AI Trajectory

Trajectory: (Expand/Collapse All)
Seq	Timestamp	Type	Name	Duration
0/0	2026/09/10 22:52	flow	patch-triage	1m Args: null Results: { "EnableConfigs": null, "FocusSymbols": [], "KMSANReasoning": "", "NeedsKMSAN": false, "Reasoning": "The patch adds kernel support for the AMD RMPOPT (RMP optimization) instruction and updates SEV-SNP host initialization/teardown paths. All modified code paths require AMD SEV-SNP host support (CC_ATTR_HOST_SEV_SNP) and hardware-specific CPU/firmware capabilities (such as X86_FEATURE_RMPOPT and Segmented RMP). In standard virtualized fuzzing environments (QEMU/GCE), X86_FEATURE_HYPERVISOR is present which prevents CC_ATTR_HOST_SEV_SNP from being enabled (in bsp_determine_snp()), making all modified logic structurally unreachable without physical bare-metal AMD hardware supporting SEV-SNP and RMPOPT.", "WorthFuzzing": false }
1/1	2026/09/10 22:52	action	read-patch-diff	0m Args: null Results: { "PatchDiff": "commit 12847baf49b8f2b5c0546710fd6f5e27ff441bc2\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate: Thu Sep 10 22:52:52 2026 +0000\n\n syz-cluster: applied patch under review\n\ndiff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h\nindex f70ee74b5f921..3b5b32d3391b5 100644\n--- a/arch/x86/include/asm/cpufeatures.h\n+++ b/arch/x86/include/asm/cpufeatures.h\n@@ -76,7 +76,7 @@\n #define X86_FEATURE_K8\t\t\t( 332+ 4) / Opteron, Athlon64 /\n #define X86_FEATURE_ZEN5\t\t( 332+ 5) /* CPU based on Zen5 microarchitecture /\n #define X86_FEATURE_ZEN6\t\t( 332+ 6) /* CPU based on Zen6 microarchitecture /\n-/ Free ( 332+ 7) /\n+#define X86_FEATURE_RMPOPT\t\t( 332+ 7) / Support for AMD RMPOPT instruction /\n #define X86_FEATURE_CONSTANT_TSC\t( 332+ 8) /* \"constant_tsc\" TSC ticks at a constant rate /\n / free: was #define X86_FEATURE_UP\t( 332+ 9) \"up\" SMP kernel running on UP /\n #define X86_FEATURE_ART\t\t\t( 332+10) /* \"art\" Always running timer (ART) /\ndiff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h\nindex 3a8e51a0c9e88..1635e2e1c576a 100644\n--- a/arch/x86/include/asm/msr-index.h\n+++ b/arch/x86/include/asm/msr-index.h\n@@ -761,6 +761,9 @@\n #define MSR_AMD64_SEG_RMP_ENABLED_BIT\t0\n #define MSR_AMD64_SEG_RMP_ENABLED\tBIT_ULL(MSR_AMD64_SEG_RMP_ENABLED_BIT)\n #define MSR_AMD64_RMP_SEGMENT_SHIFT(x)\t(((x) \u0026 GENMASK_ULL(13, 8)) \u003e\u003e 8)\n+#define MSR_AMD64_RMPOPT_BASE\t\t0xc0010139\n+#define MSR_AMD64_RMPOPT_ENABLE_BIT\t0\n+#define MSR_AMD64_RMPOPT_ENABLE\t\tBIT_ULL(MSR_AMD64_RMPOPT_ENABLE_BIT)\n \n #define MSR_SVSM_CAA\t\t\t0xc001f000\n \ndiff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h\nindex 9e7a077c445dc..3235e171647dd 100644\n--- a/arch/x86/include/asm/sev.h\n+++ b/arch/x86/include/asm/sev.h\n@@ -662,6 +662,8 @@ static inline void snp_leak_pages(u64 pfn, unsigned int pages)\n \t__snp_leak_pages(pfn, pages, true);\n }\n int snp_prepare(void);\n+void snp_rmpopt_all_physmem(void);\n+void snp_setup_rmpopt(void);\n void snp_shutdown(void);\n #else\n static inline bool snp_probe_rmptable_info(void) { return false; }\n@@ -680,6 +682,8 @@ static inline void snp_leak_pages(u64 pfn, unsigned int npages) {}\n static inline void kdump_sev_callback(void) { }\n static inline void snp_fixup_e820_tables(void) {}\n static inline int snp_prepare(void) { return -ENODEV; }\n+static inline void snp_rmpopt_all_physmem(void) {}\n+static inline void snp_setup_rmpopt(void) {}\n static inline void snp_shutdown(void) {}\n #endif\n \ndiff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c\nindex 8665a6474806c..d1795ce219dab 100644\n--- a/arch/x86/kernel/cpu/scattered.c\n+++ b/arch/x86/kernel/cpu/scattered.c\n@@ -67,6 +67,7 @@ static const struct cpuid_bit cpuid_bits[] = {\n \t{ X86_FEATURE_PERFMON_V2,\t\tCPUID_EAX, 0, 0x80000022, 0 },\n \t{ X86_FEATURE_AMD_LBR_V2,\t\tCPUID_EAX, 1, 0x80000022, 0 },\n \t{ X86_FEATURE_AMD_LBR_PMC_FREEZE,\tCPUID_EAX, 2, 0x80000022, 0 },\n+\t{ X86_FEATURE_RMPOPT,\t\t\tCPUID_EDX, 0, 0x80000025, 0 },\n \t{ X86_FEATURE_AMD_HTR_CORES,\t\tCPUID_EAX, 30, 0x80000026, 0 },\n \t{ 0, 0, 0, 0, 0 }\n };\ndiff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c\nindex 5705723f1f412..d8e6b8a08b79f 100644\n--- a/arch/x86/kvm/svm/sev.c\n+++ b/arch/x86/kvm/svm/sev.c\n@@ -3032,6 +3032,8 @@ void sev_vm_destroy(struct kvm kvm)\n \t\t /\n \t\tif (snp_decommission_context(kvm))\n \t\t\treturn;\n+\n+\t\tsnp_rmpopt_all_physmem();\n \t} else {\n \t\tsev_unbind_asid(kvm, sev-\u003ehandle);\n \t}\ndiff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c\nindex cff285d8ad8e3..c16f826423903 100644\n--- a/arch/x86/virt/svm/sev.c\n+++ b/arch/x86/virt/svm/sev.c\n@@ -19,6 +19,7 @@\n #include \u003clinux/iommu.h\u003e\n #include \u003clinux/amd-iommu.h\u003e\n #include \u003clinux/nospec.h\u003e\n+#include \u003clinux/workqueue.h\u003e\n \n #include \u003casm/sev.h\u003e\n #include \u003casm/processor.h\u003e\n@@ -124,6 +125,17 @@ static void rmp_bookkeeping __ro_after_init;\n \n static u64 probed_rmp_base, probed_rmp_size;\n \n+static u64 rmpopt_pa_start, rmpopt_pa_end;\n+\n+enum rmpopt_op_type {\n+\tRMPOPT_OP_VERIFY_AND_REPORT_STATUS,\n+\tRMPOPT_OP_REPORT_STATUS\n+};\n+\n+static struct workqueue_struct rmpopt_wq;\n+static struct delayed_work rmpopt_delayed_work;\n+static DEFINE_MUTEX(rmpopt_wq_mutex);\n+\n static LIST_HEAD(snp_leaked_pages_list);\n static DEFINE_SPINLOCK(snp_leaked_pages_list_lock);\n \n@@ -513,7 +525,6 @@ static void clear_hsave_pa(void arg)\n \n int snp_prepare(void)\n {\n-\tint ret;\n \tu64 val;\n \n \t/\n@@ -526,14 +537,18 @@ int snp_prepare(void)\n \n \tclear_rmp();\n \n-\tcpus_read_lock();\n+\t/\n+\t * No CPU may come online without SnpEn while SNP is active; disable\n+\t * hotplug here and re-enable it in snp_shutdown().\n+\t /\n+\tcpu_hotplug_disable();\n \n \tif (!cpumask_equal(cpu_online_mask, cpu_present_mask)) {\n-\t\tret = -EOPNOTSUPP;\n+\t\tcpu_hotplug_enable();\n \t\tpr_warn(\"SNP init failed: not all CPUs online. (%pbl online \u003c-\u003e %pbl present masks).\\n\",\n \t\t\tcpumask_pr_args(cpu_online_mask),\n \t\t\tcpumask_pr_args(cpu_present_mask));\n-\t\tgoto unlock;\n+\t\treturn -EOPNOTSUPP;\n \t}\n \n \twbinvd_on_all_cpus();\n@@ -548,14 +563,17 @@ int snp_prepare(void)\n \t/ SNP_INIT requires MSR_VM_HSAVE_PA to be cleared on all CPUs. /\n \ton_each_cpu(clear_hsave_pa, NULL, 1);\n \n-\tret = 0;\n+\treturn 0;\n+}\n+EXPORT_SYMBOL_FOR_MODULES(snp_prepare, \"ccp\");\n \n-unlock:\n-\tcpus_read_unlock();\n+static void rmpopt_disable(void)\n+{\n+\tguard(mutex)(\u0026rmpopt_wq_mutex);\n \n-\treturn ret;\n+\tif (rmpopt_wq)\n+\t\tcancel_delayed_work_sync(\u0026rmpopt_delayed_work);\n }\n-EXPORT_SYMBOL_FOR_MODULES(snp_prepare, \"ccp\");\n \n void snp_shutdown(void)\n {\n@@ -565,11 +583,147 @@ void snp_shutdown(void)\n \tif (syscfg \u0026 MSR_AMD64_SYSCFG_SNP_EN)\n \t\treturn;\n \n+\trmpopt_disable();\n+\n \tclear_rmp();\n \ton_each_cpu(mfd_reconfigure, NULL, 1);\n+\n+\t/\n+\t * The firmware has disabled SNP (SnpEn is clear), so re-enable CPU\n+\t * hotplug. A legacy SNP shutdown returns above with SnpEn still set and\n+\t * leaves hotplug disabled.\n+\t /\n+\tcpu_hotplug_enable();\n }\n EXPORT_SYMBOL_FOR_MODULES(snp_shutdown, \"ccp\");\n \n+static bool rmpopt_capable(void)\n+{\n+\treturn cpu_feature_enabled(X86_FEATURE_RMPOPT) \u0026\u0026\n+\t cc_platform_has(CC_ATTR_HOST_SEV_SNP);\n+}\n+\n+/\n+ * RMPOPT optimizations skip RMP checks at 1GB granularity if this range of\n+ * memory does not contain any SNP guest memory.\n+ \n+ @pa is a system physical address; RMPOPT operates on the containing 1GB.\n+ /\n+static void rmpopt(u64 pa)\n+{\n+\tenum rmpopt_op_type op = RMPOPT_OP_VERIFY_AND_REPORT_STATUS;\n+\tu64 pa_start = ALIGN_DOWN(pa, SZ_1G);\n+\n+\t/ Supported by binutils 2.48+ /\n+\tasm volatile(\".byte 0xf2, 0x0f, 0x01, 0xfc\"\n+\t\t :: \"a\" (pa_start), \"c\" (op)\n+\t\t : \"memory\", \"cc\");\n+}\n+\n+/ on_each_cpu() callback: optimize the whole RMPOPT range on this CPU. /\n+static void rmpopt_scan_range(void arg)\n+{\n+\tu64 pa;\n+\n+\tfor (pa = rmpopt_pa_start; pa \u003c rmpopt_pa_end; pa += SZ_1G)\n+\t\trmpopt(pa);\n+}\n+\n+static void do_rmpopt_work(struct work_struct work)\n+{\n+\t/\n+\t * Warm up the RMPOPT cache on this pinned per-CPU worker with interrupts\n+\t * on, so the IRQ-disabled fan-out below only issues cache-hit RMPOPTs.\n+\t /\n+\trmpopt_scan_range(NULL);\n+\n+\ton_each_cpu_mask(cpu_primary_thread_mask, rmpopt_scan_range, NULL, true);\n+}\n+\n+/\n+ * Delay, in milliseconds, before the RMP re-optimization pass runs after an SNP\n+ * guest is torn down, passed as the delay to mod_delayed_work(). This coalesces\n+ * a burst of teardowns into a single scan and gives each guest's pages time to\n+ * be converted back to the shared, hypervisor-owned state. The 10 second value\n+ * is a heuristic trading re-optimization latency against scanning too eagerly.\n+ /\n+#define RMPOPT_WORK_TIMEOUT\t(10 MSEC_PER_SEC)\n+\n+/\n+ Perform RMP optimizations on memory freed by terminating guests. The scan\n+ * is deferred, so it normally runs after sev_gmem_invalidate() has converted\n+ * this guest's pages back to shared, and picks them up then. A very large\n+ * guest whose conversion has not finished by then is picked up by a later\n+ * teardown's scan.\n+ /\n+void snp_rmpopt_all_physmem(void)\n+{\n+\tif (!rmpopt_capable())\n+\t\treturn;\n+\n+\tguard(mutex)(\u0026rmpopt_wq_mutex);\n+\n+\tif (!rmpopt_wq)\n+\t\treturn;\n+\n+\tmod_delayed_work(rmpopt_wq, \u0026rmpopt_delayed_work,\n+\t\t\t msecs_to_jiffies(RMPOPT_WORK_TIMEOUT));\n+}\n+EXPORT_SYMBOL_FOR_MODULES(snp_rmpopt_all_physmem, \"kvm-amd\");\n+\n+void snp_setup_rmpopt(void)\n+{\n+\tu64 rmpopt_base;\n+\tint cpu;\n+\n+\tif (!rmpopt_capable())\n+\t\treturn;\n+\n+\tguard(mutex)(\u0026rmpopt_wq_mutex);\n+\n+\t/\n+\t * Set up once: the workqueue and RMPOPT_BASE MSRs are left in place on\n+\t * shutdown, so a later re-initialization just re-queues the optimization\n+\t * pass rather than redoing the setup.\n+\t /\n+\tif (rmpopt_wq) {\n+\t\tqueue_delayed_work(rmpopt_wq, \u0026rmpopt_delayed_work, 0);\n+\t\treturn;\n+\t}\n+\n+\t/\n+\t * Use a dedicated per-CPU workqueue so the potentially lengthy warm-up\n+\t * scan does not tie up a shared workqueue worker.