AI Trajectory

null

{
  "EnableConfigs": null,
  "FocusSymbols": [
    "identify_secondary_cpu"
  ],
  "KMSANReasoning": "The patch refactors CPU identification logic in x86 by consolidating the initialization of `struct cpuinfo_x86` fields into a new `init_cpu_info()` function. It does not introduce any new data structures that are copied to user space, nor does it alter bounds checking or introduce complex allocations that could leak uninitialized memory. The changes are purely internal to CPU boot and hotplug initialization. Any potential memory corruption or out-of-bounds accesses introduced by this refactoring would be caught by standard KASAN. Therefore, a dedicated KMSAN session is not necessary.",
  "NeedsKMSAN": false,
  "Reasoning": "The patch refactors x86 CPU identification logic, moving initialization into a new `init_cpu_info` function and merging `generic_identify` into `identify_cpu`. These changes affect how CPU features and capabilities are detected and initialized. While much of this runs during early boot, `identify_secondary_cpu` is executed when secondary CPUs are brought online, which can be triggered via CPU hotplug operations. Fuzzing CPU hotplug could reveal uninitialized fields or incorrect feature detection introduced by this refactoring.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit a8d94556a3a7ca87af339a24894c35cea207dd5e\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Sat Aug 15 00:00:55 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c\nindex a3df21d264606..e0c70a2510afc 100644\n--- a/arch/x86/kernel/cpu/common.c\n+++ b/arch/x86/kernel/cpu/common.c\n@@ -1772,25 +1772,50 @@ static void __init cpu_parse_early_param(void)\n \t}\n }\n \n+static void init_cpu_info(struct cpuinfo_x86 *c)\n+{\n+\tc-\u003ex86_cache_size = 0;\n+\tc-\u003ex86_vendor = X86_VENDOR_UNKNOWN;\n+\tc-\u003ex86_model = c-\u003ex86_stepping = 0;\t/* So far unknown... */\n+\tc-\u003ex86_vendor_id[0] = '\\0'; /* Unset */\n+\tc-\u003ex86_model_id[0] = '\\0';  /* Unset */\n+#ifdef CONFIG_X86_64\n+\tc-\u003ex86_clflush_size = 64;\n+\tc-\u003ex86_phys_bits = 36;\n+\tc-\u003ex86_virt_bits = 48;\n+#else\n+\tc-\u003ecpuid_level = -1;\t/* CPUID not detected */\n+\tc-\u003ex86_clflush_size = 32;\n+\tc-\u003ex86_phys_bits = 32;\n+\tc-\u003ex86_virt_bits = 32;\n+#endif\n+\tc-\u003ex86_cache_alignment = c-\u003ex86_clflush_size;\n+\tmemset(\u0026c-\u003ex86_capability, 0, sizeof(c-\u003ex86_capability));\n+\tmemset(\u0026c-\u003ecpuid, 0, sizeof(c-\u003ecpuid));\n+#ifdef CONFIG_X86_VMX_FEATURE_NAMES\n+\tmemset(\u0026c-\u003evmx_capability, 0, sizeof(c-\u003evmx_capability));\n+#endif\n+\tc-\u003eextended_cpuid_level = 0;\n+}\n+\n /*\n  * Do minimum CPU detection early.\n  * Fields really needed: vendor, cpuid_level, family, model, mask,\n  * cache alignment.\n- * The others are not touched to avoid unwanted side effects.\n+ * The others are reset to their defaults here and only filled in later,\n+ * by identify_cpu().\n  *\n  * WARNING: this function is only called on the boot CPU.  Don't add code\n  * here that is supposed to run on all CPUs.\n  */\n static void __init early_identify_cpu(struct cpuinfo_x86 *c)\n {\n-\tmemset(\u0026c-\u003ex86_capability, 0, sizeof(c-\u003ex86_capability));\n-\tmemset(\u0026c-\u003ecpuid, 0, sizeof(c-\u003ecpuid));\n-\tc-\u003eextended_cpuid_level = 0;\n+\tinit_cpu_info(c);\n \n \tif (!cpuid_feature())\n \t\tidentify_cpu_without_cpuid(c);\n \n-\t/* cyrix could have cpuid enabled via c_identify()*/\n+\t/* Cyrix could have CPUID enabled via c_identify(). */\n \tif (cpuid_feature()) {\n \t\tcpuid_scan_cpu(c);\n \t\tcpu_detect(c);\n@@ -1954,16 +1979,21 @@ void check_null_seg_clears_base(struct cpuinfo_x86 *c)\n \tset_cpu_bug(c, X86_BUG_NULL_SEG);\n }\n \n-static void generic_identify(struct cpuinfo_x86 *c)\n+/*\n+ * This does the hard work of actually picking apart the CPU stuff...\n+ */\n+static void identify_cpu(struct cpuinfo_x86 *c)\n {\n-\tc-\u003eextended_cpuid_level = 0;\n+\tint i;\n+\n+\tc-\u003eloops_per_jiffy = loops_per_jiffy;\n \n \tif (!cpuid_feature())\n \t\tidentify_cpu_without_cpuid(c);\n \n-\t/* cyrix could have cpuid enabled via c_identify()*/\n+\t/* Cyrix could have CPUID enabled via c_identify(). */\n \tif (!cpuid_feature())\n-\t\treturn;\n+\t\tgoto no_cpuid;\n \n \tcpuid_scan_cpu(c);\n \tcpu_detect(c);\n@@ -1991,40 +2021,8 @@ static void generic_identify(struct cpuinfo_x86 *c)\n #ifdef CONFIG_X86_32\n \tset_cpu_bug(c, X86_BUG_ESPFIX);\n #endif\n-}\n-\n-/*\n- * This does the hard work of actually picking apart the CPU stuff...\n- */\n-static void identify_cpu(struct cpuinfo_x86 *c)\n-{\n-\tint i;\n-\n-\tc-\u003eloops_per_jiffy = loops_per_jiffy;\n-\tc-\u003ex86_cache_size = 0;\n-\tc-\u003ex86_vendor = X86_VENDOR_UNKNOWN;\n-\tc-\u003ex86_model = c-\u003ex86_stepping = 0;\t/* So far unknown... */\n-\tc-\u003ex86_vendor_id[0] = '\\0'; /* Unset */\n-\tc-\u003ex86_model_id[0] = '\\0';  /* Unset */\n-#ifdef CONFIG_X86_64\n-\tc-\u003ex86_clflush_size = 64;\n-\tc-\u003ex86_phys_bits = 36;\n-\tc-\u003ex86_virt_bits = 48;\n-#else\n-\tc-\u003ecpuid_level = -1;\t/* CPUID not detected */\n-\tc-\u003ex86_clflush_size = 32;\n-\tc-\u003ex86_phys_bits = 32;\n-\tc-\u003ex86_virt_bits = 32;\n-#endif\n-\tc-\u003ex86_cache_alignment = c-\u003ex86_clflush_size;\n-\tmemset(\u0026c-\u003ex86_capability, 0, sizeof(c-\u003ex86_capability));\n-\tmemset(\u0026c-\u003ecpuid, 0, sizeof(c-\u003ecpuid));\n-#ifdef CONFIG_X86_VMX_FEATURE_NAMES\n-\tmemset(\u0026c-\u003evmx_capability, 0, sizeof(c-\u003evmx_capability));\n-#endif\n-\n-\tgeneric_identify(c);\n \n+no_cpuid:\n \tcpu_parse_topology(c);\n \n \tif (this_cpu-\u003ec_identify)\n@@ -2116,6 +2114,9 @@ static void identify_cpu(struct cpuinfo_x86 *c)\n \tmcheck_cpu_init(c);\n \n \tnuma_add_cpu(smp_processor_id());\n+\n+\tif (IS_ENABLED(CONFIG_X86_32))\n+\t\tenable_sep_cpu();\n }\n \n /*\n@@ -2153,9 +2154,6 @@ static __init void identify_boot_cpu(void)\n \tidentify_cpu(\u0026boot_cpu_data);\n \tif (HAS_KERNEL_IBT \u0026\u0026 cpu_feature_enabled(X86_FEATURE_IBT))\n \t\tpr_info(\"CET detected: Indirect Branch Tracking enabled\\n\");\n-#ifdef CONFIG_X86_32\n-\tenable_sep_cpu();\n-#endif\n \tcpu_detect_tlb(\u0026boot_cpu_data);\n \tsetup_cr_pinning();\n \n@@ -2174,10 +2172,8 @@ void identify_secondary_cpu(unsigned int cpu)\n \t\t*c = boot_cpu_data;\n \tc-\u003ecpu_index = cpu;\n \n+\tinit_cpu_info(c);\n \tidentify_cpu(c);\n-#ifdef CONFIG_X86_32\n-\tenable_sep_cpu();\n-#endif\n \tx86_spec_ctrl_setup_ap();\n \tupdate_srbds_msr();\n \tif (boot_cpu_has_bug(X86_BUG_GDS))\n"
}

