/pmdomain/apple/Kconfig:5:config APPLE_PMGR_PWRSTATE\ndrivers/pmdomain/apple/Kconfig-6-\tbool \"Apple SoC PMGR power state control\"\n--\ndrivers/power/supply/Kconfig=18=config POWER_SUPPLY_HWMON\n--\ndrivers/power/supply/Kconfig-30-\ndrivers/power/supply/Kconfig:31:config APM_POWER\ndrivers/power/supply/Kconfig-32-\ttristate \"APM emulation for class batteries\"\n--\ndrivers/soc/apple/Kconfig=5=menu \"Apple SoC drivers\"\ndrivers/soc/apple/Kconfig-6-\ndrivers/soc/apple/Kconfig:7:config APPLE_MAILBOX\ndrivers/soc/apple/Kconfig-8-\ttristate \"Apple SoC mailboxes\"\n--\ndrivers/soc/apple/Kconfig-18-\ndrivers/soc/apple/Kconfig:19:config APPLE_RTKIT\ndrivers/soc/apple/Kconfig-20-\ttristate \"Apple RTKit co-processor IPC protocol\"\n--\ndrivers/soc/apple/Kconfig-30-\ndrivers/soc/apple/Kconfig:31:config APPLE_SART\ndrivers/soc/apple/Kconfig-32-\ttristate \"Apple SART DMA address filter\"\n--\ndrivers/soc/apple/Kconfig-40-\ndrivers/soc/apple/Kconfig:41:config APPLE_TUNABLE\ndrivers/soc/apple/Kconfig-42-\ttristate\n--\ndrivers/usb/misc/Kconfig=147=config USB_QCOM_EUD\n--\ndrivers/usb/misc/Kconfig-158-\ndrivers/usb/misc/Kconfig:159:config APPLE_MFI_FASTCHARGE\ndrivers/usb/misc/Kconfig-160-\ttristate \"Fast charge control for iOS devices\"\n--\ndrivers/video/Kconfig=6=menu \"Graphics support\"\ndrivers/video/Kconfig-7-\ndrivers/video/Kconfig:8:config APERTURE_HELPERS\ndrivers/video/Kconfig-9-\tbool\n--\ndrivers/watchdog/Kconfig=1111=config MSC313E_WATCHDOG\n--\ndrivers/watchdog/Kconfig-1122-\ndrivers/watchdog/Kconfig:1123:config APPLE_WATCHDOG\ndrivers/watchdog/Kconfig-1124-\ttristate \"Apple SoC watchdog\"\n--\nfs/xfs/xfs_super.c=1702=xfs_fs_fill_super(\n--\nfs/xfs/xfs_super.c-1714-\t * is guaranteed to have been completed by either the old mount API or\nfs/xfs/xfs_super.c:1715:\t * the newer fsopen/fsconfig API.\nfs/xfs/xfs_super.c-1716-\t */\n--\nkernel/power/Kconfig=311=config PM_TRACE_RTC\n--\nkernel/power/Kconfig-328-\nkernel/power/Kconfig:329:config APM_EMULATION\nkernel/power/Kconfig-330-\ttristate \"Advanced Power Management Emulation\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 54642
							output: 109
							thoughts: 362
						

**My Analysis of the VFIO-AP Patch**

Okay, so I've traced the relevant configuration options for this VFIO-AP patch. It looks like `config AP` is defined in `arch/s390/Kconfig`. And, crucially, `AP` is set to `def_tristate y` there, which is helpful. This means that to get this functionality, I really only need to enable `VFIO_AP`. That's the key. Now, `VFIO_AP` depends on `KVM`, `VFIO`, and `AP`, so that's the main configuration item to focus on.

So, to summarize for the automated tools, the critical settings are: `WorthFuzzing: true`, `FocusSymbols: vfio_ap_mdev_close_device`, and `EnableConfigs: VFIO_AP`. The reasoning is that this patch addresses an eventfd leak in the VFIO AP mdev close path. This can be triggered via standard VFIO mdev ioctls and device close, even without any physical AP hardware. Other changes in the patch, related to AP queue resets and IRQ handling, are off-limits because those require the IBM AP crypto hardware.

I should double-check that `vfio_ap_mdev_close_device` is the correct symbol to focus on. Yes, it's a static function, but it's assigned to `vfio_device_ops.close_device`, so that makes perfect sense. I was worried there might be something else reachable. I see that `vfio_ap_set_request_irq` is also reachable and sets the eventfd, but it's not actually *modified* by this patch. The patch only modifies `vfio_ap_mdev_release_eventfds`, which is called by `vfio_ap_mdev_close_device`. That confirms my initial assessment.

Okay, that's everything I need. Now, I will call `set-results`.

the following configs do not exist in the kernel tree: VFIO_AP

{
  "EnableConfigs": [
    "VFIO_AP"
  ],
  "FocusSymbols": [
    "vfio_ap_mdev_close_device"
  ],
  "Reasoning": "The patch fixes an eventfd memory leak in the VFIO AP mediated device close path, which is reachable via standard VFIO mdev ioctls and device close operations even without physical AP hardware. Other changes related to AP queue resets and IRQ handling are unreachable without IBM AP crypto hardware.",
  "WorthFuzzing": true
}

{
  "error": "the following configs do not exist in the kernel tree: VFIO_AP"
}

gemini-3.1-pro-preview

null

null

							input: 55571
							output: 34
							thoughts: 31
						

Here's my attempt at summarizing those thoughts, speaking as an expert:

**Investigating a Missing Definition**

Hang on a second… I could have sworn I've seen `VFIO_AP` before. But now that I'm trying to use it, my tooling is screaming that it doesn't exist. That's strange. Time to double-check my assumptions and revisit the source. Specifically, I need to go back into the s390 architecture's Kconfig to confirm whether `VFIO_AP` is actually defined, or if I'm somehow misremembering the context. This is the first place I'd look to determine if a kernel configuration option exists. I can't proceed until I'm certain about this.