\n+\t /\n+\trmpopt_wq = alloc_workqueue(\"rmpopt_wq\", WQ_PERCPU, 1);\n+\tif (!rmpopt_wq) {\n+\t\tpr_err(\"Failed to allocate RMPOPT workqueue\\n\");\n+\t\treturn;\n+\t}\n+\n+\tINIT_DELAYED_WORK(\u0026rmpopt_delayed_work, do_rmpopt_work);\n+\n+\trmpopt_pa_start = ALIGN_DOWN(PFN_PHYS(min_low_pfn), SZ_1G);\n+\trmpopt_base = rmpopt_pa_start \| MSR_AMD64_RMPOPT_ENABLE;\n+\n+\t/\n+\t * Per-CPU RMPOPT tables cover at most 2 TB. Program each core's\n+\t * RMPOPT_BASE with the start of RAM to optimize up to 2 TB.\n+\t /\n+\tfor_each_cpu(cpu, cpu_primary_thread_mask)\n+\t\twrmsrq_on_cpu(cpu, MSR_AMD64_RMPOPT_BASE, rmpopt_base);\n+\n+\trmpopt_pa_end = ALIGN(PFN_PHYS(max_pfn), SZ_1G);\n+\n+\tif ((rmpopt_pa_end - rmpopt_pa_start) \u003e SZ_2T)\n+\t\trmpopt_pa_end = rmpopt_pa_start + SZ_2T;\n+\n+\tqueue_delayed_work(rmpopt_wq, \u0026rmpopt_delayed_work, 0);\n+\n+\tpr_info(\"RMPOPT optimizations enabled\\n\");\n+}\n+EXPORT_SYMBOL_FOR_MODULES(snp_setup_rmpopt, \"ccp\");\n+\n /\n * Do the necessary preparations which are verified by the firmware as\n * described in the SNP_INIT_EX firmware command description in the SNP\n@@ -577,6 +731,8 @@ EXPORT_SYMBOL_FOR_MODULES(snp_shutdown, \"ccp\");\n /\n int __init snp_rmptable_init(void)\n {\n+\tu64 val;\n+\n \tif (WARN_ON_ONCE(!cc_platform_has(CC_ATTR_HOST_SEV_SNP)))\n \t\treturn -ENOSYS;\n \n@@ -586,6 +742,15 @@ int __init snp_rmptable_init(void)\n \tif (!setup_rmptable())\n \t\treturn -ENOSYS;\n \n+\t/\n+\t * On a kexec boot SNP may already be enabled (legacy firmware leaves\n+\t * SnpEn set across shutdown), in which case snp_prepare() bails without\n+\t * disabling CPU hotplug, so disable it here.\n+\t /\n+\trdmsrq(MSR_AMD64_SYSCFG, val);\n+\tif (val \u0026 MSR_AMD64_SYSCFG_SNP_EN)\n+\t\tcpu_hotplug_disable();\n+\n \t/\n \t * Setting crash_kexec_post_notifiers to 'true' to ensure that SNP panic\n \t * notifier is invoked to do SNP IOMMU shutdown before kdump.\n@@ -683,13 +848,21 @@ static bool probe_segmented_rmptable_info(void)\n \n bool snp_probe_rmptable_info(void)\n {\n-\tif (cpu_feature_enabled(X86_FEATURE_SEGMENTED_RMP))\n+\tif (cpu_feature_enabled(X86_FEATURE_SEGMENTED_RMP)) {\n \t\trdmsrq(MSR_AMD64_RMP_CFG, rmp_cfg);\n \n-\tif (rmp_cfg \u0026 MSR_AMD64_SEG_RMP_ENABLED)\n-\t\treturn probe_segmented_rmptable_info();\n-\telse\n-\t\treturn probe_contiguous_rmptable_info();\n+\t\tif (rmp_cfg \u0026 MSR_AMD64_SEG_RMP_ENABLED)\n+\t\t\treturn probe_segmented_rmptable_info();\n+\t}\n+\n+\t/\n+\t Segmented RMP is either not supported on the platform or is\n+\t * disabled by the firmware. RMPOPT is not supported without\n+\t * segmented RMP.\n+\t /\n+\tsetup_clear_cpu_cap(X86_FEATURE_RMPOPT);\n+\n+\treturn probe_contiguous_rmptable_info();\n }\n \n /\ndiff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c\nindex f833cb7e4da36..287a8345854ba 100644\n--- a/drivers/crypto/ccp/sev-dev.c\n+++ b/drivers/crypto/ccp/sev-dev.c\n@@ -1663,6 +1663,8 @@ static int __sev_snp_init_locked(int *error, unsigned int max_snp_asid)\n \n \tsev_es_tmr_size = SNP_TMR_SIZE;\n \n+\tsnp_setup_rmpopt();\n+\n \treturn 0;\n }\n \n" }
2/1	2026/09/10 22:52	agent	patch-evaluator	1m Model: core Args: null Results: { "EnableConfigs": null, "FocusSymbols": [], "Reasoning": "The patch adds kernel support for the AMD RMPOPT (RMP optimization) instruction and updates SEV-SNP host initialization/teardown paths. All modified code paths require AMD SEV-SNP host support (CC_ATTR_HOST_SEV_SNP) and hardware-specific CPU/firmware capabilities (such as X86_FEATURE_RMPOPT and Segmented RMP). In standard virtualized fuzzing environments (QEMU/GCE), X86_FEATURE_HYPERVISOR is present which prevents CC_ATTR_HOST_SEV_SNP from being enabled (in bsp_determine_snp()), making all modified logic structurally unreachable without physical bare-metal AMD hardware supporting SEV-SNP and RMPOPT.", "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 12847baf49b8f2b5c0546710fd6f5e27ff441bc2 Author: syz-cluster <triage@syzkaller.com> Date: Thu Sep 10 22:52:52 2026 +0000 syz-cluster: applied patch under review diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index f70ee74b5f921..3b5b32d3391b5 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -76,7 +76,7 @@ #define X86_FEATURE_K8 ( 332+ 4) / Opteron, Athlon64 / #define X86_FEATURE_ZEN5 ( 332+ 5) /* CPU based on Zen5 microarchitecture / #define X86_FEATURE_ZEN6 ( 332+ 6) /* CPU based on Zen6 microarchitecture / -/ Free ( 332+ 7) / +#define X86_FEATURE_RMPOPT ( 332+ 7) / Support for AMD RMPOPT instruction / #define X86_FEATURE_CONSTANT_TSC ( 332+ 8) /* "constant_tsc" TSC ticks at a constant rate / / free: was #define X86_FEATURE_UP ( 332+ 9) "up" SMP kernel running on UP / #define X86_FEATURE_ART ( 332+10) /* "art" Always running timer (ART) / diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h index 3a8e51a0c9e88..1635e2e1c576a 100644 --- a/arch/x86/include/asm/msr-index.h +++ b/arch/x86/include/asm/msr-index.h @@ -761,6 +761,9 @@ #define MSR_AMD64_SEG_RMP_ENABLED_BIT 0 #define MSR_AMD64_SEG_RMP_ENABLED BIT_ULL(MSR_AMD64_SEG_RMP_ENABLED_BIT) #define MSR_AMD64_RMP_SEGMENT_SHIFT(x) (((x) & GENMASK_ULL(13, 8)) >> 8) +#define MSR_AMD64_RMPOPT_BASE 0xc0010139 +#define MSR_AMD64_RMPOPT_ENABLE_BIT 0 +#define MSR_AMD64_RMPOPT_ENABLE BIT_ULL(MSR_AMD64_RMPOPT_ENABLE_BIT) #define MSR_SVSM_CAA 0xc001f000 diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index 9e7a077c445dc..3235e171647dd 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -662,6 +662,8 @@ static inline void snp_leak_pages(u64 pfn, unsigned int pages) __snp_leak_pages(pfn, pages, true); } int snp_prepare(void); +void snp_rmpopt_all_physmem(void); +void snp_setup_rmpopt(void); void snp_shutdown(void); #else static inline bool snp_probe_rmptable_info(void) { return false; } @@ -680,6 +682,8 @@ static inline void snp_leak_pages(u64 pfn, unsigned int npages) {} static inline void kdump_sev_callback(void) { } static inline void snp_fixup_e820_tables(void) {} static inline int snp_prepare(void) { return -ENODEV; } +static inline void snp_rmpopt_all_physmem(void) {} +static inline void snp_setup_rmpopt(void) {} static inline void snp_shutdown(void) {} #endif diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c index 8665a6474806c..d1795ce219dab 100644 --- a/arch/x86/kernel/cpu/scattered.c +++ b/arch/x86/kernel/cpu/scattered.c @@ -67,6 +67,7 @@ static const struct cpuid_bit cpuid_bits[] = { { X86_FEATURE_PERFMON_V2, CPUID_EAX, 0, 0x80000022, 0 }, { X86_FEATURE_AMD_LBR_V2, CPUID_EAX, 1, 0x80000022, 0 }, { X86_FEATURE_AMD_LBR_PMC_FREEZE, CPUID_EAX, 2, 0x80000022, 0 }, + { X86_FEATURE_RMPOPT, CPUID_EDX, 0, 0x80000025, 0 }, { X86_FEATURE_AMD_HTR_CORES, CPUID_EAX, 30, 0x80000026, 0 }, { 0, 0, 0, 0, 0 } }; diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 5705723f1f412..d8e6b8a08b79f 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -3032,6 +3032,8 @@ void sev_vm_destroy(struct kvm kvm) / if (snp_decommission_context(kvm)) return; + + snp_rmpopt_all_physmem(); } else { sev_unbind_asid(kvm, sev->handle); } diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c index cff285d8ad8e3..c16f826423903 100644 --- a/arch/x86/virt/svm/sev.c +++ b/arch/x86/virt/svm/sev.c @@ -19,6 +19,7 @@ #include <linux/iommu.h> #include <linux/amd-iommu.h> #include <linux/nospec.h> +#include <linux/workqueue.h> #include <asm/sev.h> #include <asm/processor.h> @@ -124,6 +125,17 @@ static void rmp_bookkeeping __ro_after_init; static u64 probed_rmp_base, probed_rmp_size; +static u64 rmpopt_pa_start, rmpopt_pa_end; + +enum rmpopt_op_type { + RMPOPT_OP_VERIFY_AND_REPORT_STATUS, + RMPOPT_OP_REPORT_STATUS +}; + +static struct workqueue_struct rmpopt_wq; +static struct delayed_work rmpopt_delayed_work; +static DEFINE_MUTEX(rmpopt_wq_mutex); + static LIST_HEAD(snp_leaked_pages_list); static DEFINE_SPINLOCK(snp_leaked_pages_list_lock); @@ -513,7 +525,6 @@ static void clear_hsave_pa(void arg) int snp_prepare(void) { - int ret; u64 val; /* @@ -526,14 +537,18 @@ int snp_prepare(void) clear_rmp(); - cpus_read_lock(); + /* + * No CPU may come online without SnpEn while SNP is active; disable + * hotplug here and re-enable it in snp_shutdown(). + / + cpu_hotplug_disable(); if (!cpumask_equal(cpu_online_mask, cpu_present_mask)) { - ret = -EOPNOTSUPP; + cpu_hotplug_enable(); pr_warn("SNP init failed: not all CPUs online. (%pbl online <-> %pbl present masks).\n", cpumask_pr_args(cpu_online_mask), cpumask_pr_args(cpu_present_mask)); - goto unlock; + return -EOPNOTSUPP; } wbinvd_on_all_cpus(); @@ -548,14 +563,17 @@ int snp_prepare(void) / SNP_INIT requires MSR_VM_HSAVE_PA to be cleared on all CPUs. / on_each_cpu(clear_hsave_pa, NULL, 1); - ret = 0; + return 0; +} +EXPORT_SYMBOL_FOR_MODULES(snp_prepare, "ccp"); -unlock: - cpus_read_unlock(); +static void rmpopt_disable(void) +{ + guard(mutex)(&rmpopt_wq_mutex); - return ret; + if (rmpopt_wq) + cancel_delayed_work_sync(&rmpopt_delayed_work); } -EXPORT_SYMBOL_FOR_MODULES(snp_prepare, "ccp"); void snp_shutdown(void) { @@ -565,11 +583,147 @@ void snp_shutdown(void) if (syscfg & MSR_AMD64_SYSCFG_SNP_EN) return; + rmpopt_disable(); + clear_rmp(); on_each_cpu(mfd_reconfigure, NULL, 1); + + / + * The firmware has disabled SNP (SnpEn is clear), so re-enable CPU + * hotplug. A legacy SNP shutdown returns above with SnpEn still set and + * leaves hotplug disabled. + / + cpu_hotplug_enable(); } EXPORT_SYMBOL_FOR_MODULES(snp_shutdown, "ccp"); +static bool rmpopt_capable(void) +{ + return cpu_feature_enabled(X86_FEATURE_RMPOPT) && + cc_platform_has(CC_ATTR_HOST_SEV_SNP); +} + +/ + * RMPOPT optimizations skip RMP checks at 1GB granularity if this range of + * memory does not contain any SNP guest memory. + * + * @pa is a system physical address; RMPOPT operates on the containing 1GB. + / +static void rmpopt(u64 pa) +{ + enum rmpopt_op_type op = RMPOPT_OP_VERIFY_AND_REPORT_STATUS; + u64 pa_start = ALIGN_DOWN(pa, SZ_1G); + + / Supported by binutils 2.48+ / + asm volatile(".byte 0xf2, 0x0f, 0x01, 0xfc" + :: "a" (pa_start), "c" (op) + : "memory", "cc"); +} + +/ on_each_cpu() callback: optimize the whole RMPOPT range on this