best-expensive

null

{
  "EnableConfigs": null,
  "FocusSymbols": [
    "identify_secondary_cpu"
  ],
  "Reasoning": "The patch refactors x86 CPU identification logic, moving initialization into a new `init_cpu_info` function and merging `generic_identify` into `identify_cpu`. These changes affect how CPU features and capabilities are detected and initialized. While much of this runs during early boot, `identify_secondary_cpu` is executed when secondary CPUs are brought online, which can be triggered via CPU hotplug operations. Fuzzing CPU hotplug could reveal uninitialized fields or incorrect feature detection introduced by this refactoring.",
  "WorthFuzzing": true
}

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

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

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

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

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


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

For your convenience, here is the diff of the changes:
commit a8d94556a3a7ca87af339a24894c35cea207dd5e
Author: syz-cluster <triage@syzkaller.com>
Date:   Sat Aug 15 00:00:55 2026 +0000

    syz-cluster: applied patch under review

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index a3df21d264606..e0c70a2510afc 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1772,25 +1772,50 @@ static void __init cpu_parse_early_param(void)
 	}
 }
 
+static void init_cpu_info(struct cpuinfo_x86 *c)
+{
+	c->x86_cache_size = 0;
+	c->x86_vendor = X86_VENDOR_UNKNOWN;
+	c->x86_model = c->x86_stepping = 0;	/* So far unknown... */
+	c->x86_vendor_id[0] = '\0'; /* Unset */
+	c->x86_model_id[0] = '\0';  /* Unset */
+#ifdef CONFIG_X86_64
+	c->x86_clflush_size = 64;
+	c->x86_phys_bits = 36;
+	c->x86_virt_bits = 48;
+#else
+	c->cpuid_level = -1;	/* CPUID not detected */
+	c->x86_clflush_size = 32;
+	c->x86_phys_bits = 32;
+	c->x86_virt_bits = 32;
+#endif
+	c->x86_cache_alignment = c->x86_clflush_size;
+	memset(&c->x86_capability, 0, sizeof(c->x86_capability));
+	memset(&c->cpuid, 0, sizeof(c->cpuid));
+#ifdef CONFIG_X86_VMX_FEATURE_NAMES
+	memset(&c->vmx_capability, 0, sizeof(c->vmx_capability));
+#endif
+	c->extended_cpuid_level = 0;
+}
+
 /*
  * Do minimum CPU detection early.
  * Fields really needed: vendor, cpuid_level, family, model, mask,
  * cache alignment.
- * The others are not touched to avoid unwanted side effects.
+ * The others are reset to their defaults here and only filled in later,
+ * by identify_cpu().
  *
  * WARNING: this function is only called on the boot CPU.  Don't add code
  * here that is supposed to run on all CPUs.
  */
 static void __init early_identify_cpu(struct cpuinfo_x86 *c)
 {
-	memset(&c->x86_capability, 0, sizeof(c->x86_capability));
-	memset(&c->cpuid, 0, sizeof(c->cpuid));
-	c->extended_cpuid_level = 0;
+	init_cpu_info(c);
 
 	if (!cpuid_feature())
 		identify_cpu_without_cpuid(c);
 