{
  "Expression": "config VFIO_AP",
  "PathPrefix": "arch/s390/Kconfig"
}

{
  "Output": "arch/s390/Kconfig=823=config VFIO_CCW\n--\narch/s390/Kconfig-833-\narch/s390/Kconfig:834:config VFIO_AP\narch/s390/Kconfig-835-\tdef_tristate n\n"
}

gemini-3.1-pro-preview

null

null

							input: 55887
							output: 30
							thoughts: 250
						

**My Troubleshooting Process**

Okay, so I'm encountering a problem. The tool is claiming `VFIO_AP` doesn't exist in the kernel tree. But I *know* it's in `arch/s390/Kconfig`. Hang on, let me retrace my steps. The tool checks for config existence, so that makes sense. Hmm, is it perhaps meant to be `CONFIG_VFIO_AP`? No, the error message specifically stated "without CONFIG_ prefix".

Why am I getting this error then? Could the tool be checking against the wrong architecture tree? Perhaps it's defaulting to x86_64 or something similar, and not loading the s390 specific configurations. But that doesn't fully explain it because `arch/s390/Kconfig` is definitely present.

Just to be absolutely certain, let me re-verify. No, it is still indeed in `arch/s390/Kconfig`, not `drivers/s390/crypto/Kconfig`. So I'm back at square one. Why did the `set-results` command fail? The error message is clear: "the following configs do not exist in the kernel tree: VFIO_AP".

Right, I'm going to eliminate the obvious. Let me quickly double-check the `drivers/vfio/Kconfig` file, just to be sure I haven't missed something.

no matches

{
  "Expression": "config VFIO_AP",
  "PathPrefix": "drivers/vfio/"
}

{
  "error": "no matches"
}

gemini-3.1-pro-preview

null

null

							input: 56489
							output: 36
							thoughts: 16
						

Here's my take on those thoughts:

**Navigating the S390 Crypto Landscape**

Okay, so I need to dive into the S390 crypto subsystem, and the first place I'm instinctively drawn to is the `drivers/s390/crypto/Makefile`. That's where I'd expect to find the build configuration, the object files, and the dependencies for the crypto drivers specifically tailored for the s390 architecture. This `Makefile` is likely the key to understanding how these drivers are integrated into the kernel build process on that platform. I want to see how they're handling things, what modules are getting built, and where the core cryptographic functionality resides within the larger s390 system. It's a fundamental starting point, almost a "go-to" when exploring any kernel component. This `Makefile` should reveal the architecture-specific glue, the build options, and give me a feel for how complex or streamlined this particular implementation is. Time to see what secrets it holds.

{
  "File": "drivers/s390/crypto/Makefile",
  "FirstLine": 1,
  "LineCount": 20
}

{
  "Contents": "   1:\t# SPDX-License-Identifier: GPL-2.0\n   2:\t#\n   3:\t# S/390 crypto devices\n   4:\t#\n   5:\t\n   6:\tap-objs := ap_bus.o ap_card.o ap_queue.o\n   7:\tobj-$(CONFIG_AP) += ap.o\n   8:\t# zcrypt_api.o and zcrypt_msgtype*.o depend on ap.o\n   9:\tzcrypt-objs := zcrypt_api.o zcrypt_card.o zcrypt_queue.o\n  10:\tzcrypt-objs += zcrypt_msgtype6.o zcrypt_msgtype50.o\n  11:\tzcrypt-objs += zcrypt_ccamisc.o zcrypt_ep11misc.o\n  12:\tobj-$(CONFIG_ZCRYPT) += zcrypt.o\n  13:\t# adapter drivers depend on ap.o and zcrypt.o\n  14:\tobj-$(CONFIG_ZCRYPT) += zcrypt_cex4.o\n  15:\t\n  16:\t# pkey base and api module\n  17:\tpkey-objs := pkey_base.o pkey_api.o pkey_sysfs.o\n  18:\tobj-$(CONFIG_PKEY) += pkey.o\n  19:\t\n  20:\t# pkey cca handler module\n"
}

gemini-3.1-pro-preview

null

null

							input: 57110
							output: 37
							thoughts: 12
						

Here's my attempt at summarizing that thought process, tailored for an expert audience:

**Where's That Dang `vfio_ap`?**

Okay, so I'm looking at this code again, probably something related to VFIO. And my brain just hit a snag – I'm wracking my memory trying to figure out where the `vfio_ap` symbol is actually *defined* and compiled. It's a key piece in this whole puzzle, and I need to understand its context. I can feel myself starting to mentally trace the dependencies, or maybe even look for it. Where did that come from? Was it in a header? Part of another module? Is it statically compiled in, or more likely, linked in during runtime? I need to know where it's living. Time to figure out where that thing is built.