CPU. / +static void rmpopt_scan_range(void arg) +{ + u64 pa; + + for (pa = rmpopt_pa_start; pa < rmpopt_pa_end; pa += SZ_1G) + rmpopt(pa); +} + +static void do_rmpopt_work(struct work_struct work) +{ + / + * Warm up the RMPOPT cache on this pinned per-CPU worker with interrupts + * on, so the IRQ-disabled fan-out below only issues cache-hit RMPOPTs. + / + rmpopt_scan_range(NULL); + + on_each_cpu_mask(cpu_primary_thread_mask, rmpopt_scan_range, NULL, true); +} + +/ + * Delay, in milliseconds, before the RMP re-optimization pass runs after an SNP + * guest is torn down, passed as the delay to mod_delayed_work(). This coalesces + * a burst of teardowns into a single scan and gives each guest's pages time to + * be converted back to the shared, hypervisor-owned state. The 10 second value + * is a heuristic trading re-optimization latency against scanning too eagerly. + / +#define RMPOPT_WORK_TIMEOUT (10 MSEC_PER_SEC) + +/* + * Perform RMP optimizations on memory freed by terminating guests. The scan + * is deferred, so it normally runs after sev_gmem_invalidate() has converted + * this guest's pages back to shared, and picks them up then. A very large + * guest whose conversion has not finished by then is picked up by a later + * teardown's scan. + / +void snp_rmpopt_all_physmem(void) +{ + if (!rmpopt_capable()) + return; + + guard(mutex)(&rmpopt_wq_mutex); + + if (!rmpopt_wq) + return; + + mod_delayed_work(rmpopt_wq, &rmpopt_delayed_work, + msecs_to_jiffies(RMPOPT_WORK_TIMEOUT)); +} +EXPORT_SYMBOL_FOR_MODULES(snp_rmpopt_all_physmem, "kvm-amd"); + +void snp_setup_rmpopt(void) +{ + u64 rmpopt_base; + int cpu; + + if (!rmpopt_capable()) + return; + + guard(mutex)(&rmpopt_wq_mutex); + + / + * Set up once: the workqueue and RMPOPT_BASE MSRs are left in place on + * shutdown, so a later re-initialization just re-queues the optimization + * pass rather than redoing the setup. + / + if (rmpopt_wq) { + queue_delayed_work(rmpopt_wq, &rmpopt_delayed_work, 0); + return; + } + + / + * Use a dedicated per-CPU workqueue so the potentially lengthy warm-up + * scan does not tie up a shared workqueue worker. + / + rmpopt_wq = alloc_workqueue("rmpopt_wq", WQ_PERCPU, 1); + if (!rmpopt_wq) { + pr_err("Failed to allocate RMPOPT workqueue\n"); + return; + } + + INIT_DELAYED_WORK(&rmpopt_delayed_work, do_rmpopt_work); + + rmpopt_pa_start = ALIGN_DOWN(PFN_PHYS(min_low_pfn), SZ_1G); + rmpopt_base = rmpopt_pa_start \| MSR_AMD64_RMPOPT_ENABLE; + + / + * Per-CPU RMPOPT tables cover at most 2 TB. Program each core's + * RMPOPT_BASE with the start of RAM to optimize up to 2 TB. + / + for_each_cpu(cpu, cpu_primary_thread_mask) + wrmsrq_on_cpu(cpu, MSR_AMD64_RMPOPT_BASE, rmpopt_base); + + rmpopt_pa_end = ALIGN(PFN_PHYS(max_pfn), SZ_1G); + + if ((rmpopt_pa_end - rmpopt_pa_start) > SZ_2T) + rmpopt_pa_end = rmpopt_pa_start + SZ_2T; + + queue_delayed_work(rmpopt_wq, &rmpopt_delayed_work, 0); + + pr_info("RMPOPT optimizations enabled\n"); +} +EXPORT_SYMBOL_FOR_MODULES(snp_setup_rmpopt, "ccp"); + / * Do the necessary preparations which are verified by the firmware as * described in the SNP_INIT_EX firmware command description in the SNP @@ -577,6 +731,8 @@ EXPORT_SYMBOL_FOR_MODULES(snp_shutdown, "ccp"); / int __init snp_rmptable_init(void) { + u64 val; + if (WARN_ON_ONCE(!cc_platform_has(CC_ATTR_HOST_SEV_SNP))) return -ENOSYS; @@ -586,6 +742,15 @@ int __init snp_rmptable_init(void) if (!setup_rmptable()) return -ENOSYS; + / + * On a kexec boot SNP may already be enabled (legacy firmware leaves + * SnpEn set across shutdown), in which case snp_prepare() bails without + * disabling CPU hotplug, so disable it here. + / + rdmsrq(MSR_AMD64_SYSCFG, val); + if (val & MSR_AMD64_SYSCFG_SNP_EN) + cpu_hotplug_disable(); + / * Setting crash_kexec_post_notifiers to 'true' to ensure that SNP panic * notifier is invoked to do SNP IOMMU shutdown before kdump. @@ -683,13 +848,21 @@ static bool probe_segmented_rmptable_info(void) bool snp_probe_rmptable_info(void) { - if (cpu_feature_enabled(X86_FEATURE_SEGMENTED_RMP)) + if (cpu_feature_enabled(X86_FEATURE_SEGMENTED_RMP)) { rdmsrq(MSR_AMD64_RMP_CFG, rmp_cfg); - if (rmp_cfg & MSR_AMD64_SEG_RMP_ENABLED) - return probe_segmented_rmptable_info(); - else - return probe_contiguous_rmptable_info(); + if (rmp_cfg & MSR_AMD64_SEG_RMP_ENABLED) + return probe_segmented_rmptable_info(); + } + + /* + * Segmented RMP is either not supported on the platform or is + * disabled by the firmware. RMPOPT is not supported without + * segmented RMP. + / + setup_clear_cpu_cap(X86_FEATURE_RMPOPT); + + return probe_contiguous_rmptable_info(); } / diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c index f833cb7e4da36..287a8345854ba 100644 --- a/drivers/crypto/ccp/sev-dev.c +++ b/drivers/crypto/ccp/sev-dev.c @@ -1663,6 +1663,8 @@ static int __sev_snp_init_locked(int *error, unsigned int max_snp_asid) sev_es_tmr_size = SNP_TMR_SIZE; + snp_setup_rmpopt(); + return 0; }
3/2	2026/09/10 22:52	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 7803 output: 21 thoughts: 586 Thoughts: Assessing the Fuzzing Potential of This Patch Series Okay, so the question is whether this patch series is a good candidate for syzkaller fuzzing. Let's break it down and see. This looks like a fairly standard triage task, just a developer QA and triage of a patch series. First, let's dive into the code changes. It looks like we're dealing with the addition of RMPOPT support, which is related to AMD's secure memory encryption technology, SEV-SNP. Here's what jumps out: * Header Files: We're introducing new definitions and prototypes in `cpufeatures.h`, `msr-index.h`, and `sev.h`. This suggests some new functionality is being enabled or controlled. * CPU Feature Detection: Changes in `scattered.c` indicate the addition of a CPUID bit for RMPOPT. This is classic; we're checking for hardware support. * KVM Integration: The `kvm/svm/sev.c` files are where the action really seems to be. We've got `sev_vm_destroy()` calling `snp_rmpopt_all_physmem()`. There are also changes within `snp_prepare()` and `snp_shutdown()` involving hotplug disable/enable. There's a lot of function activity here: `rmpopt_capable()`, `rmpopt()`, `rmpopt_scan_range()`, etc. We're clearly setting up, enabling, and managing the RMPOPT feature within the KVM/SEV-SNP context. Also within `snp_rmptable_init()` there are changes to enable via SYSCFG and calls to `cpu_hotplug_disable()`. And finally, in `snp_probe_rmptable_info()` the `X86_FEATURE_RMPOPT` will be cleared if not segmented RMP. * Crypto Driver Involvement: The `ccp/sev-dev.c` file is calling `snp_setup_rmpopt()` within its initialization. This shows integration with the crypto layer, which is relevant as memory encryption is at the heart of the SEV-SNP. Now, I'm thinking about the execution flow. I need to understand the full picture here. I should do some `grep` work or use codesearch to see where CCP, SEV-SNP, and KVM SEV are configured and how they get executed in relation to these changes. Once I understand the context, I can make a more informed decision about fuzzing. Does this interact with userspace at all? Where are the entry points? Are there new syscalls, ioctls, or exposed interfaces? If it's all internal KVM stuff, then it might be harder to fuzz effectively. If there are new interfaces or user-facing parts, it's very promising for fuzzing.
4/2	2026/09/10 22:53	tool	grepper	0m Args: { "Expression": "snp_rmptable_init" } Results: { "Output": "arch/x86/include/asm/sev.h=650=bool snp_probe_rmptable_info(void);\narch/x86/include/asm/sev.h:651:int snp_rmptable_init(void);\narch/x86/include/asm/sev.h-652-int snp_lookup_rmpentry(u64 pfn, bool assigned, int level);\n--\narch/x86/include/asm/sev.h=669=static inline bool snp_probe_rmptable_info(void) { return false; }\narch/x86/include/asm/sev.h:670:static inline int snp_rmptable_init(void) { return -ENOSYS; }\narch/x86/include/asm/sev.h-671-static inline int snp_lookup_rmpentry(u64 pfn, bool assigned, int level) { return -ENODEV; }\n--\narch/x86/virt/svm/sev.c=725=EXPORT_SYMBOL_FOR_MODULES(snp_setup_rmpopt, \"ccp\");\n--\narch/x86/virt/svm/sev.c-731- /\narch/x86/virt/svm/sev.c:732:int __init snp_rmptable_init(void)\narch/x86/virt/svm/sev.c-733-{\n--\ndrivers/iommu/amd/init.c=3395=static __init void iommu_snp_enable(void)\n--\ndrivers/iommu/amd/init.c-3432-\t /\ndrivers/iommu/amd/init.c:3433:\tif (snp_rmptable_init()) {\ndrivers/iommu/amd/init.c-3434-\t\tpr_warn(\"SNP: RMP initialization failed, SNP cannot be supported.\\n\");\n" }
5/2	2026/09/10 22:53	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 9523 output: 24 thoughts: 428 Thoughts: My Assessment of SEV-SNP Host Support in Virtualized Fuzzing Okay, let's break this down. SEV-SNP host support, right? That means specific hardware, like Zen 3+ or Zen 5/6 with the RMPOPT instruction, AMD IOMMU, CCP hardware... and probably other things. But the critical question is, can I actually test this stuff in a fuzzing environment like QEMU or GCE? That's where things get interesting. First, I need to verify reachability of this stuff, considering the fuzzing environment I'm using. The core principle is that if the code's not reachable in the standard virtualized environments, I shouldn't bother fuzzing it. I'm thinking about those structurally unreachable hardware components – vendor-specific PCIe switches, SmartNICs, GPU drivers that rely on physical ASIC/PCIe cards. Things that QEMU doesn't emulate effectively. Also, those execution paths that I can't trigger in a virtualized setup - driver teardown callbacks that are executed only during physical PCI hot-unplug, or code specific to other architectures that are not relevant to my fuzzing target. So, the critical question is: is AMD SEV host support reachable in QEMU or GCE? That's what I need to figure out first. I need to figure out if KVM SEV or CCP or SEV guest vs SEV host matters here. I need to understand what `cc_platform_has(CC_ATTR_HOST_SEV_SNP)` and `X86_FEATURE_RMPOPT` truly require. Time to start digging into those criteria and check what the documentation and source code say about `CC_ATTR_HOST_SEV_SNP` requirements.