-	/* cyrix could have cpuid enabled via c_identify()*/
+	/* Cyrix could have CPUID enabled via c_identify(). */
 	if (cpuid_feature()) {
 		cpuid_scan_cpu(c);
 		cpu_detect(c);
@@ -1954,16 +1979,21 @@ void check_null_seg_clears_base(struct cpuinfo_x86 *c)
 	set_cpu_bug(c, X86_BUG_NULL_SEG);
 }
 
-static void generic_identify(struct cpuinfo_x86 *c)
+/*
+ * This does the hard work of actually picking apart the CPU stuff...
+ */
+static void identify_cpu(struct cpuinfo_x86 *c)
 {
-	c->extended_cpuid_level = 0;
+	int i;
+
+	c->loops_per_jiffy = loops_per_jiffy;
 
 	if (!cpuid_feature())
 		identify_cpu_without_cpuid(c);
 
-	/* cyrix could have cpuid enabled via c_identify()*/
+	/* Cyrix could have CPUID enabled via c_identify(). */
 	if (!cpuid_feature())
-		return;
+		goto no_cpuid;
 
 	cpuid_scan_cpu(c);
 	cpu_detect(c);
@@ -1991,40 +2021,8 @@ static void generic_identify(struct cpuinfo_x86 *c)
 #ifdef CONFIG_X86_32
 	set_cpu_bug(c, X86_BUG_ESPFIX);
 #endif
-}
-
-/*
- * This does the hard work of actually picking apart the CPU stuff...
- */
-static void identify_cpu(struct cpuinfo_x86 *c)
-{
-	int i;
-
-	c->loops_per_jiffy = loops_per_jiffy;
-	c->x86_cache_size = 0;
-	c->x86_vendor = X86_VENDOR_UNKNOWN;
-	c->x86_model = c->x86_stepping = 0;	/* So far unknown... */
-	c->x86_vendor_id[0] = '\0'; /* Unset */
-	c->x86_model_id[0] = '\0';  /* Unset */
-#ifdef CONFIG_X86_64
-	c->x86_clflush_size = 64;
-	c->x86_phys_bits = 36;
-	c->x86_virt_bits = 48;
-#else
-	c->cpuid_level = -1;	/* CPUID not detected */
-	c->x86_clflush_size = 32;
-	c->x86_phys_bits = 32;
-	c->x86_virt_bits = 32;
-#endif
-	c->x86_cache_alignment = c->x86_clflush_size;
-	memset(&c->x86_capability, 0, sizeof(c->x86_capability));
-	memset(&c->cpuid, 0, sizeof(c->cpuid));
-#ifdef CONFIG_X86_VMX_FEATURE_NAMES
-	memset(&c->vmx_capability, 0, sizeof(c->vmx_capability));
-#endif
-
-	generic_identify(c);
 
+no_cpuid:
 	cpu_parse_topology(c);
 
 	if (this_cpu->c_identify)
@@ -2116,6 +2114,9 @@ static void identify_cpu(struct cpuinfo_x86 *c)
 	mcheck_cpu_init(c);
 
 	numa_add_cpu(smp_processor_id());
+
+	if (IS_ENABLED(CONFIG_X86_32))
+		enable_sep_cpu();
 }
 
 /*
@@ -2153,9 +2154,6 @@ static __init void identify_boot_cpu(void)
 	identify_cpu(&boot_cpu_data);
 	if (HAS_KERNEL_IBT && cpu_feature_enabled(X86_FEATURE_IBT))
 		pr_info("CET detected: Indirect Branch Tracking enabled\n");
-#ifdef CONFIG_X86_32
-	enable_sep_cpu();
-#endif
 	cpu_detect_tlb(&boot_cpu_data);
 	setup_cr_pinning();
 
@@ -2174,10 +2172,8 @@ void identify_secondary_cpu(unsigned int cpu)
 		*c = boot_cpu_data;
 	c->cpu_index = cpu;
 
+	init_cpu_info(c);
 	identify_cpu(c);
-#ifdef CONFIG_X86_32
-	enable_sep_cpu();
-#endif
 	x86_spec_ctrl_setup_ap();
 	update_srbds_msr();
 	if (boot_cpu_has_bug(X86_BUG_GDS))

gemini-3.1-pro-preview

null

null

							input: 3841
							output: 19
							thoughts: 850
						

**WorthFuzzing Analysis: CPU Identification Refactoring**

Okay, so I've got this patch that's refactoring the CPU identification code in `arch/x86/kernel/cpu/common.c`. It's moving the initialization of `struct cpuinfo_x86` into a new function, `init_cpu_info()`, and consolidating some other functions. My initial thought is to assess if this is something worth fuzzing.

Initially, it seemed like a refactoring. But wait, this `init_cpu_info()` call has been moved into `early_identify_cpu()`. That's a functional change because `init_cpu_info()` now resets a bunch of `cpuinfo_x86` members that were *not* reset previously. This part is executed very early, before the fuzzer typically runs, making it less of a priority for syzkaller.

