AI Trajectory

Trajectory: (Expand/Collapse All)
Seq	Timestamp	Type	Name	Duration
0/0	2026/10/26 17:09	flow	patch-triage	14m Args: null Results: { "EnableConfigs": null, "FocusSymbols": [], "KMSANReasoning": "", "NeedsKMSAN": false, "Reasoning": "The changes modify ARM LPAE page table walking and dirty tracking routines (io_pgtable_visit and visit_dirty) in drivers/iommu/io-pgtable-arm.c, as well as remove an unused helper (iommu_dirty_bitmap_record) from include/linux/iommu.h. The modified dirty tracking logic is only consumed by the ARM SMMU v3 driver (arm-smmu-v3), which depends on CONFIG_ARM64 and cannot be built on amd64. Furthermore, the ARM LPAE io-pgtable implementation is only used by ARM-specific platform devices and GPUs (ARM SMMU, Apple DART, Panfrost, Panthor, Qualcomm MSM) that are structurally unreachable and not emulated in standard amd64 virtualized environments. Therefore, the modified code paths are unreachable on the target architecture (amd64).", "WorthFuzzing": false }
1/1	2026/10/26 17:09	action	read-patch-diff	0m Args: null Results: { "PatchDiff": "commit ae793f2bff0dfbc4778452bbd2ecb2666a7528c4\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate: Mon Oct 26 17:09:07 2026 +0000\n\n syz-cluster: applied patch under review\n\ndiff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c\nindex 476c0e25631af1..6513dac26e7968 100644\n--- a/drivers/iommu/io-pgtable-arm.c\n+++ b/drivers/iommu/io-pgtable-arm.c\n@@ -821,7 +821,7 @@ static int io_pgtable_visit(struct arm_lpae_io_pgtable data,\n \t\treturn ret;\n \n \tif (iopte_leaf(pte, lvl, iop-\u003efmt)) {\n-\t\twalk_data-\u003eaddr += size;\n+\t\twalk_data-\u003eaddr = ALIGN_DOWN(walk_data-\u003eaddr, size) + size;\n \t\treturn 0;\n \t}\n \n@@ -868,9 +868,18 @@ static int visit_dirty(struct io_pgtable_walk_data walk_data, int lvl,\n \t\treturn 0;\n \n \tif (iopte_writeable_dirty(ptep)) {\n-\t\tiommu_dirty_bitmap_record(dirty, walk_data-\u003eaddr, size);\n-\t\tif (!(walk_data-\u003eflags \u0026 IOMMU_DIRTY_NO_CLEAR))\n+\t\tu64 iova = ALIGN_DOWN(walk_data-\u003eaddr, size);\n+\n+\t\tif (dirty-\u003ebitmap)\n+\t\t\tiova_bitmap_set(dirty-\u003ebitmap, iova, size);\n+\n+\t\tif (!(walk_data-\u003eflags \u0026 IOMMU_DIRTY_NO_CLEAR)) {\n \t\t\tiopte_set_writeable_clean(ptep);\n+\t\t\tif (dirty-\u003egather)\n+\t\t\t\tio_pgtable_tlb_add_page(walk_data-\u003eiop,\n+\t\t\t\t\t\t\tdirty-\u003egather, iova,\n+\t\t\t\t\t\t\tsize);\n+\t\t}\n \t}\n \n \treturn 0;\ndiff --git a/include/linux/iommu.h b/include/linux/iommu.h\nindex ef5043752a3651..df57ead2cc3c42 100644\n--- a/include/linux/iommu.h\n+++ b/include/linux/iommu.h\n@@ -1106,17 +1106,6 @@ static inline void iommu_dirty_bitmap_init(struct iommu_dirty_bitmap dirty,\n \tdirty-\u003egather = gather;\n }\n \n-static inline void iommu_dirty_bitmap_record(struct iommu_dirty_bitmap dirty,\n-\t\t\t\t\t unsigned long iova,\n-\t\t\t\t\t unsigned long length)\n-{\n-\tif (dirty-\u003ebitmap)\n-\t\tiova_bitmap_set(dirty-\u003ebitmap, iova, length);\n-\n-\tif (dirty-\u003egather)\n-\t\tiommu_iotlb_gather_add_range(dirty-\u003egather, iova, length);\n-}\n-\n / PCI device grouping function /\n extern struct iommu_group pci_device_group(struct device dev);\n / Generic device grouping function /\n@@ -1449,12 +1438,6 @@ static inline void iommu_dirty_bitmap_init(struct iommu_dirty_bitmap dirty,\n {\n }\n \n-static inline void iommu_dirty_bitmap_record(struct iommu_dirty_bitmap dirty,\n-\t\t\t\t\t unsigned long iova,\n-\t\t\t\t\t unsigned long length)\n-{\n-}\n-\n static inline void iommu_device_unregister(struct iommu_device iommu)\n {\n }\n" }
2/1	2026/10/26 17:09	agent	patch-evaluator	14m Model: core Args: null Results: { "EnableConfigs": null, "FocusSymbols": [], "Reasoning": "The changes modify ARM LPAE page table walking and dirty tracking routines (io_pgtable_visit and visit_dirty) in drivers/iommu/io-pgtable-arm.c, as well as remove an unused helper (iommu_dirty_bitmap_record) from include/linux/iommu.h. The modified dirty tracking logic is only consumed by the ARM SMMU v3 driver (arm-smmu-v3), which depends on CONFIG_ARM64 and cannot be built on amd64. Furthermore, the ARM LPAE io-pgtable implementation is only used by ARM-specific platform devices and GPUs (ARM SMMU, Apple DART, Panfrost, Panthor, Qualcomm MSM) that are structurally unreachable and not emulated in standard amd64 virtualized environments. Therefore, the modified code paths are unreachable on the target architecture (amd64).", "WorthFuzzing": false } Instruction: You are an expert Linux kernel maintainer and security engineer. Your job is to review a provided patch series and evaluate whether it warrants fuzzing with syzkaller. IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in your workspace. Do NOT rely on internal assumptions. You must actively use your code access tools to inspect the actual source code, callers, and surrounding context. ================================================================================ 1. CORE TRIAGE PHILOSOPHY ================================================================================ The goal of patch fuzzing is to discover crashes, regressions, exposed latent bugs, and newly triggered assertions introduced by the patch series. - REACHABILITY IS THE PRIMARY GATE: Fuzzing can only discover bugs in code that can actually execute in standard virtualized environments (GCE or QEMU, utilizing software-emulated devices like USB gadgets, netdev, tun/tap). If the modified code is structurally unreachable (see Section 2), it MUST NOT be fuzzed, regardless of whether it adds assertions or complex logic. - DO NOT BLINDLY TRUST "NO FUNCTIONAL CHANGE" (NFCI) OR "REFACTORING" CLAIMS: Patch authors routinely label changes as "cleanups", "refactorings", or state "No functional change intended". Do NOT take these claims at face value. Code refactorings that rearrange logic, introduce helper functions, or alter state management in core subsystems frequently introduce subtle semantic shifts or uncover latent kernel bugs. If reachable executable code is modified or refactored, it MUST be fuzzed. - NEW OR MODIFIED ASSERTIONS IN REACHABLE CODE MUST BE FUZZED: When a patch introduces or modifies runtime checks or assertions (e.g., WARN_ON, VM_WARN_ON, BUG_ON, lockdep_assert) in reachable code paths, it enforces new or stricter invariants. Even if the author believes the invariant always holds, fuzzing is essential to verify whether an unusual sequence of operations can violate it. ================================================================================ 2. WHEN TO RETURN WorthFuzzing=false (NEGATIVE CRITERIA) ================================================================================ Return WorthFuzzing=false ONLY IF all modified code falls strictly into one or more of these categories: - Non-kernel and non-executable changes: * Modifications to Documentation/, comments, or spelling fixes. * User-space directories, self-tests, samples, or scripts (e.g., tools/, samples/, scripts/, usr/) that do not affect the compiled kernel image (vmlinux) or kernel modules. * Purely decorative logging (e.g., message strings in pr_err, printk, dev_info) or tracepoints that do not alter control flow or data structures. * Build system or Kconfig changes that do not alter compiled C logic. - Structurally unreachable hardware: * Vendor-specific PCIe switches, SmartNICs, or GPU drivers (e.g., mlxsw, pds_core, qed, ionic, amdgpu) requiring physical ASIC/PCIe cards not emulated in standard QEMU. - Unreachable execution paths: * Driver teardown callbacks (.remove, .shutdown, pci_unregister_driver) executed only during physical PCI hot-unplug or manual sysfs driver unbinding. * Code paths exclusive to architectures other than the target architecture. ================================================================================ 3. WHEN TO RETURN WorthFuzzing=true (POSITIVE CRITERIA) ================================================================================ Return WorthFuzzing=true whenever the patch touches reachable executable code, including: - Core Subsystems: * Any logic modifications in memory management (mm/), synchronization/locking (kernel/locking/), BPF, scheduler, core networking, VFS, or syscall handling. - Refactorings and Code Cleanups: * Any restructuring of reachable data structures, helper abstractions, or algorithm flows. - Runtime Assertions and Defensive Checks: * Any introduction or alteration of assertions (WARN_ON, VM_WARN_ON, BUG_ON, etc.) in reachable paths. - Reachable Drivers and Protocols: Drivers accessible via virtual buses (virtio, USB gadget, loopback, netlink, binder, sockets, etc.). ================================================================================ 4. EXTRACTING FocusSymbols (PREVENTING DILUTION) ================================================================================ When WorthFuzzing=true, you must extract specific kernel functions into FocusSymbols to guide the fuzzer: - AVOID UBIQUITOUS LIFECYCLE HOT-PATHS: Do NOT list generic, ubiquitous functions called by almost every program in the corpus (including, but not limited to: general memory allocators and deallocators, page fault and trap handlers, or core synchronization primitives; this is not an exhaustive list). Listing ubiquitous functions causes the fuzzer to classify thousands of unrelated tests as "focused", which severely dilutes fuzzing effort away from the actual changes. - TARGET SPECIFIC FEATURE LOGIC AND ENTRYPOINTS: List functions that specifically implement the logic being added or altered, or direct API entrypoints for the subsystem feature under review. - HANDLING STATIC INLINE FUNCTIONS IN HEADERS (.h): Compiler-inlined static functions (such as static inlines in mm/.h or include/linux/.h) lack distinct symbol addresses in vmlinux and cannot be targeted directly by symbol coverage filters. If the changes are primarily in static inline helpers, identify non-static, feature-specific caller functions in .c files that exercise them (avoiding ubiquitous lifecycle wrappers). ================================================================================ 5. IDENTIFYING EnableConfigs ================================================================================ Identify any specific CONFIG_ options required to properly compile and reach the modified code: - Inspect Kconfig files and #ifdef guards; do not make assumptions. - Check "depends on" lines in Kconfig to include any non-standard parent subsystem configs needed. - Strip any '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. Prompt: Target architecture: amd64 For your convenience, here is the diff of the changes: commit ae793f2bff0dfbc4778452bbd2ecb2666a7528c4 Author: syz-cluster <triage@syzkaller.com> Date: Mon Oct 26 17:09:07 2026 +0000 syz-cluster: applied patch under review diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c index 476c0e25631af1..6513dac26e7968 100644 --- a/drivers/iommu/io-pgtable-arm.c +++ b/drivers/iommu/io-pgtable-arm.c @@ -821,7 +821,7 @@ static int io_pgtable_visit(struct arm_lpae_io_pgtable data, return ret; if (iopte_leaf(pte, lvl, iop->fmt)) { - walk_data->addr += size; + walk_data->addr = ALIGN_DOWN(walk_data->addr, size) + size; return 0; } @@ -868,9 +868,18 @@ static int visit_dirty(struct io_pgtable_walk_data walk_data, int lvl, return 0; if (iopte_writeable_dirty(ptep)) { - iommu_dirty_bitmap_record(dirty, walk_data->addr, size); - if (!(walk_data->flags & IOMMU_DIRTY_NO_CLEAR)) + u64 iova = ALIGN_DOWN(walk_data->addr, size); + + if (dirty->bitmap) + iova_bitmap_set(dirty->bitmap, iova, size); + + if (!(walk_data->flags & IOMMU_DIRTY_NO_CLEAR)) { iopte_set_writeable_clean(ptep); + if (dirty->gather) + io_pgtable_tlb_add_page(walk_data->iop, + dirty->gather, iova, + size); + } } return 0; diff --git a/include/linux/iommu.h b/include/linux/iommu.h index ef5043752a3651..df57ead2cc3c42 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -1106,17 +1106,6 @@ static inline void iommu_dirty_bitmap_init(struct iommu_dirty_bitmap dirty, dirty->gather = gather; } -static inline void iommu_dirty_bitmap_record(struct iommu_dirty_bitmap dirty, - unsigned long iova, - unsigned long length) -{ - if (dirty->bitmap) - iova_bitmap_set(dirty->bitmap, iova, length); - - if (dirty->gather) - iommu_iotlb_gather_add_range(dirty->gather, iova, length); -} - / PCI device grouping function / extern struct iommu_group pci_device_group(struct device dev); / Generic device grouping function / @@ -1449,12 +1438,6 @@ static inline void iommu_dirty_bitmap_init(struct iommu_dirty_bitmap dirty, { } -static inline void iommu_dirty_bitmap_record(struct iommu_dirty_bitmap dirty, - unsigned long iova, - unsigned long length) -{ -} - static inline void iommu_device_unregister(struct iommu_device iommu) { }
3/2	2026/10/26 17:09	llm	patch-evaluator	1m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 3697 output: 32 thoughts: 464 Thoughts: Analyzing a Patch to io-pgtable-arm.c Okay, so I'm looking at a patch that touches `drivers/iommu/io-pgtable-arm.c` and `include/linux/iommu.h`. Let's break down the changes. First, in `io-pgtable-arm.c`, I see a modification to `io_pgtable_visit`. The change seems to be correcting the address calculation. It's now aligning the address down before incrementing, which suggests they're dealing with page boundaries more carefully, ensuring proper alignment with the page size. That's a classic IOMMU concern, so it makes sense. Next, `visit_dirty` has a more substantial update. They're recording dirty page information more explicitly, using an `iova_bitmap_set`. This implies a move away from the older `iommu_dirty_bitmap_record` function, which has also been removed. The inclusion of a `gather` pointer in the `dirty` structure, along with the `io_pgtable_tlb_add_page` function call, suggests they're optimizing TLB management. The `iova` alignment before the bitmap and TLB updates is consistent with the `io_pgtable_visit` change. It looks like they're trying to improve the efficiency of tracking and clearing dirty pages, possibly for performance or to handle more complex IOMMU configurations. This could be related to some work on cache coherency for specific platforms. Okay, now for the red flag. This `io-pgtable-arm.c` file... why are we seeing changes there? This is specifically for the ARM architecture. My target architecture is amd64. This raises an immediate question: Can this code actually be compiled and used on amd64? This doesn't make intuitive sense. Something seems off here. Perhaps this code is compiled and included in the kernel, regardless of the architecture? I need to figure out who calls or depends on this code. Time to fire up `grepper` and see who's actually using this stuff. This needs investigation; there might be some misconfiguration, abstraction, or an unusual dependency going on.
4/2	2026/10/26 17:10	tool	grepper	0m Args: { "Expression": "io_pgtable.arm", "PathPrefixes": [ "drivers/iommu" ] } Results:* { "Output": "drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c=338=static void arm_smmu_test_make_s2_ste(struct arm_smmu_ste ste,\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c-352-\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c:353:\tio_pgtable.cfg.arm_lpae_s2_cfg.vttbr = 0xdaedbeefdeadbeefULL;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c:354:\tio_pgtable.cfg.arm_lpae_s2_cfg.vtcr.ps = 1;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c:355:\tio_pgtable.cfg.arm_lpae_s2_cfg.vtcr.tg = 2;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c:356:\tio_pgtable.cfg.arm_lpae_s2_cfg.vtcr.sh = 3;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c:357:\tio_pgtable.cfg.arm_lpae_s2_cfg.vtcr.orgn = 1;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c:358:\tio_pgtable.cfg.arm_lpae_s2_cfg.vtcr.irgn = 2;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c:359:\tio_pgtable.cfg.arm_lpae_s2_cfg.vtcr.sl = 3;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c:360:\tio_pgtable.cfg.arm_lpae_s2_cfg.vtcr.tsz = 4;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c-361-\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c=495=static void arm_smmu_test_make_s1_cd(struct arm_smmu_cd cd, unsigned int asid)\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c-507-\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c:508:\tio_pgtable.cfg.arm_lpae_s1_cfg.ttbr = 0xdaedbeefdeadbeefULL;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c:509:\tio_pgtable.cfg.arm_lpae_s1_cfg.tcr.ips = 1;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c:510:\tio_pgtable.cfg.arm_lpae_s1_cfg.tcr.tg = 2;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c:511:\tio_pgtable.cfg.arm_lpae_s1_cfg.tcr.sh = 3;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c:512:\tio_pgtable.cfg.arm_lpae_s1_cfg.tcr.orgn = 1;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c:513:\tio_pgtable.cfg.arm_lpae_s1_cfg.tcr.irgn = 2;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c:514:\tio_pgtable.cfg.arm_lpae_s1_cfg.tcr.tsz = 4;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c:515:\tio_pgtable.cfg.arm_lpae_s1_cfg.mair = 0xabcdef012345678ULL;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c-516-\n--\ndrivers/iommu/io-pgtable-arm-selftests.c=154=static void arm_lpae_do_selftests(struct kunit test)\n--\ndrivers/iommu/io-pgtable-arm-selftests.c-200-\ndrivers/iommu/io-pgtable-arm-selftests.c:201:static struct kunit_case io_pgtable_arm_test_cases[] = {\ndrivers/iommu/io-pgtable-arm-selftests.c-202-\tKUNIT_CASE(arm_lpae_do_selftests),\n--\ndrivers/iommu/io-pgtable-arm-selftests.c-205-\ndrivers/iommu/io-pgtable-arm-selftests.c:206:static struct kunit_suite io_pgtable_arm_test = {\ndrivers/iommu/io-pgtable-arm-selftests.c-207-\t.name = \"io-pgtable-arm-test\",\ndrivers/iommu/io-pgtable-arm-selftests.c:208:\t.test_cases = io_pgtable_arm_test_cases,\ndrivers/iommu/io-pgtable-arm-selftests.c-209-};\ndrivers/iommu/io-pgtable-arm-selftests.c-210-\ndrivers/iommu/io-pgtable-arm-selftests.c:211:kunit_test_suite(io_pgtable_arm_test);\ndrivers/iommu/io-pgtable-arm-selftests.c-212-\n--\ndrivers/iommu/io-pgtable-arm-v7s.c=644=static phys_addr_t arm_v7s_iova_to_phys(struct io_pgtable_ops ops,\n--\ndrivers/iommu/io-pgtable-arm-v7s.c-666-\ndrivers/iommu/io-pgtable-arm-v7s.c:667:static struct io_pgtable arm_v7s_alloc_pgtable(struct io_pgtable_cfg cfg,\ndrivers/iommu/io-pgtable-arm-v7s.c-668-\t\t\t\t\t\tvoid cookie)\n--\ndrivers/iommu/io-pgtable-arm-v7s.c-770-\ndrivers/iommu/io-pgtable-arm-v7s.c:771:struct io_pgtable_init_fns io_pgtable_arm_v7s_init_fns = {\ndrivers/iommu/io-pgtable-arm-v7s.c-772-\t.alloc\t= arm_v7s_alloc_pgtable,\n--\ndrivers/iommu/io-pgtable-arm.c=797=static int arm_lpae_pgtable_walk(struct io_pgtable_ops ops, unsigned long iova,\n--\ndrivers/iommu/io-pgtable-arm.c-810-\ndrivers/iommu/io-pgtable-arm.c:811:static int io_pgtable_visit(struct arm_lpae_io_pgtable data,\ndrivers/iommu/io-pgtable-arm.c-812-\t\t\t struct io_pgtable_walk_data walk_data,\n--\ndrivers/iommu/io-pgtable-arm.c=1224=arm_mali_lpae_alloc_pgtable(struct io_pgtable_cfg cfg, void cookie)\n--\ndrivers/iommu/io-pgtable-arm.c-1281-\ndrivers/iommu/io-pgtable-arm.c:1282:struct io_pgtable_init_fns io_pgtable_arm_64_lpae_s1_init_fns = {\ndrivers/iommu/io-pgtable-arm.c-1283-\t.caps\t= IO_PGTABLE_CAP_CUSTOM_ALLOCATOR,\n--\ndrivers/iommu/io-pgtable-arm.c-1287-\ndrivers/iommu/io-pgtable-arm.c:1288:struct io_pgtable_init_fns io_pgtable_arm_64_lpae_s2_init_fns = {\ndrivers/iommu/io-pgtable-arm.c-1289-\t.caps\t= IO_PGTABLE_CAP_CUSTOM_ALLOCATOR,\n--\ndrivers/iommu/io-pgtable-arm.c-1293-\ndrivers/iommu/io-pgtable-arm.c:1294:struct io_pgtable_init_fns io_pgtable_arm_32_lpae_s1_init_fns = {\ndrivers/iommu/io-pgtable-arm.c-1295-\t.caps\t= IO_PGTABLE_CAP_CUSTOM_ALLOCATOR,\n--\ndrivers/iommu/io-pgtable-arm.c-1299-\ndrivers/iommu/io-pgtable-arm.c:1300:struct io_pgtable_init_fns io_pgtable_arm_32_lpae_s2_init_fns = {\ndrivers/iommu/io-pgtable-arm.c-1301-\t.caps\t= IO_PGTABLE_CAP_CUSTOM_ALLOCATOR,\n--\ndrivers/iommu/io-pgtable-arm.c-1305-\ndrivers/iommu/io-pgtable-arm.c:1306:struct io_pgtable_init_fns io_pgtable_arm_mali_lpae_init_fns = {\ndrivers/iommu/io-pgtable-arm.c-1307-\t.caps\t= IO_PGTABLE_CAP_CUSTOM_ALLOCATOR,\n--\ndrivers/iommu/io-pgtable.c=16=io_pgtable_init_table[IO_PGTABLE_NUM_FMTS] = {\ndrivers/iommu/io-pgtable.c-17-#ifdef CONFIG_IOMMU_IO_PGTABLE_LPAE\ndrivers/iommu/io-pgtable.c:18:\t[ARM_32_LPAE_S1] = \u0026io_pgtable_arm_32_lpae_s1_init_fns,\ndrivers/iommu/io-pgtable.c:19:\t[ARM_32_LPAE_S2] = \u0026io_pgtable_arm_32_lpae_s2_init_fns,\ndrivers/iommu/io-pgtable.c:20:\t[ARM_64_LPAE_S1] = \u0026io_pgtable_arm_64_lpae_s1_init_fns,\ndrivers/iommu/io-pgtable.c:21:\t[ARM_64_LPAE_S2] = \u0026io_pgtable_arm_64_lpae_s2_init_fns,\ndrivers/iommu/io-pgtable.c:22:\t[ARM_MALI_LPAE] = \u0026io_pgtable_arm_mali_lpae_init_fns,\ndrivers/iommu/io-pgtable.c-23-#endif\n--\ndrivers/iommu/io-pgtable.c-28-#ifdef CONFIG_IOMMU_IO_PGTABLE_ARMV7S\ndrivers/iommu/io-pgtable.c:29:\t[ARM_V7S] = \u0026io_pgtable_arm_v7s_init_fns,\ndrivers/iommu/io-pgtable.c-30-#endif\n" }
5/2	2026/10/26 17:10	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 7826 output: 26 thoughts: 49 Thoughts: Okay, let's dive into this. Here's my thought process on the matter: Analyzing the Usage of `IOMMU_IO_PGTABLE_LPAE` Right, so I need to understand the practical application of this `IOMMU_IO_PGTABLE_LPAE` setting. First, the most direct path is to figure out which drivers are actually making use of it. That means I need to go hunting – I'll start by grepping the kernel source for instances where this specific symbol is being selected or utilized. My initial pass will focus on the drivers themselves to determine direct usage. Next, I need a broader perspective. I should broaden my search, so I'll also check the `Kconfig` files to see when and under what conditions this option is exposed. Finally, I'll need to review the `Makefile` structures to see how this impacts build configuration and dependency resolution. With this combined view, I'll build a map of the drivers impacted by this setting, and the conditions under which the setting is used.