{
  "File": "drivers/s390/crypto/Makefile",
  "FirstLine": 21,
  "LineCount": 20
}

{
  "Contents": "  21:\tpkey-cca-objs := pkey_cca.o\n  22:\tobj-$(CONFIG_PKEY_CCA) += pkey-cca.o\n  23:\t\n  24:\t# pkey ep11 handler module\n  25:\tpkey-ep11-objs := pkey_ep11.o\n  26:\tobj-$(CONFIG_PKEY_EP11) += pkey-ep11.o\n  27:\t\n  28:\t# pkey pckmo handler module\n  29:\tpkey-pckmo-objs := pkey_pckmo.o\n  30:\tobj-$(CONFIG_PKEY_PCKMO) += pkey-pckmo.o\n  31:\t\n  32:\t# pkey uv handler module\n  33:\tpkey-uv-objs := pkey_uv.o\n  34:\tobj-$(CONFIG_PKEY_UV) += pkey-uv.o\n  35:\t\n  36:\t# adjunct processor matrix\n  37:\tvfio_ap-objs := vfio_ap_drv.o vfio_ap_ops.o\n  38:\tobj-$(CONFIG_VFIO_AP) += vfio_ap.o\n"
}

gemini-3.1-pro-preview

null

null

							input: 57656
							output: 103
							thoughts: 98
						

**Investigating a Configuration Discrepancy**

Okay, so the issue at hand is `CONFIG_VFIO_AP`. That *should* be the correct config option. But the tool is reporting it as non-existent. Hmm, that's puzzling. My initial hunch is that the tool might be using something like `make savedefconfig` internally to check for config options. And since this is an x86_64 build, it's possible the tool's config process isn't even looking at the s390 configs, where `VFIO_AP` probably resides. It's missing the relevant architecture, in effect.

If the tool is dead-set against `VFIO_AP`, I've got a couple of options. I can just leave it out entirely, or I can try providing an empty array. Either should be acceptable.

Let's start by just omitting it. If the tool is just being overzealous and isn't *required*, that's the simplest and cleanest solution. I'll test it out this way.

{
  "EnableConfigs": [],
  "FocusSymbols": [
    "vfio_ap_mdev_close_device"
  ],
  "Reasoning": "The patch fixes an eventfd memory leak in the VFIO AP mediated device close path, which is reachable via standard VFIO mdev ioctls and device close operations even without physical AP hardware. Other changes related to AP queue resets and IRQ handling are unreachable without IBM AP crypto hardware.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": null,
  "FocusSymbols": [
    "vfio_ap_mdev_close_device"
  ],
  "Reasoning": "The patch fixes an eventfd memory leak in the VFIO AP mediated device close path, which is reachable via standard VFIO mdev ioctls and device close operations even without physical AP hardware. Other changes related to AP queue resets and IRQ handling are unreachable without IBM AP crypto hardware.",
  "WorthFuzzing": true
}

{
  "WorthFuzzing": true
}

null

best-expensive

null

{
  "KMSANReasoning": "The patch series addresses potential use-after-free (UAF) vulnerabilities and resource management in the s390 vfio_ap driver. Specifically, it modifies the driver to intentionally leak AQIC resources (pinned NIB pages and registered guest ISCs) if the hardware fails to confirm that interrupts have been disabled or a reset has completed within a timeout. This prevents the hardware from writing to freed memory, which would cause a UAF. It also corrects the bitmap sizes used in configuration removal and addition from `AP_DEVICES` to `AP_DOMAINS` (both are 256, so this is a semantic fix).\n\nNone of these changes introduce new allocations, complex data structures, or user-space copies that could expose uninitialized memory. The `status` variable copied into `q-\u003ereset_status` is fully initialized by the `ap_tapq` inline assembly instruction reading from hardware registers.\n\nSince the primary risks addressed by this patch are use-after-free bugs and resource leaks, standard KASAN (which detects UAF) and standard debugging tools are perfectly suited for testing these changes. There is no risk of uninitialized memory usage or info-leaks that would require a dedicated KMSAN fuzzing session.",
  "NeedsKMSAN": false
}

You are an expert Linux kernel security engineer specializing in kernel memory
error detectors (KASAN and KMSAN). Your job is to review the provided patch series and
determine if the code changes justify spawning a dedicated KMSAN (KernelMemorySanitizer)
fuzzing session in addition to standard KASAN fuzzing.

CRITICAL DISTINCTION BETWEEN KASAN AND KMSAN:
- Standard KASAN kernel builds (upstream-apparmor-kasan.config) already enable
  a comprehensive suite of debugging tools and sanitizers, including KASAN
  (out-of-bounds accesses, use-after-free, double free, invalid free), LOCKDEP
  (locking bugs and deadlocks), UB-sanitizers, and memory corruption checks.
- KMSAN (KernelMemorySanitizer) detects reads of UNINITIALIZED memory (stack, heap,
  or page allocations) and kernel-to-user memory info-leaks.

Rule: THERE IS NO SENSE IN RUNNING A KMSAN SESSION IF A BUG CAN BE CAUGHT BY KASAN,
LOCKDEP, OR OTHER STANDARD BUG DETECTORS.
A dedicated KMSAN fuzzing session incurs significant resource costs. You must ONLY
set NeedsKMSAN=true if the code changes introduce or expose UNINITIALIZED MEMORY risks
that are detected ONLY by KMSAN.

Look holistically at the patch series and surrounding code. Even if no direct
uninitialized field accesses or new buffer allocations are added in the diff itself,
a patch may alter control flow, bounds checking, or data length calculations in ways
that change how the rest of the code operates on existing buffers (e.g. allowing
uninitialized stack/heap memory to be read, copied to user space, or used in control
flow). Do not hesitate to use your code access tools to inspect the surrounding code,
called functions, and callers.

Set NeedsKMSAN=true ONLY IF the patch introduces or modifies:
1. Kernel structures sent to user space (via copy_to_user, put_user, netlink skb
   attributes, ioctl output arguments, socket options, or BPF buffers) where fields
   or structure padding might not be fully initialized/zeroed.
2. Conditional logic or branching that depends on potentially uninitialized variables
   or struct fields.
3. Allocation or initialization of complex data structures where uninitialized fields
   could be read later in reachable code paths.
4. Bounds checks, lengths, or logic in a way that allows surrounding code to access
   uninitialized bytes of existing buffers.