However, `identify_secondary_cpu()` is now also calling the same refactored code. And secondary CPU identification happens during CPU hotplug, which *is* something a fuzzer can trigger. That's interesting! So, the question now is, does this refactoring expose new attack surface or introduce a bug? It is very likely, since we are dealing with CPU initialization, that a bug could result in stale data on a secondary CPU.

The commit message itself is a bit generic ("syz-cluster: applied patch under review"). This suggests it's a Syzkaller-related change, which means we should err on the side of caution.

According to the documentation, if the patch only contains code that is unreachable in virtualized environments like QEMU or GCE, it's not worth fuzzing. However, this is absolutely reachable, as CPU hotplug is possible in virtual environments. This modification touches core kernel logic (x86 CPU identification) and can be reached. So, based on the documented guidelines, I should flag this as `WorthFuzzing=true`.

Now, what are the key functions to focus on? Definitely `identify_secondary_cpu`, because it's called during hotplug. `early_identify_cpu` is less important now, as it executes so early. `identify_cpu` is another key one, since it is a critical part of the CPU identification. And `enable_sep_cpu` which is called from `identify_cpu`.

I need to confirm `identify_secondary_cpu` is reachable. Yep, via CPU hotplug, that's what's key here. And `enable_sep_cpu` will now be impacted by CPU hotplug as it is called by `identify_cpu`

I'll use `grepper` to confirm my findings on `identify_secondary_cpu` and surrounding code to make sure my conclusions are sound.

{
  "Expression": "identify_secondary_cpu"
}

{
  "Output": "arch/x86/include/asm/processor.h=237=extern void early_cpu_init(void);\narch/x86/include/asm/processor.h:238:extern void identify_secondary_cpu(unsigned int cpu);\narch/x86/include/asm/processor.h-239-extern void print_cpu_info(struct cpuinfo_x86 *);\n--\narch/x86/kernel/cpu/amd.c=207=static void init_amd_k7(struct cpuinfo_x86 *c)\n--\narch/x86/kernel/cpu/amd.c-238-\narch/x86/kernel/cpu/amd.c:239:\t/* calling is from identify_secondary_cpu() ? */\narch/x86/kernel/cpu/amd.c-240-\tif (!c-\u003ecpu_index)\n--\narch/x86/kernel/cpu/common.c=2152=static __init void identify_boot_cpu(void)\n--\narch/x86/kernel/cpu/common.c-2165-\narch/x86/kernel/cpu/common.c:2166:void identify_secondary_cpu(unsigned int cpu)\narch/x86/kernel/cpu/common.c-2167-{\n--\narch/x86/kernel/cpu/intel.c=362=static void intel_smp_check(struct cpuinfo_x86 *c)\narch/x86/kernel/cpu/intel.c-363-{\narch/x86/kernel/cpu/intel.c:364:\t/* calling is from identify_secondary_cpu() ? */\narch/x86/kernel/cpu/intel.c-365-\tif (!c-\u003ecpu_index)\n--\narch/x86/kernel/smpboot.c=170=static void ap_starting(void)\n--\narch/x86/kernel/smpboot.c-189-\t/* Save the processor parameters. */\narch/x86/kernel/smpboot.c:190:\tidentify_secondary_cpu(cpuid);\narch/x86/kernel/smpboot.c-191-\n--\narch/x86/kernel/smpboot.c=211=static void ap_calibrate_delay(void)\n--\narch/x86/kernel/smpboot.c-214-\t * Calibrate the delay loop and update loops_per_jiffy in cpu_data.\narch/x86/kernel/smpboot.c:215:\t * identify_secondary_cpu() stored a value that is close but not as\narch/x86/kernel/smpboot.c-216-\t * accurate as the value just calculated.\n--\narch/x86/xen/smp_pv.c=57=static void cpu_bringup(void)\n--\narch/x86/xen/smp_pv.c-71-\tcpu = smp_processor_id();\narch/x86/xen/smp_pv.c:72:\tidentify_secondary_cpu(cpu);\narch/x86/xen/smp_pv.c-73-\tset_cpu_sibling_map(cpu);\n"
}

gemini-3.1-pro-preview

null

null

							input: 6121
							output: 20
							thoughts: 679
						

**Analyzing the Potential for Fuzzing `identify_secondary_cpu`**

Okay, let's break this down systematically. I see that `identify_secondary_cpu` is called from `ap_starting` and `cpu_bringup`, both related to CPU hotplug, which immediately piques my interest. CPU hotplug is definitely a fuzzable area, and Syzkaller can, in fact, offline and online CPUs. That makes `identify_secondary_cpu` a strong candidate for a focused fuzzing target.

Now, the patch also touches `identify_cpu`. But wait, it's `static void identify_cpu()`. Static functions are generally a bad choice for fuzzing because they are difficult to reach from the outside. So, `identify_cpu`, `init_cpu_info` and `early_identify_cpu` are out.

Okay, back to `identify_secondary_cpu`. It appears to be the primary reachable function modified by the patch, that isn't static. Let's confirm that it's exported and not static... and yes, `void identify_secondary_cpu(unsigned int cpu)` confirms it is non-static. Good.

The patch mentions a few `CONFIG` options: `CONFIG_X86_32`, `CONFIG_X86_64`, and `CONFIG_X86_VMX_FEATURE_NAMES`. The latter two are fairly standard for x86. The first might be interesting if we want to test a 32-bit x86 configuration, which isn't the Syzkaller default. The more important configuration appears to be `CONFIG_HOTPLUG_CPU`, which is standard but essential.