6/2	2026/09/10 22:53	tool	grepper	0m Args: { "Expression": "CC_ATTR_HOST_SEV_SNP" } Results: { "Output": "arch/x86/coco/core.c=70=static bool noinstr amd_cc_platform_has(enum cc_attr attr)\n--\narch/x86/coco/core.c-103-\narch/x86/coco/core.c:104:\tcase CC_ATTR_HOST_SEV_SNP:\narch/x86/coco/core.c-105-\t\treturn cc_flags.host_sev_snp;\n--\narch/x86/coco/core.c=170=static void amd_cc_platform_clear(enum cc_attr attr)\n--\narch/x86/coco/core.c-172-\tswitch (attr) {\narch/x86/coco/core.c:173:\tcase CC_ATTR_HOST_SEV_SNP:\narch/x86/coco/core.c-174-\t\tcc_flags.host_sev_snp = 0;\n--\narch/x86/coco/core.c=192=static void amd_cc_platform_set(enum cc_attr attr)\n--\narch/x86/coco/core.c-194-\tswitch (attr) {\narch/x86/coco/core.c:195:\tcase CC_ATTR_HOST_SEV_SNP:\narch/x86/coco/core.c-196-\t\tcc_flags.host_sev_snp = 1;\n--\narch/x86/kernel/cpu/amd.c=356=static void bsp_determine_snp(struct cpuinfo_x86 c)\n--\narch/x86/kernel/cpu/amd.c-373-\t\t snp_probe_rmptable_info()) {\narch/x86/kernel/cpu/amd.c:374:\t\t\tcc_platform_set(CC_ATTR_HOST_SEV_SNP);\narch/x86/kernel/cpu/amd.c-375-\t\t} else {\narch/x86/kernel/cpu/amd.c-376-\t\t\tsetup_clear_cpu_cap(X86_FEATURE_SEV_SNP);\narch/x86/kernel/cpu/amd.c:377:\t\t\tcc_platform_clear(CC_ATTR_HOST_SEV_SNP);\narch/x86/kernel/cpu/amd.c-378-\t\t}\n--\narch/x86/kernel/cpu/mtrr/generic.c=104=static inline void k8_check_syscfg_dram_mod_en(void)\n--\narch/x86/kernel/cpu/mtrr/generic.c-111-\narch/x86/kernel/cpu/mtrr/generic.c:112:\tif (cc_platform_has(CC_ATTR_HOST_SEV_SNP))\narch/x86/kernel/cpu/mtrr/generic.c-113-\t\treturn;\n--\narch/x86/kvm/svm/avic.c=1257=static bool __init avic_want_avic_enabled(void)\n--\narch/x86/kvm/svm/avic.c-1280-\narch/x86/kvm/svm/avic.c:1281:\tif (cc_platform_has(CC_ATTR_HOST_SEV_SNP) \u0026\u0026\narch/x86/kvm/svm/avic.c-1282-\t !boot_cpu_has(X86_FEATURE_HV_INUSE_WR_ALLOWED)) {\n--\narch/x86/kvm/svm/sev.c=1259=static void sev_dbg_crypt_slow_alloc(struct page page, unsigned long __va,\n--\narch/x86/kvm/svm/sev.c-1293-\t /\narch/x86/kvm/svm/sev.c:1294:\tif (cc_platform_has(CC_ATTR_HOST_SEV_SNP))\narch/x86/kvm/svm/sev.c-1295-\t\treturn (void )__get_free_page(GFP_KERNEL);\n--\narch/x86/kvm/svm/sev.c=1300=static void sev_dbg_crypt_slow_free(void buf)\narch/x86/kvm/svm/sev.c-1301-{\narch/x86/kvm/svm/sev.c:1302:\tif (cc_platform_has(CC_ATTR_HOST_SEV_SNP))\narch/x86/kvm/svm/sev.c-1303-\t\tfree_page((unsigned long)buf);\n--\narch/x86/kvm/svm/sev.c=3088=void __init sev_hardware_setup(void)\n--\narch/x86/kvm/svm/sev.c-3192-\tsev_es_supported = true;\narch/x86/kvm/svm/sev.c:3193:\tsev_snp_supported = sev_snp_enabled \u0026\u0026 cc_platform_has(CC_ATTR_HOST_SEV_SNP);\narch/x86/kvm/svm/sev.c-3194-\n--\narch/x86/kvm/svm/sev.c=4987=struct page snp_safe_alloc_page_node(int node, gfp_t gfp)\n--\narch/x86/kvm/svm/sev.c-4991-\narch/x86/kvm/svm/sev.c:4992:\tif (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))\narch/x86/kvm/svm/sev.c-4993-\t\treturn alloc_pages_node(node, gfp \| __GFP_ZERO, 0);\n--\narch/x86/kvm/svm/sev.c=5205=void sev_gmem_make_shared(kvm_pfn_t pfn, kvm_pfn_t nr_pages)\n--\narch/x86/kvm/svm/sev.c-5208-\narch/x86/kvm/svm/sev.c:5209:\tif (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))\narch/x86/kvm/svm/sev.c-5210-\t\treturn;\n--\narch/x86/mm/mem_encrypt.c=102=void __init mem_encrypt_setup_arch(void)\n--\narch/x86/mm/mem_encrypt.c-110-\t /\narch/x86/mm/mem_encrypt.c:111:\tif (cc_platform_has(CC_ATTR_HOST_SEV_SNP))\narch/x86/mm/mem_encrypt.c-112-\t\tsnp_fixup_e820_tables();\n--\narch/x86/virt/svm/cmdline.c=19=static int __init init_sev_config(char str)\n--\narch/x86/virt/svm/cmdline.c-31-\t\t\t\tsetup_clear_cpu_cap(X86_FEATURE_SEV_SNP);\narch/x86/virt/svm/cmdline.c:32:\t\t\t\tcc_platform_clear(CC_ATTR_HOST_SEV_SNP);\narch/x86/virt/svm/cmdline.c-33-\t\t\t\tcontinue;\n--\narch/x86/virt/svm/sev.c=147=static void mfd_reconfigure(void arg)\narch/x86/virt/svm/sev.c-148-{\narch/x86/virt/svm/sev.c:149:\tif (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))\narch/x86/virt/svm/sev.c-150-\t\treturn;\n--\narch/x86/virt/svm/sev.c=158=static void snp_enable(void arg)\n--\narch/x86/virt/svm/sev.c-161-\narch/x86/virt/svm/sev.c:162:\tif (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))\narch/x86/virt/svm/sev.c-163-\t\treturn;\n--\narch/x86/virt/svm/sev.c=260=static void clear_rmp(void)\n--\narch/x86/virt/svm/sev.c-264-\narch/x86/virt/svm/sev.c:265:\tif (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))\narch/x86/virt/svm/sev.c-266-\t\treturn;\n--\narch/x86/virt/svm/sev.c=600=static bool rmpopt_capable(void)\n--\narch/x86/virt/svm/sev.c-602-\treturn cpu_feature_enabled(X86_FEATURE_RMPOPT) \u0026\u0026\narch/x86/virt/svm/sev.c:603:\t cc_platform_has(CC_ATTR_HOST_SEV_SNP);\narch/x86/virt/svm/sev.c-604-}\n--\narch/x86/virt/svm/sev.c=732=int __init snp_rmptable_init(void)\n--\narch/x86/virt/svm/sev.c-735-\narch/x86/virt/svm/sev.c:736:\tif (WARN_ON_ONCE(!cc_platform_has(CC_ATTR_HOST_SEV_SNP)))\narch/x86/virt/svm/sev.c-737-\t\treturn -ENOSYS;\n--\narch/x86/virt/svm/sev.c=941=static int __snp_lookup_rmpentry(u64 pfn, struct rmpentry e, int level)\n--\narch/x86/virt/svm/sev.c-945-\narch/x86/virt/svm/sev.c:946:\tif (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))\narch/x86/virt/svm/sev.c-947-\t\treturn -ENODEV;\n--\narch/x86/virt/svm/sev.c=1067=int psmash(u64 pfn)\n--\narch/x86/virt/svm/sev.c-1071-\narch/x86/virt/svm/sev.c:1072:\tif (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))\narch/x86/virt/svm/sev.c-1073-\t\treturn -ENODEV;\n--\narch/x86/virt/svm/sev.c=1176=static int rmpupdate(u64 pfn, struct rmp_state state)\n--\narch/x86/virt/svm/sev.c-1180-\narch/x86/virt/svm/sev.c:1181:\tif (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))\narch/x86/virt/svm/sev.c-1182-\t\treturn -ENODEV;\n--\narch/x86/virt/svm/sev.c=1269=void kdump_sev_callback(void)\n--\narch/x86/virt/svm/sev.c-1274-\t /\narch/x86/virt/svm/sev.c:1275:\tif (cc_platform_has(CC_ATTR_HOST_SEV_SNP))\narch/x86/virt/svm/sev.c-1276-\t\twbinvd();\n--\ndrivers/crypto/ccp/sev-dev.c=1508=static int __sev_snp_init_locked(int error, unsigned int max_snp_asid)\n--\ndrivers/crypto/ccp/sev-dev.c-1516-\ndrivers/crypto/ccp/sev-dev.c:1517:\tif (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))\ndrivers/crypto/ccp/sev-dev.c-1518-\t\treturn -ENODEV;\n--\ndrivers/crypto/ccp/sev-dev.c=2067=static int sev_get_api_version(void)\n--\ndrivers/crypto/ccp/sev-dev.c-2076-\t /\ndrivers/crypto/ccp/sev-dev.c:2077:\tif (cc_platform_has(CC_ATTR_HOST_SEV_SNP)) {\ndrivers/crypto/ccp/sev-dev.c-2078-\t\tret = snp_get_platform_data(sev, \u0026error);\n--\ndrivers/crypto/ccp/sev-dev.c=2977=u64 sev_get_snp_policy_bits(void)\n--\ndrivers/crypto/ccp/sev-dev.c-2982-\ndrivers/crypto/ccp/sev-dev.c:2983:\tif (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))\ndrivers/crypto/ccp/sev-dev.c-2984-\t\treturn 0;\n--\ndrivers/iommu/amd/init.c=3395=static __init void iommu_snp_enable(void)\n--\ndrivers/iommu/amd/init.c-3397-#ifdef CONFIG_KVM_AMD_SEV\ndrivers/iommu/amd/init.c:3398:\tif (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))\ndrivers/iommu/amd/init.c-3399-\t\treturn;\n--\ndrivers/iommu/amd/init.c-3441-disable_snp:\ndrivers/iommu/amd/init.c:3442:\tcc_platform_clear(CC_ATTR_HOST_SEV_SNP);\ndrivers/iommu/amd/init.c-3443-#endif\n--\ndrivers/iommu/amd/init.c=3567=static int __init iommu_go_to_state(enum iommu_init_state state)\n--\ndrivers/iommu/amd/init.c-3587-\t /\ndrivers/iommu/amd/init.c:3588:\tif (ret \u0026\u0026 cc_platform_has(CC_ATTR_HOST_SEV_SNP) \u0026\u0026\ndrivers/iommu/amd/init.c-3589-\t !WARN_ON_ONCE(amd_iommu_snp_en))\ndrivers/iommu/amd/init.c:3590:\t\tcc_platform_clear(CC_ATTR_HOST_SEV_SNP);\ndrivers/iommu/amd/init.c-3591-\n--\ndrivers/iommu/amd/init.c=3694=void __init amd_iommu_detect(void)\n--\ndrivers/iommu/amd/init.c-3713-disable_snp:\ndrivers/iommu/amd/init.c:3714:\tif (cc_platform_has(CC_ATTR_HOST_SEV_SNP))\ndrivers/iommu/amd/init.c:3715:\t\tcc_platform_clear(CC_ATTR_HOST_SEV_SNP);\ndrivers/iommu/amd/init.c-3716-}\n--\ninclude/linux/cc_platform.h=22=enum cc_attr {\n--\ninclude/linux/cc_platform.h-92-\t/*\ninclude/linux/cc_platform.h:93:\t @CC_ATTR_HOST_SEV_SNP: AMD SNP enabled on the host.\ninclude/linux/cc_platform.h-94-\t \n--\ninclude/linux/cc_platform.h-97-\t /\ninclude/linux/cc_platform.h:98:\tCC_ATTR_HOST_SEV_SNP,\ninclude/linux/cc_platform.h-99-\n" }
7/2	2026/09/10 22:53	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 14397 output: 41 thoughts: 28 Thoughts: Here's my take on the thought process, as if it were my own: Investigating a Suspected SNP Behavior Okay, so I suspect something's up with how we're handling SNPs, and it's probably related to the AMD architecture. The first thing I'm going to do is zero in on the `bsp_determine_snp` function. It's almost always a key point when dealing with this kind of behavior, and specifically, I'm pretty sure it resides in the `arch/x86/kernel/cpu/amd.c` file. This is the logical place to start digging because that AMD-specific file is the right level of abstraction for investigating CPU-specific idiosyncracies. I'm going to jump straight in and take a close look at that function.
8/2	2026/09/10 22:53	tool	read-file	0m Args: { "File": "arch/x86/kernel/cpu/amd.c", "FirstLine": 355, "LineCount": 35 } Results: { "Contents": " 355:\t\n 356:\tstatic void bsp_determine_snp(struct cpuinfo_x86 c)\n 357:\t{\n 358:\t#ifdef CONFIG_ARCH_HAS_CC_PLATFORM\n 359:\t\tcc_vendor = CC_VENDOR_AMD;\n 360:\t\n 361:\t\tif (cpu_has(c, X86_FEATURE_SEV_SNP)) {\n 362:\t\t\t/\n 363:\t\t\t * RMP table entry format is not architectural and is defined by the\n 364:\t\t\t * per-processor PPR. Restrict SNP support on the known CPU models\n 365:\t\t\t * for which the RMP table entry format is currently defined or for\n 366:\t\t\t * processors which support the architecturally defined RMPREAD\n 367:\t\t\t * instruction.\n 368:\t\t\t */\n 369:\t\t\tif (!cpu_has(c, X86_FEATURE_HYPERVISOR) \u0026\u0026\n 370:\t\t\t (cpu_feature_enabled(X86_FEATURE_ZEN3) \|\|\n 371:\t\t\t cpu_feature_enabled(X86_FEATURE_ZEN4) \|\|\n 372:\t\t\t cpu_feature_enabled(X86_FEATURE_RMPREAD)) \u0026\u0026\n 373:\t\t\t snp_probe_rmptable_info()) {\n 374:\t\t\t\tcc_platform_set(CC_ATTR_HOST_SEV_SNP);\n 375:\t\t\t} else {\n 376:\t\t\t\tsetup_clear_cpu_cap(X86_FEATURE_SEV_SNP);\n 377:\t\t\t\tcc_platform_clear(CC_ATTR_HOST_SEV_SNP);\n 378:\t\t\t}\n 379:\t\t}\n 380:\t#endif\n 381:\t}\n 382:\t\n 383:\t#define ZEN_MODEL_STEP_UCODE(fam, model, step, ucode) \\\n 384:\t\tX86_MATCH_VFM_STEPS(VFM_MAKE(X86_VENDOR_AMD, fam, model), \\\n 385:\t\t\t\t step, step, ucode)\n 386:\t\n 387:\tstatic const struct x86_cpu_id amd_tsa_microcode[] = {\n 388:\t\tZEN_MODEL_STEP_UCODE(0x19, 0x01, 0x1, 0x0a0011d7),\n 389:\t\tZEN_MODEL_STEP_UCODE(0x19, 0x01, 0x2, 0x0a00123b),\n" }
9/2	2026/09/10 22:53	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 15316 output: 23 thoughts: 771 Thoughts: Analyzing SEV-SNP Initialization and RMPOPT Capabilities Alright, let's break this down. I'm looking at lines 369-370 in `arch/x86/kernel/cpu/amd.c` and immediately see a potential issue: the check `if (!cpu_has(c, X86_FEATURE_HYPERVISOR) ...)`! My mind immediately goes to the implications for running under a hypervisor like QEMU or GCE. Because if a hypervisor is present, `cpu_has(c, X86_FEATURE_HYPERVISOR)` is going to evaluate to `true`, and that means `CC_ATTR_HOST_SEV_SNP` will never be set. That's a huge problem. This tells me that setting up the `CC_ATTR_HOST_SEV_SNP` attribute, and by extension SEV-SNP support, is fundamentally tied to bare-metal AMD Zen3+ / Zen5+ hardware with SEV-SNP enabled in the BIOS/hardware. And RMPOPT seems to be a new instruction, which is for Zen6 or future CPUs. I need to circle back to what `rmpopt()` is actually doing. Okay, it's using an inline assembly instruction: `.byte 0xf2, 0x0f, 0x01, 0xfc`. That's important to keep in mind. Now, checking `rmpopt_capable()`. It requires both `cpu_feature_enabled(X86_FEATURE_RMPOPT)` and `cc_platform_has(CC_ATTR_HOST_SEV_SNP)`. If `!rmpopt_capable()`, then `snp_rmpopt_all_physmem()` and `snp_setup_rmpopt()` immediately return. This is where I start to put the pieces together. And I see that `snp_rmptable_init()` immediately returns -ENOSYS if `!cc_platform_has(CC_ATTR_HOST_SEV_SNP)`. The code won't even continue. Similarly, `snp_prepare()` is only called by the CCP driver when a SNP host is initializing via `__sev_snp_init_locked()`, and that function also checks `if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))`, returning -ENODEV if false. And `snp_shutdown()` is similarly only called via CCP during an SNP host shutdown. This is all making it clear - `snp_probe_rmptable_info()` is only called from `bsp_determine_snp()`. And that only happens at boot time on AMD BSP when `cpu_has(c, X86_FEATURE_SEV_SNP)` is true and also `!cpu_has(c, X86_FEATURE_HYPERVISOR)`. Got it. Now I should check where `snp_probe_rmptable_info()` is called. This is crucial for understanding the overall flow and potential entry points.