6/2	2026/10/26 17:10	tool	grepper	0m Args: { "Expression": "IOMMU_IO_PGTABLE_LPAE" } Results: { "Output": "drivers/gpu/drm/panfrost/Kconfig=3=config DRM_PANFROST\n--\ndrivers/gpu/drm/panfrost/Kconfig-6-\tdepends on ARM \|\| ARM64 \|\| COMPILE_TEST\ndrivers/gpu/drm/panfrost/Kconfig:7:\tdepends on !GENERIC_ATOMIC64 # for IOMMU_IO_PGTABLE_LPAE\ndrivers/gpu/drm/panfrost/Kconfig-8-\tdepends on MMU\n--\ndrivers/gpu/drm/panfrost/Kconfig-10-\tselect IOMMU_SUPPORT\ndrivers/gpu/drm/panfrost/Kconfig:11:\tselect IOMMU_IO_PGTABLE_LPAE\ndrivers/gpu/drm/panfrost/Kconfig-12-\tselect DRM_GEM_SHMEM_HELPER\n--\ndrivers/gpu/drm/panthor/Kconfig=3=config DRM_PANTHOR\n--\ndrivers/gpu/drm/panthor/Kconfig-6-\tdepends on ARM \|\| ARM64 \|\| COMPILE_TEST\ndrivers/gpu/drm/panthor/Kconfig:7:\tdepends on !GENERIC_ATOMIC64 # for IOMMU_IO_PGTABLE_LPAE\ndrivers/gpu/drm/panthor/Kconfig-8-\tdepends on MMU\n--\ndrivers/gpu/drm/panthor/Kconfig-12-\tselect DRM_SCHED\ndrivers/gpu/drm/panthor/Kconfig:13:\tselect IOMMU_IO_PGTABLE_LPAE\ndrivers/gpu/drm/panthor/Kconfig-14-\tselect IOMMU_SUPPORT\n--\ndrivers/gpu/drm/tyr/Kconfig=3=config DRM_TYR\n--\ndrivers/gpu/drm/tyr/Kconfig-8-\tdepends on MMU\ndrivers/gpu/drm/tyr/Kconfig:9:\tdepends on !GENERIC_ATOMIC64 # for IOMMU_IO_PGTABLE_LPAE\ndrivers/gpu/drm/tyr/Kconfig-10-\tdepends on COMMON_CLK\n--\ndrivers/gpu/drm/tyr/Kconfig-12-\tdefault n\ndrivers/gpu/drm/tyr/Kconfig:13:\tselect IOMMU_IO_PGTABLE_LPAE\ndrivers/gpu/drm/tyr/Kconfig-14-\tselect RUST_DRM_GEM_SHMEM_HELPER\n--\ndrivers/iommu/Kconfig=29=config IOMMU_IO_PGTABLE\n--\ndrivers/iommu/Kconfig-31-\ndrivers/iommu/Kconfig:32:config IOMMU_IO_PGTABLE_LPAE\ndrivers/iommu/Kconfig-33-\tbool \"ARMv7/v8 Long Descriptor Format\"\n--\ndrivers/iommu/Kconfig-42-\ndrivers/iommu/Kconfig:43:config IOMMU_IO_PGTABLE_LPAE_KUNIT_TEST\ndrivers/iommu/Kconfig-44-\ttristate \"KUnit tests for LPAE\"\ndrivers/iommu/Kconfig:45:\tdepends on IOMMU_IO_PGTABLE_LPAE \u0026\u0026 KUNIT\ndrivers/iommu/Kconfig-46-\tdefault KUNIT_ALL_TESTS\n--\ndrivers/iommu/Kconfig=283=config IPMMU_VMSA\n--\ndrivers/iommu/Kconfig-286-\tdepends on ARM \|\| ARM64 \|\| COMPILE_TEST\ndrivers/iommu/Kconfig:287:\tdepends on !GENERIC_ATOMIC64\t# for IOMMU_IO_PGTABLE_LPAE\ndrivers/iommu/Kconfig-288-\tselect IOMMU_API\ndrivers/iommu/Kconfig:289:\tselect IOMMU_IO_PGTABLE_LPAE\ndrivers/iommu/Kconfig-290-\tselect ARM_DMA_USE_IOMMU\n--\ndrivers/iommu/Makefile=15=obj-$(CONFIG_IOMMU_IO_PGTABLE_ARMV7S) += io-pgtable-arm-v7s.o\ndrivers/iommu/Makefile:16:obj-$(CONFIG_IOMMU_IO_PGTABLE_LPAE) += io-pgtable-arm.o\ndrivers/iommu/Makefile:17:obj-$(CONFIG_IOMMU_IO_PGTABLE_LPAE_KUNIT_TEST) += io-pgtable-arm-selftests.o\ndrivers/iommu/Makefile-18-obj-$(CONFIG_IOMMU_IO_PGTABLE_DART) += io-pgtable-dart.o\n--\ndrivers/iommu/arm/Kconfig=3=config ARM_SMMU\n--\ndrivers/iommu/arm/Kconfig-5-\tdepends on ARM64 \|\| ARM \|\| COMPILE_TEST\ndrivers/iommu/arm/Kconfig:6:\tdepends on !GENERIC_ATOMIC64\t# for IOMMU_IO_PGTABLE_LPAE\ndrivers/iommu/arm/Kconfig-7-\tselect IOMMU_API\ndrivers/iommu/arm/Kconfig:8:\tselect IOMMU_IO_PGTABLE_LPAE\ndrivers/iommu/arm/Kconfig-9-\tselect ARM_DMA_USE_IOMMU if ARM\n--\ndrivers/iommu/arm/Kconfig=76=config ARM_SMMU_V3\n--\ndrivers/iommu/arm/Kconfig-79-\tselect IOMMU_API\ndrivers/iommu/arm/Kconfig:80:\tselect IOMMU_IO_PGTABLE_LPAE\ndrivers/iommu/arm/Kconfig-81-\tselect GENERIC_MSI_IRQ\n--\ndrivers/iommu/arm/Kconfig=133=config QCOM_IOMMU\n--\ndrivers/iommu/arm/Kconfig-136-\tdepends on ARCH_QCOM \|\| COMPILE_TEST\ndrivers/iommu/arm/Kconfig:137:\tdepends on !GENERIC_ATOMIC64\t# for IOMMU_IO_PGTABLE_LPAE\ndrivers/iommu/arm/Kconfig-138-\tselect QCOM_SCM\ndrivers/iommu/arm/Kconfig-139-\tselect IOMMU_API\ndrivers/iommu/arm/Kconfig:140:\tselect IOMMU_IO_PGTABLE_LPAE\ndrivers/iommu/arm/Kconfig-141-\tselect ARM_DMA_USE_IOMMU\n--\ndrivers/iommu/io-pgtable.c=16=io_pgtable_init_table[IO_PGTABLE_NUM_FMTS] = {\ndrivers/iommu/io-pgtable.c:17:#ifdef CONFIG_IOMMU_IO_PGTABLE_LPAE\ndrivers/iommu/io-pgtable.c-18-\t[ARM_32_LPAE_S1] = \u0026io_pgtable_arm_32_lpae_s1_init_fns,\n" }
7/2	2026/10/26 17:10	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 9862 output: 17 thoughts: 57 Thoughts: Okay, here's the summary, tailored for an expert audience, in the first person, reflecting the thought process: A Quick Trace of the Dirty Bit Accessors Hold on a second! I need to understand the call chain here. Where are the core functions like `arm_lpae_pgtable_walk`, `io_pgtable_visit`, and the `visit_dirty` function actually being invoked from within the system? I'm missing the top-level context. Let me take a targeted approach. Rather than wading through the entire codebase, I'll start with a focused search. Specifically, I'll go directly for `visit_dirty` or potentially `read_and_clear_dirty`, given that these are the key functions handling the dirty bit logic I'm most interested in. Let's see what the tree reveals.
8/2	2026/10/26 17:11	tool	grepper	0m Args: { "Expression": "visit_dirty" } Results: { "Output": "drivers/iommu/io-pgtable-arm.c=836=static int __arm_lpae_iopte_walk(struct arm_lpae_io_pgtable data,\n--\ndrivers/iommu/io-pgtable-arm.c-861-\ndrivers/iommu/io-pgtable-arm.c:862:static int visit_dirty(struct io_pgtable_walk_data walk_data, int lvl,\ndrivers/iommu/io-pgtable-arm.c-863-\t\t arm_lpae_iopte ptep, size_t size)\n--\ndrivers/iommu/io-pgtable-arm.c=888=static int arm_lpae_read_and_clear_dirty(struct io_pgtable_ops ops,\n--\ndrivers/iommu/io-pgtable-arm.c-897-\t\t.data = dirty,\ndrivers/iommu/io-pgtable-arm.c:898:\t\t.visit = visit_dirty,\ndrivers/iommu/io-pgtable-arm.c-899-\t\t.flags = flags,\n" }
9/2	2026/10/26 17:11	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 10411 output: 21 thoughts: 28 Thoughts: Okay, let's dive into this. Here's my summary, taking the first-person perspective as requested: Investigating `arm_lpae_read_and_clear_dirty` Alright, my immediate thought is to trace the usage of `arm_lpae_read_and_clear_dirty`. I need to figure out how this function is integrated into the bigger picture. I'm going to quickly check where it's called within the codebase. Knowing the call sites will reveal the contexts in which it's used. Beyond calls, I need to know if it's assigned to any operation structures (`ops`). Often, these kinds of functions are plugged into a table of function pointers, which makes it important to find any assignments to a relevant "ops" structure. That'll let me understand its specific role within the larger mechanism, and how the surrounding data structures utilize the dirty bit reading and clearing. It is this bit of information, the `ops` structure, that I must track to understand the function.
10/2	2026/10/26 17:11	tool	grepper	0m Args: { "Expression": "read_and_clear_dirty" } Results: { "Output": "drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c=4492=static void arm_smmu_release_device(struct device dev)\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c-4504-\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:4505:static int arm_smmu_read_and_clear_dirty(struct iommu_domain domain,\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c-4506-\t\t\t\t\t unsigned long iova, size_t size,\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c-4512-\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:4513:\treturn ops-\u003eread_and_clear_dirty(ops, iova, size, flags, dirty);\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c-4514-}\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c=4617=static struct iommu_dirty_ops arm_smmu_dirty_ops = {\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:4618:\t.read_and_clear_dirty\t= arm_smmu_read_and_clear_dirty,\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c-4619-\t.set_dirty_tracking = arm_smmu_set_dirty_tracking,\n--\ndrivers/iommu/generic_pt/iommu_pt.h=242=static void record_dirty(struct pt_state pts,\n--\ndrivers/iommu/generic_pt/iommu_pt.h-262-\ndrivers/iommu/generic_pt/iommu_pt.h:263:static inline int __read_and_clear_dirty(struct pt_range range, void arg,\ndrivers/iommu/generic_pt/iommu_pt.h-264-\t\t\t\t\t unsigned int level,\n--\ndrivers/iommu/generic_pt/iommu_pt.h-272-\t\tif (pts.type == PT_ENTRY_TABLE) {\ndrivers/iommu/generic_pt/iommu_pt.h:273:\t\t\tret = pt_descend(\u0026pts, arg, __read_and_clear_dirty);\ndrivers/iommu/generic_pt/iommu_pt.h-274-\t\t\tif (ret)\n--\ndrivers/iommu/generic_pt/iommu_pt.h-284-/\ndrivers/iommu/generic_pt/iommu_pt.h:285: read_and_clear_dirty() - Manipulate the HW set write dirty state\ndrivers/iommu/generic_pt/iommu_pt.h-286- * @domain: Domain to manipulate\n--\ndrivers/iommu/generic_pt/iommu_pt.h-300- /\ndrivers/iommu/generic_pt/iommu_pt.h:301:int DOMAIN_NS(read_and_clear_dirty)(struct iommu_domain domain,\ndrivers/iommu/generic_pt/iommu_pt.h-302-\t\t\t\t unsigned long iova, size_t size,\n--\ndrivers/iommu/generic_pt/iommu_pt.h-322-\ndrivers/iommu/generic_pt/iommu_pt.h:323:\tret = pt_walk_range(\u0026range, __read_and_clear_dirty, \u0026dirty_args);\ndrivers/iommu/generic_pt/iommu_pt.h-324-\tPT_WARN_ON(ret);\n--\ndrivers/iommu/generic_pt/iommu_pt.h-326-}\ndrivers/iommu/generic_pt/iommu_pt.h:327:EXPORT_SYMBOL_NS_GPL(DOMAIN_NS(read_and_clear_dirty), \"GENERIC_PT_IOMMU\");\ndrivers/iommu/generic_pt/iommu_pt.h-328-\n--\ndrivers/iommu/io-pgtable-arm.c=862=static int visit_dirty(struct io_pgtable_walk_data walk_data, int lvl,\n--\ndrivers/iommu/io-pgtable-arm.c-887-\ndrivers/iommu/io-pgtable-arm.c:888:static int arm_lpae_read_and_clear_dirty(struct io_pgtable_ops ops,\ndrivers/iommu/io-pgtable-arm.c-889-\t\t\t\t\t unsigned long iova, size_t size,\n--\ndrivers/iommu/io-pgtable-arm.c=960=arm_lpae_alloc_pgtable(struct io_pgtable_cfg cfg)\n--\ndrivers/iommu/io-pgtable-arm.c-993-\t\t.iova_to_phys\t= arm_lpae_iova_to_phys,\ndrivers/iommu/io-pgtable-arm.c:994:\t\t.read_and_clear_dirty = arm_lpae_read_and_clear_dirty,\ndrivers/iommu/io-pgtable-arm.c-995-\t\t.pgtable_walk\t= arm_lpae_pgtable_walk,\n--\ndrivers/iommu/iommufd/hw_pagetable.c=482=int iommufd_hwpt_get_dirty_bitmap(struct iommufd_ucmd ucmd)\n--\ndrivers/iommu/iommufd/hw_pagetable.c-497-\tioas = hwpt_paging-\u003eioas;\ndrivers/iommu/iommufd/hw_pagetable.c:498:\trc = iopt_read_and_clear_dirty_data(\ndrivers/iommu/iommufd/hw_pagetable.c-499-\t\t\u0026ioas-\u003eiopt, hwpt_paging-\u003ecommon.domain, cmd-\u003eflags, cmd);\n--\ndrivers/iommu/iommufd/io_pagetable.c=529=struct iova_bitmap_fn_arg {\n--\ndrivers/iommu/iommufd/io_pagetable.c-535-\ndrivers/iommu/iommufd/io_pagetable.c:536:static int __iommu_read_and_clear_dirty(struct iova_bitmap bitmap,\ndrivers/iommu/iommufd/io_pagetable.c-537-\t\t\t\t\tunsigned long iova, size_t length,\n--\ndrivers/iommu/iommufd/io_pagetable.c-552-\ndrivers/iommu/iommufd/io_pagetable.c:553:\t\tret = ops-\u003eread_and_clear_dirty(domain, iter.cur_iova,\ndrivers/iommu/iommufd/io_pagetable.c-554-\t\t\t\t\t\tlast - iter.cur_iova + 1, flags,\n--\ndrivers/iommu/iommufd/io_pagetable.c=565=static int\ndrivers/iommu/iommufd/io_pagetable.c:566:iommu_read_and_clear_dirty(struct iommu_domain domain,\ndrivers/iommu/iommufd/io_pagetable.c-567-\t\t\t struct io_pagetable iopt, unsigned long flags,\n--\ndrivers/iommu/iommufd/io_pagetable.c-576-\ndrivers/iommu/iommufd/io_pagetable.c:577:\tif (!ops \|\| !ops-\u003eread_and_clear_dirty)\ndrivers/iommu/iommufd/io_pagetable.c-578-\t\treturn -EOPNOTSUPP;\n--\ndrivers/iommu/iommufd/io_pagetable.c-591-\targ.dirty = \u0026dirty;\ndrivers/iommu/iommufd/io_pagetable.c:592:\tret = iova_bitmap_for_each(iter, \u0026arg, __iommu_read_and_clear_dirty);\ndrivers/iommu/iommufd/io_pagetable.c-593-\n--\ndrivers/iommu/iommufd/io_pagetable.c=602=int iommufd_check_iova_range(struct io_pagetable iopt,\n--\ndrivers/iommu/iommufd/io_pagetable.c-630-\ndrivers/iommu/iommufd/io_pagetable.c:631:int iopt_read_and_clear_dirty_data(struct io_pagetable iopt,\ndrivers/iommu/iommufd/io_pagetable.c-632-\t\t\t\t struct iommu_domain domain,\n--\ndrivers/iommu/iommufd/io_pagetable.c-642-\tdown_read(\u0026iopt-\u003eiova_rwsem);\ndrivers/iommu/iommufd/io_pagetable.c:643:\tret = iommu_read_and_clear_dirty(domain, iopt, flags, bitmap);\ndrivers/iommu/iommufd/io_pagetable.c-644-\tup_read(\u0026iopt-\u003eiova_rwsem);\n--\ndrivers/iommu/iommufd/io_pagetable.c=649=static int iopt_clear_dirty_data(struct io_pagetable iopt,\n--\ndrivers/iommu/iommufd/io_pagetable.c-666-\ndrivers/iommu/iommufd/io_pagetable.c:667:\t\tret = ops-\u003eread_and_clear_dirty(domain, iopt_area_iova(area),\ndrivers/iommu/iommufd/io_pagetable.c-668-\t\t\t\t\t\tiopt_area_length(area), 0,\n--\ndrivers/iommu/iommufd/iommufd_private.h=125=static inline int iopt_get_phys(struct io_pagetable iopt, unsigned long iova,\n--\ndrivers/iommu/iommufd/iommufd_private.h-131-\ndrivers/iommu/iommufd/iommufd_private.h:132:int iopt_read_and_clear_dirty_data(struct io_pagetable iopt,\ndrivers/iommu/iommufd/iommufd_private.h-133-\t\t\t\t struct iommu_domain domain,\n--\ninclude/linux/generic_pt/iommu.h=89=struct pt_iommu_ops {\n--\ninclude/linux/generic_pt/iommu.h-145-\t * This is only used by iommufd testing. It makes the iova dirty so that\ninclude/linux/generic_pt/iommu.h:146:\t * read_and_clear_dirty() will see it as dirty. Unlike all the other ops\ninclude/linux/generic_pt/iommu.h-147-\t * this one is safe to call without holding any locking. It may return\n--\ninclude/linux/generic_pt/iommu.h=232=struct pt_iommu_cfg {\n--\ninclude/linux/generic_pt/iommu.h-253-\t\t\t\t\t\t dma_addr_t iova); \\\ninclude/linux/generic_pt/iommu.h:254:\tint pt_iommu_##fmt##_read_and_clear_dirty( \\\ninclude/linux/generic_pt/iommu.h-255-\t\tstruct iommu_domain domain, unsigned long iova, size_t size, \\\n--\ninclude/linux/generic_pt/iommu.h-275-#define IOMMU_PT_DIRTY_OPS(fmt) \\\ninclude/linux/generic_pt/iommu.h:276:\t.read_and_clear_dirty = \u0026pt_iommu_##fmt##_read_and_clear_dirty\ninclude/linux/generic_pt/iommu.h-277-\n--\ninclude/linux/io-pgtable.h=196=struct arm_lpae_io_pgtable_walk_data {\n--\ninclude/linux/io-pgtable.h-206- @pgtable_walk: (optional) Perform a page table walk for a given iova.\ninclude/linux/io-pgtable.h:207: * @read_and_clear_dirty: Record dirty info per IOVA. If an IOVA is dirty,\ninclude/linux/io-pgtable.h-208- \t\t\t clear its dirty state from the PTE unless the\n--\ninclude/linux/io-pgtable.h=214=struct io_pgtable_ops {\n--\ninclude/linux/io-pgtable.h-223-\tint (pgtable_walk)(struct io_pgtable_ops ops, unsigned long iova, void wd);\ninclude/linux/io-pgtable.h:224:\tint (read_and_clear_dirty)(struct io_pgtable_ops ops,\ninclude/linux/io-pgtable.h-225-\t\t\t\t unsigned long iova, size_t size,\n--\ninclude/linux/iommu.h=402=struct iommu_dirty_bitmap {\n--\ninclude/linux/iommu.h-409- * @set_dirty_tracking: Enable or Disable dirty tracking on the iommu domain\ninclude/linux/iommu.h:410: * @read_and_clear_dirty: Walk IOMMU page tables for dirtied PTEs marshalled\ninclude/linux/iommu.h-411- * into a bitmap, with a bit represented as a page.\n--\ninclude/linux/iommu.h=415=struct iommu_dirty_ops {\ninclude/linux/iommu.h-416-\tint (set_dirty_tracking)(struct iommu_domain domain, bool enabled);\ninclude/linux/iommu.h:417:\tint (read_and_clear_dirty)(struct iommu_domain domain,\ninclude/linux/iommu.h-418-\t\t\t\t unsigned long iova, size_t size,\n" }
11/2	2026/10/26 17:11	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 14381 output: 22 thoughts: 210 Thoughts: Investigating the `arm_lpae_read_and_clear_dirty` Function Okay, so the `arm_lpae_read_and_clear_dirty` function – let's see, it looks like it's only directly hooked up within the `drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c` file. Interesting. But is that it? Is it truly only used there? I need to be sure. Let me take a step back and examine its parent function, `read_and_clear_dirty`, which is part of `io_pgtable_ops`. I know `drivers/iommu/io-pgtable-arm.c` is where the ARM-specific implementations live. Ah, here it is: ```c static struct arm_lpae_io_pgtable * arm_lpae_alloc_pgtable(struct io_pgtable_cfg cfg) { ... .read_and_clear_dirty = arm_lpae_read_and_clear_dirty, ``` Okay, `arm_lpae_read_and_clear_dirty` is assigned to `.read_and_clear_dirty`. So, who's actually using* `alloc_io_pgtable_ops` and, more importantly, with LPAE formats? I need to trace this back to understand the entire call chain. Let's see who is actually calling `alloc_io_pgtable_ops` now.
12/2	2026/10/26 17:12	tool	grepper	0m Args: { "Expression": "alloc_io_pgtable_ops" } Results: { "Output": "drivers/gpu/drm/msm/msm_iommu.c=516=struct msm_mmu msm_iommu_pagetable_create(struct msm_mmu parent, bool kernel_managed)\n--\ndrivers/gpu/drm/msm/msm_iommu.c-579-\tpagetable-\u003eiommu_dev = ttbr1_cfg-\u003eiommu_dev;\ndrivers/gpu/drm/msm/msm_iommu.c:580:\tpagetable-\u003epgtbl_ops = alloc_io_pgtable_ops(ARM_64_LPAE_S1,\ndrivers/gpu/drm/msm/msm_iommu.c-581-\t\t\u0026ttbr0_cfg, pagetable);\n--\ndrivers/gpu/drm/panfrost/panfrost_mmu.c=783=struct panfrost_mmu panfrost_mmu_ctx_create(struct panfrost_device pfdev)\n--\ndrivers/gpu/drm/panfrost/panfrost_mmu.c-824-\ndrivers/gpu/drm/panfrost/panfrost_mmu.c:825:\tmmu-\u003epgtbl_ops = alloc_io_pgtable_ops(fmt, \u0026mmu-\u003epgtbl_cfg, mmu);\ndrivers/gpu/drm/panfrost/panfrost_mmu.c-826-\tif (!mmu-\u003epgtbl_ops) {\n--\ndrivers/gpu/drm/panthor/panthor_mmu.c=2852=panthor_vm_create(struct panthor_device ptdev, bool for_mcu,\n--\ndrivers/gpu/drm/panthor/panthor_mmu.c-2925-\ndrivers/gpu/drm/panthor/panthor_mmu.c:2926:\tvm-\u003epgtbl_ops = alloc_io_pgtable_ops(ARM_64_LPAE_S1, \u0026pgtbl_cfg, vm);\ndrivers/gpu/drm/panthor/panthor_mmu.c-2927-\tif (!vm-\u003epgtbl_ops) {\n--\ndrivers/iommu/apple-dart.c=598=static int apple_dart_finalize_domain(struct apple_dart_domain dart_domain,\n--\ndrivers/iommu/apple-dart.c-629-\ndrivers/iommu/apple-dart.c:630:\tdart_domain-\u003epgtbl_ops = alloc_io_pgtable_ops(dart-\u003ehw-\u003efmt, \u0026pgtbl_cfg,\ndrivers/iommu/apple-dart.c-631-\t\t\t\t\t\t \u0026dart_domain-\u003edomain);\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c=3061=static int arm_smmu_domain_finalise(struct arm_smmu_domain smmu_domain,\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c-3106-\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:3107:\tpgtbl_ops = alloc_io_pgtable_ops(fmt, \u0026pgtbl_cfg, smmu_domain);\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c-3108-\tif (!pgtbl_ops)\n--\ndrivers/iommu/arm/arm-smmu/arm-smmu.c=675=static int arm_smmu_init_domain_context(struct arm_smmu_domain smmu_domain,\n--\ndrivers/iommu/arm/arm-smmu/arm-smmu.c-824-\ndrivers/iommu/arm/arm-smmu/arm-smmu.c:825:\tpgtbl_ops = alloc_io_pgtable_ops(fmt, \u0026pgtbl_cfg, smmu_domain);\ndrivers/iommu/arm/arm-smmu/arm-smmu.c-826-\tif (!pgtbl_ops) {\n--\ndrivers/iommu/arm/arm-smmu/qcom_iommu.c=216=static int qcom_iommu_init_domain(struct iommu_domain domain,\n--\ndrivers/iommu/arm/arm-smmu/qcom_iommu.c-241-\ndrivers/iommu/arm/arm-smmu/qcom_iommu.c:242:\tpgtbl_ops = alloc_io_pgtable_ops(ARM_32_LPAE_S1, \u0026pgtbl_cfg, qcom_domain);\ndrivers/iommu/arm/arm-smmu/qcom_iommu.c-243-\tif (!pgtbl_ops) {\n--\ndrivers/iommu/io-pgtable-arm-selftests.c=51=static int arm_lpae_run_tests(struct kunit test, struct io_pgtable_cfg cfg)\n--\ndrivers/iommu/io-pgtable-arm-selftests.c-64-\t\tcfg_cookie = cfg;\ndrivers/iommu/io-pgtable-arm-selftests.c:65:\t\tops = alloc_io_pgtable_ops(fmts[i], cfg, cfg);\ndrivers/iommu/io-pgtable-arm-selftests.c-66-\t\tif (!ops) {\n--\ndrivers/iommu/io-pgtable-arm-v7s.c=817=static int __init arm_v7s_do_selftests(void)\n--\ndrivers/iommu/io-pgtable-arm-v7s.c-835-\ndrivers/iommu/io-pgtable-arm-v7s.c:836:\tops = alloc_io_pgtable_ops(ARM_V7S, \u0026cfg, \u0026cfg);\ndrivers/iommu/io-pgtable-arm-v7s.c-837-\tif (!ops) {\n--\ndrivers/iommu/io-pgtable.c=33=static int check_custom_allocator(enum io_pgtable_fmt fmt,\n--\ndrivers/iommu/io-pgtable.c-52-\ndrivers/iommu/io-pgtable.c:53:struct io_pgtable_ops alloc_io_pgtable_ops(enum io_pgtable_fmt fmt,\ndrivers/iommu/io-pgtable.c-54-\t\t\t\t\t struct io_pgtable_cfg cfg,\n--\ndrivers/iommu/io-pgtable.c-79-}\ndrivers/iommu/io-pgtable.c:80:EXPORT_SYMBOL_GPL(alloc_io_pgtable_ops);\ndrivers/iommu/io-pgtable.c-81-\n--\ndrivers/iommu/ipmmu-vmsa.c=417=static int ipmmu_domain_init_context(struct ipmmu_vmsa_domain domain)\n--\ndrivers/iommu/ipmmu-vmsa.c-454-\ndrivers/iommu/ipmmu-vmsa.c:455:\tdomain-\u003eiop = alloc_io_pgtable_ops(ARM_32_LPAE_S1, \u0026domain-\u003ecfg,\ndrivers/iommu/ipmmu-vmsa.c-456-\t\t\t\t\t domain);\n--\ndrivers/iommu/msm_iommu.c=339=static int msm_iommu_domain_config(struct msm_priv priv)\n--\ndrivers/iommu/msm_iommu.c-350-\ndrivers/iommu/msm_iommu.c:351:\tpriv-\u003eiop = alloc_io_pgtable_ops(ARM_V7S, \u0026priv-\u003ecfg, priv);\ndrivers/iommu/msm_iommu.c-352-\tif (!priv-\u003eiop) {\n--\ndrivers/iommu/mtk_iommu.c=654=static int mtk_iommu_domain_finalise(struct mtk_iommu_domain dom,\n--\ndrivers/iommu/mtk_iommu.c-685-\ndrivers/iommu/mtk_iommu.c:686:\tdom-\u003eiop = alloc_io_pgtable_ops(ARM_V7S, \u0026dom-\u003ecfg, data);\ndrivers/iommu/mtk_iommu.c-687-\tif (!dom-\u003eiop) {\n--\ninclude/linux/io-pgtable.h=214=struct io_pgtable_ops {\n--\ninclude/linux/io-pgtable.h-230-/*\ninclude/linux/io-pgtable.h:231: alloc_io_pgtable_ops() - Allocate a page table allocator for use by an IOMMU.\ninclude/linux/io-pgtable.h-232- \n--\ninclude/linux/io-pgtable.h-241- /\ninclude/linux/io-pgtable.h:242:struct io_pgtable_ops alloc_io_pgtable_ops(enum io_pgtable_fmt fmt,\ninclude/linux/io-pgtable.h-243-\t\t\t\t\t struct io_pgtable_cfg cfg,\n--\ninclude/linux/io-pgtable.h-250- \ninclude/linux/io-pgtable.h:251: @ops: The ops returned from alloc_io_pgtable_ops.\ninclude/linux/io-pgtable.h-252- */\n--\nrust/kernel/iommu/pgtable.rs=81= pub fn new(dev: \u0026'a Device\u003cBound\u003e, config: Config) -\u003e Result\u003cIoPageTable\u003c'a, F\u003e\u003e {\n--\nrust/kernel/iommu/pgtable.rs-98- let ops = unsafe {\nrust/kernel/iommu/pgtable.rs:99: bindings::alloc_io_pgtable_ops(F::FORMAT, \u0026mut raw_cfg, core::ptr::null_mut())\nrust/kernel/iommu/pgtable.rs-100- };\n" }
13/2	2026/10/26 17:12	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 17496 output: 35 thoughts: 198 Thoughts: Investigating the Usage of `ARM_64_LPAE_S1` Okay, let's see where this `ARM_64_LPAE_S1` is actually being utilized. I see it's allocated across a few key areas: `drivers/gpu/drm/msm/msm_iommu.c`, `drivers/gpu/drm/panfrost/panfrost_mmu.c`, and `drivers/gpu/drm/panthor/panthor_mmu.c` – that makes sense for the graphics side of things. I also see it in several iommu driver implementations: `drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c`, `drivers/iommu/arm/arm-smmu/arm-smmu.c`, as well as a selftest, `drivers/iommu/io-pgtable-arm-selftests.c`. Hmm, I'm trying to mentally map out where this might be relevant... Wait a second, this makes me think. Are there any iommufd tests, mock domains, or any selftests using this LPAE configuration? Given that it's related to iommu and LPAE, it would be logical to see its usage tested in that context. It's time to check the `drivers/iommu/iommufd/` directory. Let's see if we can find any relevant implementations there.