Looking at the patch itself, I see that `generic_identify` has been merged into `identify_cpu`. Essentially, `identify_cpu` has been updated and now holds the functionality of the merged function.

So, in summary, I'm going to focus my fuzzing efforts on `identify_secondary_cpu`, ensuring that I have `CONFIG_HOTPLUG_CPU` enabled. I'll need to remember that `CONFIG_X86_32` might be relevant if I want to explore 32-bit specific behavior. I should also be mindful of the changes to `identify_cpu`, even though it's static, since those changes are now part of the `identify_secondary_cpu` call chain. I'll double check the code in `arch/x86/kernel/cpu/common.c` to be sure I haven't missed anything. This seems like a reasonable and focused approach to this patch.

{
  "Expression": "void identify_secondary_cpu"
}

{
  "Output": "arch/x86/include/asm/processor.h=237=extern void early_cpu_init(void);\narch/x86/include/asm/processor.h:238:extern void identify_secondary_cpu(unsigned int cpu);\narch/x86/include/asm/processor.h-239-extern void print_cpu_info(struct cpuinfo_x86 *);\n--\narch/x86/kernel/cpu/common.c=2152=static __init void identify_boot_cpu(void)\n--\narch/x86/kernel/cpu/common.c-2165-\narch/x86/kernel/cpu/common.c:2166:void identify_secondary_cpu(unsigned int cpu)\narch/x86/kernel/cpu/common.c-2167-{\n"
}

gemini-3.1-pro-preview

null

null

							input: 7593
							output: 20
							thoughts: 123
						

**Analyzing CPU Configuration Dependencies**

Okay, so I'm looking at this `identify_secondary_cpu` function and it's definitely not a static function, which is something to keep in mind for how it's used and what it might depend on. Let's see what other configurations might be relevant here.

Right, I see that `CONFIG_X86_32` and `CONFIG_X86_64` are both being used, which makes sense given the architecture-specific nature of CPU identification. I also spot `CONFIG_X86_VMX_FEATURE_NAMES` which is interesting, I'll keep that in the back of my mind.

Now, a quick thought: should we be explicitly enabling `HOTPLUG_CPU` here? It's often enabled by default, but it might be worth making that dependency explicit for clarity and to ensure we don't run into any unexpected issues. I'll just double-check that `HOTPLUG_CPU` is the correct name for the config before I add it. Gotta make sure I have all the details right.

{
  "Expression": "config HOTPLUG_CPU"
}

{
  "Output": "arch/arm/Kconfig=1051=config NR_CPUS\n--\narch/arm/Kconfig-1062-\narch/arm/Kconfig:1063:config HOTPLUG_CPU\narch/arm/Kconfig-1064-\tbool \"Support for hot-pluggable CPUs\"\n--\narch/arm64/Kconfig=1567=config NR_CPUS\n--\narch/arm64/Kconfig-1571-\narch/arm64/Kconfig:1572:config HOTPLUG_CPU\narch/arm64/Kconfig-1573-\tbool \"Support for hot-pluggable CPUs\"\n--\narch/csky/Kconfig=330=config DRAM_BASE\n--\narch/csky/Kconfig-333-\narch/csky/Kconfig:334:config HOTPLUG_CPU\narch/csky/Kconfig-335-\tbool \"Support for hot-pluggable CPUs\"\n--\narch/loongarch/Kconfig=514=config SMP\n--\narch/loongarch/Kconfig-531-\narch/loongarch/Kconfig:532:config HOTPLUG_CPU\narch/loongarch/Kconfig-533-\tbool \"Support for hot-pluggable CPUs\"\n--\narch/mips/Kconfig=2704=config SMP\n--\narch/mips/Kconfig-2725-\narch/mips/Kconfig:2726:config HOTPLUG_CPU\narch/mips/Kconfig-2727-\tbool \"Support for hot-pluggable CPUs\"\n--\narch/parisc/Kconfig=331=config IRQSTACKS\n--\narch/parisc/Kconfig-338-\narch/parisc/Kconfig:339:config HOTPLUG_CPU\narch/parisc/Kconfig-340-\tbool\n--\narch/powerpc/Kconfig=580=config PPC_FTRACE_OUT_OF_LINE_NUM_RESERVE\n--\narch/powerpc/Kconfig-591-\narch/powerpc/Kconfig:592:config HOTPLUG_CPU\narch/powerpc/Kconfig-593-\tbool \"Support for enabling/disabling CPUs\"\n--\narch/riscv/Kconfig=450=config NR_CPUS\n--\narch/riscv/Kconfig-459-\narch/riscv/Kconfig:460:config HOTPLUG_CPU\narch/riscv/Kconfig-461-\tbool \"Support for hot-pluggable CPUs\"\n--\narch/s390/Kconfig=525=config NR_CPUS\n--\narch/s390/Kconfig-536-\narch/s390/Kconfig:537:config HOTPLUG_CPU\narch/s390/Kconfig-538-\tdef_bool y\n--\narch/sh/Kconfig=591=config NR_CPUS\n--\narch/sh/Kconfig-604-\narch/sh/Kconfig:605:config HOTPLUG_CPU\narch/sh/Kconfig-606-\tbool \"Support for hot-pluggable CPUs (EXPERIMENTAL)\"\n--\narch/sparc/Kconfig=220=config EARLYFB\n--\narch/sparc/Kconfig-228-\narch/sparc/Kconfig:229:config HOTPLUG_CPU\narch/sparc/Kconfig-230-\tbool \"Support for hot-pluggable CPUs\"\n--\narch/x86/Kconfig=2150=config ADDRESS_MASKING\n--\narch/x86/Kconfig-2161-\narch/x86/Kconfig:2162:config HOTPLUG_CPU\narch/x86/Kconfig-2163-\tdef_bool y\n--\narch/xtensa/Kconfig=253=config NR_CPUS\n--\narch/xtensa/Kconfig-258-\narch/xtensa/Kconfig:259:config HOTPLUG_CPU\narch/xtensa/Kconfig-260-\tbool \"Enable CPU hotplug support\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 9013
							output: 144
							thoughts: 403
						

**My Analysis of the x86 CPU Identification Patch**

Okay, so `HOTPLUG_CPU` is *always* enabled on x86 – duh, `def_bool y`. No need to even think about adding it to any configuration list. That's straightforward.