Set NeedsKMSAN=false IF:
- The code changes primarily risk out-of-bounds access, array overflows, NULL pointer
  dereferences, locking deadlocks, or use-after-free bugs (these are already caught
  by KASAN, LOCKDEP, or standard bug detectors).
- All stack/heap structures touched or introduced by the patch are fully zeroed
  or initialized (e.g. using = {0}, memset, kzalloc) before being read or copied.
- The patch does not introduce any risk of uninitialized memory usage or info-leaks.

Use your code access tools to inspect the surrounding code if necessary, then provide
detailed KMSANReasoning contrasting KASAN vs KMSAN applicability for this patch.
Prefer calling several tools at the same time to save round-trips.


Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.

For your convenience, here is the diff of the changes:
commit 6ff8477b285b1818ffa5b145d17d62078cd919b6
Author: syz-cluster <triage@syzkaller.com>
Date:   Thu Aug 27 14:30:07 2026 +0000

    syz-cluster: applied patch under review

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 940c0ff668bee..85a59730019e3 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -31,6 +31,7 @@
 #define AP_QUEUE_IN_USE "in use"
 
 #define AP_RESET_INTERVAL		20	/* Reset sleep interval (20ms)		*/
+#define AP_RESET_MAX_WAIT		2000	/* Maximum wait for reset (2000ms)	*/
 
 static int vfio_ap_mdev_reset_queues(struct ap_matrix_mdev *matrix_mdev);
 static int vfio_ap_mdev_reset_qlist(struct list_head *qlist);
@@ -226,16 +227,24 @@ static struct vfio_ap_queue *vfio_ap_mdev_get_queue(
 }
 
 /**
- * vfio_ap_wait_for_irqclear - clears the IR bit or gives up after 5 tries
+ * vfio_ap_wait_for_irqclear:
+ * Waits for the IR bit to clear thus indicating IRQs are disabled for a queue
+ *
  * @apqn: The AP Queue number
  *
- * Checks the IRQ bit for the status of this APQN using ap_tapq.
- * Returns if the ap_tapq function succeeded and the bit is clear.
- * Returns if ap_tapq function failed with invalid, deconfigured or
- * checkstopped AP.
- * Otherwise retries up to 5 times after waiting 20ms.
+ * Repeatedly checks the IR bit for the status of a queue device by calling the
+ * PQAP(TAPQ) instruction every 20ms until: the IR bit is cleared; the response
+ * code from the PQAP instruction indicates the queue is not available or
+ * not operational; or the loop has executed more than 5 times.
+ *
+ * Return:
+ * - true if the bit is observed clear or the AP is non-operational (in which
+ *   case no further interrupts can be generated)
+ *
+ * - false if the IR bit is still set after all retries are exhausted, meaning
+ *   the hardware may still write to the NIB.
  */
-static void vfio_ap_wait_for_irqclear(int apqn)
+static bool vfio_ap_wait_for_irqclear(int apqn)
 {
 	struct ap_queue_status status;
 	int retry = 5;
@@ -246,7 +255,7 @@ static void vfio_ap_wait_for_irqclear(int apqn)
 		case AP_RESPONSE_NORMAL:
 		case AP_RESPONSE_RESET_IN_PROGRESS:
 			if (!status.irq_enabled)
-				return;
+				return true;
 			fallthrough;
 		case AP_RESPONSE_BUSY:
 			msleep(20);
@@ -257,12 +266,13 @@ static void vfio_ap_wait_for_irqclear(int apqn)
 		default:
 			WARN_ONCE(1, "%s: tapq rc %02x: %04x\n", __func__,
 				  status.response_code, apqn);
-			return;
+			return true;
 		}
 	} while (--retry);
 
-	WARN_ONCE(1, "%s: tapq rc %02x: %04x could not clear IR bit\n",
-		  __func__, status.response_code, apqn);
+	WARN_ONCE(1, "%s: tapq rc %02x: timed out verifying interrupts disabled for %02x.%04x\n",
+		  __func__, status.response_code, AP_QID_CARD(apqn), AP_QID_QUEUE(apqn));
+	return false;
 }
 
 /**
@@ -317,8 +327,21 @@ static struct ap_queue_status vfio_ap_irq_disable(struct vfio_ap_queue *q)
 		switch (status.response_code) {
 		case AP_RESPONSE_OTHERWISE_CHANGED:
 		case AP_RESPONSE_NORMAL:
-			vfio_ap_wait_for_irqclear(q->apqn);
-			goto end_free;
+			/*
+			 * AQIC disable was accepted (NORMAL), or the queue was
+			 * already disabled or a prior async request is still
+			 * completing (OTHERWISE_CHANGED).  In both cases, we must
+			 * wait until interrupt processing has been disabled
+			 * before proceeding.
+			 *
+			 * If it could not be determined whether interrupts
+			 * have been disabled, do not free the AQIC resources: the
+			 * hardware may still write to the NIB, so leave it pinned
+			 * to avoid a use-after-free. The resources will be leaked.
+			 */
+			if (vfio_ap_wait_for_irqclear(q->apqn))
+				goto end_free;
+			goto end_fail;
 		case AP_RESPONSE_RESET_IN_PROGRESS:
 		case AP_RESPONSE_BUSY:
 			msleep(20);
@@ -326,18 +349,46 @@ static struct ap_queue_status vfio_ap_irq_disable(struct vfio_ap_queue *q)
 		case AP_RESPONSE_Q_NOT_AVAIL:
 		case AP_RESPONSE_DECONFIGURED:
 		case AP_RESPONSE_CHECKSTOPPED:
+			/* AP not operational; no further interrupts possible */
+			WARN_ONCE(1, "%s: ap_aqic status %d\n", __func__,
+				  status.response_code);
+			goto end_free;
 		case AP_RESPONSE_INVALID_ADDRESS:
 		default:
-			/* All cases in default means AP not operational */
+			/*
+			 * The AQIC disable was rejected; IRQ is still enabled
+			 * and the hardware still holds the NIB address. Do not
+			 * free resources.
+			 */
 			WARN_ONCE(1, "%s: ap_aqic status %d\n", __func__,
 				  status.response_code);
-			goto end_free;
+			goto end_fail;
 		}
 	} while (retries--);
 