14/2	2026/10/26 17:12	tool	grepper	0m Args: { "Expression": "mock\|selftest", "PathPrefixes": [ "drivers/iommu/iommufd" ] } Results: { "Output": "\nFull output is too long, showing 200 out of 1179 lines.\nUse more precise expression or PathPrefixes if possible.\n\nNumber of matching lines per file (7 files in total):\ndrivers/iommu/iommufd/Kconfig:1\ndrivers/iommu/iommufd/Makefile:1\ndrivers/iommu/iommufd/device.c:3\ndrivers/iommu/iommufd/iommufd_private.h:3\ndrivers/iommu/iommufd/iommufd_test.h:14\ndrivers/iommu/iommufd/main.c:1\ndrivers/iommu/iommufd/selftest.c:397\n\ndrivers/iommu/iommufd/Kconfig=51=config IOMMUFD_TEST\n--\ndrivers/iommu/iommufd/Kconfig-61-\t This is dangerous, do not enable unless running\ndrivers/iommu/iommufd/Kconfig:62:\t tools/testing/selftests/iommu\ndrivers/iommu/iommufd/Kconfig-63-endif\n--\ndrivers/iommu/iommufd/Makefile=13=iommufd-$(CONFIG_IOMMUFD_NOIOMMU) += hwpt_noiommu.o\ndrivers/iommu/iommufd/Makefile:14:iommufd-$(CONFIG_IOMMUFD_TEST) += selftest.o\ndrivers/iommu/iommufd/Makefile-15-\n--\ndrivers/iommu/iommufd/device.c=210=void iommufd_device_destroy(struct iommufd_object obj)\n--\ndrivers/iommu/iommufd/device.c-220-\tiommufd_put_group(idev-\u003eigroup);\ndrivers/iommu/iommufd/device.c:221:\tif (!iommufd_selftest_is_mock_dev(idev-\u003edev))\ndrivers/iommu/iommufd/device.c-222-\t\tiommufd_ctx_put(idev-\u003eictx);\n--\ndrivers/iommu/iommufd/device.c=225=static int iommufd_bind_iommu(struct iommufd_device idev)\n--\ndrivers/iommu/iommufd/device.c-248-\t /\ndrivers/iommu/iommufd/device.c:249:\tif (!iommufd_selftest_is_mock_dev(dev) \u0026\u0026\ndrivers/iommu/iommufd/device.c-250-\t !iommu_group_has_isolated_msi(igroup-\u003egroup)) {\n--\ndrivers/iommu/iommufd/device.c=310=struct iommufd_device iommufd_device_bind(struct iommufd_ctx ictx,\n--\ndrivers/iommu/iommufd/device.c-333-\t /\ndrivers/iommu/iommufd/device.c:334:\tif (!iommufd_selftest_is_mock_dev(dev))\ndrivers/iommu/iommufd/device.c-335-\t\tiommufd_ctx_get(ictx);\n--\ndrivers/iommu/iommufd/iommufd_private.h=733=int iommufd_test(struct iommufd_ucmd ucmd);\ndrivers/iommu/iommufd/iommufd_private.h:734:void iommufd_selftest_destroy(struct iommufd_object obj);\ndrivers/iommu/iommufd/iommufd_private.h-735-extern size_t iommufd_test_memory_limit;\n--\ndrivers/iommu/iommufd/iommufd_private.h=740=void iommufd_test_exit(void);\ndrivers/iommu/iommufd/iommufd_private.h:741:bool iommufd_selftest_is_mock_dev(struct device dev);\ndrivers/iommu/iommufd/iommufd_private.h-742-int iommufd_test_dma_buf_iommufd_map(struct dma_buf_attachment attachment,\n--\ndrivers/iommu/iommufd/iommufd_private.h=758=static inline void iommufd_test_exit(void)\n--\ndrivers/iommu/iommufd/iommufd_private.h-760-}\ndrivers/iommu/iommufd/iommufd_private.h:761:static inline bool iommufd_selftest_is_mock_dev(struct device dev)\ndrivers/iommu/iommufd/iommufd_private.h-762-{\n--\ndrivers/iommu/iommufd/iommufd_test.h=81=struct iommu_test_cmd {\n--\ndrivers/iommu/iommufd/iommufd_test.h-95-\t\t\t__u32 out_idev_id;\ndrivers/iommu/iommufd/iommufd_test.h:96:\t\t} mock_domain;\ndrivers/iommu/iommufd/iommufd_test.h-97-\t\tstruct {\n--\ndrivers/iommu/iommufd/iommufd_test.h-100-\t\t\t__u32 out_idev_id;\ndrivers/iommu/iommufd/iommufd_test.h:101:\t\t\t/ Expand mock_domain to set mock device flags /\ndrivers/iommu/iommufd/iommufd_test.h-102-\t\t\t__u32 dev_flags;\ndrivers/iommu/iommufd/iommufd_test.h:103:\t\t} mock_domain_flags;\ndrivers/iommu/iommufd/iommufd_test.h-104-\t\tstruct {\ndrivers/iommu/iommufd/iommufd_test.h-105-\t\t\t__u32 pt_id;\ndrivers/iommu/iommufd/iommufd_test.h:106:\t\t} mock_domain_replace;\ndrivers/iommu/iommufd/iommufd_test.h-107-\t\tstruct {\n--\ndrivers/iommu/iommufd/iommufd_test.h=208=struct iommu_test_hw_info {\n--\ndrivers/iommu/iommufd/iommufd_test.h-218-/\ndrivers/iommu/iommufd/iommufd_test.h:219: struct iommu_hwpt_selftest\ndrivers/iommu/iommufd/iommufd_test.h-220- \ndrivers/iommu/iommufd/iommufd_test.h:221: @iotlb: default mock iotlb value, IOMMU_TEST_IOTLB_DEFAULT\ndrivers/iommu/iommufd/iommufd_test.h-222- /\ndrivers/iommu/iommufd/iommufd_test.h:223:struct iommu_hwpt_selftest {\ndrivers/iommu/iommufd/iommufd_test.h-224-\t__u32 iotlb;\n--\ndrivers/iommu/iommufd/iommufd_test.h-232-/\ndrivers/iommu/iommufd/iommufd_test.h:233: struct iommu_hwpt_invalidate_selftest - Invalidation data for Mock driver\ndrivers/iommu/iommufd/iommufd_test.h-234- * (IOMMU_HWPT_INVALIDATE_DATA_SELFTEST)\n--\ndrivers/iommu/iommufd/iommufd_test.h-239- /\ndrivers/iommu/iommufd/iommufd_test.h:240:struct iommu_hwpt_invalidate_selftest {\ndrivers/iommu/iommufd/iommufd_test.h-241-#define IOMMU_TEST_INVALIDATE_FLAG_ALL\t(1 \u003c\u003c 0)\n--\ndrivers/iommu/iommufd/iommufd_test.h-248-/\ndrivers/iommu/iommufd/iommufd_test.h:249: struct iommu_viommu_selftest - vIOMMU data for Mock driver\ndrivers/iommu/iommufd/iommufd_test.h-250- * (IOMMU_VIOMMU_TYPE_SELFTEST)\n--\ndrivers/iommu/iommufd/iommufd_test.h-257- /\ndrivers/iommu/iommufd/iommufd_test.h:258:struct iommu_viommu_selftest {\ndrivers/iommu/iommufd/iommufd_test.h-259-\t__u32 in_data;\n--\ndrivers/iommu/iommufd/iommufd_test.h-269-/\ndrivers/iommu/iommufd/iommufd_test.h:270: struct iommu_viommu_invalidate_selftest - Invalidation data for Mock VIOMMU\ndrivers/iommu/iommufd/iommufd_test.h-271- * (IOMMU_VIOMMU_INVALIDATE_DATA_SELFTEST)\n--\ndrivers/iommu/iommufd/iommufd_test.h-276- /\ndrivers/iommu/iommufd/iommufd_test.h:277:struct iommu_viommu_invalidate_selftest {\ndrivers/iommu/iommufd/iommufd_test.h-278-#define IOMMU_TEST_INVALIDATE_FLAG_ALL (1 \u003c\u003c 0)\n--\ndrivers/iommu/iommufd/iommufd_test.h-285-\ndrivers/iommu/iommufd/iommufd_test.h:286:struct iommu_viommu_event_selftest {\ndrivers/iommu/iommufd/iommufd_test.h-287-\t__u32 virt_id;\n--\ndrivers/iommu/iommufd/main.c=716=static const struct iommufd_object_ops iommufd_object_ops[] = {\n--\ndrivers/iommu/iommufd/main.c-755-\t[IOMMUFD_OBJ_SELFTEST] = {\ndrivers/iommu/iommufd/main.c:756:\t\t.destroy = iommufd_selftest_destroy,\ndrivers/iommu/iommufd/main.c-757-\t},\n--\ndrivers/iommu/iommufd/selftest.c-3- \ndrivers/iommu/iommufd/selftest.c:4: * Kernel side components to support tools/testing/selftests/iommu\ndrivers/iommu/iommufd/selftest.c-5- /\n--\ndrivers/iommu/iommufd/selftest.c=27=static struct dentry dbgfs_root;\ndrivers/iommu/iommufd/selftest.c:28:static struct platform_device selftest_iommu_dev;\ndrivers/iommu/iommufd/selftest.c:29:static const struct iommu_ops mock_ops;\ndrivers/iommu/iommufd/selftest.c-30-static struct iommu_domain_ops domain_nested_ops;\n--\ndrivers/iommu/iommufd/selftest.c=32=size_t iommufd_test_memory_limit = 65536;\ndrivers/iommu/iommufd/selftest.c-33-\ndrivers/iommu/iommufd/selftest.c:34:struct mock_bus_type {\ndrivers/iommu/iommufd/selftest.c-35-\tstruct bus_type bus;\n--\ndrivers/iommu/iommufd/selftest.c-38-\ndrivers/iommu/iommufd/selftest.c:39:static struct mock_bus_type iommufd_mock_bus_type = {\ndrivers/iommu/iommufd/selftest.c-40-\t.bus = {\ndrivers/iommu/iommufd/selftest.c:41:\t\t.name = \"iommufd_mock\",\ndrivers/iommu/iommufd/selftest.c-42-\t},\n--\ndrivers/iommu/iommufd/selftest.c-44-\ndrivers/iommu/iommufd/selftest.c:45:static DEFINE_IDA(mock_dev_ida);\ndrivers/iommu/iommufd/selftest.c-46-\ndrivers/iommu/iommufd/selftest.c=47=enum {\n--\ndrivers/iommu/iommufd/selftest.c-50-\ndrivers/iommu/iommufd/selftest.c:51:static int mock_dev_enable_iopf(struct device dev, struct iommu_domain domain);\ndrivers/iommu/iommufd/selftest.c:52:static void mock_dev_disable_iopf(struct device dev, struct iommu_domain domain);\ndrivers/iommu/iommufd/selftest.c-53-\n--\ndrivers/iommu/iommufd/selftest.c=100=void iommufd_test_syz_conv_iova_id(struct iommufd_ucmd ucmd,\n--\ndrivers/iommu/iommufd/selftest.c-115-\ndrivers/iommu/iommufd/selftest.c:116:struct mock_iommu_domain {\ndrivers/iommu/iommufd/selftest.c-117-\tunion {\n--\ndrivers/iommu/iommufd/selftest.c-123-};\ndrivers/iommu/iommufd/selftest.c:124:PT_IOMMU_CHECK_DOMAIN(struct mock_iommu_domain, iommu, domain);\ndrivers/iommu/iommufd/selftest.c:125:PT_IOMMU_CHECK_DOMAIN(struct mock_iommu_domain, amdv1.iommu, domain);\ndrivers/iommu/iommufd/selftest.c-126-\ndrivers/iommu/iommufd/selftest.c:127:static inline struct mock_iommu_domain \ndrivers/iommu/iommufd/selftest.c:128:to_mock_domain(struct iommu_domain domain)\ndrivers/iommu/iommufd/selftest.c-129-{\ndrivers/iommu/iommufd/selftest.c:130:\treturn container_of(domain, struct mock_iommu_domain, domain);\ndrivers/iommu/iommufd/selftest.c-131-}\ndrivers/iommu/iommufd/selftest.c-132-\ndrivers/iommu/iommufd/selftest.c:133:struct mock_iommu_domain_nested {\ndrivers/iommu/iommufd/selftest.c-134-\tstruct iommu_domain domain;\ndrivers/iommu/iommufd/selftest.c:135:\tstruct mock_viommu mock_viommu;\ndrivers/iommu/iommufd/selftest.c-136-\tu32 iotlb[MOCK_NESTED_DOMAIN_IOTLB_NUM];\n--\ndrivers/iommu/iommufd/selftest.c-138-\ndrivers/iommu/iommufd/selftest.c:139:static inline struct mock_iommu_domain_nested \ndrivers/iommu/iommufd/selftest.c:140:to_mock_nested(struct iommu_domain domain)\ndrivers/iommu/iommufd/selftest.c-141-{\ndrivers/iommu/iommufd/selftest.c:142:\treturn container_of(domain, struct mock_iommu_domain_nested, domain);\ndrivers/iommu/iommufd/selftest.c-143-}\ndrivers/iommu/iommufd/selftest.c-144-\ndrivers/iommu/iommufd/selftest.c:145:struct mock_viommu {\ndrivers/iommu/iommufd/selftest.c-146-\tstruct iommufd_viommu core;\ndrivers/iommu/iommufd/selftest.c:147:\tstruct mock_iommu_domain s2_parent;\ndrivers/iommu/iommufd/selftest.c:148:\tstruct mock_hw_queue hw_queue[IOMMU_TEST_HW_QUEUE_MAX];\ndrivers/iommu/iommufd/selftest.c-149-\tstruct mutex queue_mutex;\n--\ndrivers/iommu/iommufd/selftest.c-154-\ndrivers/iommu/iommufd/selftest.c:155:static inline struct mock_viommu to_mock_viommu(struct iommufd_viommu viommu)\ndrivers/iommu/iommufd/selftest.c-156-{\ndrivers/iommu/iommufd/selftest.c:157:\treturn container_of(viommu, struct mock_viommu, core);\ndrivers/iommu/iommufd/selftest.c-158-}\ndrivers/iommu/iommufd/selftest.c-159-\ndrivers/iommu/iommufd/selftest.c:160:struct mock_hw_queue {\ndrivers/iommu/iommufd/selftest.c-161-\tstruct iommufd_hw_queue core;\ndrivers/iommu/iommufd/selftest.c:162:\tstruct mock_viommu mock_viommu;\ndrivers/iommu/iommufd/selftest.c:163:\tstruct mock_hw_queue prev;\ndrivers/iommu/iommufd/selftest.c-164-\tu16 index;\n--\ndrivers/iommu/iommufd/selftest.c-166-\ndrivers/iommu/iommufd/selftest.c:167:static inline struct mock_hw_queue \ndrivers/iommu/iommufd/selftest.c:168:to_mock_hw_queue(struct iommufd_hw_queue hw_queue)\ndrivers/iommu/iommufd/selftest.c-169-{\ndrivers/iommu/iommufd/selftest.c:170:\treturn container_of(hw_queue, struct mock_hw_queue, core);\ndrivers/iommu/iommufd/selftest.c-171-}\ndrivers/iommu/iommufd/selftest.c-172-\ndrivers/iommu/iommufd/selftest.c:173:enum selftest_obj_type {\ndrivers/iommu/iommufd/selftest.c-174-\tTYPE_IDEV,\n--\ndrivers/iommu/iommufd/selftest.c-176-\ndrivers/iommu/iommufd/selftest.c:177:struct mock_dev {\ndrivers/iommu/iommufd/selftest.c-178-\tstruct device dev;\ndrivers/iommu/iommufd/selftest.c:179:\tstruct mock_viommu viommu;\ndrivers/iommu/iommufd/selftest.c-180-\tstruct rw_semaphore viommu_rwsem;\n--\ndrivers/iommu/iommufd/selftest.c-190-\ndrivers/iommu/iommufd/selftest.c:191:static inline struct mock_dev to_mock_dev(struct device dev)\ndrivers/iommu/iommufd/selftest.c-192-{\ndrivers/iommu/iommufd/selftest.c:193:\treturn container_of(dev, struct mock_dev, dev);\ndrivers/iommu/iommufd/selftest.c-194-}\ndrivers/iommu/iommufd/selftest.c-195-\ndrivers/iommu/iommufd/selftest.c:196:struct selftest_obj {\n\n" }
15/2	2026/10/26 17:12	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 23445 output: 43 thoughts: 62 Thoughts: Here's my analysis of the provided snippet, framed as my own thought process: Diving into the IOMMU Domain Test Okay, so I need to understand this `mock_iommu_domain` functionality within the IOMMU File Descriptor self-test. The context is `drivers/iommu/iommufd/selftest.c`, obviously. Let's see... the most pertinent section seems to be lines 110 through 150. I'm going to focus my attention there. What's the goal here? They are likely setting up a test environment, perhaps mocking an IOMMU domain for isolated testing purposes. This is interesting. Let's see what methods are included or stubbed. I need to get into the nitty-gritty of how they're handling domain creation, address space allocation, and potentially, page table management. I need to understand if they are employing a full simulation or a simpler proxy.
16/2	2026/10/26 17:13	tool	read-file	0m Args: { "File": "drivers/iommu/iommufd/selftest.c", "FirstLine": 110, "LineCount": 40 } Results: { "Contents": " 110:\t\tif (IS_ERR(ioas))\n 111:\t\t\treturn;\n 112:\t\tiova = __iommufd_test_syz_conv_iova(\u0026ioas-\u003eiopt, iova);\n 113:\t\tiommufd_put_object(ucmd-\u003eictx, \u0026ioas-\u003eobj);\n 114:\t}\n 115:\t\n 116:\tstruct mock_iommu_domain {\n 117:\t\tunion {\n 118:\t\t\tstruct iommu_domain domain;\n 119:\t\t\tstruct pt_iommu iommu;\n 120:\t\t\tstruct pt_iommu_amdv1 amdv1;\n 121:\t\t};\n 122:\t\tunsigned long flags;\n 123:\t};\n 124:\tPT_IOMMU_CHECK_DOMAIN(struct mock_iommu_domain, iommu, domain);\n 125:\tPT_IOMMU_CHECK_DOMAIN(struct mock_iommu_domain, amdv1.iommu, domain);\n 126:\t\n 127:\tstatic inline struct mock_iommu_domain \n 128:\tto_mock_domain(struct iommu_domain domain)\n 129:\t{\n 130:\t\treturn container_of(domain, struct mock_iommu_domain, domain);\n 131:\t}\n 132:\t\n 133:\tstruct mock_iommu_domain_nested {\n 134:\t\tstruct iommu_domain domain;\n 135:\t\tstruct mock_viommu mock_viommu;\n 136:\t\tu32 iotlb[MOCK_NESTED_DOMAIN_IOTLB_NUM];\n 137:\t};\n 138:\t\n 139:\tstatic inline struct mock_iommu_domain_nested \n 140:\tto_mock_nested(struct iommu_domain domain)\n 141:\t{\n 142:\t\treturn container_of(domain, struct mock_iommu_domain_nested, domain);\n 143:\t}\n 144:\t\n 145:\tstruct mock_viommu {\n 146:\t\tstruct iommufd_viommu core;\n 147:\t\tstruct mock_iommu_domain s2_parent;\n 148:\t\tstruct mock_hw_queue hw_queue[IOMMU_TEST_HW_QUEUE_MAX];\n 149:\t\tstruct mutex queue_mutex;\n" }
17/2	2026/10/26 17:13	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 24423 output: 44 thoughts: 120 Thoughts: Okay, let's break this down. Investigating the `io-pgtable-arm` Landscape My primary concern is that `mock_iommu_domain` seems to be leveraging `pt_iommu` or `pt_iommu_amdv1`, which ultimately points to the `generic_pt` path and not the expected `io-pgtable-arm.c` implementation. This discrepancy immediately raises a red flag. I need to understand the relationship and any potential conflicts. My next immediate action is to thoroughly review `drivers/iommu/io-pgtable-arm.c`, paying close attention to both its direct function calls and how it is used by other parts of the system. I need to map the dependencies and understand where the ARM page table implementation is truly employed. Hold on a second... what about those self-tests? The `io-pgtable-arm-selftests.c` file has to be considered. It's possible that the self-tests are exercising a different code path or highlighting something important that I'm overlooking. Therefore, I'll now pivot to a focused inspection of `drivers/iommu/io-pgtable-arm-selftests.c`. It's crucial to understand how those tests are structured and what aspects of the ARM page table implementation they are specifically targeting. This might offer valuable insights into the architecture and possible integration points that could be related to the `mock_iommu_domain` behavior.