10/2	2026/09/10 22:53	tool	grepper	0m Args: { "Expression": "snp_probe_rmptable_info" } Results: { "Output": "arch/x86/include/asm/sev.h=645=static inline u64 savic_ghcb_msr_read(u32 reg) { return 0; }\n--\narch/x86/include/asm/sev.h-649-#ifdef CONFIG_KVM_AMD_SEV\narch/x86/include/asm/sev.h:650:bool snp_probe_rmptable_info(void);\narch/x86/include/asm/sev.h-651-int snp_rmptable_init(void);\n--\narch/x86/include/asm/sev.h=667=void snp_shutdown(void);\narch/x86/include/asm/sev.h-668-#else\narch/x86/include/asm/sev.h:669:static inline bool snp_probe_rmptable_info(void) { return false; }\narch/x86/include/asm/sev.h-670-static inline int snp_rmptable_init(void) { return -ENOSYS; }\n--\narch/x86/kernel/cpu/amd.c=356=static void bsp_determine_snp(struct cpuinfo_x86 *c)\n--\narch/x86/kernel/cpu/amd.c-372-\t\t cpu_feature_enabled(X86_FEATURE_RMPREAD)) \u0026\u0026\narch/x86/kernel/cpu/amd.c:373:\t\t snp_probe_rmptable_info()) {\narch/x86/kernel/cpu/amd.c-374-\t\t\tcc_platform_set(CC_ATTR_HOST_SEV_SNP);\n--\narch/x86/virt/svm/sev.c=805=static bool probe_segmented_rmptable_info(void)\n--\narch/x86/virt/svm/sev.c-848-\narch/x86/virt/svm/sev.c:849:bool snp_probe_rmptable_info(void)\narch/x86/virt/svm/sev.c-850-{\n" }
11/2	2026/09/10 22:53	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 17329 output: 19 thoughts: 241 Thoughts: My Analysis of `sev_vm_destroy()` and SEV-SNP Guest Handling Okay, let's dive into `sev_vm_destroy()` within `arch/x86/kvm/svm/sev.c`. I'm specifically looking at how this function handles the destruction of a KVM VM, particularly focusing on the Secure Encrypted Virtualization (SEV) and, more importantly, the SEV-SNP (Secure Nested Paging) aspects. Looking at the code snippet, if the VM is an SEV-SNP guest (checked by `sev_snp_guest(kvm)`), the function takes specific actions. It appears there might be a scenario where `sev_es_init_vm()` could fail after `snp_init_vm()`. If that happens, then we need to ensure that the context gets decommissioned via a call to `snp_decommission_context(kvm)`. If that call is successful, we bail out. Otherwise, it triggers `snp_rmpopt_all_physmem()`. If the VM isn't an SEV-SNP guest, the `sev_unbind_asid()` function gets called. This raises an interesting question: Can a guest VM emulate `sev_snp_guest(kvm)` and run as if it were an SEV-SNP guest under QEMU without actual physical AMD SEV-SNP hardware? I need to clarify that condition. I'll need to check the definition and implementation of `sev_snp_guest` to understand the conditions that trigger this conditional logic. Knowing this will clarify how it's handled in a purely virtualized environment versus one with true hardware support.
12/2	2026/09/10 22:53	tool	grepper	0m Args: { "Expression": "sev_snp_guest" } Results: { "Output": "arch/x86/kvm/svm/sev.c=140=static bool sev_es_guest(struct kvm kvm)\n--\narch/x86/kvm/svm/sev.c-145-\narch/x86/kvm/svm/sev.c:146:static bool sev_snp_guest(struct kvm kvm)\narch/x86/kvm/svm/sev.c-147-{\narch/x86/kvm/svm/sev.c-148-\tkvm_lockdep_assert_sev_lock_held(kvm);\narch/x86/kvm/svm/sev.c:149:\treturn ____sev_snp_guest(kvm);\narch/x86/kvm/svm/sev.c-150-}\n--\narch/x86/kvm/svm/sev.c=209=static bool snp_is_secure_tsc_enabled(struct kvm kvm)\n--\narch/x86/kvm/svm/sev.c-213-\treturn (sev-\u003evmsa_features \u0026 SVM_SEV_FEAT_SECURE_TSC) \u0026\u0026\narch/x86/kvm/svm/sev.c:214:\t !WARN_ON_ONCE(!sev_snp_guest(kvm));\narch/x86/kvm/svm/sev.c-215-}\n--\narch/x86/kvm/svm/sev.c=2136=int sev_vm_move_enc_context_from(struct kvm kvm, unsigned int source_fd)\n--\narch/x86/kvm/svm/sev.c-2157-\tif (kvm-\u003earch.vm_type != source_kvm-\u003earch.vm_type \|\|\narch/x86/kvm/svm/sev.c:2158:\t sev_guest(kvm) \|\| !sev_guest(source_kvm) \|\| sev_snp_guest(source_kvm)) {\narch/x86/kvm/svm/sev.c-2159-\t\tret = -EINVAL;\n--\narch/x86/kvm/svm/sev.c=2277=static int snp_launch_start(struct kvm kvm, struct kvm_sev_cmd argp)\n--\narch/x86/kvm/svm/sev.c-2283-\narch/x86/kvm/svm/sev.c:2284:\tif (!sev_snp_guest(kvm))\narch/x86/kvm/svm/sev.c-2285-\t\treturn -ENOTTY;\n--\narch/x86/kvm/svm/sev.c=2421=static int snp_launch_update(struct kvm kvm, struct kvm_sev_cmd argp)\n--\narch/x86/kvm/svm/sev.c-2429-\narch/x86/kvm/svm/sev.c:2430:\tif (!sev_snp_guest(kvm) \|\| !sev-\u003esnp_context)\narch/x86/kvm/svm/sev.c-2431-\t\treturn -EINVAL;\n--\narch/x86/kvm/svm/sev.c=2562=static int snp_launch_finish(struct kvm kvm, struct kvm_sev_cmd argp)\n--\narch/x86/kvm/svm/sev.c-2569-\narch/x86/kvm/svm/sev.c:2570:\tif (!sev_snp_guest(kvm))\narch/x86/kvm/svm/sev.c-2571-\t\treturn -ENOTTY;\n--\narch/x86/kvm/svm/sev.c=2638=static int snp_enable_certs(struct kvm kvm)\narch/x86/kvm/svm/sev.c-2639-{\narch/x86/kvm/svm/sev.c:2640:\tif (kvm-\u003ecreated_vcpus \|\| !sev_snp_guest(kvm))\narch/x86/kvm/svm/sev.c-2641-\t\treturn -EINVAL;\n--\narch/x86/kvm/svm/sev.c=2648=int sev_mem_enc_ioctl(struct kvm kvm, void __user argp)\n--\narch/x86/kvm/svm/sev.c-2672-\t /\narch/x86/kvm/svm/sev.c:2673:\tif (sev_snp_guest(kvm) \u0026\u0026 sev_cmd.id \u003c KVM_SEV_SNP_LAUNCH_START)\narch/x86/kvm/svm/sev.c-2674-\t\treturn -EPERM;\n--\narch/x86/kvm/svm/sev.c=2859=int sev_vm_copy_enc_context_from(struct kvm kvm, unsigned int source_fd)\n--\narch/x86/kvm/svm/sev.c-2883-\t /\narch/x86/kvm/svm/sev.c:2884:\tif (sev_guest(kvm) \|\| !sev_guest(source_kvm) \|\| sev_snp_guest(source_kvm) \|\|\narch/x86/kvm/svm/sev.c-2885-\t is_mirroring_enc_context(source_kvm) \|\| kvm-\u003ecreated_vcpus) {\n--\narch/x86/kvm/svm/sev.c=2977=void sev_vm_destroy(struct kvm kvm)\n--\narch/x86/kvm/svm/sev.c-3025-\narch/x86/kvm/svm/sev.c:3026:\tif (sev_snp_guest(kvm)) {\narch/x86/kvm/svm/sev.c-3027-\t\tsnp_guest_req_cleanup(kvm);\n--\narch/x86/kvm/svm/sev.c=3335=void sev_guest_memory_reclaimed(struct kvm kvm)\n--\narch/x86/kvm/svm/sev.c-3347-\t /\narch/x86/kvm/svm/sev.c:3348:\tif (!____sev_guest(kvm) \|\| ____sev_snp_guest(kvm))\narch/x86/kvm/svm/sev.c-3349-\t\treturn;\n--\narch/x86/kvm/svm/sev.c=3547=void sev_free_vcpu(struct kvm_vcpu vcpu)\n--\narch/x86/kvm/svm/sev.c-3560-\t /\narch/x86/kvm/svm/sev.c:3561:\tif (is_sev_snp_guest(vcpu)) {\narch/x86/kvm/svm/sev.c-3562-\t\tu64 pfn = __pa(svm-\u003esev_es.vmsa) \u003e\u003e PAGE_SHIFT;\n--\narch/x86/kvm/svm/sev.c=4220=static int snp_handle_guest_req(struct vcpu_svm svm, gpa_t req_gpa, gpa_t resp_gpa)\n--\narch/x86/kvm/svm/sev.c-4227-\narch/x86/kvm/svm/sev.c:4228:\tif (!is_sev_snp_guest(\u0026svm-\u003evcpu))\narch/x86/kvm/svm/sev.c-4229-\t\treturn -EINVAL;\n--\narch/x86/kvm/svm/sev.c=4289=static int snp_handle_ext_guest_req(struct vcpu_svm svm, gpa_t req_gpa, gpa_t resp_gpa)\n--\narch/x86/kvm/svm/sev.c-4295-\narch/x86/kvm/svm/sev.c:4296:\tif (!is_sev_snp_guest(vcpu))\narch/x86/kvm/svm/sev.c-4297-\t\treturn -EINVAL;\n--\narch/x86/kvm/svm/sev.c=4351=static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm svm)\n--\narch/x86/kvm/svm/sev.c-4430-\tcase GHCB_MSR_PREF_GPA_REQ:\narch/x86/kvm/svm/sev.c:4431:\t\tif (!is_sev_snp_guest(vcpu))\narch/x86/kvm/svm/sev.c-4432-\t\t\tgoto out_terminate;\n--\narch/x86/kvm/svm/sev.c-4441-\narch/x86/kvm/svm/sev.c:4442:\t\tif (!is_sev_snp_guest(vcpu))\narch/x86/kvm/svm/sev.c-4443-\t\t\tgoto out_terminate;\n--\narch/x86/kvm/svm/sev.c-4456-\tcase GHCB_MSR_PSC_REQ:\narch/x86/kvm/svm/sev.c:4457:\t\tif (!is_sev_snp_guest(vcpu))\narch/x86/kvm/svm/sev.c-4458-\t\t\tgoto out_terminate;\n--\narch/x86/kvm/svm/sev.c=4508=int sev_handle_vmgexit(struct kvm_vcpu vcpu)\n--\narch/x86/kvm/svm/sev.c-4541-\t/ SEV-SNP guest requires that the GHCB GPA must be registered /\narch/x86/kvm/svm/sev.c:4542:\tif (is_sev_snp_guest(vcpu) \u0026\u0026\narch/x86/kvm/svm/sev.c-4543-\t !ghcb_gpa_is_registered(svm, control-\u003eghcb_gpa)) {\n--\narch/x86/kvm/svm/sev.c-4557-\narch/x86/kvm/svm/sev.c:4558:\tif (is_snp_only_vmgexit(control-\u003eexit_code) \u0026\u0026 !is_sev_snp_guest(vcpu)) {\narch/x86/kvm/svm/sev.c-4559-\t\tvcpu_unimpl(vcpu, \"vmgexit: exit code %#llx is SNP-only\\n\",\n--\narch/x86/kvm/svm/sev.c=4844=void sev_init_vmcb(struct vcpu_svm svm, bool init_event)\n--\narch/x86/kvm/svm/sev.c-4856-\narch/x86/kvm/svm/sev.c:4857:\tif (init_event \u0026\u0026 is_sev_snp_guest(vcpu))\narch/x86/kvm/svm/sev.c-4858-\t\tsev_snp_init_protected_guest_state(vcpu);\n--\narch/x86/kvm/svm/sev.c=4891=void sev_es_prepare_switch_to_guest(struct vcpu_svm svm, struct sev_es_save_area hostsa)\n--\narch/x86/kvm/svm/sev.c-4931-\t (cpu_feature_enabled(X86_FEATURE_DEBUG_SWAP) \u0026\u0026\narch/x86/kvm/svm/sev.c:4932:\t is_sev_snp_guest(\u0026svm-\u003evcpu))) {\narch/x86/kvm/svm/sev.c-4933-\t\thostsa-\u003edr0_addr_mask = amd_get_dr_addr_mask(0);\n--\narch/x86/kvm/svm/sev.c=5155=int sev_gmem_make_private(struct kvm kvm, gfn_t gfn, kvm_pfn_t pfn, kvm_pfn_t nr_pages)\n--\narch/x86/kvm/svm/sev.c-5162-\narch/x86/kvm/svm/sev.c:5163:\tif (!sev_snp_guest(kvm))\narch/x86/kvm/svm/sev.c-5164-\t\treturn 0;\n--\narch/x86/kvm/svm/sev.c=5268=void sev_gmem_invalidate_range(struct kvm kvm, struct kvm_gfn_range range)\n--\narch/x86/kvm/svm/sev.c-5280-\t /\narch/x86/kvm/svm/sev.c:5281:\tif (!____sev_snp_guest(kvm))\narch/x86/kvm/svm/sev.c-5282-\t\treturn;\n--\narch/x86/kvm/svm/sev.c=5303=int sev_gmem_max_mapping_level(struct kvm kvm, kvm_pfn_t pfn, bool is_private)\n--\narch/x86/kvm/svm/sev.c-5307-\narch/x86/kvm/svm/sev.c:5308:\tif (!sev_snp_guest(kvm))\narch/x86/kvm/svm/sev.c-5309-\t\treturn 0;\n--\narch/x86/kvm/svm/sev.c=5318=struct vmcb_save_area sev_decrypt_vmsa(struct kvm_vcpu vcpu)\n--\narch/x86/kvm/svm/sev.c-5338-\t/ Check if the SEV policy allows debugging /\narch/x86/kvm/svm/sev.c:5339:\tif (is_sev_snp_guest(vcpu)) {\narch/x86/kvm/svm/sev.c-5340-\t\tif (!(sev-\u003epolicy \u0026 SNP_POLICY_MASK_DEBUG))\n--\narch/x86/kvm/svm/sev.c-5346-\narch/x86/kvm/svm/sev.c:5347:\tif (is_sev_snp_guest(vcpu)) {\narch/x86/kvm/svm/sev.c-5348-\t\tstruct sev_data_snp_dbg dbg = {0};\n--\narch/x86/kvm/svm/svm.c=1974=static int npf_interception(struct kvm_vcpu vcpu)\n--\narch/x86/kvm/svm/svm.c-2020-\narch/x86/kvm/svm/svm.c:2021:\tif (is_sev_snp_guest(vcpu) \u0026\u0026 (error_code \u0026 PFERR_GUEST_ENC_MASK))\narch/x86/kvm/svm/svm.c-2022-\t\terror_code \|= PFERR_PRIVATE_ACCESS;\n--\narch/x86/kvm/svm/svm.c=3426=static void dump_vmcb(struct kvm_vcpu vcpu)\n--\narch/x86/kvm/svm/svm.c-3440-\narch/x86/kvm/svm/svm.c:3441:\tvm_type = is_sev_snp_guest(vcpu) ? \"SEV-SNP\" :\narch/x86/kvm/svm/svm.c-3442-\t\t is_sev_es_guest(vcpu) ? \"SEV-ES\" :\n--\narch/x86/kvm/svm/svm.h=405=static __always_inline bool ____sev_es_guest(struct kvm kvm)\n--\narch/x86/kvm/svm/svm.h-411-\narch/x86/kvm/svm/svm.h:412:static __always_inline bool ____sev_snp_guest(struct kvm kvm)\narch/x86/kvm/svm/svm.h-413-{\n--\narch/x86/kvm/svm/svm.h=424=static __always_inline bool is_sev_es_guest(struct kvm_vcpu vcpu)\n--\narch/x86/kvm/svm/svm.h-428-\narch/x86/kvm/svm/svm.h:429:static __always_inline bool is_sev_snp_guest(struct kvm_vcpu vcpu)\narch/x86/kvm/svm/svm.h-430-{\narch/x86/kvm/svm/svm.h:431:\treturn ____sev_snp_guest(vcpu-\u003ekvm);\narch/x86/kvm/svm/svm.h-432-}\n--\narch/x86/kvm/svm/svm.h=438=static __always_inline bool is_sev_es_guest(struct kvm_vcpu vcpu)\n--\narch/x86/kvm/svm/svm.h-442-\narch/x86/kvm/svm/svm.h:443:static __always_inline bool is_sev_snp_guest(struct kvm_vcpu *vcpu)\narch/x86/kvm/svm/svm.h-444-{\n" }
13/2	2026/09/10 22:53	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 22421 output: 42 thoughts: 35 Thoughts: Okay, here's my summary, taking on the persona you requested: Deconstructing `____sev_snp_guest(kvm)` and `KVM_X86_SNP_VM` Alright, let's dive in. My immediate focus is understanding the genesis and mechanics of `____sev_snp_guest(kvm)`. I need to figure out how this function is defined within the KVM framework and, crucially, how it interacts with the `KVM_X86_SNP_VM` structure. My understanding of the architectural underpinnings is robust, but I always want to make sure the implementation specifics align perfectly. I need to trace the creation of `KVM_X86_SNP_VM`. Where is it being instantiated? What are the key parameters being passed? What are the implications of those parameters in the larger context of SEV-SNP guest virtualization? I need a clear mental map of the data flow and function calls. This will provide the foundation I need to understand any optimizations, security implications, or potential areas for improvement. It's a fundamental step toward building a true understanding of the system.