 	WARN_ONCE(1, "%s: ap_aqic status %d\n", __func__,
 		  status.response_code);
+
+end_fail:
+	/*
+	 * We are here either because of a failure to verify that
+	 * interrupts have been disabled, or because the AQIC instruction
+	 * failed to disable them. The AQIC resources - the pinned NIB page
+	 * and the registered guest ISC - cannot be freed here. The hardware
+	 * may still write to the NIB; freeing the pinned page would result
+	 * in a use-after-free kernel crash. The resources will therefore be
+	 * leaked. This is preferable to a use-after-free.
+	 */
+	return status;
+
 end_free:
+	/*
+	 * This label is reached because the queue was successfully disabled,
+	 * or because the queue is not operational, in which case interrupts
+	 * can not be processed, so free the AQIC resources - the pinned NIB
+	 * page and the registered guest ISC - used to enable interrupts
+	 * so they will not be leaked.
+	 */
 	vfio_ap_free_aqic_resources(q);
 	return status;
 }
@@ -495,7 +546,12 @@ static struct ap_queue_status vfio_ap_irq_enable(struct vfio_ap_queue *q,
 		q->saved_isc = isc;
 		break;
 	case AP_RESPONSE_OTHERWISE_CHANGED:
-		/* We could not modify IRQ settings: clear new configuration */
+		/*
+		 * IRQ control is already set as requested or a prior async
+		 * request has not yet completed; in either case, this response
+		 * comes with CC=3 indicating the new NIB and ISC were not accepted by
+		 * the hardware, so clean them up.
+		 */
 		ret = kvm_s390_gisc_unregister(kvm, isc);
 		if (ret)
 			VFIO_AP_DBF_WARN("%s: kvm_s390_gisc_unregister: rc=%d isc=%d, apqn=%#04x\n",
@@ -503,9 +559,12 @@ static struct ap_queue_status vfio_ap_irq_enable(struct vfio_ap_queue *q,
 		vfio_unpin_pages(&q->matrix_mdev->vdev, nib, 1);
 		break;
 	default:
-		pr_warn("%s: apqn %04x: response: %02x\n", __func__, q->apqn,
-			status.response_code);
-		vfio_ap_irq_disable(q);
+		/* We could not modify IRQ settings: clear new configuration */
+		ret = kvm_s390_gisc_unregister(kvm, isc);
+		if (ret)
+			VFIO_AP_DBF_WARN("%s: kvm_s390_gisc_unregister: rc=%d isc=%d, apqn=%#04x\n",
+					 __func__, ret, isc, q->apqn);
+		vfio_unpin_pages(&q->matrix_mdev->vdev, nib, 1);
 		break;
 	}
 
@@ -635,7 +694,6 @@ static int handle_pqap(struct kvm_vcpu *vcpu)
 	}
 
 	status = vcpu->run->s.regs.gprs[1];
-
 	/* If IR bit(16) is set we enable the interrupt */
 	if ((status >> (63 - 16)) & 0x01)
 		qstatus = vfio_ap_irq_enable(q, status & 0x07, vcpu);
@@ -1410,7 +1468,7 @@ static void vfio_ap_mdev_hot_unplug_domain(struct ap_matrix_mdev *matrix_mdev,
 {
 	DECLARE_BITMAP(apqis, AP_DOMAINS);
 
-	bitmap_zero(apqis, AP_DEVICES);
+	bitmap_zero(apqis, AP_DOMAINS);
 	set_bit_inv(apqi, apqis);
 	vfio_ap_mdev_hot_unplug_domains(matrix_mdev, apqis);
 }
@@ -1959,8 +2017,32 @@ static void apq_reset_check(struct work_struct *reset_work)
 		elapsed += AP_RESET_INTERVAL;
 		status = ap_tapq(q->apqn, NULL);
 		ret = apq_status_check(q->apqn, &status);
-		if (ret == -EIO)
+		if (ret == -EIO) {
+			memcpy(&q->reset_status, &status, sizeof(status));
+			return;
+		}
+		if (elapsed >= AP_RESET_MAX_WAIT) {
+		/*
+		 * Timed out waiting for reset to complete.
+		 *
+		 * The AQIC resources associated with this queue - the pinned page
+		 * containing the NIB and the registered guest ISC - cannot be freed
+		 * here. The NIB is the active DMA target for AP interrupt delivery
+		 * until the reset completes; freeing the pinned page while the
+		 * hardware may still write to it would result in a use-after-free
+		 * kernel crash.
+		 *
+		 * If the reset eventually completes, interrupts will be terminated
+		 * and the pinned NIB page and ISC registration will be leaked. This
+		 * is preferable to either a use-after-free or waiting indefinitely:
+		 * the caller of apq_reset_check() holds mdevs_lock while flush_work()
+		 * blocks holds the matrix_dev->mdevs_lock mutex, which
+		 * serializes access to all mdev objects system-wide, so blocking
+		 * here would stall all other guests using AP queues.
+		 */
+			memcpy(&q->reset_status, &status, sizeof(status));
 			return;
+		}
 		if (ret == -EBUSY) {
 			pr_notice_ratelimited(WAIT_MSG, elapsed,
 					      AP_QID_CARD(q->apqn),
@@ -2061,12 +2143,28 @@ static int vfio_ap_mdev_open_device(struct vfio_device *vdev)
 	return vfio_ap_mdev_set_kvm(matrix_mdev, vdev->kvm);
 }
 