18/2	2026/10/26 17:13	tool	read-file	0m Args: { "File": "drivers/iommu/io-pgtable-arm-selftests.c", "FirstLine": 1, "LineCount": 80 } Results: { "Contents": " 1:\t// SPDX-License-Identifier: GPL-2.0-only\n 2:\t/\n 3:\t CPU-agnostic ARM page table allocator.\n 4:\t \n 5:\t Copyright (C) 2014 ARM Limited\n 6:\t \n 7:\t Author: Will Deacon \u003cwill.deacon@arm.com\u003e\n 8:\t /\n 9:\t\n 10:\t#define pr_fmt(fmt)\t\"arm-lpae io-pgtable: \" fmt\n 11:\t\n 12:\t#include \u003ckunit/device.h\u003e\n 13:\t#include \u003ckunit/test.h\u003e\n 14:\t#include \u003clinux/io-pgtable.h\u003e\n 15:\t#include \u003clinux/kernel.h\u003e\n 16:\t\n 17:\t#include \"io-pgtable-arm.h\"\n 18:\t\n 19:\tstatic struct io_pgtable_cfg cfg_cookie;\n 20:\t\n 21:\tstatic void dummy_tlb_flush_all(void cookie)\n 22:\t{\n 23:\t\tWARN_ON(cookie != cfg_cookie);\n 24:\t}\n 25:\t\n 26:\tstatic void dummy_tlb_flush(unsigned long iova, size_t size,\n 27:\t\t\t\t size_t granule, void cookie)\n 28:\t{\n 29:\t\tWARN_ON(cookie != cfg_cookie);\n 30:\t\tWARN_ON(!(size \u0026 cfg_cookie-\u003epgsize_bitmap));\n 31:\t}\n 32:\t\n 33:\tstatic void dummy_tlb_add_page(struct iommu_iotlb_gather gather,\n 34:\t\t\t\t unsigned long iova, size_t granule,\n 35:\t\t\t\t void cookie)\n 36:\t{\n 37:\t\tdummy_tlb_flush(iova, granule, granule, cookie);\n 38:\t}\n 39:\t\n 40:\tstatic const struct iommu_flush_ops dummy_tlb_ops = {\n 41:\t\t.tlb_flush_all\t= dummy_tlb_flush_all,\n 42:\t\t.tlb_flush_walk\t= dummy_tlb_flush,\n 43:\t\t.tlb_add_page\t= dummy_tlb_add_page,\n 44:\t};\n 45:\t\n 46:\t#define __FAIL(test, i) ({\t\t\t\t\t\t\t\\\n 47:\t\t\tKUNIT_FAIL(test, \"test failed for fmt idx %d\\n\", (i));\t\t\\\n 48:\t\t\t-EFAULT;\t\t\t\t\t\t\t\\\n 49:\t})\n 50:\t\n 51:\tstatic int arm_lpae_run_tests(struct kunit test, struct io_pgtable_cfg cfg)\n 52:\t{\n 53:\t\tstatic const enum io_pgtable_fmt fmts[] = {\n 54:\t\t\tARM_64_LPAE_S1,\n 55:\t\t\tARM_64_LPAE_S2,\n 56:\t\t};\n 57:\t\n 58:\t\tint i, j;\n 59:\t\tunsigned long iova;\n 60:\t\tsize_t size, mapped;\n 61:\t\tstruct io_pgtable_ops ops;\n 62:\t\n 63:\t\tfor (i = 0; i \u003c ARRAY_SIZE(fmts); ++i) {\n 64:\t\t\tcfg_cookie = cfg;\n 65:\t\t\tops = alloc_io_pgtable_ops(fmts[i], cfg, cfg);\n 66:\t\t\tif (!ops) {\n 67:\t\t\t\tkunit_err(test, \"failed to allocate io pgtable ops\\n\");\n 68:\t\t\t\treturn -ENOMEM;\n 69:\t\t\t}\n 70:\t\n 71:\t\t\t/\n 72:\t\t\t * Initial sanity checks.\n 73:\t\t\t * Empty page tables shouldn't provide any translations.\n 74:\t\t\t */\n 75:\t\t\tif (ops-\u003eiova_to_phys(ops, 42))\n 76:\t\t\t\treturn __FAIL(test, i);\n 77:\t\n 78:\t\t\tif (ops-\u003eiova_to_phys(ops, SZ_1G + 42))\n 79:\t\t\t\treturn __FAIL(test, i);\n 80:\t\n" }
19/2	2026/10/26 17:13	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 26032 output: 34 thoughts: 209 Thoughts: Investigating the Reach of an ARM-Specific KUnit Test Okay, so I'm looking at `io-pgtable-arm-selftests.c`, which I understand is a KUnit test. Now, the immediate concern is that KUnit tests aren't normally targeted by syzkaller's dynamic fuzzing via syscalls. That's fine, but it raises the question of why this test is relevant to my work. What I need to figure out is, what drivers depend on `io-pgtable-arm.c` and could potentially be relevant on an x86_64 system, or indeed, any architecture other than ARM. Let's start by looking into the places where LPAE (Large Physical Address Extension) is configured or used. That's a key clue. My immediate thought is to check `drivers/iommu/arm/arm-smmu-v3/`, because I know that's related to memory management, and it's ARM-specific. Now, a critical question arises: Can an ARM SMMU v3 even run on an x86_64 system? I need to know if this is a cross-architecture test or if there's some kind of emulation in play. Then it hits me, QEMU! I know QEMU provides an emulation of arm-smmu-v3 for the aarch64 virt machine (using the `-M virt` option). However, the target architecture here is x86_64! The test is probably meant to test the behaviour of the ARM SMMU V3 driver on the ARM platform, so this could mean that I need to investigate the test's relation to other platforms and if it's possible to reproduce its behaviour on the current target platform. The question then becomes: can arm-smmu-v3 be present or relevant on an x86_64 system, maybe through emulation or some other mechanism? To clarify this, I need to check the `drivers/iommu/arm/Kconfig` file, specifically for the `ARM_SMMU_V3` option. That'll be the best place to understand the conditions under which this driver is configured and if it can possibly be configured for other architectures.
20/2	2026/10/26 17:14	tool	grepper	0m Args: { "Expression": "ARM_SMMU_V3", "PathPrefixes": [ "drivers/iommu" ] } Results: { "Output": "drivers/iommu/arm/Kconfig=74=endif\ndrivers/iommu/arm/Kconfig-75-\ndrivers/iommu/arm/Kconfig:76:config ARM_SMMU_V3\ndrivers/iommu/arm/Kconfig-77-\ttristate \"ARM Ltd. System MMU Version 3 (SMMUv3) Support\"\n--\ndrivers/iommu/arm/Kconfig-89-\ndrivers/iommu/arm/Kconfig:90:if ARM_SMMU_V3\ndrivers/iommu/arm/Kconfig:91:config ARM_SMMU_V3_SVA\ndrivers/iommu/arm/Kconfig-92-\tbool \"Shared Virtual Addressing support for the ARM SMMUv3\"\n--\ndrivers/iommu/arm/Kconfig-102-\ndrivers/iommu/arm/Kconfig:103:config ARM_SMMU_V3_IOMMUFD\ndrivers/iommu/arm/Kconfig-104-\tbool \"Enable IOMMUFD features for ARM SMMUv3 (EXPERIMENTAL)\"\n--\ndrivers/iommu/arm/Kconfig-111-\ndrivers/iommu/arm/Kconfig:112:config ARM_SMMU_V3_KUNIT_TEST\ndrivers/iommu/arm/Kconfig-113-\ttristate \"KUnit tests for arm-smmu-v3 driver\" if !KUNIT_ALL_TESTS\ndrivers/iommu/arm/Kconfig-114-\tdepends on KUNIT\ndrivers/iommu/arm/Kconfig:115:\tdepends on ARM_SMMU_V3_SVA\ndrivers/iommu/arm/Kconfig-116-\tdefault KUNIT_ALL_TESTS\n--\ndrivers/iommu/arm/arm-smmu-v3/Makefile-1-# SPDX-License-Identifier: GPL-2.0\ndrivers/iommu/arm/arm-smmu-v3/Makefile:2:obj-$(CONFIG_ARM_SMMU_V3) += arm_smmu_v3.o\ndrivers/iommu/arm/arm-smmu-v3/Makefile-3-arm_smmu_v3-y := arm-smmu-v3.o\ndrivers/iommu/arm/arm-smmu-v3/Makefile:4:arm_smmu_v3-$(CONFIG_ARM_SMMU_V3_IOMMUFD) += arm-smmu-v3-iommufd.o\ndrivers/iommu/arm/arm-smmu-v3/Makefile:5:arm_smmu_v3-$(CONFIG_ARM_SMMU_V3_SVA) += arm-smmu-v3-sva.o\ndrivers/iommu/arm/arm-smmu-v3/Makefile-6-arm_smmu_v3-$(CONFIG_TEGRA241_CMDQV) += tegra241-cmdqv.o\ndrivers/iommu/arm/arm-smmu-v3/Makefile-7-\ndrivers/iommu/arm/arm-smmu-v3/Makefile:8:obj-$(CONFIG_ARM_SMMU_V3_KUNIT_TEST) += arm-smmu-v3-test.o\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c=3298=static int arm_smmu_enable_iopf(struct arm_smmu_master master,\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c-3304-\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:3305:\tif (!IS_ENABLED(CONFIG_ARM_SMMU_V3_SVA))\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c-3306-\t\treturn -EOPNOTSUPP;\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c=3334=static void arm_smmu_disable_iopf(struct arm_smmu_master master,\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c-3338-\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:3339:\tif (!IS_ENABLED(CONFIG_ARM_SMMU_V3_SVA))\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c-3340-\t\treturn;\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h-7-\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h:8:#ifndef _ARM_SMMU_V3_H\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h:9:#define _ARM_SMMU_V3_H\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h-10-\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h=1285=bool arm_smmu_erratum_repeat_tlbi_cfgi(void);\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h-1286-\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h:1287:#ifdef CONFIG_ARM_SMMU_V3_SVA\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h-1288-bool arm_smmu_sva_supported(struct arm_smmu_device smmu);\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h=1290=struct iommu_domain arm_smmu_sva_domain_alloc(struct device dev,\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h-1291-\t\t\t\t\t struct mm_struct mm);\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h:1292:#else /* CONFIG_ARM_SMMU_V3_SVA /\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h-1293-static inline bool arm_smmu_sva_supported(struct arm_smmu_device smmu)\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h=1298=static inline void arm_smmu_sva_notifier_synchronize(void) {}\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h-1301-\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h:1302:#endif /* CONFIG_ARM_SMMU_V3_SVA /\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h-1303-\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h=1314=struct arm_vsmmu {\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h-1320-\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h:1321:#if IS_ENABLED(CONFIG_ARM_SMMU_V3_IOMMUFD)\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h-1322-void arm_smmu_hw_info(struct device dev, u32 length,\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h=1363=static inline int arm_vmaster_report_event(struct arm_smmu_vmaster vmaster,\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h-1367-}\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h:1368:#endif / CONFIG_ARM_SMMU_V3_IOMMUFD /\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h-1369-\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h:1370:#endif / _ARM_SMMU_V3_H */\n" }
21/2	2026/10/26 17:14	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 29043 output: 37 thoughts: 30 Thoughts: Here's my thought process, summarized as you requested: Digging into ARM SMMU v3 Dependencies Okay, before I go any further, I need to make absolutely sure I've got a handle on the dependencies for the `ARM_SMMU_V3` driver. I know this area inside and out, but it's always worth a quick sanity check to avoid wasting time later. Let's head over to the `drivers/iommu/arm/Kconfig` file. That's the logical place to find the configuration options and their associated dependencies. I want to quickly review which other features or kernel configurations need to be enabled for `ARM_SMMU_V3` to build and function correctly. It's about ensuring I'm not missing any subtle interactions or assuming anything that isn't explicitly defined in the Kconfig file. Better safe than sorry.
22/2	2026/10/26 17:14	tool	read-file	0m Args: { "File": "drivers/iommu/arm/Kconfig", "FirstLine": 70, "LineCount": 30 } Results: { "Contents": " 70:\t\n 71:\t\t Say Y here to enable debug for issues such as context faults\n 72:\t\t or TLB sync timeouts which requires implementation defined\n 73:\t\t register dumps.\n 74:\tendif\n 75:\t\n 76:\tconfig ARM_SMMU_V3\n 77:\t\ttristate \"ARM Ltd. System MMU Version 3 (SMMUv3) Support\"\n 78:\t\tdepends on ARM64\n 79:\t\tselect IOMMU_API\n 80:\t\tselect IOMMU_IO_PGTABLE_LPAE\n 81:\t\tselect GENERIC_MSI_IRQ\n 82:\t\tselect IOMMUFD_DRIVER if IOMMUFD\n 83:\t\thelp\n 84:\t\t Support for implementations of the ARM System MMU architecture\n 85:\t\t version 3 providing translation support to a PCIe root complex.\n 86:\t\n 87:\t\t Say Y here if your system includes an IOMMU device implementing\n 88:\t\t the ARM SMMUv3 architecture.\n 89:\t\n 90:\tif ARM_SMMU_V3\n 91:\tconfig ARM_SMMU_V3_SVA\n 92:\t\tbool \"Shared Virtual Addressing support for the ARM SMMUv3\"\n 93:\t\tselect IOMMU_SVA\n 94:\t\tselect IOMMU_IOPF\n 95:\t\tselect MMU_NOTIFIER\n 96:\t\thelp\n 97:\t\t Support for sharing process address spaces with devices using the\n 98:\t\t SMMUv3.\n 99:\t\n" }
23/2	2026/10/26 17:14	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 29721 output: 23 thoughts: 895 Thoughts: Analyzing IOMMU and LPAE for amd64 Compatibility Okay, so I'm thinking about `ARM_SMMU_V3`. It clearly depends on `ARM64`, which immediately raises a flag. This isn't an `amd64` thing, so it throws off my initial assumptions. I need to figure out if any driver using LPAE can actually be built and run on `amd64`. First, let me check all the drivers that use `IOMMU_IO_PGTABLE_LPAE`. I have these: `ARM_SMMU`, `ARM_SMMU_V3`, `QCOM_IOMMU`, `IPMMU_VMSA`, `DRM_PANFROST`, `DRM_PANTHOR`, and `DRM_TYR`. Looking at the dependencies, only `ARM_SMMU_V3` directly locks to `ARM64`. `ARM_SMMU` has a broader dependency that includes `ARM64`, `ARM`, or `COMPILE_TEST`. The others seem to target ARM architectures as well. Now, a crucial question: is `IOMMU_IO_PGTABLE_LPAE` user-selectable in Kconfig? Let's check `drivers/iommu/Kconfig`. Yes, it is user-selectable – it's a `bool` option. So, I can enable it. But the real test is if it can execute on `amd64` without actual ARM hardware. I have to consider the fuzzing criteria. I need to determine if it is "WorthFuzzing=false" because the code path is unreachable on my target architecture which is amd64. I have to look for "Unreachable execution paths" and "Code paths exclusive to architectures other than the target architecture." I'm starting to think about whether any code path can actually reach `visit_dirty` or `io_pgtable_visit` on `amd64`. To do this, I will check the `include/linux/iommu.h` to see if there is anything that is affected by my target architecture. Hey wait! `iommu_dirty_bitmap_record` was deleted! I need to determine if it was used anywhere else. Let me grep for `iommu_dirty_bitmap_record`.
24/2	2026/10/26 17:14	tool	grepper	0m Args: { "Expression": "iommu_dirty_bitmap_record" } Results: { "Output": "drivers/iommu/generic_pt/iommu_pt.h=1351=MODULE_IMPORT_NS(\"GENERIC_PT\");\ndrivers/iommu/generic_pt/iommu_pt.h:1352:/* For iommu_dirty_bitmap_record() */\ndrivers/iommu/generic_pt/iommu_pt.h-1353-MODULE_IMPORT_NS(\"IOMMUFD\");\n" }
25/2	2026/10/26 17:15	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 31274 output: 45 thoughts: 142 Thoughts: Okay, here's my understanding, expressed as a first-person summary, keeping in mind I'm an expert in this field: Investigating a Potentially Unused Function in the IOMMU Driver Alright, I'm looking at this code and I see a comment, seemingly alone, referencing `iommu_pt.h` in the `drivers/iommu/generic_pt` directory. That immediately piques my interest. It looks like the function `iommu_dirty_bitmap_record` is the target of the investigation. Let me see... I recall that `iommu_dirty_bitmap_record` was only called from `drivers/iommu/io-pgtable-arm.c:visit_dirty`. Now, the question arises: is this function even relevant to the `generic_pt` IOMMU implementation? Or, did they define their own equivalent? Let's verify this, I need to check the header file. I'm going to jump into `drivers/iommu/generic_pt/iommu_pt.h` and take a look around line 242. That should give me the answer.
26/2	2026/10/26 17:15	tool	read-file	0m Args: { "File": "drivers/iommu/generic_pt/iommu_pt.h", "FirstLine": 240, "LineCount": 40 } Results: { "Contents": " 240:\t};\n 241:\t\n 242:\tstatic void record_dirty(struct pt_state pts,\n 243:\t\t\t\t struct pt_iommu_dirty_args dirty)\n 244:\t{\n 245:\t\tunsigned int lg2sz = pt_entry_oa_lg2sz(pts);\n 246:\t\tpt_vaddr_t start_va = log2_set_mod(pts-\u003erange-\u003eva, 0, lg2sz);\n 247:\t\tpt_vaddr_t dirty_len = log2_to_int(lg2sz);\n 248:\t\n 249:\t\tif (dirty-\u003edirty-\u003ebitmap)\n 250:\t\t\tiova_bitmap_set(dirty-\u003edirty-\u003ebitmap, start_va, dirty_len);\n 251:\t\n 252:\t\tif (!(dirty-\u003eflags \u0026 IOMMU_DIRTY_NO_CLEAR)) {\n 253:\t\t\t/\n 254:\t\t\t No write log required because DMA incoherence and atomic\n 255:\t\t\t * dirty tracking bits can't work together\n 256:\t\t\t /\n 257:\t\t\tpt_entry_make_write_clean(pts);\n 258:\t\t\tiommu_iotlb_gather_add_range(dirty-\u003edirty-\u003egather, start_va,\n 259:\t\t\t\t\t\t dirty_len);\n 260:\t\t}\n 261:\t}\n 262:\t\n 263:\tstatic inline int __read_and_clear_dirty(struct pt_range range, void arg,\n 264:\t\t\t\t\t\t unsigned int level,\n 265:\t\t\t\t\t\t struct pt_table_p table)\n 266:\t{\n 267:\t\tstruct pt_state pts = pt_init(range, level, table);\n 268:\t\tstruct pt_iommu_dirty_args *dirty = arg;\n 269:\t\tint ret;\n 270:\t\n 271:\t\tfor_each_pt_level_entry(\u0026pts) {\n 272:\t\t\tif (pts.type == PT_ENTRY_TABLE) {\n 273:\t\t\t\tret = pt_descend(\u0026pts, arg, __read_and_clear_dirty);\n 274:\t\t\t\tif (ret)\n 275:\t\t\t\t\treturn ret;\n 276:\t\t\t\tcontinue;\n 277:\t\t\t}\n 278:\t\t\tif (pts.type == PT_ENTRY_OA \u0026\u0026 pt_entry_is_write_dirty(\u0026pts))\n 279:\t\t\t\trecord_dirty(\u0026pts, dirty);\n" }
27/2	2026/10/26 17:15	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 32376 output: 43 thoughts: 143 Thoughts: Okay, let's dive into this IOMMU dirty bit situation. Investigating IOMMU Dirty Bit Recording Right, so `generic_pt` has its own `record_dirty` function – good, that's the first clue. And it doesn't call `iommu_dirty_bitmap_record`, which is interesting. Now, I need to understand the relationship and how the dirty bit is actually being tracked and propagated. My next step is to examine `io_pgtable_visit` and `visit_dirty`, specifically within the `drivers/iommu/io-pgtable-arm.c` file. I need to understand the intent of the code and the context of the whole file. I'm thinking that I should find out what `io_pgtable_visit` and `visit_dirty` are doing. My goal is to grasp the overall architecture of `drivers/iommu/io-pgtable-arm.c`. Time to get into the details around lines 800-920, and get a better understanding of how the dirty bit logic is implemented in this specific ARM IOMMU driver.
28/2	2026/10/26 17:16	tool	read-file	0m Args: { "File": "drivers/iommu/io-pgtable-arm.c", "FirstLine": 800, "LineCount": 110 } Results: { "Contents": " 800:\t\tstruct arm_lpae_io_pgtable data = io_pgtable_ops_to_data(ops);\n 801:\t\tstruct io_pgtable_walk_data walk_data = {\n 802:\t\t\t.data = wd,\n 803:\t\t\t.visit = visit_pgtable_walk,\n 804:\t\t\t.addr = iova,\n 805:\t\t\t.end = iova + 1,\n 806:\t\t};\n 807:\t\n 808:\t\treturn __arm_lpae_iopte_walk(data, \u0026walk_data, data-\u003epgd, data-\u003estart_level);\n 809:\t}\n 810:\t\n 811:\tstatic int io_pgtable_visit(struct arm_lpae_io_pgtable data,\n 812:\t\t\t\t struct io_pgtable_walk_data walk_data,\n 813:\t\t\t\t arm_lpae_iopte ptep, int lvl)\n 814:\t{\n 815:\t\tstruct io_pgtable iop = \u0026data-\u003eiop;\n 816:\t\tarm_lpae_iopte pte = READ_ONCE(ptep);\n 817:\t\n 818:\t\tsize_t size = ARM_LPAE_BLOCK_SIZE(lvl, data);\n 819:\t\tint ret = walk_data-\u003evisit(walk_data, lvl, ptep, size);\n 820:\t\tif (ret)\n 821:\t\t\treturn ret;\n 822:\t\n 823:\t\tif (iopte_leaf(pte, lvl, iop-\u003efmt)) {\n 824:\t\t\twalk_data-\u003eaddr = ALIGN_DOWN(walk_data-\u003eaddr, size) + size;\n 825:\t\t\treturn 0;\n 826:\t\t}\n 827:\t\n 828:\t\tif (!iopte_table(pte, lvl)) {\n 829:\t\t\treturn -EINVAL;\n 830:\t\t}\n 831:\t\n 832:\t\tptep = iopte_deref(pte, data);\n 833:\t\treturn __arm_lpae_iopte_walk(data, walk_data, ptep, lvl + 1);\n 834:\t}\n 835:\t\n 836:\tstatic int __arm_lpae_iopte_walk(struct arm_lpae_io_pgtable data,\n 837:\t\t\t\t\t struct io_pgtable_walk_data walk_data,\n 838:\t\t\t\t\t arm_lpae_iopte ptep,\n 839:\t\t\t\t\t int lvl)\n 840:\t{\n 841:\t\tu32 idx;\n 842:\t\tint max_entries, ret;\n 843:\t\n 844:\t\tif (WARN_ON(lvl == ARM_LPAE_MAX_LEVELS))\n 845:\t\t\treturn -EINVAL;\n 846:\t\n 847:\t\tif (lvl == data-\u003estart_level)\n 848:\t\t\tmax_entries = ARM_LPAE_PGD_SIZE(data) / sizeof(arm_lpae_iopte);\n 849:\t\telse\n 850:\t\t\tmax_entries = ARM_LPAE_PTES_PER_TABLE(data);\n 851:\t\n 852:\t\tfor (idx = ARM_LPAE_LVL_IDX(walk_data-\u003eaddr, lvl, data);\n 853:\t\t (idx \u003c max_entries) \u0026\u0026 (walk_data-\u003eaddr \u003c walk_data-\u003eend); ++idx) {\n 854:\t\t\tret = io_pgtable_visit(data, walk_data, ptep + idx, lvl);\n 855:\t\t\tif (ret)\n 856:\t\t\t\treturn ret;\n 857:\t\t}\n 858:\t\n 859:\t\treturn 0;\n 860:\t}\n 861:\t\n 862:\tstatic int visit_dirty(struct io_pgtable_walk_data walk_data, int lvl,\n 863:\t\t\t arm_lpae_iopte ptep, size_t size)\n 864:\t{\n 865:\t\tstruct iommu_dirty_bitmap dirty = walk_data-\u003edata;\n 866:\t\n 867:\t\tif (!iopte_leaf(ptep, lvl, walk_data-\u003eiop-\u003efmt))\n 868:\t\t\treturn 0;\n 869:\t\n 870:\t\tif (iopte_writeable_dirty(ptep)) {\n 871:\t\t\tu64 iova = ALIGN_DOWN(walk_data-\u003eaddr, size);\n 872:\t\n 873:\t\t\tif (dirty-\u003ebitmap)\n 874:\t\t\t\tiova_bitmap_set(dirty-\u003ebitmap, iova, size);\n 875:\t\n 876:\t\t\tif (!(walk_data-\u003eflags \u0026 IOMMU_DIRTY_NO_CLEAR)) {\n 877:\t\t\t\tiopte_set_writeable_clean(ptep);\n 878:\t\t\t\tif (dirty-\u003egather)\n 879:\t\t\t\t\tio_pgtable_tlb_add_page(walk_data-\u003eiop,\n 880:\t\t\t\t\t\t\t\tdirty-\u003egather, iova,\n 881:\t\t\t\t\t\t\t\tsize);\n 882:\t\t\t}\n 883:\t\t}\n 884:\t\n 885:\t\treturn 0;\n 886:\t}\n 887:\t\n 888:\tstatic int arm_lpae_read_and_clear_dirty(struct io_pgtable_ops ops,\n 889:\t\t\t\t\t\t unsigned long iova, size_t size,\n 890:\t\t\t\t\t\t unsigned long flags,\n 891:\t\t\t\t\t\t struct iommu_dirty_bitmap dirty)\n 892:\t{\n 893:\t\tstruct arm_lpae_io_pgtable data = io_pgtable_ops_to_data(ops);\n 894:\t\tstruct io_pgtable_cfg cfg = \u0026data-\u003eiop.cfg;\n 895:\t\tstruct io_pgtable_walk_data walk_data = {\n 896:\t\t\t.iop = \u0026data-\u003eiop,\n 897:\t\t\t.data = dirty,\n 898:\t\t\t.visit = visit_dirty,\n 899:\t\t\t.flags = flags,\n" }
29/2	2026/10/26 17:16	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 34452 output: 22 thoughts: 689 Thoughts: Analyzing the Call Chain for `arm_lpae_read_and_clear_dirty` Okay, let's break this down. My initial thought is that `arm_lpae_read_and_clear_dirty` is the only function that sets `visit` to `visit_dirty`. That’s the key. Now, where is it called? A quick look reveals that `arm_lpae_read_and_clear_dirty` is called through `ops->read_and_clear_dirty`, and this `ops` is of type `io_pgtable_ops`. So, the next question becomes: who uses `ops->read_and_clear_dirty`? Ah, looking at the code, it's pretty clear. It's used by `arm_smmu_read_and_clear_dirty` within `arm-smmu-v3.c`. Specifically: ```c static int arm_smmu_read_and_clear_dirty(struct iommu_domain domain, unsigned long iova, size_t size, unsigned long flags, struct iommu_dirty_bitmap dirty) { struct arm_smmu_domain smmu_domain = to_smmu_domain(domain); struct io_pgtable_ops ops = smmu_domain->pgtbl_ops; return ops->read_and_clear_dirty(ops, iova, size, flags, dirty); } ``` Now, let's broaden the scope. Does anything else utilize `ops->read_and_clear_dirty`? To ensure complete understanding, I need to check every instance of `read_and_clear_dirty` in the kernel source. We have already grepped the kernel for `read_and_clear_dirty`: 1. `drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c` (as expected) 2. `drivers/iommu/generic_pt/iommu_pt.h` which contains `DOMAIN_NS(read_and_clear_dirty)`. This tells me nothing concretely. 3. `drivers/iommu/io-pgtable-arm.c` (where `arm_lpae_read_and_clear_dirty` is defined). 4. `drivers/iommu/iommufd/hw_pagetable.c` and `drivers/iommu/iommufd/io_pagetable.c`. These look interesting. Specifically, in `drivers/iommu/iommufd/io_pagetable.c`: ```c static int __iommu_read_and_clear_dirty(struct iova_bitmap bitmap, unsigned long iova, size_t length, void opaque) ... const struct iommu_dirty_ops ops = domain->dirty_ops; ... ret = ops->read_and_clear_dirty(domain, iter.cur_iova, last - iter.cur_iova + 1, flags, &dirty); ``` Here, `ops` is not* `io_pgtable_ops`. It's actually `domain->dirty_ops`, which suggests a different, IOMMU domain-specific dirty operations structure. The next question becomes: which drivers are implementing the `iommu_dirty_ops` struct? I need to analyze all implementations of `struct iommu_dirty_ops`!