14/2	2026/09/10 22:53	tool	read-file	0m Args: { "File": "arch/x86/kvm/svm/svm.h", "FirstLine": 405, "LineCount": 40 } Results: { "Contents": " 405:\tstatic __always_inline bool ____sev_es_guest(struct kvm kvm)\n 406:\t{\n 407:\t\tstruct kvm_sev_info sev = to_kvm_sev_info(kvm);\n 408:\t\n 409:\t\treturn sev-\u003ees_active \u0026\u0026 !WARN_ON_ONCE(!sev-\u003eactive);\n 410:\t}\n 411:\t\n 412:\tstatic __always_inline bool ____sev_snp_guest(struct kvm kvm)\n 413:\t{\n 414:\t\tstruct kvm_sev_info sev = to_kvm_sev_info(kvm);\n 415:\t\n 416:\t\treturn (sev-\u003evmsa_features \u0026 SVM_SEV_FEAT_SNP_ACTIVE) \u0026\u0026\n 417:\t\t !WARN_ON_ONCE(!____sev_es_guest(kvm));\n 418:\t}\n 419:\t\n 420:\tstatic __always_inline bool is_sev_guest(struct kvm_vcpu vcpu)\n 421:\t{\n 422:\t\treturn ____sev_guest(vcpu-\u003ekvm);\n 423:\t}\n 424:\tstatic __always_inline bool is_sev_es_guest(struct kvm_vcpu vcpu)\n 425:\t{\n 426:\t\treturn ____sev_es_guest(vcpu-\u003ekvm);\n 427:\t}\n 428:\t\n 429:\tstatic __always_inline bool is_sev_snp_guest(struct kvm_vcpu vcpu)\n 430:\t{\n 431:\t\treturn ____sev_snp_guest(vcpu-\u003ekvm);\n 432:\t}\n 433:\t#else\n 434:\tstatic __always_inline bool is_sev_guest(struct kvm_vcpu vcpu)\n 435:\t{\n 436:\t\treturn false;\n 437:\t}\n 438:\tstatic __always_inline bool is_sev_es_guest(struct kvm_vcpu vcpu)\n 439:\t{\n 440:\t\treturn false;\n 441:\t}\n 442:\t\n 443:\tstatic __always_inline bool is_sev_snp_guest(struct kvm_vcpu vcpu)\n 444:\t{\n" }
15/2	2026/09/10 22:53	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 23379 output: 25 thoughts: 23 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: Diving into KVM's AMD Secure Nested Paging (SNP) VM Initialization Okay, so I'm digging into how KVM handles the initialization of `sev->vmsa_features` or, more specifically, how it sets things up for an AMD Secure Nested Paging (SNP) virtual machine. I need to understand the critical path for this, as it's foundational to the security posture. I'm especially interested in how the specific features supported by the AMD SEV-SNP are enabled, and I'm guessing this involves parsing platform information and then configuring the appropriate bits and pieces within the VMSA structures. Where does the code actually determine what SNP features are advertised, and how does it ensure they're correctly set during the VM launch sequence? I need to trace through the initialization process to confirm this. I bet it is a function of the Hypervisor. Let's start with tracing the code where the `sev` struct is getting built. From there, I'll need to look for any interactions with the AMD SEV-SNP specific hardware bits. I'll need to figure out where the KVM gets the information about the capabilities of the hardware. The documentation is generally good but the code tells the truth. I'll look for functions related to getting and setting those features. I'm going to follow the trail of execution, looking for the critical points.
16/2	2026/09/10 22:53	tool	grepper	0m Args: { "Expression": "SVM_SEV_FEAT_SNP_ACTIVE" } Results: { "Output": "arch/x86/include/asm/svm.h=306=static_assert((X2AVIC_4K_MAX_PHYSICAL_ID \u0026 AVIC_PHYSICAL_MAX_INDEX_MASK) == X2AVIC_4K_MAX_PHYSICAL_ID);\narch/x86/include/asm/svm.h-307-\narch/x86/include/asm/svm.h:308:#define SVM_SEV_FEAT_SNP_ACTIVE\t\t\t\tBIT(0)\narch/x86/include/asm/svm.h-309-#define SVM_SEV_FEAT_RESTRICTED_INJECTION\t\tBIT(3)\n--\narch/x86/kvm/svm/sev.c=491=static int __sev_guest_init(struct kvm kvm, struct kvm_sev_cmd argp,\n--\narch/x86/kvm/svm/sev.c-536-\tif (snp_active)\narch/x86/kvm/svm/sev.c:537:\t\tsev-\u003evmsa_features \|= SVM_SEV_FEAT_SNP_ACTIVE;\narch/x86/kvm/svm/sev.c-538-\n--\narch/x86/kvm/svm/svm.h=412=static __always_inline bool ____sev_snp_guest(struct kvm *kvm)\n--\narch/x86/kvm/svm/svm.h-415-\narch/x86/kvm/svm/svm.h:416:\treturn (sev-\u003evmsa_features \u0026 SVM_SEV_FEAT_SNP_ACTIVE) \u0026\u0026\narch/x86/kvm/svm/svm.h-417-\t !WARN_ON_ONCE(!____sev_es_guest(kvm));\n" }
17/2	2026/09/10 22:53	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 24193 output: 42 thoughts: 29 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: Diving into `__sev_guest_init` Okay, time to dig into the `__sev_guest_init` function. Right, that's in `arch/x86/kvm/svm/sev.c`. I need to refresh my understanding of how guest initialization is handled within the SEV framework, especially for AMD processors. I want to see precisely how they're setting things up in the hypervisor and how it interfaces with the SEV-ES or SEV-SNP functionality. I suspect there'll be some crucial logic regarding page mapping, key derivation, and potentially initial guest register configuration that needs close scrutiny to understand the implications for security and performance. Let's see how they're handling the platform initialization, and if there are any gotchas in this implementation that affect how it integrates with KVM's existing mechanisms. This is likely where the magic, or the potential vulnerabilities, lie.
18/2	2026/09/10 22:53	tool	read-file	0m Args: { "File": "arch/x86/kvm/svm/sev.c", "FirstLine": 485, "LineCount": 60 } Results: { "Contents": " 485:\t\t\t__free_page(virt_to_page(sev-\u003eguest_req_buf));\n 486:\t\n 487:\t\tsev-\u003eguest_req_buf = NULL;\n 488:\t\tsev-\u003eguest_resp_buf = NULL;\n 489:\t}\n 490:\t\n 491:\tstatic int __sev_guest_init(struct kvm kvm, struct kvm_sev_cmd argp,\n 492:\t\t\t\t struct kvm_sev_init data,\n 493:\t\t\t\t unsigned long vm_type)\n 494:\t{\n 495:\t\tstruct kvm_sev_info sev = to_kvm_sev_info(kvm);\n 496:\t\tstruct sev_platform_init_args init_args = {0};\n 497:\t\tbool es_active = vm_type != KVM_X86_SEV_VM;\n 498:\t\tbool snp_active = vm_type == KVM_X86_SNP_VM;\n 499:\t\tu64 valid_vmsa_features = es_active ? sev_supported_vmsa_features : 0;\n 500:\t\tint ret;\n 501:\t\n 502:\t\tif (kvm-\u003ecreated_vcpus)\n 503:\t\t\treturn -EINVAL;\n 504:\t\n 505:\t\tif (data-\u003eflags)\n 506:\t\t\treturn -EINVAL;\n 507:\t\n 508:\t\tif (!snp_active)\n 509:\t\t\tvalid_vmsa_features \u0026= ~SVM_SEV_FEAT_SECURE_TSC;\n 510:\t\n 511:\t\tif (data-\u003evmsa_features \u0026 ~valid_vmsa_features)\n 512:\t\t\treturn -EINVAL;\n 513:\t\n 514:\t\tif (data-\u003eghcb_version \u003e GHCB_VERSION_MAX \|\| (!es_active \u0026\u0026 data-\u003eghcb_version))\n 515:\t\t\treturn -EINVAL;\n 516:\t\n 517:\t\t/\n 518:\t\t KVM supports the full range of mandatory features defined by version\n 519:\t\t * 2 of the GHCB protocol, so default to that for SEV-ES guests created\n 520:\t\t * via KVM_SEV_INIT2 (KVM_SEV_INIT forces version 1).\n 521:\t\t */\n 522:\t\tif (es_active \u0026\u0026 !data-\u003eghcb_version)\n 523:\t\t\tdata-\u003eghcb_version = 2;\n 524:\t\n 525:\t\tif (snp_active \u0026\u0026 data-\u003eghcb_version \u003c 2)\n 526:\t\t\treturn -EINVAL;\n 527:\t\n 528:\t\tif (unlikely(sev-\u003eactive))\n 529:\t\t\treturn -EINVAL;\n 530:\t\n 531:\t\tsev-\u003eactive = true;\n 532:\t\tsev-\u003ees_active = es_active;\n 533:\t\tsev-\u003evmsa_features = data-\u003evmsa_features;\n 534:\t\tsev-\u003eghcb_version = data-\u003eghcb_version;\n 535:\t\n 536:\t\tif (snp_active)\n 537:\t\t\tsev-\u003evmsa_features \|= SVM_SEV_FEAT_SNP_ACTIVE;\n 538:\t\n 539:\t\tret = sev_asid_new(sev, vm_type);\n 540:\t\tif (ret)\n 541:\t\t\tgoto e_no_asid;\n 542:\t\n 543:\t\tinit_args.probe = false;\n 544:\t\tret = sev_platform_init(\u0026init_args);\n" }
19/2	2026/09/10 22:53	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 25456 output: 24 thoughts: 131 Thoughts: Analyzing the SEV-SNP Initialization Process Okay, let's break this down step-by-step. First, `sev_platform_init(&init_args)` looks like the entry point, and it's calling the CCP driver. That's the expected path. Then, there's `sev_snp_supported` within `sev_hardware_setup`, and it seems like the check is: ```c sev_snp_supported = sev_snp_enabled && cc_platform_has(CC_ATTR_HOST_SEV_SNP); ``` That's straightforward. It's verifying both that SEV-SNP is enabled generally, and that the host platform actually supports it, using `cc_platform_has()`. No surprises there. But hold on a second... I'm missing something important. How is `sev_vm_init` or, more generally, `kvm_arch_init_vm` setting the `kvm->arch.vm_type`? I need to understand how the KVM's architecture-specific VM type is being configured. It's crucial for the SNP behavior. I need to trace where the `KVM_X86_SNP_VM` flag is being set and used within KVM. This will determine how the rest of the SNP functionality gets hooked up. Time to dig in and see where `KVM_X86_SNP_VM` is actually utilized.