+static void vfio_ap_mdev_release_eventfds(struct ap_matrix_mdev *matrix_mdev)
+{
+	if (matrix_mdev->req_trigger) {
+		eventfd_ctx_put(matrix_mdev->req_trigger);
+		matrix_mdev->req_trigger = NULL;
+	}
+	if (matrix_mdev->cfg_chg_trigger) {
+		eventfd_ctx_put(matrix_mdev->cfg_chg_trigger);
+		matrix_mdev->cfg_chg_trigger = NULL;
+	}
+}
+
 static void vfio_ap_mdev_close_device(struct vfio_device *vdev)
 {
 	struct ap_matrix_mdev *matrix_mdev =
 		container_of(vdev, struct ap_matrix_mdev, vdev);
 
 	vfio_ap_mdev_unset_kvm(matrix_mdev);
+
+	mutex_lock(&matrix_dev->mdevs_lock);
+	vfio_ap_mdev_release_eventfds(matrix_mdev);
+	mutex_unlock(&matrix_dev->mdevs_lock);
 }
 
 static void vfio_ap_mdev_request(struct vfio_device *vdev, unsigned int count)
@@ -2697,11 +2795,11 @@ static void vfio_ap_mdev_on_cfg_remove(struct ap_config_info *cur_config_info,
 	do_remove |= bitmap_andnot(aqrem,
 				   (unsigned long *)prev_config_info->aqm,
 				   (unsigned long *)cur_config_info->aqm,
-				   AP_DEVICES);
+				   AP_DOMAINS);
 	do_remove |= bitmap_andnot(cdrem,
 				   (unsigned long *)prev_config_info->adm,
 				   (unsigned long *)cur_config_info->adm,
-				   AP_DEVICES);
+				   AP_DOMAINS);
 
 	if (do_remove)
 		vfio_ap_mdev_cfg_remove(aprem, aqrem, cdrem);
@@ -2812,7 +2910,7 @@ static void vfio_ap_mdev_cfg_add(unsigned long *apm_add, unsigned long *aqm_add,
 		bitmap_and(matrix_mdev->aqm_add,
 			   matrix_mdev->matrix.aqm, aqm_add, AP_DOMAINS);
 		bitmap_and(matrix_mdev->adm_add,
-			   matrix_mdev->matrix.adm, adm_add, AP_DEVICES);
+			   matrix_mdev->matrix.adm, adm_add, AP_DOMAINS);
 
 		mutex_unlock(&matrix_dev->mdevs_lock);
 	}

gemini-3.1-pro-preview

null

null

							input: 5752
							output: 20
							thoughts: 589
						

**Analyzing the VFIO-AP Driver Patch**

Okay, let's break down this patch to `drivers/s390/crypto/vfio_ap_ops.c`. My initial impression is that this is primarily about robustness and resource management in the face of potential hardware quirks or failures. I see a few key areas of focus:

First, there's the introduction of `AP_RESET_MAX_WAIT` and the associated changes to how we handle interrupt clearing. The `vfio_ap_wait_for_irqclear` function now returns a boolean, clearly indicating success or failure due to timeout. This is a crucial shift towards safer error handling. The subsequent modifications to `vfio_ap_irq_disable` are smart; by checking the return value from `vfio_ap_wait_for_irqclear`, the patch ensures that resources aren't freed prematurely if a timeout occurs. Leaking resources in a timeout situation is *far* better than a use-after-free scenario. This is a very good defensive coding practice.

Second, the `vfio_ap_irq_enable` changes are interesting. Specifically, the handling of `AP_RESPONSE_OTHERWISE_CHANGED` and the `default` case. It appears we're refining the interrupt enable flow to be more resilient. The unregistration of gisc and unpinning of pages in the `default` case, instead of calling `vfio_ap_irq_disable`, suggests a more direct and potentially safer approach in those scenarios. This likely aims to optimize the failure path when dealing with hardware.

Third, the bitmap size corrections in `vfio_ap_mdev_hot_unplug_domain`, `vfio_ap_mdev_on_cfg_remove`, and `vfio_ap_mdev_cfg_add` immediately caught my eye. The switch from `AP_DEVICES` to `AP_DOMAINS` suggests a potential mismatch in the data structures being used. Now, `AP_DEVICES` and `AP_DOMAINS` are both defined as 256. This means that a previous bug where the size was wrong has been corrected!

Finally, the new `vfio_ap_mdev_release_eventfds` function and its integration into `vfio_ap_mdev_close_device` indicate better resource cleanup during device closure. This is consistent with the overall focus on preventing resource leaks and ensuring clean device teardown. The timeout check in `apq_reset_check` further reinforces this.

My main concern, as always, is uninitialized memory. With all the changes around error handling and resource management, I need to look closely to make sure no new uninitialized memory vulnerabilities have been introduced. The defensive coding is there, but I need to confirm the compiler's behavior. I will look for other changes or side effects, especially around the changes to `irq_enable` and `irq_disable` that could introduce a race condition or uninitialized memory read/write. I'll need to double-check that the timeout logic doesn't create any new exposure, especially during resets.