Now, let's see, what else does this patch touch? `check_null_seg_clears_base` is untouched, good. `identify_boot_cpu` is `__init`, as is `early_identify_cpu`.  `init_cpu_info` and `identify_cpu` are both static. That leaves us with `identify_secondary_cpu`, which seems to be the only function potentially affected.

Alright, let's take a closer look at the actual code changes. *Clickity-click, scrolling...* Ah, it looks like a refactoring. The old `generic_identify` function is gone, replaced with `identify_cpu`. The comment suggests this is where the *real* CPU identification logic resides. There's some changes within the `identify_cpu` function itself. It's initializing `c->loops_per_jiffy` now, and the previous check for CPUID is now done via a call to `cpuid_feature()`.

Hmm, is this worth fuzzing? Yes, this definitely warrants fuzzing! This modifies core x86 CPU identification logic! It's *reachable* during CPU hotplug, and any changes in this area could be problematic. Refactoring, however minor it seems, is an opportunity to introduce subtle bugs. We could have uninitialized fields, incorrect CPU feature detection, or something just plain broken, which might manifest as a crash later. Let's get this into the fuzzing pipeline, stat! Okay, I need to call `set-results` now.

{
  "EnableConfigs": [],
  "FocusSymbols": [
    "identify_secondary_cpu"
  ],
  "Reasoning": "The patch refactors x86 CPU identification logic, moving initialization into a new `init_cpu_info` function and merging `generic_identify` into `identify_cpu`. These changes affect how CPU features and capabilities are detected and initialized. While much of this runs during early boot, `identify_secondary_cpu` is executed when secondary CPUs are brought online, which can be triggered via CPU hotplug operations. Fuzzing CPU hotplug could reveal uninitialized fields or incorrect feature detection introduced by this refactoring.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": null,
  "FocusSymbols": [
    "identify_secondary_cpu"
  ],
  "Reasoning": "The patch refactors x86 CPU identification logic, moving initialization into a new `init_cpu_info` function and merging `generic_identify` into `identify_cpu`. These changes affect how CPU features and capabilities are detected and initialized. While much of this runs during early boot, `identify_secondary_cpu` is executed when secondary CPUs are brought online, which can be triggered via CPU hotplug operations. Fuzzing CPU hotplug could reveal uninitialized fields or incorrect feature detection introduced by this refactoring.",
  "WorthFuzzing": true
}

{
  "WorthFuzzing": true
}

null

best-expensive

null

{
  "KMSANReasoning": "The patch refactors CPU identification logic in x86 by consolidating the initialization of `struct cpuinfo_x86` fields into a new `init_cpu_info()` function. It does not introduce any new data structures that are copied to user space, nor does it alter bounds checking or introduce complex allocations that could leak uninitialized memory. The changes are purely internal to CPU boot and hotplug initialization. Any potential memory corruption or out-of-bounds accesses introduced by this refactoring would be caught by standard KASAN. Therefore, a dedicated KMSAN session is not necessary.",
  "NeedsKMSAN": false
}

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

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

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

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

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

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

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


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

For your convenience, here is the diff of the changes:
commit a8d94556a3a7ca87af339a24894c35cea207dd5e
Author: syz-cluster <triage@syzkaller.com>
Date:   Sat Aug 15 00:00:55 2026 +0000

    syz-cluster: applied patch under review

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index a3df21d264606..e0c70a2510afc 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1772,25 +1772,50 @@ static void __init cpu_parse_early_param(void)
 	}
 }
 
+static void init_cpu_info(struct cpuinfo_x86 *c)
+{
+	c->x86_cache_size = 0;
+	c->x86_vendor = X86_VENDOR_UNKNOWN;
+	c->x86_model = c->x86_stepping = 0;	/* So far unknown... */
+	c->x86_vendor_id[0] = '\0'; /* Unset */
+	c->x86_model_id[0] = '\0';  /* Unset */
+#ifdef CONFIG_X86_64
+	c->x86_clflush_size = 64;
+	c->x86_phys_bits = 36;
+	c->x86_virt_bits = 48;
+#else
+	c->cpuid_level = -1;	/* CPUID not detected */
+	c->x86_clflush_size = 32;
+	c->x86_phys_bits = 32;
+	c->x86_virt_bits = 32;
+#endif
+	c->x86_cache_alignment = c->x86_clflush_size;
+	memset(&c->x86_capability, 0, sizeof(c->x86_capability));
+	memset(&c->cpuid, 0, sizeof(c->cpuid));
+#ifdef CONFIG_X86_VMX_FEATURE_NAMES
+	memset(&c->vmx_capability, 0, sizeof(c->vmx_capability));
+#endif
+	c->extended_cpuid_level = 0;
+}
+
 /*
  * Do minimum CPU detection early.
  * Fields really needed: vendor, cpuid_level, family, model, mask,
  * cache alignment.
- * The others are not touched to avoid unwanted side effects.
+ * The others are reset to their defaults here and only filled in later,
+ * by identify_cpu().
  *
  * WARNING: this function is only called on the boot CPU.  Don't add code
  * here that is supposed to run on all CPUs.
  */
 static void __init early_identify_cpu(struct cpuinfo_x86 *c)
 {
-	memset(&c->x86_capability, 0, sizeof(c->x86_capability));
-	memset(&c->cpuid, 0, sizeof(c->cpuid));
-	c->extended_cpuid_level = 0;
+	init_cpu_info(c);
 
 	if (!cpuid_feature())
 		identify_cpu_without_cpuid(c);
 