20/2	2026/09/10 22:53	tool	grepper	0m Args: { "Expression": "KVM_X86_SNP_VM" } Results: { "Output": "Documentation/virt/kvm/api.rst=9512=means the VM type with value @n is supported. Possible values of @n are::\n--\nDocumentation/virt/kvm/api.rst-9517- #define KVM_X86_SEV_ES_VM\t3\nDocumentation/virt/kvm/api.rst:9518: #define KVM_X86_SNP_VM\t4\nDocumentation/virt/kvm/api.rst-9519- #define KVM_X86_TDX_VM\t5\n--\narch/x86/include/uapi/asm/kvm.h=927=struct kvm_hyperv_eventfd {\n--\narch/x86/include/uapi/asm/kvm.h-973-#define KVM_X86_SEV_ES_VM\t3\narch/x86/include/uapi/asm/kvm.h:974:#define KVM_X86_SNP_VM\t\t4\narch/x86/include/uapi/asm/kvm.h-975-#define KVM_X86_TDX_VM\t\t5\n--\narch/x86/kvm/svm/sev.c=265=static int sev_asid_new(struct kvm_sev_info sev, unsigned long vm_type)\n--\narch/x86/kvm/svm/sev.c-273-\narch/x86/kvm/svm/sev.c:274:\tif (vm_type == KVM_X86_SNP_VM) {\narch/x86/kvm/svm/sev.c-275-\t\tmin_asid = min_snp_asid;\n--\narch/x86/kvm/svm/sev.c=491=static int __sev_guest_init(struct kvm kvm, struct kvm_sev_cmd argp,\n--\narch/x86/kvm/svm/sev.c-497-\tbool es_active = vm_type != KVM_X86_SEV_VM;\narch/x86/kvm/svm/sev.c:498:\tbool snp_active = vm_type == KVM_X86_SNP_VM;\narch/x86/kvm/svm/sev.c-499-\tu64 valid_vmsa_features = es_active ? sev_supported_vmsa_features : 0;\n--\narch/x86/kvm/svm/sev.c=604=static int sev_guest_init2(struct kvm kvm, struct kvm_sev_cmd argp)\n--\narch/x86/kvm/svm/sev.c-612-\t kvm-\u003earch.vm_type != KVM_X86_SEV_ES_VM \u0026\u0026\narch/x86/kvm/svm/sev.c:613:\t kvm-\u003earch.vm_type != KVM_X86_SNP_VM)\narch/x86/kvm/svm/sev.c-614-\t\treturn -EINVAL;\n--\narch/x86/kvm/svm/sev.c=2955=void sev_vm_init(struct kvm kvm)\n--\narch/x86/kvm/svm/sev.c-2960-\t\tbreak;\narch/x86/kvm/svm/sev.c:2961:\tcase KVM_X86_SNP_VM:\narch/x86/kvm/svm/sev.c-2962-\t\tkvm-\u003earch.has_private_mem = true;\n--\narch/x86/kvm/svm/sev.c=3088=void __init sev_hardware_setup(void)\n--\narch/x86/kvm/svm/sev.c-3233-\tif (sev_snp_supported)\narch/x86/kvm/svm/sev.c:3234:\t\tvm_types \|= BIT(KVM_X86_SNP_VM);\narch/x86/kvm/svm/sev.c-3235-\tvm_types \u0026= sev_firmware_supported_vm_types();\n--\narch/x86/kvm/svm/sev.c-3248-\t\tpr_info(\"SEV-SNP %s (ASIDs %u - %u)\\n\",\narch/x86/kvm/svm/sev.c:3249:\t\t\tsev_str_feature_state(sev_snp_supported, vm_types \u0026 BIT(KVM_X86_SNP_VM)),\narch/x86/kvm/svm/sev.c-3250-\t\t\tmin_snp_asid, max_snp_asid);\n--\ndrivers/crypto/ccp/sev-dev.c=3147=int sev_firmware_supported_vm_types(void)\n--\ndrivers/crypto/ccp/sev-dev.c-3161-\ndrivers/crypto/ccp/sev-dev.c:3162:\tsupported_vm_types \|= BIT(KVM_X86_SNP_VM);\ndrivers/crypto/ccp/sev-dev.c-3163-\n--\ntools/arch/x86/include/uapi/asm/kvm.h=927=struct kvm_hyperv_eventfd {\n--\ntools/arch/x86/include/uapi/asm/kvm.h-973-#define KVM_X86_SEV_ES_VM\t3\ntools/arch/x86/include/uapi/asm/kvm.h:974:#define KVM_X86_SNP_VM\t\t4\ntools/arch/x86/include/uapi/asm/kvm.h-975-#define KVM_X86_TDX_VM\t\t5\n--\ntools/testing/selftests/kvm/include/x86/sev.h=34=static inline bool is_sev_snp_vm(struct kvm_vm vm)\ntools/testing/selftests/kvm/include/x86/sev.h-35-{\ntools/testing/selftests/kvm/include/x86/sev.h:36:\treturn vm-\u003etype == KVM_X86_SNP_VM;\ntools/testing/selftests/kvm/include/x86/sev.h-37-}\n--\ntools/testing/selftests/kvm/lib/kvm_util.c=478=static bool is_guest_memfd_required(struct vm_shape shape)\n--\ntools/testing/selftests/kvm/lib/kvm_util.c-480-#ifdef __x86_64__\ntools/testing/selftests/kvm/lib/kvm_util.c:481:\treturn shape.type == KVM_X86_SNP_VM;\ntools/testing/selftests/kvm/lib/kvm_util.c-482-#else\n--\ntools/testing/selftests/kvm/lib/x86/sev.c=74=void snp_vm_init(struct kvm_vm vm)\n--\ntools/testing/selftests/kvm/lib/x86/sev.c-77-\ntools/testing/selftests/kvm/lib/x86/sev.c:78:\tTEST_ASSERT_EQ(vm-\u003etype, KVM_X86_SNP_VM);\ntools/testing/selftests/kvm/lib/x86/sev.c-79-\tvm_sev_ioctl(vm, KVM_SEV_INIT2, \u0026init);\n--\ntools/testing/selftests/kvm/x86/sev_init2_tests.c=76=void test_vm_types(void)\n--\ntools/testing/selftests/kvm/x86/sev_init2_tests.c-83-\tif (have_snp)\ntools/testing/selftests/kvm/x86/sev_init2_tests.c:84:\t\ttest_init2(KVM_X86_SNP_VM, \u0026(struct kvm_sev_init){});\ntools/testing/selftests/kvm/x86/sev_init2_tests.c-85-\n--\ntools/testing/selftests/kvm/x86/sev_init2_tests.c=118=int main(int argc, char argv[])\n--\ntools/testing/selftests/kvm/x86/sev_init2_tests.c-145-\ntools/testing/selftests/kvm/x86/sev_init2_tests.c:146:\thave_snp = kvm_check_cap(KVM_CAP_VM_TYPES) \u0026 BIT(KVM_X86_SNP_VM);\ntools/testing/selftests/kvm/x86/sev_init2_tests.c-147-\tTEST_ASSERT(!have_snp \|\| kvm_cpu_has(X86_FEATURE_SEV_SNP),\n--\ntools/testing/selftests/kvm/x86/sev_init2_tests.c-155-\tif (have_snp)\ntools/testing/selftests/kvm/x86/sev_init2_tests.c:156:\t\ttest_flags(KVM_X86_SNP_VM);\ntools/testing/selftests/kvm/x86/sev_init2_tests.c-157-\n--\ntools/testing/selftests/kvm/x86/sev_init2_tests.c-161-\tif (have_snp)\ntools/testing/selftests/kvm/x86/sev_init2_tests.c:162:\t\ttest_features(KVM_X86_SNP_VM, supported_vmsa_features);\ntools/testing/selftests/kvm/x86/sev_init2_tests.c-163-\n--\ntools/testing/selftests/kvm/x86/sev_migrate_tests.c=316=static void test_sev_snp_migrate_reject(void)\n--\ntools/testing/selftests/kvm/x86/sev_migrate_tests.c-320-\ntools/testing/selftests/kvm/x86/sev_migrate_tests.c:321:\tsrc_vm = vm_create_barebones_type(KVM_X86_SNP_VM);\ntools/testing/selftests/kvm/x86/sev_migrate_tests.c-322-\tsnp_vm_init(src_vm);\n--\ntools/testing/selftests/kvm/x86/sev_migrate_tests.c-325-\ntools/testing/selftests/kvm/x86/sev_migrate_tests.c:326:\tdst_vm = vm_create_barebones_type(KVM_X86_SNP_VM);\ntools/testing/selftests/kvm/x86/sev_migrate_tests.c-327-\t__vm_vcpu_add(dst_vm, 0);\n--\ntools/testing/selftests/kvm/x86/sev_migrate_tests.c=338=static void test_sev_snp_mirror_reject(void)\n--\ntools/testing/selftests/kvm/x86/sev_migrate_tests.c-342-\ntools/testing/selftests/kvm/x86/sev_migrate_tests.c:343:\tsrc_vm = vm_create_barebones_type(KVM_X86_SNP_VM);\ntools/testing/selftests/kvm/x86/sev_migrate_tests.c-344-\tsnp_vm_init(src_vm);\n--\ntools/testing/selftests/kvm/x86/sev_smoke_test.c=221=static void test_sev_smoke(void guest, u32 type, u64 policy)\n--\ntools/testing/selftests/kvm/x86/sev_smoke_test.c-224-\ntools/testing/selftests/kvm/x86/sev_smoke_test.c:225:\tif (type == KVM_X86_SNP_VM)\ntools/testing/selftests/kvm/x86/sev_smoke_test.c-226-\t\ttest_sev(guest, type, policy \| SNP_POLICY_DBG);\n--\ntools/testing/selftests/kvm/x86/sev_smoke_test.c-238-\t\ttest_sync_vmsa(type, policy);\ntools/testing/selftests/kvm/x86/sev_smoke_test.c:239:\t\tif (type == KVM_X86_SNP_VM)\ntools/testing/selftests/kvm/x86/sev_smoke_test.c-240-\t\t\ttest_sync_vmsa(type, policy \| SNP_POLICY_DBG);\n--\ntools/testing/selftests/kvm/x86/sev_smoke_test.c=246=int main(int argc, char *argv[])\n--\ntools/testing/selftests/kvm/x86/sev_smoke_test.c-261-\ntools/testing/selftests/kvm/x86/sev_smoke_test.c:262:\tif (kvm_check_cap(KVM_CAP_VM_TYPES) \u0026 BIT(KVM_X86_SNP_VM))\ntools/testing/selftests/kvm/x86/sev_smoke_test.c:263:\t\ttest_sev_smoke(guest_snp_code, KVM_X86_SNP_VM, snp_default_policy());\ntools/testing/selftests/kvm/x86/sev_smoke_test.c-264-\n" }
21/2	2026/09/10 22:53	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 29402 output: 39 thoughts: 77 Thoughts: Okay, let's break this down. Investigating KVM and SEV-SNP Compatibility Alright, so I'm wondering about something specific regarding KVM and SEV-SNP: Can I successfully use `KVM_CREATE_VM` with the `KVM_X86_SNP_VM` flag, even if the underlying hardware doesn't support SEV-SNP? I suspect there might be some graceful fallback, or perhaps an error is explicitly thrown. To figure this out, I should dive into the kernel code. My instinct is that the `kvm_arch_init_vm` function, probably found in `arch/x86/kvm/x86.c`, is the best place to start. Or maybe there's some setup related to SEV hardware, something called `sev_hardware_setup`, that handles this initialization path and the required checks for SEV-SNP support. I need to trace through the relevant code paths to understand the logic. I'm going to start with `kvm_arch_init_vm` and go from there, and see where `sev_hardware_setup` fits in if needed. I need to understand if the kernel attempts to detect or gracefully handle unsupported features. Let's get to work.
22/2	2026/09/10 22:53	tool	grepper	0m Args: { "Expression": "KVM_X86_SNP_VM", "PathPrefix": "arch/x86/kvm/" } Results: { "Output": "arch/x86/kvm/svm/sev.c=265=static int sev_asid_new(struct kvm_sev_info sev, unsigned long vm_type)\n--\narch/x86/kvm/svm/sev.c-273-\narch/x86/kvm/svm/sev.c:274:\tif (vm_type == KVM_X86_SNP_VM) {\narch/x86/kvm/svm/sev.c-275-\t\tmin_asid = min_snp_asid;\n--\narch/x86/kvm/svm/sev.c=491=static int __sev_guest_init(struct kvm kvm, struct kvm_sev_cmd argp,\n--\narch/x86/kvm/svm/sev.c-497-\tbool es_active = vm_type != KVM_X86_SEV_VM;\narch/x86/kvm/svm/sev.c:498:\tbool snp_active = vm_type == KVM_X86_SNP_VM;\narch/x86/kvm/svm/sev.c-499-\tu64 valid_vmsa_features = es_active ? sev_supported_vmsa_features : 0;\n--\narch/x86/kvm/svm/sev.c=604=static int sev_guest_init2(struct kvm kvm, struct kvm_sev_cmd argp)\n--\narch/x86/kvm/svm/sev.c-612-\t kvm-\u003earch.vm_type != KVM_X86_SEV_ES_VM \u0026\u0026\narch/x86/kvm/svm/sev.c:613:\t kvm-\u003earch.vm_type != KVM_X86_SNP_VM)\narch/x86/kvm/svm/sev.c-614-\t\treturn -EINVAL;\n--\narch/x86/kvm/svm/sev.c=2955=void sev_vm_init(struct kvm kvm)\n--\narch/x86/kvm/svm/sev.c-2960-\t\tbreak;\narch/x86/kvm/svm/sev.c:2961:\tcase KVM_X86_SNP_VM:\narch/x86/kvm/svm/sev.c-2962-\t\tkvm-\u003earch.has_private_mem = true;\n--\narch/x86/kvm/svm/sev.c=3088=void __init sev_hardware_setup(void)\n--\narch/x86/kvm/svm/sev.c-3233-\tif (sev_snp_supported)\narch/x86/kvm/svm/sev.c:3234:\t\tvm_types \|= BIT(KVM_X86_SNP_VM);\narch/x86/kvm/svm/sev.c-3235-\tvm_types \u0026= sev_firmware_supported_vm_types();\n--\narch/x86/kvm/svm/sev.c-3248-\t\tpr_info(\"SEV-SNP %s (ASIDs %u - %u)\\n\",\narch/x86/kvm/svm/sev.c:3249:\t\t\tsev_str_feature_state(sev_snp_supported, vm_types \u0026 BIT(KVM_X86_SNP_VM)),\narch/x86/kvm/svm/sev.c-3250-\t\t\tmin_snp_asid, max_snp_asid);\n" }
23/2	2026/09/10 22:53	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 30698 output: 32 thoughts: 31 Thoughts: Here's my take on the thought process, as requested: Diving into KVM Initialization on x86 Okay, so I need to understand how the KVM architecture initializes on x86. The best place to start, as I recall, is probably the core initialization function. Let's see... kvm_arch_init_vm in `arch/x86/kvm/x86.c`. That file makes the most sense. This is where the low-level, x86-specific parts of virtual machine setup are handled within the KVM framework. I need to refresh my memory on the critical data structures and entry points involved in the VM's architectural initialization, so digging into this will be a good starting point.