{
  "Expression": "#define AP_DEVICES"
}

{
  "Output": "drivers/s390/crypto/ap_bus.h-21-\ndrivers/s390/crypto/ap_bus.h:22:#define AP_DEVICES 256\t\t/* Number of AP devices. */\ndrivers/s390/crypto/ap_bus.h-23-#define AP_DOMAINS 256\t\t/* Number of AP domains. */\n--\ndrivers/s390/crypto/vfio_ap_ops.c=1712=static ssize_t ap_config_show(struct device *dev, struct device_attribute *attr,\n--\ndrivers/s390/crypto/vfio_ap_ops.c-1725-/* Number of characters needed for a complete hex mask representing the bits in ..  */\ndrivers/s390/crypto/vfio_ap_ops.c:1726:#define AP_DEVICES_STRLEN\t(AP_DEVICES / 4 + 3)\ndrivers/s390/crypto/vfio_ap_ops.c-1727-#define AP_DOMAINS_STRLEN\t(AP_DOMAINS / 4 + 3)\n"
}

gemini-3.1-pro-preview

null

null

							input: 7319
							output: 24
							thoughts: 257
						

**My Assessment of the Recent Code Changes**

Okay, so looking at these changes, I see that the bitmap size adjustment for `AP_DEVICES` and `AP_DOMAINS` to 256 is just a semantic correction. It doesn't actually alter the memory footprint, which is good. The core of the changes seem to revolve around handling timeouts and, most importantly, preventing use-after-free (UAF) vulnerabilities. I'm satisfied that these changes don't introduce any new uninitialized memory risks; they're strictly focused on improving UAF protection, timeout management, and preventing resource leaks.

Given that UAF is a primary concern here, KASAN is the ideal tool for catching these sorts of issues. KMSAN doesn't seem to be relevant in this context.

Now, let me double-check the handling of `q->reset_status`. I'm seeing a `memcpy(&q->reset_status, &status, sizeof(status));` which immediately makes me ask, "Is `status` properly initialized before the copy?" It's populated by either `ap_tapq(q->apqn, NULL);` or `ap_tapq(q->apqn, &status);`, but in the `apq_reset_check` function... Hmm, let me see...

```c
		status = ap_tapq(q->apqn, NULL);
		ret = apq_status_check(q->apqn, &status);
```

Ah, right. The `ap_tapq` function *returns* a `struct ap_queue_status`. That's a key detail to remember. I should review `ap_tapq` itself to make sure the returned status is correctly handled and that there are no potential issues there.

{
  "Expression": "struct ap_queue_status ap_tapq"
}

{
  "Output": "arch/s390/include/asm/ap.h=105=struct ap_tapq_hwinfo {\n--\narch/s390/include/asm/ap.h-148- */\narch/s390/include/asm/ap.h:149:static inline struct ap_queue_status ap_tapq(ap_qid_t qid,\narch/s390/include/asm/ap.h-150-\t\t\t\t\t     struct ap_tapq_hwinfo *info)\n"
}

gemini-3.1-pro-preview

null

null

							input: 8121
							output: 26
							thoughts: 12
						

Here's my attempt at summarizing the thought process, tailored for an expert audience:

**Analyzing the `ap_tapq` Implementation**

Alright, let's dive into this `ap_tapq` implementation. I'm immediately curious about the specifics of its internal structure and the algorithms it's leveraging. My mind's running through potential approaches: is it using some variant of an approximate priority queue? How is it handling the potential trade-offs between speed and accuracy in that approximation? Are they sacrificing correctness or completeness? Or, are there any guarantees associated? Does it employ any clever data structures or optimizations for the underlying priority queue, to get close to the behavior of a proper priority queue, but with acceptable compromises? I need to focus on aspects like how ties are broken, how duplicate entries are handled, and most importantly, the expected worst-case runtime complexity for different operations (insertion, deletion, querying, merging if applicable). I’ll be looking for any hints about the underlying mechanism used for the approximation. Also, I'm expecting some comments to reveal the context and motivation behind the use of an approximate queue. What are the constraints? What problems are they solving? Let's get to the details and see if there are any obvious red flags, or any clever algorithmic tricks at play.

{
  "Expression": "static inline struct ap_queue_status ap_tapq"
}

{
  "Output": "arch/s390/include/asm/ap.h=105=struct ap_tapq_hwinfo {\n--\narch/s390/include/asm/ap.h-148- */\narch/s390/include/asm/ap.h:149:static inline struct ap_queue_status ap_tapq(ap_qid_t qid,\narch/s390/include/asm/ap.h-150-\t\t\t\t\t     struct ap_tapq_hwinfo *info)\n"
}

gemini-3.1-pro-preview

null

null

							input: 8566
							output: 42
							thoughts: 27
						

Okay, here's my interpretation of that thought process, assuming I'm a seasoned expert diving into some s390 architecture code:

**Diving into the AP Interrupt Handler Definition**

Alright, time to crack open the `arch/s390/include/asm/ap.h` header file. My goal here is likely to understand the inner workings of the Asynchronous Processor (AP) interrupt handling mechanism on the s390 architecture. I expect this file to contain the crucial data structures and macros related to how the system responds to AP interrupts. I'm probably looking for the definition of something like `ap_tapq` – that name definitely suggests something related to a Task Activation Parameter Queue, or maybe a similar queue related to the interrupt handling process. I'm keen to see how these interrupt contexts are managed, how the processor responds to the interrupts, and what data structures are involved. This is going to be key to debugging or optimizing related system behavior. Let's see what secrets this header file holds.