-	/* cyrix could have cpuid enabled via c_identify()*/
+	/* Cyrix could have CPUID enabled via c_identify(). */
 	if (cpuid_feature()) {
 		cpuid_scan_cpu(c);
 		cpu_detect(c);
@@ -1954,16 +1979,21 @@ void check_null_seg_clears_base(struct cpuinfo_x86 *c)
 	set_cpu_bug(c, X86_BUG_NULL_SEG);
 }
 
-static void generic_identify(struct cpuinfo_x86 *c)
+/*
+ * This does the hard work of actually picking apart the CPU stuff...
+ */
+static void identify_cpu(struct cpuinfo_x86 *c)
 {
-	c->extended_cpuid_level = 0;
+	int i;
+
+	c->loops_per_jiffy = loops_per_jiffy;
 
 	if (!cpuid_feature())
 		identify_cpu_without_cpuid(c);
 
-	/* cyrix could have cpuid enabled via c_identify()*/
+	/* Cyrix could have CPUID enabled via c_identify(). */
 	if (!cpuid_feature())
-		return;
+		goto no_cpuid;
 
 	cpuid_scan_cpu(c);
 	cpu_detect(c);
@@ -1991,40 +2021,8 @@ static void generic_identify(struct cpuinfo_x86 *c)
 #ifdef CONFIG_X86_32
 	set_cpu_bug(c, X86_BUG_ESPFIX);
 #endif
-}
-
-/*
- * This does the hard work of actually picking apart the CPU stuff...
- */
-static void identify_cpu(struct cpuinfo_x86 *c)
-{
-	int i;
-
-	c->loops_per_jiffy = loops_per_jiffy;
-	c->x86_cache_size = 0;
-	c->x86_vendor = X86_VENDOR_UNKNOWN;
-	c->x86_model = c->x86_stepping = 0;	/* So far unknown... */
-	c->x86_vendor_id[0] = '\0'; /* Unset */
-	c->x86_model_id[0] = '\0';  /* Unset */
-#ifdef CONFIG_X86_64
-	c->x86_clflush_size = 64;
-	c->x86_phys_bits = 36;
-	c->x86_virt_bits = 48;
-#else
-	c->cpuid_level = -1;	/* CPUID not detected */
-	c->x86_clflush_size = 32;
-	c->x86_phys_bits = 32;
-	c->x86_virt_bits = 32;
-#endif
-	c->x86_cache_alignment = c->x86_clflush_size;
-	memset(&c->x86_capability, 0, sizeof(c->x86_capability));
-	memset(&c->cpuid, 0, sizeof(c->cpuid));
-#ifdef CONFIG_X86_VMX_FEATURE_NAMES
-	memset(&c->vmx_capability, 0, sizeof(c->vmx_capability));
-#endif
-
-	generic_identify(c);
 
+no_cpuid:
 	cpu_parse_topology(c);
 
 	if (this_cpu->c_identify)
@@ -2116,6 +2114,9 @@ static void identify_cpu(struct cpuinfo_x86 *c)
 	mcheck_cpu_init(c);
 
 	numa_add_cpu(smp_processor_id());
+
+	if (IS_ENABLED(CONFIG_X86_32))
+		enable_sep_cpu();
 }
 
 /*
@@ -2153,9 +2154,6 @@ static __init void identify_boot_cpu(void)
 	identify_cpu(&boot_cpu_data);
 	if (HAS_KERNEL_IBT && cpu_feature_enabled(X86_FEATURE_IBT))
 		pr_info("CET detected: Indirect Branch Tracking enabled\n");
-#ifdef CONFIG_X86_32
-	enable_sep_cpu();
-#endif
 	cpu_detect_tlb(&boot_cpu_data);
 	setup_cr_pinning();
 
@@ -2174,10 +2172,8 @@ void identify_secondary_cpu(unsigned int cpu)
 		*c = boot_cpu_data;
 	c->cpu_index = cpu;
 
+	init_cpu_info(c);
 	identify_cpu(c);
-#ifdef CONFIG_X86_32
-	enable_sep_cpu();
-#endif
 	x86_spec_ctrl_setup_ap();
 	update_srbds_msr();
 	if (boot_cpu_has_bug(X86_BUG_GDS))

gemini-3.1-pro-preview

null

null

							input: 3838
							output: 42
							thoughts: 690
						

**Analyzing the CPU Identification Refactor**

Okay, so this patch is touching `arch/x86/kernel/cpu/common.c`, specifically the CPU identification logic. My initial thought is to immediately assess potential uninitialized memory risks. The refactoring introduces a new function, `init_cpu_info(struct cpuinfo_x86 *c)`, which seems to be responsible for initializing the fields of the `struct cpuinfo_x86`. It's called in both `early_identify_cpu()` and `identify_secondary_cpu()`, and the old `generic_identify()` has been merged into `identify_cpu()`. Initialization logic has also been moved from `identify_cpu()` to `init_cpu_info()`.

My immediate reaction is that this actually *adds* initialization in `early_identify_cpu()` and `identify_secondary_cpu()`. Previously, `early_identify_cpu()` was doing only a `memset` on a few key areas (`x86_capability`, `cpuid`) and setting `extended_cpuid_level` to 0. Now, `init_cpu_info(c)` is called which does this and more. That’s a good sign, reduces the risk of some subtle, lurking issue.