30/2	2026/10/26 17:16	tool	grepper	0m Args: { "Expression": "struct iommu_dirty_ops" } Results: { "Output": "drivers/iommu/amd/iommu.c=2900=static const struct iommu_domain_ops amdv1_ops = {\n--\ndrivers/iommu/amd/iommu.c-2909-\ndrivers/iommu/amd/iommu.c:2910:static const struct iommu_dirty_ops amdv1_dirty_ops = {\ndrivers/iommu/amd/iommu.c-2911-\tIOMMU_PT_DIRTY_OPS(amdv1),\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c=48=static const struct iommu_ops arm_smmu_ops;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:49:static struct iommu_dirty_ops arm_smmu_dirty_ops;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c-50-\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c=4585=static const struct iommu_ops arm_smmu_ops = {\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c-4616-\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:4617:static struct iommu_dirty_ops arm_smmu_dirty_ops = {\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c-4618-\t.read_and_clear_dirty\t= arm_smmu_read_and_clear_dirty,\n--\ndrivers/iommu/intel/iommu.c=3011=static unsigned int compute_vasz_lg2_ss(struct intel_iommu iommu,\n--\ndrivers/iommu/intel/iommu.c-3035-\ndrivers/iommu/intel/iommu.c:3036:static const struct iommu_dirty_ops intel_second_stage_dirty_ops = {\ndrivers/iommu/intel/iommu.c-3037-\tIOMMU_PT_DIRTY_OPS(vtdss),\n--\ndrivers/iommu/iommufd/io_pagetable.c=536=static int __iommu_read_and_clear_dirty(struct iova_bitmap bitmap,\n--\ndrivers/iommu/iommufd/io_pagetable.c-544-\tstruct iommu_dirty_bitmap dirty = arg-\u003edirty;\ndrivers/iommu/iommufd/io_pagetable.c:545:\tconst struct iommu_dirty_ops ops = domain-\u003edirty_ops;\ndrivers/iommu/iommufd/io_pagetable.c-546-\tunsigned long last_iova = iova + length - 1;\n--\ndrivers/iommu/iommufd/io_pagetable.c=566=iommu_read_and_clear_dirty(struct iommu_domain domain,\n--\ndrivers/iommu/iommufd/io_pagetable.c-569-{\ndrivers/iommu/iommufd/io_pagetable.c:570:\tconst struct iommu_dirty_ops ops = domain-\u003edirty_ops;\ndrivers/iommu/iommufd/io_pagetable.c-571-\tstruct iommu_iotlb_gather gather;\n--\ndrivers/iommu/iommufd/io_pagetable.c=649=static int iopt_clear_dirty_data(struct io_pagetable iopt,\n--\ndrivers/iommu/iommufd/io_pagetable.c-651-{\ndrivers/iommu/iommufd/io_pagetable.c:652:\tconst struct iommu_dirty_ops ops = domain-\u003edirty_ops;\ndrivers/iommu/iommufd/io_pagetable.c-653-\tstruct iommu_iotlb_gather gather;\n--\ndrivers/iommu/iommufd/io_pagetable.c=678=int iopt_set_dirty_tracking(struct io_pagetable iopt,\n--\ndrivers/iommu/iommufd/io_pagetable.c-680-{\ndrivers/iommu/iommufd/io_pagetable.c:681:\tconst struct iommu_dirty_ops ops = domain-\u003edirty_ops;\ndrivers/iommu/iommufd/io_pagetable.c-682-\tint ret = 0;\n--\ndrivers/iommu/iommufd/selftest.c=412=static const struct iommu_domain_ops amdv1_mock_huge_ops = {\n--\ndrivers/iommu/iommufd/selftest.c-420-\ndrivers/iommu/iommufd/selftest.c:421:static const struct iommu_dirty_ops amdv1_mock_dirty_ops = {\ndrivers/iommu/iommufd/selftest.c-422-\tIOMMU_PT_DIRTY_OPS(amdv1_mock),\n--\ninclude/linux/iommu.h=40=struct iommu_domain_ops;\ninclude/linux/iommu.h:41:struct iommu_dirty_ops;\ninclude/linux/iommu.h-42-struct notifier_block;\n--\ninclude/linux/iommu.h=223=struct iommu_domain {\n--\ninclude/linux/iommu.h-227-\tconst struct iommu_domain_ops ops;\ninclude/linux/iommu.h:228:\tconst struct iommu_dirty_ops dirty_ops;\ninclude/linux/iommu.h-229-\tconst struct iommu_ops owner; / Whose domain_alloc we came from /\n--\ninclude/linux/iommu.h=402=struct iommu_dirty_bitmap {\n--\ninclude/linux/iommu.h-407-/\ninclude/linux/iommu.h:408: struct iommu_dirty_ops - domain specific dirty tracking operations\ninclude/linux/iommu.h-409- * @set_dirty_tracking: Enable or Disable dirty tracking on the iommu domain\n--\ninclude/linux/iommu.h-414- /\ninclude/linux/iommu.h:415:struct iommu_dirty_ops {\ninclude/linux/iommu.h-416-\tint (set_dirty_tracking)(struct iommu_domain *domain, bool enabled);\n--\ninclude/linux/iommu.h=1225=struct iommu_dirty_bitmap {};\ninclude/linux/iommu.h:1226:struct iommu_dirty_ops {};\ninclude/linux/iommu.h-1227-\n" }
31/2	2026/10/26 17:16	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 37756 output: 18 thoughts: 370 Thoughts: Digging into the `iommu_dirty_ops` Implementation Okay, let's see what's going on here. Interesting, the only places using `iommu_dirty_ops` are these four: `amd/iommu.c`, `intel/iommu.c`, `iommufd/selftest.c`, and `arm/arm-smmu-v3/arm-smmu-v3.c`. And it looks like the first three all leverage `generic_pt`, which is as expected. But `arm-smmu-v3.c` is calling `ops->read_and_clear_dirty`, which, as I can see, resolves to `arm_lpae_read_and_clear_dirty` in `io-pgtable-arm.c`. Now, the important question is whether there are other callers of this function. Let's see... what about `io_pgtable_visit`? It appears `io_pgtable_visit` is called by `arm_lpae_pgtable_walk` and recursively by `__arm_lpae_iopte_walk`. I need to figure out who calls `arm_lpae_pgtable_walk`. Right, it's `arm_lpae_alloc_pgtable`, specifically through `.pgtable_walk = arm_lpae_pgtable_walk`. Alright, back to the `iommu_dirty_ops` structure to figure out who calls `ops->pgtable_walk`. Let's check!
32/2	2026/10/26 17:17	tool	grepper	0m Args: { "Expression": "pgtable_walk" } Results: { "Output": "\nFull output is too long, showing 200 out of 732 lines.\nUse more precise expression or PathPrefixes if possible.\n\nNumber of matching lines per file (19 files in total):\narch/arm64/include/asm/kvm_pgtable.h:23\narch/arm64/include/asm/kvm_pkvm.h:3\narch/arm64/kvm/hyp/nvhe/mem_protect.c:3\narch/arm64/kvm/hyp/nvhe/mm.c:8\narch/arm64/kvm/hyp/nvhe/setup.c:7\narch/arm64/kvm/hyp/pgtable.c:78\narch/arm64/kvm/mmu.c:3\narch/arm64/kvm/pkvm.c:3\narch/arm64/kvm/ptdump.c:3\ndrivers/gpu/drm/msm/msm_iommu.c:3\ndrivers/iommu/intel/debugfs.c:3\ndrivers/iommu/intel/iommu.c:4\ndrivers/iommu/io-pgtable-arm.c:15\ninclude/linux/io-pgtable.h:4\ninclude/linux/mm.h:2\ninclude/linux/pagewalk.h:1\nmm/gup.c:2\nmm/memory.c:2\nmm/pagewalk.c:2\n\narch/arm64/include/asm/kvm_pgtable.h=308=typedef bool (kvm_pgtable_force_pte_cb_t)(u64 addr, u64 end,\n--\narch/arm64/include/asm/kvm_pgtable.h-311-/\narch/arm64/include/asm/kvm_pgtable.h:312: enum kvm_pgtable_walk_flags - Flags to control a depth-first page-table walk.\narch/arm64/include/asm/kvm_pgtable.h-313- * @KVM_PGTABLE_WALK_LEAF:\t\tVisit leaf entries, including invalid\n--\narch/arm64/include/asm/kvm_pgtable.h-329- /\narch/arm64/include/asm/kvm_pgtable.h:330:enum kvm_pgtable_walk_flags {\narch/arm64/include/asm/kvm_pgtable.h-331-\tKVM_PGTABLE_WALK_LEAF\t\t\t= BIT(0),\n--\narch/arm64/include/asm/kvm_pgtable.h=340=struct kvm_pgtable_visit_ctx {\n--\narch/arm64/include/asm/kvm_pgtable.h-348-\ts8\t\t\t\t\tlevel;\narch/arm64/include/asm/kvm_pgtable.h:349:\tenum kvm_pgtable_walk_flags\t\tflags;\narch/arm64/include/asm/kvm_pgtable.h-350-};\n--\narch/arm64/include/asm/kvm_pgtable.h=352=typedef int (kvm_pgtable_visitor_fn_t)(const struct kvm_pgtable_visit_ctx ctx,\narch/arm64/include/asm/kvm_pgtable.h:353:\t\t\t\t\tenum kvm_pgtable_walk_flags visit);\narch/arm64/include/asm/kvm_pgtable.h-354-\narch/arm64/include/asm/kvm_pgtable.h:355:static inline bool kvm_pgtable_walk_shared(const struct kvm_pgtable_visit_ctx ctx)\narch/arm64/include/asm/kvm_pgtable.h-356-{\n--\narch/arm64/include/asm/kvm_pgtable.h-360-/*\narch/arm64/include/asm/kvm_pgtable.h:361: struct kvm_pgtable_walker - Hook into a page-table walk.\narch/arm64/include/asm/kvm_pgtable.h-362- * @cb:\t\tCallback function to invoke during the walk.\n--\narch/arm64/include/asm/kvm_pgtable.h-366- /\narch/arm64/include/asm/kvm_pgtable.h:367:struct kvm_pgtable_walker {\narch/arm64/include/asm/kvm_pgtable.h-368-\tconst kvm_pgtable_visitor_fn_t\t\tcb;\narch/arm64/include/asm/kvm_pgtable.h-369-\tvoid const\t\t\t\targ;\narch/arm64/include/asm/kvm_pgtable.h:370:\tconst enum kvm_pgtable_walk_flags\tflags;\narch/arm64/include/asm/kvm_pgtable.h-371-};\n--\narch/arm64/include/asm/kvm_pgtable.h=380=typedef kvm_pte_t kvm_pteref_t;\narch/arm64/include/asm/kvm_pgtable.h-381-\narch/arm64/include/asm/kvm_pgtable.h:382:static inline kvm_pte_t kvm_dereference_pteref(struct kvm_pgtable_walker walker,\narch/arm64/include/asm/kvm_pgtable.h-383-\t\t\t\t\t\tkvm_pteref_t pteref)\n--\narch/arm64/include/asm/kvm_pgtable.h=388=static inline kvm_pte_t kvm_dereference_pteref_raw(kvm_pteref_t pteref)\n--\narch/arm64/include/asm/kvm_pgtable.h-392-\narch/arm64/include/asm/kvm_pgtable.h:393:static inline int kvm_pgtable_walk_begin(struct kvm_pgtable_walker walker)\narch/arm64/include/asm/kvm_pgtable.h-394-{\n--\narch/arm64/include/asm/kvm_pgtable.h-404-\narch/arm64/include/asm/kvm_pgtable.h:405:static inline void kvm_pgtable_walk_end(struct kvm_pgtable_walker walker) {}\narch/arm64/include/asm/kvm_pgtable.h-406-\narch/arm64/include/asm/kvm_pgtable.h:407:static inline bool kvm_pgtable_walk_lock_held(void)\narch/arm64/include/asm/kvm_pgtable.h-408-{\n--\narch/arm64/include/asm/kvm_pgtable.h=414=typedef kvm_pte_t __rcu kvm_pteref_t;\narch/arm64/include/asm/kvm_pgtable.h-415-\narch/arm64/include/asm/kvm_pgtable.h:416:static inline kvm_pte_t kvm_dereference_pteref(struct kvm_pgtable_walker walker,\narch/arm64/include/asm/kvm_pgtable.h-417-\t\t\t\t\t\tkvm_pteref_t pteref)\n--\narch/arm64/include/asm/kvm_pgtable.h=422=static inline kvm_pte_t kvm_dereference_pteref_raw(kvm_pteref_t pteref)\n--\narch/arm64/include/asm/kvm_pgtable.h-426-\narch/arm64/include/asm/kvm_pgtable.h:427:static inline int kvm_pgtable_walk_begin(struct kvm_pgtable_walker walker)\narch/arm64/include/asm/kvm_pgtable.h-428-{\n--\narch/arm64/include/asm/kvm_pgtable.h-434-\narch/arm64/include/asm/kvm_pgtable.h:435:static inline void kvm_pgtable_walk_end(struct kvm_pgtable_walker walker)\narch/arm64/include/asm/kvm_pgtable.h-436-{\n--\narch/arm64/include/asm/kvm_pgtable.h-440-\narch/arm64/include/asm/kvm_pgtable.h:441:static inline bool kvm_pgtable_walk_lock_held(void)\narch/arm64/include/asm/kvm_pgtable.h-442-{\n--\narch/arm64/include/asm/kvm_pgtable.h=680=int kvm_pgtable_stage2_map(struct kvm_pgtable pgt, u64 addr, u64 size,\narch/arm64/include/asm/kvm_pgtable.h-681-\t\t\t u64 phys, enum kvm_pgtable_prot prot,\narch/arm64/include/asm/kvm_pgtable.h:682:\t\t\t void mc, enum kvm_pgtable_walk_flags flags);\narch/arm64/include/asm/kvm_pgtable.h-683-\n--\narch/arm64/include/asm/kvm_pgtable.h=757=void kvm_pgtable_stage2_mkyoung(struct kvm_pgtable pgt, u64 addr,\narch/arm64/include/asm/kvm_pgtable.h:758:\t\t\t\tenum kvm_pgtable_walk_flags flags);\narch/arm64/include/asm/kvm_pgtable.h-759-\n--\narch/arm64/include/asm/kvm_pgtable.h=800=int kvm_pgtable_stage2_relax_perms(struct kvm_pgtable pgt, u64 addr,\narch/arm64/include/asm/kvm_pgtable.h-801-\t\t\t\t enum kvm_pgtable_prot prot,\narch/arm64/include/asm/kvm_pgtable.h:802:\t\t\t\t enum kvm_pgtable_walk_flags flags);\narch/arm64/include/asm/kvm_pgtable.h-803-\n--\narch/arm64/include/asm/kvm_pgtable.h=835=int kvm_pgtable_stage2_split(struct kvm_pgtable pgt, u64 addr, u64 size,\n--\narch/arm64/include/asm/kvm_pgtable.h-838-/\narch/arm64/include/asm/kvm_pgtable.h:839: kvm_pgtable_walk() - Walk a page-table.\narch/arm64/include/asm/kvm_pgtable.h-840- * @pgt:\tPage-table structure initialised by kvm_pgtable__init().\n--\narch/arm64/include/asm/kvm_pgtable.h-858- /\narch/arm64/include/asm/kvm_pgtable.h:859:int kvm_pgtable_walk(struct kvm_pgtable pgt, u64 addr, u64 size,\narch/arm64/include/asm/kvm_pgtable.h:860:\t\t struct kvm_pgtable_walker walker);\narch/arm64/include/asm/kvm_pgtable.h-861-\n--\narch/arm64/include/asm/kvm_pgtable.h=881=int kvm_pgtable_get_leaf(struct kvm_pgtable pgt, u64 addr,\narch/arm64/include/asm/kvm_pgtable.h-882-\t\t\t kvm_pte_t ptep, s8 level,\narch/arm64/include/asm/kvm_pgtable.h:883:\t\t\t enum kvm_pgtable_walk_flags flags);\narch/arm64/include/asm/kvm_pgtable.h-884-\n--\narch/arm64/include/asm/kvm_pkvm.h=356=int pkvm_pgtable_stage2_map(struct kvm_pgtable pgt, u64 addr, u64 size, u64 phys,\narch/arm64/include/asm/kvm_pkvm.h-357-\t\t\t enum kvm_pgtable_prot prot, void mc,\narch/arm64/include/asm/kvm_pkvm.h:358:\t\t\t enum kvm_pgtable_walk_flags flags);\narch/arm64/include/asm/kvm_pkvm.h-359-int pkvm_pgtable_stage2_unmap(struct kvm_pgtable pgt, u64 addr, u64 size);\n--\narch/arm64/include/asm/kvm_pkvm.h=363=int pkvm_pgtable_stage2_relax_perms(struct kvm_pgtable pgt, u64 addr, enum kvm_pgtable_prot prot,\narch/arm64/include/asm/kvm_pkvm.h:364:\t\t\t\t enum kvm_pgtable_walk_flags flags);\narch/arm64/include/asm/kvm_pkvm.h-365-void pkvm_pgtable_stage2_mkyoung(struct kvm_pgtable pgt, u64 addr,\narch/arm64/include/asm/kvm_pkvm.h:366:\t\t\t\t enum kvm_pgtable_walk_flags flags);\narch/arm64/include/asm/kvm_pkvm.h-367-int pkvm_pgtable_stage2_split(struct kvm_pgtable pgt, u64 addr, u64 size,\n--\narch/arm64/kvm/hyp/nvhe/mem_protect.c=814=static int __check_page_state_visitor(const struct kvm_pgtable_visit_ctx ctx,\narch/arm64/kvm/hyp/nvhe/mem_protect.c:815:\t\t\t\t enum kvm_pgtable_walk_flags visit)\narch/arm64/kvm/hyp/nvhe/mem_protect.c-816-{\n--\narch/arm64/kvm/hyp/nvhe/mem_protect.c=822=static int check_page_state_range(struct kvm_pgtable pgt, u64 addr, u64 size,\n--\narch/arm64/kvm/hyp/nvhe/mem_protect.c-824-{\narch/arm64/kvm/hyp/nvhe/mem_protect.c:825:\tstruct kvm_pgtable_walker walker = {\narch/arm64/kvm/hyp/nvhe/mem_protect.c-826-\t\t.cb\t= __check_page_state_visitor,\n--\narch/arm64/kvm/hyp/nvhe/mem_protect.c-830-\narch/arm64/kvm/hyp/nvhe/mem_protect.c:831:\treturn kvm_pgtable_walk(pgt, addr, size, \u0026walker);\narch/arm64/kvm/hyp/nvhe/mem_protect.c-832-}\n--\narch/arm64/kvm/hyp/nvhe/mm.c=361=static int __create_fixmap_slot_cb(const struct kvm_pgtable_visit_ctx ctx,\narch/arm64/kvm/hyp/nvhe/mm.c:362:\t\t\t\t enum kvm_pgtable_walk_flags visit)\narch/arm64/kvm/hyp/nvhe/mm.c-363-{\n--\narch/arm64/kvm/hyp/nvhe/mm.c=382=static int create_fixmap_slot(u64 addr, u64 cpu)\narch/arm64/kvm/hyp/nvhe/mm.c-383-{\narch/arm64/kvm/hyp/nvhe/mm.c:384:\tstruct kvm_pgtable_walker walker = {\narch/arm64/kvm/hyp/nvhe/mm.c-385-\t\t.cb\t= __create_fixmap_slot_cb,\n--\narch/arm64/kvm/hyp/nvhe/mm.c-389-\narch/arm64/kvm/hyp/nvhe/mm.c:390:\treturn kvm_pgtable_walk(\u0026pkvm_pgtable, addr, PAGE_SIZE, \u0026walker);\narch/arm64/kvm/hyp/nvhe/mm.c-391-}\n--\narch/arm64/kvm/hyp/nvhe/mm.c=399=static int create_fixblock(void)\n--\narch/arm64/kvm/hyp/nvhe/mm.c-401-#ifdef HAS_FIXBLOCK\narch/arm64/kvm/hyp/nvhe/mm.c:402:\tstruct kvm_pgtable_walker walker = {\narch/arm64/kvm/hyp/nvhe/mm.c-403-\t\t.cb\t= __create_fixmap_slot_cb,\n--\narch/arm64/kvm/hyp/nvhe/mm.c-430-\narch/arm64/kvm/hyp/nvhe/mm.c:431:\tret = kvm_pgtable_walk(\u0026pkvm_pgtable, addr, PMD_SIZE, \u0026walker);\narch/arm64/kvm/hyp/nvhe/mm.c-432-\n--\narch/arm64/kvm/hyp/nvhe/mm.c=579=static int check_host_ownership_walker(const struct kvm_pgtable_visit_ctx ctx,\narch/arm64/kvm/hyp/nvhe/mm.c:580:\t\t\t\t enum kvm_pgtable_walk_flags visit)\narch/arm64/kvm/hyp/nvhe/mm.c-581-{\n--\narch/arm64/kvm/hyp/nvhe/mm.c=599=int pkvm_check_host_ownership(void)\narch/arm64/kvm/hyp/nvhe/mm.c-600-{\narch/arm64/kvm/hyp/nvhe/mm.c:601:\tstruct kvm_pgtable_walker walker = {\narch/arm64/kvm/hyp/nvhe/mm.c-602-\t\t.cb\t= check_host_ownership_walker,\n--\narch/arm64/kvm/hyp/nvhe/mm.c-606-\t/ The private range and the vmemmap share one quarter of the VA space. /\narch/arm64/kvm/hyp/nvhe/mm.c:607:\treturn kvm_pgtable_walk(\u0026pkvm_pgtable, __io_map_base,\narch/arm64/kvm/hyp/nvhe/mm.c-608-\t\t\t\tBIT(pkvm_pgtable.ia_bits - 2), \u0026walker);\n--\narch/arm64/kvm/hyp/nvhe/setup.c=190=static int fix_host_ownership_walker(const struct kvm_pgtable_visit_ctx ctx,\narch/arm64/kvm/hyp/nvhe/setup.c:191:\t\t\t\t enum kvm_pgtable_walk_flags visit)\narch/arm64/kvm/hyp/nvhe/setup.c-192-{\n--\narch/arm64/kvm/hyp/nvhe/setup.c=242=static int fix_hyp_pgtable_refcnt_walker(const struct kvm_pgtable_visit_ctx ctx,\narch/arm64/kvm/hyp/nvhe/setup.c:243:\t\t\t\t\t enum kvm_pgtable_walk_flags visit)\narch/arm64/kvm/hyp/nvhe/setup.c-244-{\n--\narch/arm64/kvm/hyp/nvhe/setup.c=256=static int fix_host_ownership(void)\narch/arm64/kvm/hyp/nvhe/setup.c-257-{\narch/arm64/kvm/hyp/nvhe/setup.c:258:\tstruct kvm_pgtable_walker walker = {\narch/arm64/kvm/hyp/nvhe/setup.c-259-\t\t.cb\t= fix_host_ownership_walker,\n--\narch/arm64/kvm/hyp/nvhe/setup.c-267-\narch/arm64/kvm/hyp/nvhe/setup.c:268:\t\tret = kvm_pgtable_walk(\u0026pkvm_pgtable, start, reg-\u003esize, \u0026walker);\narch/arm64/kvm/hyp/nvhe/setup.c-269-\t\tif (ret)\n--\narch/arm64/kvm/hyp/nvhe/setup.c-277-\narch/arm64/kvm/hyp/nvhe/setup.c:278:\t\tret = kvm_pgtable_walk(\u0026pkvm_pgtable, start, NVHE_STACK_SIZE, \u0026walker);\narch/arm64/kvm/hyp/nvhe/setup.c-279-\t\tif (ret)\n--\narch/arm64/kvm/hyp/nvhe/setup.c=286=static int fix_hyp_pgtable_refcnt(void)\narch/arm64/kvm/hyp/nvhe/setup.c-287-{\narch/arm64/kvm/hyp/nvhe/setup.c:288:\tstruct kvm_pgtable_walker walker = {\narch/arm64/kvm/hyp/nvhe/setup.c-289-\t\t.cb\t= fix_hyp_pgtable_refcnt_walker,\n--\narch/arm64/kvm/hyp/nvhe/setup.c-293-\narch/arm64/kvm/hyp/nvhe/setup.c:294:\treturn kvm_pgtable_walk(\u0026pkvm_pgtable, 0, BIT(pkvm_pgtable.ia_bits),\narch/arm64/kvm/hyp/nvhe/setup.c-295-\t\t\t\t\u0026walker);\n--\narch/arm64/kvm/hyp/pgtable.c-14-\narch/arm64/kvm/hyp/pgtable.c:15:struct kvm_pgtable_walk_data {\narch/arm64/kvm/hyp/pgtable.c:16:\tstruct kvm_pgtable_walker\twalker;\narch/arm64/kvm/hyp/pgtable.c-17-\n--\narch/arm64/kvm/hyp/pgtable.c-22-\narch/arm64/kvm/hyp/pgtable.c:23:static bool kvm_pgtable_walk_skip_bbm_tlbi(const struct kvm_pgtable_visit_ctx *ctx)\narch/arm64/kvm/hyp/pgtable.c-24-{\n--\narch/arm64/kvm/hyp/pgtable.c-27-\n\n" }
33/2	2026/10/26 17:17	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 44352 output: 33 thoughts: 30 Thoughts: Okay, here's my take on those thoughts, framed as an expert's internal monologue: Diving into the MSM IOMMU for Pgtables Alright, time to get to the heart of this IOMMU issue. My gut feeling is that the problem probably lies somewhere deep in the page table handling, so let's zero in on the `msm_iommu.c` driver. Specifically, I need to take a look at how it implements `pgtable_walk`. This is where the magic happens, or in this case, where the potential problem is brewing. I need to understand exactly how the driver traverses the page tables, maps virtual addresses to physical ones, and handles any potential faults or inconsistencies. I need to see how it's interacting with the hardware and if it's handling things like TLB flushes correctly. A deep dive into `pgtable_walk` will likely reveal the root cause and let me figure out how to debug this. I'm hoping I can find the answer inside.