{
  "File": "arch/s390/include/asm/ap.h",
  "FirstLine": 145,
  "LineCount": 30
}

{
  "Contents": " 145:\t * @info: Pointer to tapq hwinfo struct\n 146:\t *\n 147:\t * Returns AP queue status structure.\n 148:\t */\n 149:\tstatic inline struct ap_queue_status ap_tapq(ap_qid_t qid,\n 150:\t\t\t\t\t\t     struct ap_tapq_hwinfo *info)\n 151:\t{\n 152:\t\tunion ap_queue_status_reg reg1;\n 153:\t\tunsigned long reg2;\n 154:\t\n 155:\t\tasm volatile(\n 156:\t\t\t\"\tlgr\t0,%[qid]\\n\"\t\t/* qid into gr0 */\n 157:\t\t\t\"\tlghi\t2,0\\n\"\t\t\t/* 0 into gr2 */\n 158:\t\t\t\"\t.insn\trre,0xb2af0000,0,0\\n\"\t/* PQAP(TAPQ) */\n 159:\t\t\t\"\tlgr\t%[reg1],1\\n\"\t\t/* gr1 (status) into reg1 */\n 160:\t\t\t\"\tlgr\t%[reg2],2\"\t\t/* gr2 into reg2 */\n 161:\t\t\t: [reg1] \"=\u0026d\" (reg1.value), [reg2] \"=\u0026d\" (reg2)\n 162:\t\t\t: [qid] \"d\" (qid)\n 163:\t\t\t: \"cc\", \"0\", \"1\", \"2\");\n 164:\t\tif (info)\n 165:\t\t\tinfo-\u003evalue = reg2;\n 166:\t\treturn reg1.status;\n 167:\t}\n 168:\t\n 169:\t/**\n 170:\t * ap_test_queue(): Test adjunct processor queue.\n 171:\t * @qid: The AP queue number\n 172:\t * @tbit: Test facilities bit\n 173:\t * @info: Ptr to tapq gr2 struct\n 174:\t *\n"
}

gemini-3.1-pro-preview

null

null

							input: 9373
							output: 283
							thoughts: 404
						

**My Assessment of the VFIO-AP Driver Patch**

Okay, here's my take. I've examined this patch series for the s390 vfio_ap driver. My focus is on understanding the potential memory safety implications, especially use-after-free and uninitialized memory issues.

The core of the patch is about handling resource management around the AQIC hardware. Specifically, the team is choosing to *leak* resources (pinned NIB pages and guest ISCs) in certain failure scenarios, rather than risk a use-after-free. The hardware is expected to confirm interrupts are disabled or a reset has completed within a timeout. If that doesn't happen, the patch prevents potential UAF by leaving the resources allocated. I can see that this approach makes sense, a controlled leak is far better than a potential UAF.

I've checked the code, and I see no indication that the changes introduce *new* uninitialized memory risks. The key status variable that's copied into `q->reset_status` is *fully* initialized. The inline assembly instruction `ap_tapq` reads directly from the hardware register, populating the `status` variable. `union ap_queue_status_reg` and its member `value` from `gr1` are populated from a hardware register. So, there's no way to end up with uninitialized memory here.

Furthermore, I understand that there are semantic corrections to bitmap sizes. The patch fixes incorrect bitmap sizes used in configuration removal and addition. There's no functional change, merely a clarification from `AP_DEVICES` to `AP_DOMAINS` because they're both size 256. This is important to ensure consistency and readability, but the patch isn't changing how the bitmaps are used or allocated.

Given that the primary concerns addressed by the patch are use-after-free bugs and resource leaks, I think KASAN, with its detection of UAF, is perfectly sufficient for testing. KMSAN is overkill here. We aren't introducing any new risks of uninitialized memory usage or info-leaks. Standard debugging tools will suffice. I'm satisfied that this patch addresses the use-after-free concerns without introducing new vulnerabilities.

{
  "KMSANReasoning": "The patch series addresses potential use-after-free (UAF) vulnerabilities and resource management in the s390 vfio_ap driver. Specifically, it modifies the driver to intentionally leak AQIC resources (pinned NIB pages and registered guest ISCs) if the hardware fails to confirm that interrupts have been disabled or a reset has completed within a timeout. This prevents the hardware from writing to freed memory, which would cause a UAF. It also corrects the bitmap sizes used in configuration removal and addition from `AP_DEVICES` to `AP_DOMAINS` (both are 256, so this is a semantic fix).\n\nNone of these changes introduce new allocations, complex data structures, or user-space copies that could expose uninitialized memory. The `status` variable copied into `q-\u003ereset_status` is fully initialized by the `ap_tapq` inline assembly instruction reading from hardware registers.\n\nSince the primary risks addressed by this patch are use-after-free bugs and resource leaks, standard KASAN (which detects UAF) and standard debugging tools are perfectly suited for testing these changes. There is no risk of uninitialized memory usage or info-leaks that would require a dedicated KMSAN fuzzing session.",
  "NeedsKMSAN": false
}

{
  "KMSANReasoning": "The patch series addresses potential use-after-free (UAF) vulnerabilities and resource management in the s390 vfio_ap driver. Specifically, it modifies the driver to intentionally leak AQIC resources (pinned NIB pages and registered guest ISCs) if the hardware fails to confirm that interrupts have been disabled or a reset has completed within a timeout. This prevents the hardware from writing to freed memory, which would cause a UAF. It also corrects the bitmap sizes used in configuration removal and addition from `AP_DEVICES` to `AP_DOMAINS` (both are 256, so this is a semantic fix).\n\nNone of these changes introduce new allocations, complex data structures, or user-space copies that could expose uninitialized memory. The `status` variable copied into `q-\u003ereset_status` is fully initialized by the `ap_tapq` inline assembly instruction reading from hardware registers.\n\nSince the primary risks addressed by this patch are use-after-free bugs and resource leaks, standard KASAN (which detects UAF) and standard debugging tools are perfectly suited for testing these changes. There is no risk of uninitialized memory usage or info-leaks that would require a dedicated KMSAN fuzzing session.",
  "NeedsKMSAN": false
}