But then, I need to understand how the secondary CPU identification logic works. In `identify_secondary_cpu()`, I see:

```c
	if (c == &boot_cpu_data)
		*c = boot_cpu_data;
	c->cpu_index = cpu;

	init_cpu_info(c);
	identify_cpu(c);
```

My initial thought was that it sets `*c = boot_cpu_data` if `c` is the boot CPU. But *c* is a pointer! I need to double-check that. Let's trace it back. Okay, the original code had:

```c
	if (c == &boot_cpu_data)
		*c = boot_cpu_data;
```

That can't be right; it would be a no-op! Ah, that's not right, let me check the original code again. The original code was:

```c
	if (c == &boot_cpu_data)
		return;
```

Okay, I need to see the actual diff. Let's look:

```c
@@ -2174,10 +2172,8 @@ void identify_secondary_cpu(unsigned int cpu)
 		*c = boot_cpu_data;
 	c->cpu_index = cpu;
 
+	init_cpu_info(c);
 	identify_cpu(c);
```

Okay, the context around that diff:

```c
 	if (c == &boot_cpu_data)
 		*c = boot_cpu_data;
 	c->cpu_index = cpu;
```

Ah, right! I need the full context from the file itself.

```c
void identify_secondary_cpu(unsigned int cpu)
{
	struct cpuinfo_x86 *c = &cpu_data(cpu);

	if (c == &boot_cpu_data)
		return; // wait, no, the diff says:
```

So, the original code returned if it was the boot CPU, while now `init_cpu_info(c)` is called. This is the difference, so no issue if `c == &boot_cpu_data` is true. Good. All in all, this looks like a good refactor. It's adding initialization, which reduces the chance of some obscure bug. Need to double-check some corner cases, but overall, seems solid.

{
  "File": "arch/x86/kernel/cpu/common.c",
  "FirstLine": 2165,
  "LineCount": 20
}

{
  "Contents": "2165:\t\n2166:\tvoid identify_secondary_cpu(unsigned int cpu)\n2167:\t{\n2168:\t\tstruct cpuinfo_x86 *c = \u0026cpu_data(cpu);\n2169:\t\n2170:\t\t/* Copy boot_cpu_data only on the first bringup */\n2171:\t\tif (!c-\u003einitialized)\n2172:\t\t\t*c = boot_cpu_data;\n2173:\t\tc-\u003ecpu_index = cpu;\n2174:\t\n2175:\t\tinit_cpu_info(c);\n2176:\t\tidentify_cpu(c);\n2177:\t\tx86_spec_ctrl_setup_ap();\n2178:\t\tupdate_srbds_msr();\n2179:\t\tif (boot_cpu_has_bug(X86_BUG_GDS))\n2180:\t\t\tupdate_gds_msr();\n2181:\t\n2182:\t\ttsx_ap_init();\n2183:\t\tc-\u003einitialized = true;\n2184:\t}\n"
}

gemini-3.1-pro-preview

null

null

							input: 5681
							output: 145
							thoughts: 301
						

**My Assessment of the CPU Identification Refactoring**

Okay, so I'm looking at this patch that's refactoring the CPU identification logic. Right, so `init_cpu_info(c)` is being called, which then sets the CPU information. This seems pretty straightforward, no new structures are being exposed to user space, which is good. The code itself, as I see it, sets the initial data in the boot of the CPU, it's not changing any bounds checks, nor is it introducing uninitialized memory risks. Essentially, the patch is just cleaning up the initialization process within `init_cpu_info()`. The changes are all internal to the CPU identification routines during boot and hotplug, which, from what I'm seeing, is a positive change.

Therefore, since the changes are internal, and it is a refactoring, there is no need for a dedicated KMSAN fuzzing session. KASAN and the usual standard detectors should be sufficient to catch anything.

Let me just double-check that there aren't any sneaky information leaks here. The `struct cpuinfo_x86` isn't directly copied to user space, which is great – it's exposed via `/proc/cpuinfo`, but that only prints specific fields, right? So, no uninitialized memory should be exposed, and there aren't any control flow hazards, as far as I can see.

So, here's the reasoning: the patch is about CPU identification refactoring and consolidation, with the initialization of `struct cpuinfo_x86` consolidated into `init_cpu_info()`. No new data structures are introduced that might leak information. No uninitialized fields are exposed, which removes any risk of memory leaks or use in control flow. Standard KASAN should be enough to take care of any potential memory corruption bugs that may exist here. It looks safe.

{
  "KMSANReasoning": "The patch refactors CPU identification logic in x86 by consolidating the initialization of `struct cpuinfo_x86` fields into a new `init_cpu_info()` function. It does not introduce any new data structures that are copied to user space, nor does it alter bounds checking or introduce complex allocations that could leak uninitialized memory. The changes are purely internal to CPU boot and hotplug initialization. Any potential memory corruption or out-of-bounds accesses introduced by this refactoring would be caught by standard KASAN. Therefore, a dedicated KMSAN session is not necessary.",
  "NeedsKMSAN": false
}

{
  "KMSANReasoning": "The patch refactors CPU identification logic in x86 by consolidating the initialization of `struct cpuinfo_x86` fields into a new `init_cpu_info()` function. It does not introduce any new data structures that are copied to user space, nor does it alter bounds checking or introduce complex allocations that could leak uninitialized memory. The changes are purely internal to CPU boot and hotplug initialization. Any potential memory corruption or out-of-bounds accesses introduced by this refactoring would be caught by standard KASAN. Therefore, a dedicated KMSAN session is not necessary.",
  "NeedsKMSAN": false
}