34/2	2026/10/26 17:17	tool	grepper	0m Args: { "Expression": "pgtable_walk", "PathPrefixes": [ "drivers/gpu/drm/msm" ] } Results: { "Output": "drivers/gpu/drm/msm/msm_iommu.c=284=msm_iommu_pagetable_walk(struct msm_mmu mmu, unsigned long iova, uint64_t ptes[4])\n--\ndrivers/gpu/drm/msm/msm_iommu.c-286-\tstruct msm_iommu_pagetable pagetable;\ndrivers/gpu/drm/msm/msm_iommu.c:287:\tstruct arm_lpae_io_pgtable_walk_data wd = {};\ndrivers/gpu/drm/msm/msm_iommu.c-288-\n--\ndrivers/gpu/drm/msm/msm_iommu.c-293-\ndrivers/gpu/drm/msm/msm_iommu.c:294:\tif (!pagetable-\u003epgtbl_ops-\u003epgtable_walk)\ndrivers/gpu/drm/msm/msm_iommu.c-295-\t\treturn -EINVAL;\ndrivers/gpu/drm/msm/msm_iommu.c-296-\ndrivers/gpu/drm/msm/msm_iommu.c:297:\tpagetable-\u003epgtbl_ops-\u003epgtable_walk(pagetable-\u003epgtbl_ops, iova, \u0026wd);\ndrivers/gpu/drm/msm/msm_iommu.c-298-\n" }
35/2	2026/10/26 17:17	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 44999 output: 44 thoughts: 662 Thoughts: Dissecting IOMMU Page Table Walks Okay, so I'm looking at this function, `msm_iommu_pagetable_walk`, and it's calling `pagetable->pgtbl_ops->pgtable_walk`. The trace is interesting, but what's 'msm'? Ah, right, Qualcomm Snapdragon DRM driver. That means we're dealing with Adreno GPUs, not the generic QEMU amd64 setup. This is probably related to an Adreno GPU crashdump or debugging through debugfs, right? Now, hold on. What about `io_pgtable_visit`? That could be a key. Let me dive into `io-pgtable-arm.c`. Here's the relevant code in `io_pgtable_visit`: ```c if (iopte_leaf(pte, lvl, iop->fmt)) { - walk_data->addr += size; + walk_data->addr = ALIGN_DOWN(walk_data->addr, size) + size; return 0; } ``` And in `visit_dirty`: ```c if (iopte_writeable_dirty(ptep)) { - iommu_dirty_bitmap_record(dirty, walk_data->addr, size); - if (!(walk_data->flags & IOMMU_DIRTY_NO_CLEAR)) + u64 iova = ALIGN_DOWN(walk_data->addr, size); + + if (dirty->bitmap) + iova_bitmap_set(dirty->bitmap, iova, size); + + if (!(walk_data->flags & IOMMU_DIRTY_NO_CLEAR)) { iopte_set_writeable_clean(ptep); + if (dirty->gather) + io_pgtable_tlb_add_page(walk_data->iop, + dirty->gather, iova, + size); + } } ``` Can these functions be hit on AMD64? That's the core question. I need to check which drivers even use* `io-pgtable-arm.c`. Okay, let's see: first, `ARM_SMMU_V3`. The `Kconfig` says it `depends on ARM64`. So, no, that's a dead end. Can't even be enabled on AMD64. Next, `ARM_SMMU`. The `Kconfig` says, `depends on ARM64 \|\| ARM \|\| COMPILE_TEST`. Ah, `COMPILE_TEST`. That allows it to compile but can it probe on AMD64? Let's look at `drivers/iommu/arm/arm-smmu/arm-smmu.c`. It is an OF/platform/ACPI device, that is promising. I need to dig deeper into what this driver requires.
36/2	2026/10/26 17:17	tool	grepper	0m Args: { "Expression": "module_platform_driver\|platform_driver_register", "PathPrefixes": [ "drivers/iommu/arm/arm-smmu" ] } Results: { "Output": "drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c=842=int __init qcom_smmu_module_init(void)\ndrivers/iommu/arm/arm-smmu/arm-smmu-qcom.c-843-{\ndrivers/iommu/arm/arm-smmu/arm-smmu-qcom.c:844:\treturn platform_driver_register(\u0026qcom_smmu_tbu_driver);\ndrivers/iommu/arm/arm-smmu/arm-smmu-qcom.c-845-}\n--\ndrivers/iommu/arm/arm-smmu/arm-smmu.c=2364=static int __init arm_smmu_init(void)\n--\ndrivers/iommu/arm/arm-smmu/arm-smmu.c-2367-\ndrivers/iommu/arm/arm-smmu/arm-smmu.c:2368:\tret = platform_driver_register(\u0026arm_smmu_driver);\ndrivers/iommu/arm/arm-smmu/arm-smmu.c-2369-\tif (ret)\n--\ndrivers/iommu/arm/arm-smmu/qcom_iommu.c=939=static int __init qcom_iommu_init(void)\n--\ndrivers/iommu/arm/arm-smmu/qcom_iommu.c-942-\ndrivers/iommu/arm/arm-smmu/qcom_iommu.c:943:\tret = platform_driver_register(\u0026qcom_iommu_ctx_driver);\ndrivers/iommu/arm/arm-smmu/qcom_iommu.c-944-\tif (ret)\n--\ndrivers/iommu/arm/arm-smmu/qcom_iommu.c-946-\ndrivers/iommu/arm/arm-smmu/qcom_iommu.c:947:\tret = platform_driver_register(\u0026qcom_iommu_driver);\ndrivers/iommu/arm/arm-smmu/qcom_iommu.c-948-\tif (ret)\n" }
37/2	2026/10/26 17:17	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 46935 output: 44 thoughts: 110 Thoughts: My Assessment of the ARM SMMU Driver and Dirty Page Tracking Okay, so I'm looking at this ARM SMMU driver. It's set up to be a platform driver, which means it uses Device Tree (OF) or ACPI for device matching, standard stuff. Now, here's where it gets interesting. Even if the `arm_smmu_driver` probes correctly, the base `arm-smmu.c` file doesn't appear to support dirty page tracking directly. That's a crucial function for optimization and, as I recall, a fairly common feature in modern IOMMUs. Ah, I see a note that only the `arm-smmu-v3` implementation has `read_and_clear_dirty` function. Let me double check the `drivers/iommu/arm/arm-smmu/arm-smmu.c` source code to be absolutely certain. My next step is to search for either `read_and_clear_dirty` or, failing that, a direct mention of `dirty` to confirm whether or not any form of dirty page tracking is implemented, or if I'm going to have to dive deeper.
38/2	2026/10/26 17:18	tool	grepper	0m Error: no matches Args: { "Expression": "read_and_clear_dirty\|dirty_ops", "PathPrefixes": [ "drivers/iommu/arm/arm-smmu" ] } Results: { "error": "no matches" }
39/2	2026/10/26 17:18	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 47360 output: 84 thoughts: 72 Thoughts: Here's my summary, as I see it: Dirty Tracking Deep Dive: A Quick Audit Okay, so I'm thinking about memory management units (MMUs) and how they handle dirty page tracking. It's striking me that the older versions of `arm-smmu` (v1 and v2) don't seem to implement any dirty tracking whatsoever. This raises a red flag. What are the implications for performance and coherency in those architectures? Now I'm running through my mental rolodex of other implementations I'm familiar with, like Panfrost, Panthor, Apple's DART, and IPMMU-VMSA. My question is, do any of those drivers actually utilize `read_and_clear_dirty` or, perhaps more tellingly, the `pgtable_walk` function during their page table operations? If they are, that would give a reasonable foundation to compare to. I need to dig into the codebases of those projects to confirm my suspicions and verify how other MMU drivers approach this crucial aspect of memory management. That's the next step; time for some code spelunking.
40/2	2026/10/26 17:18	tool	grepper	0m Error: no matches Args: { "Expression": "pgtable_walk\|read_and_clear_dirty", "PathPrefixes": [ "drivers/gpu/drm/panfrost", "drivers/gpu/drm/panthor", "drivers/iommu/apple-dart.c", "drivers/iommu/ipmmu-vmsa.c" ] } Results: { "error": "no matches" }
41/2	2026/10/26 17:18	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 47775 output: 51 thoughts: 81 Thoughts: Investigating the Missing Function Calls Okay, so I'm diving into this code, and the immediate observation is striking: it seems none of the relevant functions are directly calling either `pgtable_walk` or `read_and_clear_dirty`. That's a red flag. These are core operations, and if they're not being invoked, there's a problem with the intended workflow. But, hold on. Before I jump to conclusions, I need to consider all possibilities. I vaguely recall something about `io_pgtable_arm-selftests.c`. It's a testing file, and it's possible these functions are being utilized there to validate core logic. It's the most likely candidate for unexpected calls. So, the next logical step is to confirm. I'll need to meticulously check `io-pgtable-arm-selftests.c` to see if that file actually utilizes `read_and_clear_dirty` or `pgtable_walk` in its testing procedures. I'll search the code base for these calls and find out if they are called in this specific context. This is the key.
42/2	2026/10/26 17:18	tool	grepper	0m Error: no matches Args: { "Expression": "pgtable_walk\|read_and_clear_dirty", "PathPrefixes": [ "drivers/iommu/io-pgtable-arm-selftests.c" ] } Results: { "error": "no matches" }
43/2	2026/10/26 17:18	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 48170 output: 45 thoughts: 91 Thoughts: Here's my summary, as though I'm thinking through this myself: Investigating the io-pgtable-arm-selftests.c Source Okay, this is strange. I was expecting `io-pgtable-arm-selftests.c` to be using `pgtable_walk` or `read_and_clear_dirty`, but a quick glance confirms... it doesn't even call them! That's not what I anticipated at all. It's time to dig deeper. I need to understand what this test actually does. Let me take a closer look. I'll focus on the heart of it – lines 70 through 160 of `drivers/iommu/io-pgtable-arm-selftests.c`. That should give me the core logic and operations of this test. I'm hoping I can piece together the intended functionality from there. I need to see what data structures it's manipulating and which functions it is using. This is going to be my starting point.
44/2	2026/10/26 17:19	tool	read-file	0m Args: { "File": "drivers/iommu/io-pgtable-arm-selftests.c", "FirstLine": 70, "LineCount": 60 } Results: { "Contents": " 70:\t\n 71:\t\t\t/\n 72:\t\t\t Initial sanity checks.\n 73:\t\t\t * Empty page tables shouldn't provide any translations.\n 74:\t\t\t /\n 75:\t\t\tif (ops-\u003eiova_to_phys(ops, 42))\n 76:\t\t\t\treturn __FAIL(test, i);\n 77:\t\n 78:\t\t\tif (ops-\u003eiova_to_phys(ops, SZ_1G + 42))\n 79:\t\t\t\treturn __FAIL(test, i);\n 80:\t\n 81:\t\t\tif (ops-\u003eiova_to_phys(ops, SZ_2G + 42))\n 82:\t\t\t\treturn __FAIL(test, i);\n 83:\t\n 84:\t\t\t/\n 85:\t\t\t * Distinct mappings of different granule sizes.\n 86:\t\t\t /\n 87:\t\t\tiova = 0;\n 88:\t\t\tfor_each_set_bit(j, \u0026cfg-\u003epgsize_bitmap, BITS_PER_LONG) {\n 89:\t\t\t\tsize = 1UL \u003c\u003c j;\n 90:\t\n 91:\t\t\t\tif (ops-\u003emap_pages(ops, iova, iova, size, 1,\n 92:\t\t\t\t\t\t IOMMU_READ \| IOMMU_WRITE \|\n 93:\t\t\t\t\t\t IOMMU_NOEXEC \| IOMMU_CACHE,\n 94:\t\t\t\t\t\t GFP_KERNEL, \u0026mapped))\n 95:\t\t\t\t\treturn __FAIL(test, i);\n 96:\t\n 97:\t\t\t\t/ Overlapping mappings /\n 98:\t\t\t\tif (!ops-\u003emap_pages(ops, iova, iova + size, size, 1,\n 99:\t\t\t\t\t\t IOMMU_READ \| IOMMU_NOEXEC,\n 100:\t\t\t\t\t\t GFP_KERNEL, \u0026mapped))\n 101:\t\t\t\t\treturn __FAIL(test, i);\n 102:\t\n 103:\t\t\t\tif (ops-\u003eiova_to_phys(ops, iova + 42) != (iova + 42))\n 104:\t\t\t\t\treturn __FAIL(test, i);\n 105:\t\n 106:\t\t\t\tiova += SZ_1G;\n 107:\t\t\t}\n 108:\t\n 109:\t\t\t/ Full unmap /\n 110:\t\t\tiova = 0;\n 111:\t\t\tfor_each_set_bit(j, \u0026cfg-\u003epgsize_bitmap, BITS_PER_LONG) {\n 112:\t\t\t\tsize = 1UL \u003c\u003c j;\n 113:\t\n 114:\t\t\t\tif (ops-\u003eunmap_pages(ops, iova, size, 1, NULL) != size)\n 115:\t\t\t\t\treturn __FAIL(test, i);\n 116:\t\n 117:\t\t\t\tif (ops-\u003eiova_to_phys(ops, iova + 42))\n 118:\t\t\t\t\treturn __FAIL(test, i);\n 119:\t\n 120:\t\t\t\t/ Remap full block */\n 121:\t\t\t\tif (ops-\u003emap_pages(ops, iova, iova, size, 1,\n 122:\t\t\t\t\t\t IOMMU_WRITE, GFP_KERNEL, \u0026mapped))\n 123:\t\t\t\t\treturn __FAIL(test, i);\n 124:\t\n 125:\t\t\t\tif (ops-\u003eiova_to_phys(ops, iova + 42) != (iova + 42))\n 126:\t\t\t\t\treturn __FAIL(test, i);\n 127:\t\n 128:\t\t\t\tiova += SZ_1G;\n 129:\t\t\t}\n" }
45/2	2026/10/26 17:19	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 49457 output: 46 thoughts: 35 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: Analyzing `io-pgtable-arm-selftests.c` for Potential Issues Okay, I need to zero in on a specific section of this self-test code. Let's start by looking at lines 130 through 180 within `drivers/iommu/io-pgtable-arm-selftests.c`. I need to understand what's happening within that block. My initial thought is to quickly scan for any obvious red flags, such as: * Potential race conditions: Does this section involve any shared data or resources that might be accessed concurrently? If so, are proper synchronization primitives being employed (e.g., spinlocks, mutexes)? I need to ensure that the test is designed with concurrency in mind, if it involves any. * Memory allocation/deallocation issues: I'll be looking for `kmalloc`, `kfree`, or similar calls. Are there any potential memory leaks or double-frees? This is a common source of bugs in kernel code. Is there error handling that can manage the allocations? * Incorrect assumptions about memory ordering or cache coherency: Specifically in ARM architecture, are there any assumptions about how memory is being accessed and updated by the CPU? This test might be missing `dmb`, `dsb`, or `isb` instructions where they are required. I will need to think critically about potential issues. * Unusual register use or access: I should evaluate what registers are being used and how. I'm also looking for anything that seems overly complex or hard to follow, which might indicate a bug. I want to quickly evaluate the logic and flow. With these tests, the logic should be straightforward and easy to understand.
46/2	2026/10/26 17:19	tool	read-file	0m Args: { "File": "drivers/iommu/io-pgtable-arm-selftests.c", "FirstLine": 130, "LineCount": 50 } Results: { "Contents": " 130:\t\n 131:\t\t\t/\n 132:\t\t\t Map/unmap the last largest supported page of the IAS, this can\n 133:\t\t\t * trigger corner cases in the concatednated page tables.\n 134:\t\t\t /\n 135:\t\t\tmapped = 0;\n 136:\t\t\tsize = 1UL \u003c\u003c __fls(cfg-\u003epgsize_bitmap);\n 137:\t\t\tiova = (1UL \u003c\u003c cfg-\u003eias) - size;\n 138:\t\t\tif (ops-\u003emap_pages(ops, iova, iova, size, 1,\n 139:\t\t\t\t\t IOMMU_READ \| IOMMU_WRITE \|\n 140:\t\t\t\t\t IOMMU_NOEXEC \| IOMMU_CACHE,\n 141:\t\t\t\t\t GFP_KERNEL, \u0026mapped))\n 142:\t\t\t\treturn __FAIL(test, i);\n 143:\t\t\tif (mapped != size)\n 144:\t\t\t\treturn __FAIL(test, i);\n 145:\t\t\tif (ops-\u003eunmap_pages(ops, iova, size, 1, NULL) != size)\n 146:\t\t\t\treturn __FAIL(test, i);\n 147:\t\n 148:\t\t\tfree_io_pgtable_ops(ops);\n 149:\t\t}\n 150:\t\n 151:\t\treturn 0;\n 152:\t}\n 153:\t\n 154:\tstatic void arm_lpae_do_selftests(struct kunit test)\n 155:\t{\n 156:\t\tstatic const unsigned long pgsize[] = {\n 157:\t\t\tSZ_4K \| SZ_2M \| SZ_1G,\n 158:\t\t\tSZ_16K \| SZ_32M,\n 159:\t\t\tSZ_64K \| SZ_512M,\n 160:\t\t};\n 161:\t\n 162:\t\tstatic const unsigned int address_size[] = {\n 163:\t\t\t32, 36, 40, 42, 44, 48,\n 164:\t\t};\n 165:\t\n 166:\t\tint i, j, k, pass = 0, fail = 0;\n 167:\t\tstruct device *dev;\n 168:\t\tstruct io_pgtable_cfg cfg = {\n 169:\t\t\t.tlb = \u0026dummy_tlb_ops,\n 170:\t\t\t.coherent_walk = true,\n 171:\t\t\t.quirks = IO_PGTABLE_QUIRK_NO_WARN,\n 172:\t\t};\n 173:\t\n 174:\t\tdev = kunit_device_register(test, \"io-pgtable-test\");\n 175:\t\tKUNIT_EXPECT_NOT_ERR_OR_NULL(test, dev);\n 176:\t\tif (IS_ERR_OR_NULL(dev))\n 177:\t\t\treturn;\n 178:\t\n 179:\t\tcfg.iommu_dev = dev;\n" }
47/2	2026/10/26 17:19	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 50713 output: 25 thoughts: 1135 Thoughts: Analyzing Code Paths for Fuzzing Eligibility Okay, so the initial selftests didn't touch `read_and_clear_dirty` or `pgtable_walk`. Let's dig deeper into the codebase to determine if any of the potentially interesting functions are even relevant to my target architecture, `amd64`. My first thought was `ARM_SMMU_V3`. It's an obvious candidate, but I need to confirm if it's restricted to `ARM64`. A quick look at `drivers/iommu/arm/Kconfig` confirms it: `depends on ARM64`. Definitely not applicable to `amd64`. This confirms my suspicion. So, since I'm targeting amd64, can I dismiss this whole area? Not so fast. I need to be more methodical. Let's revisit the fuzzing criteria. The instructions specify that code paths exclusive to architectures other than the target architecture are not worth fuzzing. The key is to see if any code paths could be executed on `amd64`, even indirectly. Now, let's focus on `io_pgtable_visit` and `visit_dirty`. What does `io_pgtable_visit` do? It's static within `drivers/iommu/io-pgtable-arm.c`. This is where it gets interesting. I need to understand who calls `io_pgtable_visit`. The code reveals that only `__arm_lpae_iopte_walk` calls `io_pgtable_visit`. And who calls `__arm_lpae_iopte_walk`? It's called from two functions in `io-pgtable-arm.c`: `arm_lpae_pgtable_walk` and `arm_lpae_read_and_clear_dirty`. These are the core functions that I need to trace back. Now, I look for calls to `ops->pgtable_walk`. This is where `arm_lpae_pgtable_walk` is used. The code reveals a single call site in the kernel: `drivers/gpu/drm/msm/msm_iommu.c`. Aha! This is the Qualcomm Snapdragon Adreno GPU driver (`CONFIG_DRM_MSM`). Snapdragon is Qualcomm's ARM SoC. Can that run on `amd64`? Absolutely not. It's a hardware dependency. Furthermore, I will check whether `msm_iommu_pagetable_walk` is called from anywhere. That would be an amd64 call site I'd need to worry about.
48/2	2026/10/26 17:19	tool	grepper	0m Args: { "Expression": "msm_iommu_pagetable_walk" } Results: { "Output": "drivers/gpu/drm/msm/msm_gpu.c=364=static void msm_gpu_crashstate_capture(struct msm_gpu gpu,\n--\ndrivers/gpu/drm/msm/msm_gpu.c-393-\t\t\t\t\t \u0026info-\u003easid);\ndrivers/gpu/drm/msm/msm_gpu.c:394:\t\tmsm_iommu_pagetable_walk(mmu, info-\u003eiova, info-\u003eptes);\ndrivers/gpu/drm/msm/msm_gpu.c-395-\t}\n--\ndrivers/gpu/drm/msm/msm_iommu.c=283=int\ndrivers/gpu/drm/msm/msm_iommu.c:284:msm_iommu_pagetable_walk(struct msm_mmu mmu, unsigned long iova, uint64_t ptes[4])\ndrivers/gpu/drm/msm/msm_iommu.c-285-{\n--\ndrivers/gpu/drm/msm/msm_mmu.h=90=int msm_iommu_pagetable_params(struct msm_mmu mmu, phys_addr_t ttbr,\ndrivers/gpu/drm/msm/msm_mmu.h-91-\t\t\t int asid);\ndrivers/gpu/drm/msm/msm_mmu.h:92:int msm_iommu_pagetable_walk(struct msm_mmu mmu, unsigned long iova, uint64_t ptes[4]);\ndrivers/gpu/drm/msm/msm_mmu.h-93-struct iommu_domain_geometry msm_iommu_get_geometry(struct msm_mmu mmu);\n" }
49/2	2026/10/26 17:19	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 52905 output: 46 thoughts: 2086 Thoughts: Analyzing the IOMMU Dirty Page Tracking Patch Okay, so this is about the `msm_gpu_crashstate_capture` function, specifically related to Adreno GPU crashes. The problem seems to be linked to how dirty pages are handled within the IOMMU. My initial thought is to trace the function `ops->read_and_clear_dirty`, that's what seems to be the critical function here. I'm wondering who calls this specific operation. My first finding is that `arm_smmu_read_and_clear_dirty` is the only direct caller, which resides in the `drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c` file. Important to note that this code is only compiled if `ARM64` is defined, which implies it's architecture-specific and cannot be enabled on an amd64 system. This seems like a dead end for an amd64 crash. However, I need to be absolutely sure. I'm going to do a comprehensive search for any other occurrences of `->read_and_clear_dirty` or `read_and_clear_dirty` within the entire kernel tree. My earlier search showed me a bunch of places that use this function, with the first being `drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c`. The search shows this function in a few other places as well: `drivers/iommu/generic_pt/iommu_pt.h`, `drivers/iommu/io-pgtable-arm.c` and `drivers/iommu/iommufd/io_pagetable.c`. Okay, there are two distinct structs involved: `struct io_pgtable_ops` and `struct iommu_dirty_ops`. The former, which includes the `read_and_clear_dirty` function pointer, is used for page table operations. The latter (specifically in `iommufd/io_pagetable.c`), belongs to the IOMMU domain. I've got it. The `io_pgtable_arm` module actually uses the `arm_smmu_dirty_ops`! Which also depends on `ARM64`. So that confirms the earlier conclusion. Then, there's a header file change, which seems to remove a helper function, `iommu_dirty_bitmap_record` from `include/linux/iommu.h`. This function seems to have been used in the `io-pgtable-arm.c` module, within the `visit_dirty` function. It seems to have been inlined, with calls to `io_pgtable_tlb_add_page` in its place. I wish I had git available here to properly check the commit history and message, but alas, it's not available. However, from the diff, I can confirm that the `iommu_dirty_bitmap_record` function has been removed from `include/linux/iommu.h` and its functionality has been integrated directly into `visit_dirty` in `io-pgtable-arm.c`. Finally, to be completely thorough, I'm checking if there are any other uses of LPAE page tables (`io-pgtable-arm.c`) outside of the ARM64 context. I'll search the `drivers/iommu/iommufd/` directory (where the `iommufd` selftest code lies) for mentions of `alloc_io_pgtable_ops` or `io_pgtable` to see if there's any mock or virtual device usage. That's the next step.
50/2	2026/10/26 17:20	tool	grepper	0m Error: no matches Args: { "Expression": "alloc_io_pgtable_ops\|io_pgtable_arm", "PathPrefixes": [ "drivers/iommu/iommufd" ] } Results: { "error": "no matches" }
51/2	2026/10/26 17:20	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 55858 output: 34 thoughts: 352 Thoughts: Investigating the `io-pgtable-arm` Absence Okay, so I'm trying to figure out why the selftest infrastructure isn't leveraging `io-pgtable-arm`. My initial thought was to examine `drivers/iommu/iommu.c`, but let's quickly confirm that `iommu.c` isn't using `alloc_io_pgtable_ops`. No, we checked that earlier and it doesn't. And that's confirmed by looking at the callers. The list of callers to `alloc_io_pgtable_ops` are: * `drivers/gpu/drm/msm/msm_iommu.c` * `drivers/gpu/drm/panfrost/panfrost_mmu.c` * `drivers/gpu/drm/panthor/panthor_mmu.c` * `drivers/iommu/apple-dart.c` * `drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c` * `drivers/iommu/arm/arm-smmu/arm-smmu.c` * `drivers/iommu/arm/arm-smmu/qcom_iommu.c` * `drivers/iommu/io-pgtable-arm-selftests.c` * `drivers/iommu/io-pgtable-arm-v7s.c` * `drivers/iommu/ipmmu-vmsa.c` * `drivers/iommu/msm_iommu.c` * `drivers/iommu/mtk_iommu.c` * `rust/kernel/iommu/pgtable.rs` Hold on a second. What's this `rust/kernel/iommu/pgtable.rs` thing doing in there? I need to check that out.
52/2	2026/10/26 17:20	tool	grepper	0m Args: { "Expression": "FORMAT", "PathPrefixes": [ "rust/kernel/iommu/pgtable.rs" ] } Results: { "Output": "rust/kernel/iommu/pgtable.rs=73=pub trait IoPageTableFmt: 'static {\nrust/kernel/iommu/pgtable.rs-74- /// The value representing this format.\nrust/kernel/iommu/pgtable.rs:75: const FORMAT: io_pgtable_fmt;\nrust/kernel/iommu/pgtable.rs-76-}\n--\nrust/kernel/iommu/pgtable.rs=81= pub fn new(dev: \u0026'a Device\u003cBound\u003e, config: Config) -\u003e Result\u003cIoPageTable\u003c'a, F\u003e\u003e {\n--\nrust/kernel/iommu/pgtable.rs-98- let ops = unsafe {\nrust/kernel/iommu/pgtable.rs:99: bindings::alloc_io_pgtable_ops(F::FORMAT, \u0026mut raw_cfg, core::ptr::null_mut())\nrust/kernel/iommu/pgtable.rs-100- };\n--\nrust/kernel/iommu/pgtable.rs=239=impl IoPageTableFmt for ARM64LPAES1 {\nrust/kernel/iommu/pgtable.rs:240: const FORMAT: io_pgtable_fmt = bindings::io_pgtable_fmt_ARM_64_LPAE_S1 as io_pgtable_fmt;\nrust/kernel/iommu/pgtable.rs-241-}\n" }
53/2	2026/10/26 17:20	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 57052 output: 25 thoughts: 14 Thoughts: Okay, here's my summary, tailored for an expert audience, as if I'm thinking these thoughts: Analyzing `IoPageTable` Usage in Rust Alright, let's dive into this. The objective is to understand the current usage of `IoPageTable` within the Rust ecosystem. I need to get a clear picture of where and how this abstraction is being employed. Given that I'm dealing with a low-level construct like a page table, I'm expecting to find it primarily in projects focused on operating systems, hypervisors, and embedded systems, or perhaps even in advanced memory management libraries. My immediate approach would be to leverage the standard tooling. I'd begin by utilizing a code search tool that can understand Rust code, like search.crates.io, or even better, an IDE with robust code indexing. I'd be looking for direct references to the `IoPageTable` type, but also for indirect usages – functions that accept or return it, traits that define its behavior, and associated structures or enums that are closely tied to it. The next thing that I would look for would be to review the documentation. How does it work? Is it an interface? Is it a struct? If so, what does it contain? What are its methods? I would have to look for any documentation, examples, and existing tests associated with `IoPageTable`. Ultimately, I want to form an assessment of `IoPageTable`. I need to figure out the use-cases and the rationale behind choosing `IoPageTable` over any alternative strategies, and I want to determine if there is code that implements `IoPageTable` that are worth using as an example for comparison, or for further reuse.
54/2	2026/10/26 17:21	tool	grepper	0m Args: { "Expression": "IoPageTable", "PathPrefixes": [ "rust" ] } Results: { "Output": "rust/kernel/iommu/pgtable.rs=43=pub struct Config {\n--\nrust/kernel/iommu/pgtable.rs-60-/// The pointer references a valid io page table.\nrust/kernel/iommu/pgtable.rs:61:pub struct IoPageTable\u003c'a, F: IoPageTableFmt\u003e {\nrust/kernel/iommu/pgtable.rs-62- ptr: NonNull\u003cbindings::io_pgtable_ops\u003e,\n--\nrust/kernel/iommu/pgtable.rs-67-// SAFETY: `struct io_pgtable_ops` is not restricted to a single thread.\nrust/kernel/iommu/pgtable.rs:68:unsafe impl\u003cF: IoPageTableFmt\u003e Send for IoPageTable\u003c'_, F\u003e {}\nrust/kernel/iommu/pgtable.rs-69-// SAFETY: `struct io_pgtable_ops` may be accessed concurrently.\nrust/kernel/iommu/pgtable.rs:70:unsafe impl\u003cF: IoPageTableFmt\u003e Sync for IoPageTable\u003c'_, F\u003e {}\nrust/kernel/iommu/pgtable.rs-71-\nrust/kernel/iommu/pgtable.rs-72-/// The format used by this page table.\nrust/kernel/iommu/pgtable.rs:73:pub trait IoPageTableFmt: 'static {\nrust/kernel/iommu/pgtable.rs-74- /// The value representing this format.\n--\nrust/kernel/iommu/pgtable.rs-77-\nrust/kernel/iommu/pgtable.rs:78:impl\u003c'a, F: IoPageTableFmt\u003e IoPageTable\u003c'a, F\u003e {\nrust/kernel/iommu/pgtable.rs:79: /// Create a new `IoPageTable`.\nrust/kernel/iommu/pgtable.rs-80- #[inline]\nrust/kernel/iommu/pgtable.rs:81: pub fn new(dev: \u0026'a Device\u003cBound\u003e, config: Config) -\u003e Result\u003cIoPageTable\u003c'a, F\u003e\u003e {\nrust/kernel/iommu/pgtable.rs-82- let mut raw_cfg = bindings::io_pgtable_cfg {\n--\nrust/kernel/iommu/pgtable.rs-102- // INVARIANT: We successfully created a valid page table.\nrust/kernel/iommu/pgtable.rs:103: Ok(IoPageTable {\nrust/kernel/iommu/pgtable.rs-104- ptr: NonNull::new(ops).ok_or(ENOMEM)?,\n--\nrust/kernel/iommu/pgtable.rs=220=extern \"C\" fn rust_tlb_flush_walk_noop(\n--\nrust/kernel/iommu/pgtable.rs-227-\nrust/kernel/iommu/pgtable.rs:228:impl\u003cF: IoPageTableFmt\u003e Drop for IoPageTable\u003c'_, F\u003e {\nrust/kernel/iommu/pgtable.rs-229- fn drop(\u0026mut self) {\n--\nrust/kernel/iommu/pgtable.rs=237=pub enum ARM64LPAES1 {}\nrust/kernel/iommu/pgtable.rs-238-\nrust/kernel/iommu/pgtable.rs:239:impl IoPageTableFmt for ARM64LPAES1 {\nrust/kernel/iommu/pgtable.rs-240- const FORMAT: io_pgtable_fmt = bindings::io_pgtable_fmt_ARM_64_LPAE_S1 as io_pgtable_fmt;\n--\nrust/kernel/iommu/pgtable.rs-242-\nrust/kernel/iommu/pgtable.rs:243:impl IoPageTable\u003c'_, ARM64LPAES1\u003e {\nrust/kernel/iommu/pgtable.rs-244- /// Access the `ttbr` field of the configuration.\n" }
55/2	2026/10/26 17:21	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 58448 output: 25 thoughts: 16 Thoughts: Here's a summary of my thought process, as requested: Investigating `IoPageTable` Usage Beyond the Core Rust Codebase Okay, so I'm thinking about the `IoPageTable`. I know it's a critical component, but I need to get a clear picture of its usage, and that means looking beyond the standard `rust/` directory. My aim is to understand how widespread its integration is and if there are any external dependencies or potential compatibility issues I should be aware of. I need to know the broader context of its use, and to begin, I'm going to start by getting a comprehensive list of instances of its use. This is just the first step in painting a full picture, and will likely inform my next action.
56/2	2026/10/26 17:21	tool	grepper	0m Args: { "Expression": "IoPageTable", "PathPrefixes": [ "drivers" ] } Results: { "Output": "drivers/gpu/drm/tyr/mmu/address_space.rs-23- Config,\ndrivers/gpu/drm/tyr/mmu/address_space.rs:24: IoPageTable,\ndrivers/gpu/drm/tyr/mmu/address_space.rs-25- ARM64LPAES1, //\n--\ndrivers/gpu/drm/tyr/mmu/address_space.rs=75=pub(crate) struct VmAsData\u003c'drm\u003e {\n--\ndrivers/gpu/drm/tyr/mmu/address_space.rs-84- #[pin]\ndrivers/gpu/drm/tyr/mmu/address_space.rs:85: pub(crate) page_table: IoPageTable\u003c'drm, ARM64LPAES1\u003e,\ndrivers/gpu/drm/tyr/mmu/address_space.rs-86-}\n--\ndrivers/gpu/drm/tyr/mmu/address_space.rs=90= pub(crate) fn new\u003c'a\u003e(\n--\ndrivers/gpu/drm/tyr/mmu/address_space.rs-103-\ndrivers/gpu/drm/tyr/mmu/address_space.rs:104: let page_table_init = IoPageTable::new(dev, pt_config);\ndrivers/gpu/drm/tyr/mmu/address_space.rs-105-\n--\ndrivers/gpu/drm/tyr/vm.rs-39- prot,\ndrivers/gpu/drm/tyr/vm.rs:40: IoPageTable,\ndrivers/gpu/drm/tyr/vm.rs-41- ARM64LPAES1, //\n--\ndrivers/gpu/drm/tyr/vm.rs=221=pub(crate) struct PtUpdateContext\u003c'ctx, 'drm\u003e {\n--\ndrivers/gpu/drm/tyr/vm.rs-225- /// Page table.\ndrivers/gpu/drm/tyr/vm.rs:226: pt: \u0026'ctx IoPageTable\u003c'drm, ARM64LPAES1\u003e,\ndrivers/gpu/drm/tyr/vm.rs-227-\n--\ndrivers/gpu/drm/tyr/vm.rs=250= fn new(\ndrivers/gpu/drm/tyr/vm.rs-251- dev: \u0026'ctx Device\u003cBound\u003e,\ndrivers/gpu/drm/tyr/vm.rs:252: pt: \u0026'ctx IoPageTable\u003c'drm, ARM64LPAES1\u003e,\ndrivers/gpu/drm/tyr/vm.rs-253- mmu: \u0026'ctx Mmu\u003c'drm\u003e,\n--\ndrivers/gpu/drm/tyr/vm.rs=827=fn pt_map(\ndrivers/gpu/drm/tyr/vm.rs-828- dev: \u0026Device,\ndrivers/gpu/drm/tyr/vm.rs:829: pt: \u0026IoPageTable\u003c'_, ARM64LPAES1\u003e,\ndrivers/gpu/drm/tyr/vm.rs-830- iova: u64,\n--\ndrivers/gpu/drm/tyr/vm.rs-907-/// automatically handling different page sizes that may be present.\ndrivers/gpu/drm/tyr/vm.rs:908:fn pt_unmap(dev: \u0026Device, pt: \u0026IoPageTable\u003c'_, ARM64LPAES1\u003e, range: Range\u003cu64\u003e) -\u003e Result {\ndrivers/gpu/drm/tyr/vm.rs-909- let mut iova = range.start;\n" }
57/2	2026/10/26 17:21	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 59531 output: 25 thoughts: 890 Thoughts: Analyzing Page Table Walks and Dirty Page Tracking Okay, so I'm looking at this experimental DRM driver, `tyr`, for ARM Mali Valhall GPUs, written in Rust. My initial thought is to figure out how it handles dirty page tracking, since that's often a key performance consideration. I know from experience that drivers like `panfrost`, `panthor`, and `msm` don't use `read_and_clear_dirty` directly. I'm curious if `tyr` is doing something novel. Right, so `visit_dirty` seems to be the critical function here. From what I can tell, it's only called by `arm_lpae_read_and_clear_dirty`. And `arm_lpae_read_and_clear_dirty`, in turn, is only called by `arm_smmu_read_and_clear_dirty` in `arm-smmu-v3.c`. And that specific file is only compiled on ARM64 architectures. This narrows the scope somewhat; it looks like the ARM64 side is where the interesting things happen. But wait, there's that change to `io_pgtable_visit` that I need to investigate. I'm wondering if this update affects how the dirty page mechanism is leveraged elsewhere. The code snippet I pulled shows a change, now aligning `walk_data->addr` down before adding the `size`. Let's dig deeper and figure out who is calling it. Okay, let's trace this. Looking at the surrounding code, `io_pgtable_visit` is called from `__arm_lpae_iopte_walk`. I need to figure out where that's called from. From a code review, it appears `__arm_lpae_iopte_walk` is called from: 1. `arm_lpae_pgtable_walk` - probably for basic table traversal 2. `arm_lpae_read_and_clear_dirty` - as we saw previously, relevant to our analysis 3. `io_pgtable_visit` - in a recursive manner, to descend into child page tables I'm confident in saying that that's it. There are no other callers of `io_pgtable_visit` or `__arm_lpae_iopte_walk` anywhere in the kernel. Just to be absolutely sure, I'll run a quick `grepper` check to verify. That will confirm that our analysis is correct.
58/2	2026/10/26 17:21	tool	grepper	0m Args: { "Expression": "__arm_lpae_iopte_walk" } Results: { "Output": "drivers/iommu/io-pgtable-arm.c=739=struct io_pgtable_walk_data {\n--\ndrivers/iommu/io-pgtable-arm.c-748-\ndrivers/iommu/io-pgtable-arm.c:749:static int __arm_lpae_iopte_walk(struct arm_lpae_io_pgtable data,\ndrivers/iommu/io-pgtable-arm.c-750-\t\t\t\t struct io_pgtable_walk_data walk_data,\n--\ndrivers/iommu/io-pgtable-arm.c=768=static phys_addr_t arm_lpae_iova_to_phys(struct io_pgtable_ops ops,\n--\ndrivers/iommu/io-pgtable-arm.c-780-\ndrivers/iommu/io-pgtable-arm.c:781:\tret = __arm_lpae_iopte_walk(data, \u0026walk_data, data-\u003epgd, data-\u003estart_level);\ndrivers/iommu/io-pgtable-arm.c-782-\tif (ret)\n--\ndrivers/iommu/io-pgtable-arm.c=797=static int arm_lpae_pgtable_walk(struct io_pgtable_ops ops, unsigned long iova,\n--\ndrivers/iommu/io-pgtable-arm.c-807-\ndrivers/iommu/io-pgtable-arm.c:808:\treturn __arm_lpae_iopte_walk(data, \u0026walk_data, data-\u003epgd, data-\u003estart_level);\ndrivers/iommu/io-pgtable-arm.c-809-}\n--\ndrivers/iommu/io-pgtable-arm.c=811=static int io_pgtable_visit(struct arm_lpae_io_pgtable data,\n--\ndrivers/iommu/io-pgtable-arm.c-832-\tptep = iopte_deref(pte, data);\ndrivers/iommu/io-pgtable-arm.c:833:\treturn __arm_lpae_iopte_walk(data, walk_data, ptep, lvl + 1);\ndrivers/iommu/io-pgtable-arm.c-834-}\ndrivers/iommu/io-pgtable-arm.c-835-\ndrivers/iommu/io-pgtable-arm.c:836:static int __arm_lpae_iopte_walk(struct arm_lpae_io_pgtable data,\ndrivers/iommu/io-pgtable-arm.c-837-\t\t\t\t struct io_pgtable_walk_data walk_data,\n--\ndrivers/iommu/io-pgtable-arm.c=888=static int arm_lpae_read_and_clear_dirty(struct io_pgtable_ops ops,\n--\ndrivers/iommu/io-pgtable-arm.c-912-\ndrivers/iommu/io-pgtable-arm.c:913:\treturn __arm_lpae_iopte_walk(data, \u0026walk_data, ptep, lvl);\ndrivers/iommu/io-pgtable-arm.c-914-}\n" }
59/2	2026/10/26 17:21	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 61833 output: 42 thoughts: 59 Thoughts: Here's my take on those thoughts, tailored for an expert audience: Diving into the IOVA-to-Physical Address Translation Hold on a second! I need to take a closer look at that `arm_lpae_iova_to_phys` function. That name rings a bell, I bet it is the key to this whole problem! Okay, let's zoom in on that critical block of code. I'm going to jump into `drivers/iommu/io-pgtable-arm.c` and focus on lines 760 through 795. Let me see... I need to refresh my memory on the LPAE translation process for ARM. It has been a minute. I need to see what's going on with the page table walks, the address calculations, and especially how the IO Virtual Address (IOVA) is being mapped to a physical address. I'm looking for any potential points of contention. Let's dig in and figure out why this isn't behaving as expected. It's likely something related to page table entries, cache coherency, or the interaction between the IOMMU and the system's memory management unit. I'm expecting something rather subtle, like an off-by-one error or a corner case that the code doesn't gracefully handle.
60/2	2026/10/26 17:21	tool	read-file	0m Args: { "File": "drivers/iommu/io-pgtable-arm.c", "FirstLine": 760, "LineCount": 35 } Results: { "Contents": " 760:\t\t\t\t arm_lpae_iopte ptep, size_t size)\n 761:\t{\n 762:\t\tstruct iova_to_phys_data data = walk_data-\u003edata;\n 763:\t\tdata-\u003epte = ptep;\n 764:\t\tdata-\u003elvl = lvl;\n 765:\t\treturn 0;\n 766:\t}\n 767:\t\n 768:\tstatic phys_addr_t arm_lpae_iova_to_phys(struct io_pgtable_ops ops,\n 769:\t\t\t\t\t\t unsigned long iova)\n 770:\t{\n 771:\t\tstruct arm_lpae_io_pgtable data = io_pgtable_ops_to_data(ops);\n 772:\t\tstruct iova_to_phys_data d;\n 773:\t\tstruct io_pgtable_walk_data walk_data = {\n 774:\t\t\t.data = \u0026d,\n 775:\t\t\t.visit = visit_iova_to_phys,\n 776:\t\t\t.addr = iova,\n 777:\t\t\t.end = iova + 1,\n 778:\t\t};\n 779:\t\tint ret;\n 780:\t\n 781:\t\tret = __arm_lpae_iopte_walk(data, \u0026walk_data, data-\u003epgd, data-\u003estart_level);\n 782:\t\tif (ret)\n 783:\t\t\treturn 0;\n 784:\t\n 785:\t\tiova \u0026= (ARM_LPAE_BLOCK_SIZE(d.lvl, data) - 1);\n 786:\t\treturn iopte_to_paddr(d.pte, data) \| iova;\n 787:\t}\n 788:\t\n 789:\tstatic int visit_pgtable_walk(struct io_pgtable_walk_data walk_data, int lvl,\n 790:\t\t\t\t arm_lpae_iopte ptep, size_t size)\n 791:\t{\n 792:\t\tstruct arm_lpae_io_pgtable_walk_data data = walk_data-\u003edata;\n 793:\t\tdata-\u003eptes[lvl] = *ptep;\n 794:\t\treturn 0;\n" }
61/2	2026/10/26 17:21	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 62825 output: 50 thoughts: 1831 Thoughts: Analyzing the Reachability of `arm_lpae_iova_to_phys` on AMD64 Okay, so `arm_lpae_iova_to_phys` calls `__arm_lpae_iopte_walk`, which in turn calls `io_pgtable_visit`. I need to understand this `walk_data` structure and how it's used. It looks like the `addr` and `end` fields are set initially, and then iterated through. The critical point seems to be that `io_pgtable_visit` now has this `ALIGN_DOWN` in the leaf check. My main question is, can I even reach `arm_lpae_iova_to_phys` on an AMD64 system? I need to figure out which code paths call `iova_to_phys`, especially with LPAE-style page tables, and whether those paths are relevant to the target architecture. Let's see who's calling `alloc_io_pgtable_ops` with LPAE formats. The list of potential callers is extensive. Okay, starting from the top: MSM, Panfrost, Panthor, Tyr, Apple DART, ARM SMMUs (v3, v1/v2), Qualcomm IOMMU, Renesas IPMMU-VMSA, and a KUnit test. The question is: can any of these be meaningfully fuzzed on AMD64? 1. MSM: Snapdragon GPU. No, I know QEMU doesn't emulate the Adreno GPU, so that's a dead end. 2. Panfrost/Panthor/Tyr: These are ARM Mali GPUs. ARM-specific, so not relevant on AMD64. 3. Apple DART: Apple Silicon. Definitely not an AMD64 emulation target. 4. ARM SMMU v3/v1/v2, Qualcomm IOMMU, Renesas IPMMU-VMSA: ARM platform-specific devices. Again, not running natively on AMD64. 5. io-pgtable-arm-selftests: A KUnit test! Hmm, syzkaller probably can't run KUnit tests, can it? No, KUnit tests are typically run at boot or module load. Syzkaller doesn't fuzz KUnit tests via syscalls. It's not reachable. Okay, let's go back to the reachability criteria. The criteria specifically mention structurally unreachable hardware and code paths exclusive to other architectures. `io-pgtable-arm.c` is clearly associated with ARM architectures. The list of users confirms this: ARM SMMUs, Qualcomm, Renesas, Apple, ARM Mali. These are all ARM-specific devices. The key question is, are any of these devices emulated by QEMU on AMD64? No. QEMU uses Intel VT-d or AMD-Vi for IOMMU on AMD64, or virtio-iommu. None of them use the `io-pgtable-arm.c`. Okay, but what about `virtio-iommu`? Does `virtio-iommu` use `io-pgtable-arm.c`? No! Therefore, the code in `arm_lpae_iova_to_phys`, and consequently the `ALIGN_DOWN` change, is not reachable via syzkaller on an AMD64 target. It's confined to ARM platforms and hardware not emulated in the standard QEMU setup. WorthFuzzing=false.
62/2	2026/10/26 17:22	tool	grepper	0m Error: no matches Args: { "Expression": "alloc_io_pgtable_ops\|ARM_.LPAE", "PathPrefixes": [ "drivers/iommu/virtio-iommu.c" ] } Results:* { "error": "no matches" }
63/2	2026/10/26 17:22	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 65497 output: 41 thoughts: 36 Thoughts: Okay, let's dive into this. Here's how I'd approach this task, as if these were my internal thoughts: Investigating the Implementation of `virtio-iommu` Alright, I need to get a handle on what's going on with `virtio-iommu`. My first instinct is to go straight to the source, to the code itself. I want to see how this thing is implemented. Specifically, I'll be looking in the kernel source tree for the driver implementation. My expectation is, given the naming convention, that it's going to be in `drivers/iommu/virtio-iommu.c`. That should be the file to check, as this is the likely source file for the `virtio-iommu` driver.
64/2	2026/10/26 17:22	tool	grepper	0m Error: no matches Args: { "Expression": "pgtbl\|ops-\u003emap", "PathPrefixes": [ "drivers/iommu/virtio-iommu.c" ] } Results: { "error": "no matches" }
65/2	2026/10/26 17:22	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 65762 output: 41 thoughts: 18 Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience, presented in the first person: Investigating the `virtio-iommu` Page Table Implementation Right, let's dive into the core of how `virtio-iommu` handles its page tables. I need to refresh my memory on the specifics here. What's the exact implementation they're going with? Are they using a nested page table structure? Is it based on a particular architecture's MMU extensions, or a more custom approach? Are there any clever optimizations in place for I/O page table walks, considering the inherent performance bottlenecks? Perhaps they've got some interesting hardware assists in play? I need to check the code. I wonder if they chose a specific hardware acceleration technique, perhaps some kind of lookaside buffer or prefetching to reduce I/O latency. I'll need to look at the relevant source files and documentation to figure out the exact details. The devil, as always, is in the details, so let's get started.
66/2	2026/10/26 17:22	tool	grepper	0m Error: no matches Args: { "Expression": "alloc_io_pgtable", "PathPrefixes": [ "drivers/iommu/virtio-iommu.c" ] } Results: { "error": "no matches" }
67/2	2026/10/26 17:22	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 66058 output: 38 thoughts: 86 Thoughts: Here's my understanding of the situation, framed as if it were my thought process: Virtio-IOMMU: Direct Host Communication Okay, so the `virtio-iommu` driver isn't actually messing around with page tables within the guest kernel, which is interesting. It's essentially acting as a conduit, right? My initial assumption was that it might have some level of guest-side management, but this is clearly not the case. Instead, it's constructing and transmitting `VIRTIO_IOMMU_T_MAP` and `VIRTIO_IOMMU_T_UNMAP` requests straight over the virtqueue to the host's QEMU. That's a fundamental architectural detail I need to fully grasp. I'll need to drill down into `drivers/iommu/virtio-iommu.c` to see how this direct communication is implemented and, more importantly, why they chose this architecture. Understanding the rationale behind this design – the performance trade-offs, security considerations, and overall simplicity – will be key to understanding the full picture here. I need to confirm the flow and ensure the source confirms my assumption.
68/2	2026/10/26 17:22	tool	grepper	0m Args: { "Expression": "map_pages", "PathPrefixes": [ "drivers/iommu/virtio-iommu.c" ] } Results: { "Output": "drivers/iommu/virtio-iommu.c=819=static void viommu_detach_dev(struct viommu_endpoint vdev)\n--\ndrivers/iommu/virtio-iommu.c-841-\ndrivers/iommu/virtio-iommu.c:842:static int viommu_map_pages(struct iommu_domain domain, unsigned long iova,\ndrivers/iommu/virtio-iommu.c-843-\t\t\t phys_addr_t paddr, size_t pgsize, size_t pgcount,\n--\ndrivers/iommu/virtio-iommu.c-885-\ndrivers/iommu/virtio-iommu.c:886:static size_t viommu_unmap_pages(struct iommu_domain *domain, unsigned long iova,\ndrivers/iommu/virtio-iommu.c-887-\t\t\t\t size_t pgsize, size_t pgcount,\n--\ndrivers/iommu/virtio-iommu.c=1091=static const struct iommu_ops viommu_ops = {\n--\ndrivers/iommu/virtio-iommu.c-1102-\t\t.attach_dev\t\t= viommu_attach_dev,\ndrivers/iommu/virtio-iommu.c:1103:\t\t.map_pages\t\t= viommu_map_pages,\ndrivers/iommu/virtio-iommu.c:1104:\t\t.unmap_pages\t\t= viommu_unmap_pages,\ndrivers/iommu/virtio-iommu.c-1105-\t\t.iova_to_phys\t\t= viommu_iova_to_phys,\n" }
69/2	2026/10/26 17:22	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 66888 output: 27 thoughts: 98 Thoughts: My Current Assessment of the Virtio-IOMMU and IOMMU Frameworks Right, so virtio-iommu bypasses the io-pgtable approach altogether. That much is clear. But hang on, a question is surfacing... what about generic_pt? Does generic_pt actually leverage the code found in `io-pgtable-arm.c`? No, no, I'm pretty sure generic_pt is a newer framework, residing within `drivers/iommu/generic_pt/`. Time to drill down into that directory. I need to refresh my understanding and determine precisely which page table formats generic_pt supports and how it differentiates itself.
70/2	2026/10/26 17:22	tool	codesearch-dir-index	0m Args: { "Dir": "drivers/iommu/generic_pt" } Results: { "Files": [ "iommu_pt.h", "kunit_generic_pt.h", "kunit_iommu.h", "kunit_iommu_pt.h", "pt_common.h", "pt_defs.h", "pt_fmt_defaults.h", "pt_iter.h", "pt_log2.h" ], "Subdirs": [ "fmt" ] }
71/2	2026/10/26 17:22	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 67276 output: 29 thoughts: 20 Thoughts: Okay, here's the summary, assuming I'm a seasoned kernel developer: Delving into the Generic Page Table Formatting Alright, let's get down to brass tacks. I'm taking a look at `drivers/iommu/generic_pt/fmt`. This isn't just a casual glance; I need to understand the specifics of how the generic page table is formatted. I'm after the details. I need to know how the bits are laid out. What's the structure? What are the implications for performance and, more importantly, correctness? I'm anticipating that this is where the core logic that defines the in-memory representation of the page tables for the IOMMU lives. Gotta understand this before I can look at any higher-level abstractions. Let's see what gems are hidden in there.
72/2	2026/10/26 17:22	tool	codesearch-dir-index	0m Args: { "Dir": "drivers/iommu/generic_pt/fmt" } Results: { "Files": [ "amdv1.h", "bcm2712.h", "defs_amdv1.h", "defs_bcm2712.h", "defs_riscv.h", "defs_vtdss.h", "defs_x86_64.h", "iommu_amdv1.c", "iommu_bcm2712.c", "iommu_mock.c", "iommu_riscv64.c", "iommu_template.h", "iommu_vtdss.c", "iommu_x86_64.c", "riscv.h", "vtdss.h", "x86_64.h" ], "Subdirs": null }
73/2	2026/10/26 17:22	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 67702 output: 34 thoughts: 1102 Thoughts: Analysis of IOMMU and io-pgtable-arm.c Reachability on AMD64 Okay, let's break this down. My initial assessment is that `generic_pt` covers several architectures: `amdv1`, `bcm2712`, `mock`, `riscv64`, `vtdss`, and crucially, `x86_64`. I'm concerned about the absence of ARM LPAE references specifically in the context of `io-pgtable-arm.c`. My immediate thought then goes to `iommufd`. Does it utilize `io-pgtable-arm.c`? A quick check reveals that `selftest.c` within `drivers/iommu/iommufd/` uses `mock_iommu_domain` with `generic_pt`, encompassing `amdv1`, so that's a data point. Then, there's that function removal in `include/linux/iommu.h`: ```c -static inline void iommu_dirty_bitmap_record(struct iommu_dirty_bitmap dirty, - unsigned long iova, - unsigned long length) -{ - if (dirty->bitmap) - iova_bitmap_set(dirty->bitmap, iova, length); - - if (dirty->gather) - iommu_iotlb_gather_add_range(dirty->gather, iova, length); -} ``` I need to be sure this deletion is safe. I've confirmed via `grepper` that no other code in the entire kernel actually uses* this function. Only a comment in `iommu_pt.h` references it. Hence, the removal is benign and has no implications for amd64 code. Now, let's focus on the modifications to `io-pgtable-arm.c`. 1. `io_pgtable_visit` modifications: `walk_data->addr = ALIGN_DOWN(walk_data->addr, size) + size;` 2. `visit_dirty` fix: `u64 iova = ALIGN_DOWN(walk_data->addr, size);` `io_pgtable_tlb_add_page(walk_data->iop, dirty->gather, iova, size);` The core question now: is `io-pgtable-arm.c` ever reachable on AMD64? Let's check if any of the drivers using `io-pgtable-arm.c` can function on AMD64. The relevant drivers are: * `ARM_SMMU_V3`: Requires `ARM64`, so it's a no-go on AMD64. * `ARM_SMMU`: An ARM platform driver. Requires ARM hardware, so no good for AMD64. * `QCOM_IOMMU`: Qualcomm platform driver. * `IPMMU_VMSA`: Renesas platform driver. * `APPLE_DART`: Apple platform driver. * `DRM_PANFROST`, `DRM_PANTHOR`, `DRM_TYR`: ARM Mali GPU platform drivers. * `DRM_MSM`: Qualcomm Adreno GPU platform driver. I need to confirm if those platform drivers could be instantiated in user space, by device tree, or even by a test module? The answer is no. AMD64 utilizes ACPI, not the Device Tree, and even if DT were enabled, there are no DTBs. More critically, these are physical GPU and IOMMU hardware drivers. They would require physical hardware registers, interrupts, DMA, etc. – which is just structurally unreachable hardware not emulated in standard QEMU x86_64. What about `io-pgtable-arm-selftests.c`? The `CONFIG_IOMMU_IO_PGTABLE_LPAE_KUNIT_TEST` is relevant. This is a KUnit test. Can KUnit tests be fuzzed? No. Syzkaller is the fuzzer that's typically used, and Syzkaller targets user-space interfaces such as syscalls, sysfs, etc., but KUnit tests aren't syscall interfaces and are not fuzzed by Syzkaller. Further investigation shows `io-pgtable-arm-selftests.c` does NOT even call `read_and_clear_dirty`, `pgtable_walk` or `io_pgtable_visit` with dirty tracking. Ultimately, is there any syscall or user-facing interface on amd6
74/2	2026/10/26 17:23	tool	grepper	0m Args: { "Expression": "ARM_(32\|64)_LPAE\|ARM_MALI_LPAE" } Results: { "Output": "drivers/gpu/drm/msm/msm_iommu.c=516=struct msm_mmu msm_iommu_pagetable_create(struct msm_mmu parent, bool kernel_managed)\n--\ndrivers/gpu/drm/msm/msm_iommu.c-579-\tpagetable-\u003eiommu_dev = ttbr1_cfg-\u003eiommu_dev;\ndrivers/gpu/drm/msm/msm_iommu.c:580:\tpagetable-\u003epgtbl_ops = alloc_io_pgtable_ops(ARM_64_LPAE_S1,\ndrivers/gpu/drm/msm/msm_iommu.c-581-\t\t\u0026ttbr0_cfg, pagetable);\n--\ndrivers/gpu/drm/panfrost/panfrost_mmu.c=245=static int panfrost_mmu_cfg_init(struct panfrost_mmu mmu,\n--\ndrivers/gpu/drm/panfrost/panfrost_mmu.c-250-\tswitch (fmt) {\ndrivers/gpu/drm/panfrost/panfrost_mmu.c:251:\tcase ARM_64_LPAE_S1:\ndrivers/gpu/drm/panfrost/panfrost_mmu.c-252-\t\treturn mmu_cfg_init_aarch64_4k(mmu);\ndrivers/gpu/drm/panfrost/panfrost_mmu.c:253:\tcase ARM_MALI_LPAE:\ndrivers/gpu/drm/panfrost/panfrost_mmu.c-254-\t\treturn mmu_cfg_init_mali_lpae(mmu);\n--\ndrivers/gpu/drm/panfrost/panfrost_mmu.c=783=struct panfrost_mmu panfrost_mmu_ctx_create(struct panfrost_device pfdev)\n--\ndrivers/gpu/drm/panfrost/panfrost_mmu.c-796-\t\t}\ndrivers/gpu/drm/panfrost/panfrost_mmu.c:797:\t\tfmt = ARM_64_LPAE_S1;\ndrivers/gpu/drm/panfrost/panfrost_mmu.c-798-\t} else {\ndrivers/gpu/drm/panfrost/panfrost_mmu.c:799:\t\tfmt = ARM_MALI_LPAE;\ndrivers/gpu/drm/panfrost/panfrost_mmu.c-800-\t}\n--\ndrivers/gpu/drm/panthor/panthor_mmu.c=2852=panthor_vm_create(struct panthor_device ptdev, bool for_mcu,\n--\ndrivers/gpu/drm/panthor/panthor_mmu.c-2925-\ndrivers/gpu/drm/panthor/panthor_mmu.c:2926:\tvm-\u003epgtbl_ops = alloc_io_pgtable_ops(ARM_64_LPAE_S1, \u0026pgtbl_cfg, vm);\ndrivers/gpu/drm/panthor/panthor_mmu.c-2927-\tif (!vm-\u003epgtbl_ops) {\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c=3061=static int arm_smmu_domain_finalise(struct arm_smmu_domain smmu_domain,\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c-3087-\t\t\tpgtbl_cfg.quirks \|= IO_PGTABLE_QUIRK_ARM_HD;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:3088:\t\tfmt = ARM_64_LPAE_S1;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c-3089-\t\tfinalise_stage_fn = arm_smmu_domain_finalise_s1;\n--\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c-3096-\t\tpgtbl_cfg.oas = smmu-\u003eoas;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:3097:\t\tfmt = ARM_64_LPAE_S2;\ndrivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c-3098-\t\tfinalise_stage_fn = arm_smmu_domain_finalise_s2;\n--\ndrivers/iommu/arm/arm-smmu/arm-smmu.c=675=static int arm_smmu_init_domain_context(struct arm_smmu_domain smmu_domain,\n--\ndrivers/iommu/arm/arm-smmu/arm-smmu.c-747-\t\tif (cfg-\u003efmt == ARM_SMMU_CTX_FMT_AARCH64) {\ndrivers/iommu/arm/arm-smmu/arm-smmu.c:748:\t\t\tfmt = ARM_64_LPAE_S1;\ndrivers/iommu/arm/arm-smmu/arm-smmu.c-749-\t\t} else if (cfg-\u003efmt == ARM_SMMU_CTX_FMT_AARCH32_L) {\ndrivers/iommu/arm/arm-smmu/arm-smmu.c:750:\t\t\tfmt = ARM_32_LPAE_S1;\ndrivers/iommu/arm/arm-smmu/arm-smmu.c-751-\t\t\tias = min(ias, 32UL);\n--\ndrivers/iommu/arm/arm-smmu/arm-smmu.c-770-\t\tif (cfg-\u003efmt == ARM_SMMU_CTX_FMT_AARCH64) {\ndrivers/iommu/arm/arm-smmu/arm-smmu.c:771:\t\t\tfmt = ARM_64_LPAE_S2;\ndrivers/iommu/arm/arm-smmu/arm-smmu.c-772-\t\t} else {\ndrivers/iommu/arm/arm-smmu/arm-smmu.c:773:\t\t\tfmt = ARM_32_LPAE_S2;\ndrivers/iommu/arm/arm-smmu/arm-smmu.c-774-\t\t\tias = min(ias, 40UL);\n--\ndrivers/iommu/arm/arm-smmu/qcom_iommu.c=216=static int qcom_iommu_init_domain(struct iommu_domain domain,\n--\ndrivers/iommu/arm/arm-smmu/qcom_iommu.c-241-\ndrivers/iommu/arm/arm-smmu/qcom_iommu.c:242:\tpgtbl_ops = alloc_io_pgtable_ops(ARM_32_LPAE_S1, \u0026pgtbl_cfg, qcom_domain);\ndrivers/iommu/arm/arm-smmu/qcom_iommu.c-243-\tif (!pgtbl_ops) {\n--\ndrivers/iommu/io-pgtable-arm-selftests.c=51=static int arm_lpae_run_tests(struct kunit test, struct io_pgtable_cfg cfg)\n--\ndrivers/iommu/io-pgtable-arm-selftests.c-53-\tstatic const enum io_pgtable_fmt fmts[] = {\ndrivers/iommu/io-pgtable-arm-selftests.c:54:\t\tARM_64_LPAE_S1,\ndrivers/iommu/io-pgtable-arm-selftests.c:55:\t\tARM_64_LPAE_S2,\ndrivers/iommu/io-pgtable-arm-selftests.c-56-\t};\n--\ndrivers/iommu/io-pgtable-arm.c-137-\ndrivers/iommu/io-pgtable-arm.c:138:#define ARM_MALI_LPAE_TTBR_ADRMODE_TABLE (3u \u003c\u003c 0)\ndrivers/iommu/io-pgtable-arm.c:139:#define ARM_MALI_LPAE_TTBR_READ_INNER\tBIT(2)\ndrivers/iommu/io-pgtable-arm.c:140:#define ARM_MALI_LPAE_TTBR_SHARE_OUTER\tBIT(4)\ndrivers/iommu/io-pgtable-arm.c-141-\ndrivers/iommu/io-pgtable-arm.c:142:#define ARM_MALI_LPAE_MEMATTR_IMP_DEF\t0x88ULL\ndrivers/iommu/io-pgtable-arm.c:143:#define ARM_MALI_LPAE_MEMATTR_WRITE_ALLOC 0x8DULL\ndrivers/iommu/io-pgtable-arm.c-144-\n--\ndrivers/iommu/io-pgtable-arm.c=169=static inline bool iopte_leaf(arm_lpae_iopte pte, int lvl,\n--\ndrivers/iommu/io-pgtable-arm.c-171-{\ndrivers/iommu/io-pgtable-arm.c:172:\tif (lvl == (ARM_LPAE_MAX_LEVELS - 1) \u0026\u0026 fmt != ARM_MALI_LPAE)\ndrivers/iommu/io-pgtable-arm.c-173-\t\treturn iopte_type(pte) == ARM_LPAE_PTE_TYPE_PAGE;\n--\ndrivers/iommu/io-pgtable-arm.c=371=static void __arm_lpae_init_pte(struct arm_lpae_io_pgtable data,\n--\ndrivers/iommu/io-pgtable-arm.c-379-\ndrivers/iommu/io-pgtable-arm.c:380:\tif (data-\u003eiop.fmt != ARM_MALI_LPAE \u0026\u0026 lvl == ARM_LPAE_MAX_LEVELS - 1)\ndrivers/iommu/io-pgtable-arm.c-381-\t\tpte \|= ARM_LPAE_PTE_TYPE_PAGE;\n--\ndrivers/iommu/io-pgtable-arm.c=513=static arm_lpae_iopte arm_lpae_prot_to_pte(struct arm_lpae_io_pgtable data,\n--\ndrivers/iommu/io-pgtable-arm.c-517-\ndrivers/iommu/io-pgtable-arm.c:518:\tif (data-\u003eiop.fmt == ARM_64_LPAE_S1 \|\|\ndrivers/iommu/io-pgtable-arm.c:519:\t data-\u003eiop.fmt == ARM_32_LPAE_S1) {\ndrivers/iommu/io-pgtable-arm.c-520-\t\tpte = ARM_LPAE_PTE_nG;\n--\ndrivers/iommu/io-pgtable-arm.c-538-\t /\ndrivers/iommu/io-pgtable-arm.c:539:\tif (data-\u003eiop.fmt == ARM_64_LPAE_S2 \|\|\ndrivers/iommu/io-pgtable-arm.c:540:\t data-\u003eiop.fmt == ARM_32_LPAE_S2) {\ndrivers/iommu/io-pgtable-arm.c-541-\t\tif (prot \u0026 IOMMU_MMIO) {\n--\ndrivers/iommu/io-pgtable-arm.c-565-\t /\ndrivers/iommu/io-pgtable-arm.c:566:\tif (prot \u0026 IOMMU_CACHE \u0026\u0026 data-\u003eiop.fmt != ARM_MALI_LPAE)\ndrivers/iommu/io-pgtable-arm.c-567-\t\tpte \|= ARM_LPAE_PTE_SH_IS;\n--\ndrivers/iommu/io-pgtable-arm.c-576-\ndrivers/iommu/io-pgtable-arm.c:577:\tif (data-\u003eiop.fmt != ARM_MALI_LPAE)\ndrivers/iommu/io-pgtable-arm.c-578-\t\tpte \|= ARM_LPAE_PTE_AF;\n--\ndrivers/iommu/io-pgtable-arm.c=888=static int arm_lpae_read_and_clear_dirty(struct io_pgtable_ops ops,\n--\ndrivers/iommu/io-pgtable-arm.c-909-\t\treturn -EINVAL;\ndrivers/iommu/io-pgtable-arm.c:910:\tif (data-\u003eiop.fmt != ARM_64_LPAE_S1)\ndrivers/iommu/io-pgtable-arm.c-911-\t\treturn -EINVAL;\n--\ndrivers/iommu/io-pgtable-arm.c=1224=arm_mali_lpae_alloc_pgtable(struct io_pgtable_cfg cfg, void cookie)\n--\ndrivers/iommu/io-pgtable-arm.c-1253-\tcfg-\u003earm_mali_lpae_cfg.memattr =\ndrivers/iommu/io-pgtable-arm.c:1254:\t\t(ARM_MALI_LPAE_MEMATTR_IMP_DEF\ndrivers/iommu/io-pgtable-arm.c-1255-\t\t \u003c\u003c ARM_LPAE_MAIR_ATTR_SHIFT(ARM_LPAE_MAIR_ATTR_IDX_NC)) \|\ndrivers/iommu/io-pgtable-arm.c:1256:\t\t(ARM_MALI_LPAE_MEMATTR_WRITE_ALLOC\ndrivers/iommu/io-pgtable-arm.c-1257-\t\t \u003c\u003c ARM_LPAE_MAIR_ATTR_SHIFT(ARM_LPAE_MAIR_ATTR_IDX_CACHE)) \|\ndrivers/iommu/io-pgtable-arm.c:1258:\t\t(ARM_MALI_LPAE_MEMATTR_IMP_DEF\ndrivers/iommu/io-pgtable-arm.c-1259-\t\t \u003c\u003c ARM_LPAE_MAIR_ATTR_SHIFT(ARM_LPAE_MAIR_ATTR_IDX_DEV));\n--\ndrivers/iommu/io-pgtable-arm.c-1269-\tcfg-\u003earm_mali_lpae_cfg.transtab = virt_to_phys(data-\u003epgd) \|\ndrivers/iommu/io-pgtable-arm.c:1270:\t\t\t\t\t ARM_MALI_LPAE_TTBR_READ_INNER \|\ndrivers/iommu/io-pgtable-arm.c:1271:\t\t\t\t\t ARM_MALI_LPAE_TTBR_ADRMODE_TABLE;\ndrivers/iommu/io-pgtable-arm.c-1272-\tif (cfg-\u003ecoherent_walk)\ndrivers/iommu/io-pgtable-arm.c:1273:\t\tcfg-\u003earm_mali_lpae_cfg.transtab \|= ARM_MALI_LPAE_TTBR_SHARE_OUTER;\ndrivers/iommu/io-pgtable-arm.c-1274-\n--\ndrivers/iommu/io-pgtable.c=16=io_pgtable_init_table[IO_PGTABLE_NUM_FMTS] = {\ndrivers/iommu/io-pgtable.c-17-#ifdef CONFIG_IOMMU_IO_PGTABLE_LPAE\ndrivers/iommu/io-pgtable.c:18:\t[ARM_32_LPAE_S1] = \u0026io_pgtable_arm_32_lpae_s1_init_fns,\ndrivers/iommu/io-pgtable.c:19:\t[ARM_32_LPAE_S2] = \u0026io_pgtable_arm_32_lpae_s2_init_fns,\ndrivers/iommu/io-pgtable.c:20:\t[ARM_64_LPAE_S1] = \u0026io_pgtable_arm_64_lpae_s1_init_fns,\ndrivers/iommu/io-pgtable.c:21:\t[ARM_64_LPAE_S2] = \u0026io_pgtable_arm_64_lpae_s2_init_fns,\ndrivers/iommu/io-pgtable.c:22:\t[ARM_MALI_LPAE] = \u0026io_pgtable_arm_mali_lpae_init_fns,\ndrivers/iommu/io-pgtable.c-23-#endif\n--\ndrivers/iommu/ipmmu-vmsa.c=417=static int ipmmu_domain_init_context(struct ipmmu_vmsa_domain *domain)\n--\ndrivers/iommu/ipmmu-vmsa.c-454-\ndrivers/iommu/ipmmu-vmsa.c:455:\tdomain-\u003eiop = alloc_io_pgtable_ops(ARM_32_LPAE_S1, \u0026domain-\u003ecfg,\ndrivers/iommu/ipmmu-vmsa.c-456-\t\t\t\t\t domain);\n--\ninclude/linux/io-pgtable.h=11=enum io_pgtable_fmt {\ninclude/linux/io-pgtable.h:12:\tARM_32_LPAE_S1,\ninclude/linux/io-pgtable.h:13:\tARM_32_LPAE_S2,\ninclude/linux/io-pgtable.h:14:\tARM_64_LPAE_S1,\ninclude/linux/io-pgtable.h:15:\tARM_64_LPAE_S2,\ninclude/linux/io-pgtable.h-16-\tARM_V7S,\ninclude/linux/io-pgtable.h:17:\tARM_MALI_LPAE,\ninclude/linux/io-pgtable.h-18-\tAPPLE_DART,\n--\nrust/kernel/iommu/pgtable.rs=229= fn drop(\u0026mut self) {\n--\nrust/kernel/iommu/pgtable.rs-235-\nrust/kernel/iommu/pgtable.rs:236:/// The `ARM_64_LPAE_S1` page table format.\nrust/kernel/iommu/pgtable.rs-237-pub enum ARM64LPAES1 {}\n--\nrust/kernel/iommu/pgtable.rs=239=impl IoPageTableFmt for ARM64LPAES1 {\nrust/kernel/iommu/pgtable.rs:240: const FORMAT: io_pgtable_fmt = bindings::io_pgtable_fmt_ARM_64_LPAE_S1 as io_pgtable_fmt;\nrust/kernel/iommu/pgtable.rs-241-}\n" }
75/2	2026/10/26 17:23	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 74666 output: 219 thoughts: 1130 Thoughts: Analysis of Unreachability on amd64 Architecture Okay, let's break this down. That list of callers… it's crystal clear. Every single one, and I'm talking about: `ARM_SMMU_V3`, `ARM_SMMU`, `QCOM_IOMMU`, `IPMMU_VMSA`, `DRM_PANFROST`, `DRM_PANTHOR`, `DRM_TYR`, `DRM_MSM`, and `io-pgtable-arm-selftests.c`, points directly to ARM-specific or ARM64-dependent functionality. We're looking at ARM platform drivers and GPU drivers—nothing that realistically exists or is emulated on amd64 in a standard environment, like a QEMU setup or GCE. The patch itself modifies `io_pgtable_visit` and `visit_dirty` within `drivers/iommu/io-pgtable-arm.c`. Specifically, `visit_dirty` is exclusively called by `arm_lpae_read_and_clear_dirty`. That function has a check: `if (data->iop.fmt != ARM_64_LPAE_S1) return -EINVAL;`. This check, coupled with the fact that `arm_lpae_read_and_clear_dirty` is only invoked via `arm_smmu_read_and_clear_dirty` in `drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c` (which is itself ARM64-only), seals the deal. The rest of the `io_pgtable_visit` functionality in `drivers/iommu/io-pgtable-arm.c` is only instantiated by drivers for ARM-specific hardware. So we have ARM SMMU, Mali GPUs, Snapdragon GPUs, or KUnit tests. On amd64, we can't even build `ARM_SMMU_V3` due to the `ARM64` dependency. The other drivers, like `msm`, `panfrost`, and `panthor`, are platform device drivers for ARM SoCs, and are not designed to probe or work on amd64 VMs. Plus, the removal of the dead helper `iommu_dirty_bitmap_record` simply removes an unused function that was only called by `io-pgtable-arm.c`. Consequently, this means the modified code is structurally unreachable on the amd64 architecture. Now, let's review the guidelines. The "negative criteria" in the documentation is key. We're looking at code paths that are strictly: "exclusive to architectures other than the target architecture", which means that this patch fits perfectly within that category. We're also dealing with "structurally unreachable hardware", which requires ARM SoCs/SMMU, and therefore can't be emulated in standard x86_64/amd64 QEMU. We've covered all angles. There are no specific symbols to focus on, nor any configs to enable in this "WorthFuzzing=false" scenario. The reasoning is: 1. The patch impacts ARM LPAE page table walking and dirty tracking in `drivers/iommu/io-pgtable-arm.c` and removes an unused helper. 2. Dirty tracking is exclusively linked to `ARM_SMMU_V3`, and that depends on `CONFIG_ARM64`, which cannot be built or run on amd64. 3. The LPAE page table logic is only used by ARM-specific SoC hardware, which won't probe or execute in an amd64 QEMU environment. 4. Therefore, all the modified code is structurally unreachable on amd64. Looks like everything is covered, time to call `set-results`.
76/2	2026/10/26 17:23	tool	set-results	0m Args: { "EnableConfigs": [], "FocusSymbols": [], "Reasoning": "The changes modify ARM LPAE page table walking and dirty tracking routines (io_pgtable_visit and visit_dirty) in drivers/iommu/io-pgtable-arm.c, as well as remove an unused helper (iommu_dirty_bitmap_record) from include/linux/iommu.h. The modified dirty tracking logic is only consumed by the ARM SMMU v3 driver (arm-smmu-v3), which depends on CONFIG_ARM64 and cannot be built on amd64. Furthermore, the ARM LPAE io-pgtable implementation is only used by ARM-specific platform devices and GPUs (ARM SMMU, Apple DART, Panfrost, Panthor, Qualcomm MSM) that are structurally unreachable and not emulated in standard amd64 virtualized environments. Therefore, the modified code paths are unreachable on the target architecture (amd64).", "WorthFuzzing": false } Results: { "EnableConfigs": null, "FocusSymbols": [], "Reasoning": "The changes modify ARM LPAE page table walking and dirty tracking routines (io_pgtable_visit and visit_dirty) in drivers/iommu/io-pgtable-arm.c, as well as remove an unused helper (iommu_dirty_bitmap_record) from include/linux/iommu.h. The modified dirty tracking logic is only consumed by the ARM SMMU v3 driver (arm-smmu-v3), which depends on CONFIG_ARM64 and cannot be built on amd64. Furthermore, the ARM LPAE io-pgtable implementation is only used by ARM-specific platform devices and GPUs (ARM SMMU, Apple DART, Panfrost, Panthor, Qualcomm MSM) that are structurally unreachable and not emulated in standard amd64 virtualized environments. Therefore, the modified code paths are unreachable on the target architecture (amd64).", "WorthFuzzing": false }
77/1	2026/10/26 17:23	action	If	0m Args: { "WorthFuzzing": false } Results: null

LLM Calls Summary:
Total Calls	Total Tokens	Avg Tokens	Total Duration (Seconds)	Avg Duration (Seconds)

Tool Calls Summary:
Total Calls	Total Duration (Seconds)	Avg Duration (Seconds)