24/2	2026/09/10 22:53	tool	grepper	0m Args: { "Expression": "vm_type", "PathPrefix": "arch/x86/kvm/" } Results: { "Output": "arch/x86/kvm/mmu.h=392=static inline bool kvm_has_mirrored_tdp(const struct kvm kvm)\narch/x86/kvm/mmu.h-393-{\narch/x86/kvm/mmu.h:394:\treturn kvm-\u003earch.vm_type == KVM_X86_TDX_VM;\narch/x86/kvm/mmu.h-395-}\n--\narch/x86/kvm/mmu/mmu.c=5954=static inline int kvm_mmu_get_tdp_level(struct kvm_vcpu vcpu)\n--\narch/x86/kvm/mmu/mmu.c-5957-\narch/x86/kvm/mmu/mmu.c:5958:\tif (vcpu-\u003ekvm-\u003earch.vm_type == KVM_X86_TDX_VM)\narch/x86/kvm/mmu/mmu.c-5959-\t\tmaxpa = cpuid_query_maxguestphyaddr(vcpu);\n--\narch/x86/kvm/mmu/mmu.c=6567=int noinline kvm_mmu_page_fault(struct kvm_vcpu vcpu, gpa_t cr2_or_gpa, u64 error_code,\n--\narch/x86/kvm/mmu/mmu.c-6585-\t !(error_code \u0026 PFERR_RSVD_MASK) \u0026\u0026\narch/x86/kvm/mmu/mmu.c:6586:\t vcpu-\u003ekvm-\u003earch.vm_type == KVM_X86_SW_PROTECTED_VM \u0026\u0026\narch/x86/kvm/mmu/mmu.c-6587-\t kvm_mem_is_private(vcpu-\u003ekvm, gpa_to_gfn(cr2_or_gpa)))\n--\narch/x86/kvm/mmu/mmu.c=7608=void kvm_arch_flush_shadow_memslot(struct kvm kvm,\n--\narch/x86/kvm/mmu/mmu.c-7617-\t};\narch/x86/kvm/mmu/mmu.c:7618:\tbool zap_all = kvm-\u003earch.vm_type == KVM_X86_DEFAULT_VM \u0026\u0026\narch/x86/kvm/mmu/mmu.c-7619-\t\t kvm_check_has_quirk(kvm, KVM_X86_QUIRK_SLOT_ZAP_ALL);\n--\narch/x86/kvm/mmu/page_track.c=189=static int kvm_enable_external_write_tracking(struct kvm kvm)\n--\narch/x86/kvm/mmu/page_track.c-194-\narch/x86/kvm/mmu/page_track.c:195:\tif (kvm-\u003earch.vm_type == KVM_X86_TDX_VM)\narch/x86/kvm/mmu/page_track.c-196-\t\treturn -EOPNOTSUPP;\n--\narch/x86/kvm/svm/avic.c-16-\narch/x86/kvm/svm/avic.c:17:#include \u003clinux/kvm_types.h\u003e\narch/x86/kvm/svm/avic.c-18-#include \u003clinux/hashtable.h\u003e\n--\narch/x86/kvm/svm/nested.c-16-\narch/x86/kvm/svm/nested.c:17:#include \u003clinux/kvm_types.h\u003e\narch/x86/kvm/svm/nested.c-18-#include \u003clinux/kvm_host.h\u003e\n--\narch/x86/kvm/svm/sev.c-10-\narch/x86/kvm/svm/sev.c:11:#include \u003clinux/kvm_types.h\u003e\narch/x86/kvm/svm/sev.c-12-#include \u003clinux/kvm_host.h\u003e\n--\narch/x86/kvm/svm/sev.c=243=static unsigned int sev_alloc_asid(unsigned int min_asid, unsigned int max_asid)\n--\narch/x86/kvm/svm/sev.c-264-\narch/x86/kvm/svm/sev.c:265:static int sev_asid_new(struct kvm_sev_info sev, unsigned long vm_type)\narch/x86/kvm/svm/sev.c-266-{\n--\narch/x86/kvm/svm/sev.c-273-\narch/x86/kvm/svm/sev.c:274:\tif (vm_type == KVM_X86_SNP_VM) {\narch/x86/kvm/svm/sev.c-275-\t\tmin_asid = min_snp_asid;\n--\narch/x86/kvm/svm/sev.c=491=static int __sev_guest_init(struct kvm kvm, struct kvm_sev_cmd argp,\narch/x86/kvm/svm/sev.c-492-\t\t\t struct kvm_sev_init data,\narch/x86/kvm/svm/sev.c:493:\t\t\t unsigned long vm_type)\narch/x86/kvm/svm/sev.c-494-{\n--\narch/x86/kvm/svm/sev.c-496-\tstruct sev_platform_init_args init_args = {0};\narch/x86/kvm/svm/sev.c:497:\tbool es_active = vm_type != KVM_X86_SEV_VM;\narch/x86/kvm/svm/sev.c:498:\tbool snp_active = vm_type == KVM_X86_SNP_VM;\narch/x86/kvm/svm/sev.c-499-\tu64 valid_vmsa_features = es_active ? sev_supported_vmsa_features : 0;\n--\narch/x86/kvm/svm/sev.c-538-\narch/x86/kvm/svm/sev.c:539:\tret = sev_asid_new(sev, vm_type);\narch/x86/kvm/svm/sev.c-540-\tif (ret)\n--\narch/x86/kvm/svm/sev.c=581=static int sev_guest_init(struct kvm kvm, struct kvm_sev_cmd argp)\n--\narch/x86/kvm/svm/sev.c-586-\t};\narch/x86/kvm/svm/sev.c:587:\tunsigned long vm_type;\narch/x86/kvm/svm/sev.c-588-\narch/x86/kvm/svm/sev.c:589:\tif (kvm-\u003earch.vm_type != KVM_X86_DEFAULT_VM)\narch/x86/kvm/svm/sev.c-590-\t\treturn -EINVAL;\narch/x86/kvm/svm/sev.c-591-\narch/x86/kvm/svm/sev.c:592:\tvm_type = (argp-\u003eid == KVM_SEV_INIT ? KVM_X86_SEV_VM : KVM_X86_SEV_ES_VM);\narch/x86/kvm/svm/sev.c-593-\n--\narch/x86/kvm/svm/sev.c-597-\t /\narch/x86/kvm/svm/sev.c:598:\tif (vm_type == KVM_X86_SEV_ES_VM)\narch/x86/kvm/svm/sev.c-599-\t\tdata.ghcb_version = GHCB_VERSION_MIN;\narch/x86/kvm/svm/sev.c-600-\narch/x86/kvm/svm/sev.c:601:\treturn __sev_guest_init(kvm, argp, \u0026data, vm_type);\narch/x86/kvm/svm/sev.c-602-}\n--\narch/x86/kvm/svm/sev.c=604=static int sev_guest_init2(struct kvm kvm, struct kvm_sev_cmd argp)\n--\narch/x86/kvm/svm/sev.c-610-\narch/x86/kvm/svm/sev.c:611:\tif (kvm-\u003earch.vm_type != KVM_X86_SEV_VM \u0026\u0026\narch/x86/kvm/svm/sev.c:612:\t kvm-\u003earch.vm_type != KVM_X86_SEV_ES_VM \u0026\u0026\narch/x86/kvm/svm/sev.c:613:\t kvm-\u003earch.vm_type != KVM_X86_SNP_VM)\narch/x86/kvm/svm/sev.c-614-\t\treturn -EINVAL;\n--\narch/x86/kvm/svm/sev.c-618-\narch/x86/kvm/svm/sev.c:619:\treturn __sev_guest_init(kvm, argp, \u0026data, kvm-\u003earch.vm_type);\narch/x86/kvm/svm/sev.c-620-}\n--\narch/x86/kvm/svm/sev.c=968=static int sev_es_sync_vmsa(struct vcpu_svm svm)\n--\narch/x86/kvm/svm/sev.c-1027-\t /\narch/x86/kvm/svm/sev.c:1028:\tif (vcpu-\u003ekvm-\u003earch.vm_type != KVM_X86_DEFAULT_VM) {\narch/x86/kvm/svm/sev.c-1029-\t\txsave = \u0026vcpu-\u003earch.guest_fpu.fpstate-\u003eregs.xsave;\n--\narch/x86/kvm/svm/sev.c=2136=int sev_vm_move_enc_context_from(struct kvm kvm, unsigned int source_fd)\n--\narch/x86/kvm/svm/sev.c-2156-\t/ Do not allow SNP VM migration until additional state transfer is implemented /\narch/x86/kvm/svm/sev.c:2157:\tif (kvm-\u003earch.vm_type != source_kvm-\u003earch.vm_type \|\|\narch/x86/kvm/svm/sev.c-2158-\t sev_guest(kvm) \|\| !sev_guest(source_kvm) \|\| sev_snp_guest(source_kvm)) {\n--\narch/x86/kvm/svm/sev.c=2955=void sev_vm_init(struct kvm kvm)\narch/x86/kvm/svm/sev.c-2956-{\narch/x86/kvm/svm/sev.c:2957:\tswitch (kvm-\u003earch.vm_type) {\narch/x86/kvm/svm/sev.c-2958-\tcase KVM_X86_DEFAULT_VM:\n--\narch/x86/kvm/svm/sev.c-2971-\tdefault:\narch/x86/kvm/svm/sev.c:2972:\t\tWARN_ONCE(1, \"Unsupported VM type %u\", kvm-\u003earch.vm_type);\narch/x86/kvm/svm/sev.c-2973-\t\tbreak;\n--\narch/x86/kvm/svm/sev.c=3088=void __init sev_hardware_setup(void)\n--\narch/x86/kvm/svm/sev.c-3094-\tbool sev_supported = false;\narch/x86/kvm/svm/sev.c:3095:\tu32 vm_types = 0;\narch/x86/kvm/svm/sev.c-3096-\n--\narch/x86/kvm/svm/sev.c-3229-\tif (sev_supported \u0026\u0026 min_sev_asid \u003c= max_sev_asid)\narch/x86/kvm/svm/sev.c:3230:\t\tvm_types \|= BIT(KVM_X86_SEV_VM);\narch/x86/kvm/svm/sev.c-3231-\tif (sev_es_supported \u0026\u0026 min_sev_es_asid \u003c= max_sev_es_asid)\narch/x86/kvm/svm/sev.c:3232:\t\tvm_types \|= BIT(KVM_X86_SEV_ES_VM);\narch/x86/kvm/svm/sev.c-3233-\tif (sev_snp_supported)\narch/x86/kvm/svm/sev.c:3234:\t\tvm_types \|= BIT(KVM_X86_SNP_VM);\narch/x86/kvm/svm/sev.c:3235:\tvm_types \u0026= sev_firmware_supported_vm_types();\narch/x86/kvm/svm/sev.c-3236-\narch/x86/kvm/svm/sev.c:3237:\tkvm_caps.supported_vm_types \|= vm_types;\narch/x86/kvm/svm/sev.c-3238-\n--\narch/x86/kvm/svm/sev.c-3240-\t\tpr_info(\"SEV %s (ASIDs %u - %u)\\n\",\narch/x86/kvm/svm/sev.c:3241:\t\t\tsev_str_feature_state(sev_supported, vm_types \u0026 BIT(KVM_X86_SEV_VM)),\narch/x86/kvm/svm/sev.c-3242-\t\t\tmin_sev_asid, max_sev_asid);\n--\narch/x86/kvm/svm/sev.c-3244-\t\tpr_info(\"SEV-ES %s (ASIDs %u - %u)\\n\",\narch/x86/kvm/svm/sev.c:3245:\t\t\tsev_str_feature_state(sev_es_supported, vm_types \u0026 BIT(KVM_X86_SEV_ES_VM)),\narch/x86/kvm/svm/sev.c-3246-\t\t\tmin_sev_es_asid, max_sev_es_asid);\n--\narch/x86/kvm/svm/sev.c-3248-\t\tpr_info(\"SEV-SNP %s (ASIDs %u - %u)\\n\",\narch/x86/kvm/svm/sev.c:3249:\t\t\tsev_str_feature_state(sev_snp_supported, vm_types \u0026 BIT(KVM_X86_SNP_VM)),\narch/x86/kvm/svm/sev.c-3250-\t\t\tmin_snp_asid, max_snp_asid);\n--\narch/x86/kvm/svm/svm.c=3426=static void dump_vmcb(struct kvm_vcpu vcpu)\n--\narch/x86/kvm/svm/svm.c-3431-\tstruct vmcb_save_area save01 = \u0026svm-\u003evmcb01.ptr-\u003esave;\narch/x86/kvm/svm/svm.c:3432:\tchar vm_type;\narch/x86/kvm/svm/svm.c-3433-\n--\narch/x86/kvm/svm/svm.c-3440-\narch/x86/kvm/svm/svm.c:3441:\tvm_type = is_sev_snp_guest(vcpu) ? \"SEV-SNP\" :\narch/x86/kvm/svm/svm.c-3442-\t\t is_sev_es_guest(vcpu) ? \"SEV-ES\" :\n--\narch/x86/kvm/svm/svm.c-3445-\tpr_err(\"%s vCPU%u VMCB %p, last attempted VMRUN on CPU %d\\n\",\narch/x86/kvm/svm/svm.c:3446:\t vm_type, vcpu-\u003evcpu_id, svm-\u003ecurrent_vmcb-\u003eptr, vcpu-\u003earch.last_vmentry_cpu);\narch/x86/kvm/svm/svm.c-3447-\tpr_err(\"VMCB Control Area:\\n\");\n--\narch/x86/kvm/svm/svm.h-17-\narch/x86/kvm/svm/svm.h:18:#include \u003clinux/kvm_types.h\u003e\narch/x86/kvm/svm/svm.h-19-#include \u003clinux/kvm_host.h\u003e\n--\narch/x86/kvm/vmx/common.h=60=static __always_inline bool is_td(struct kvm kvm)\narch/x86/kvm/vmx/common.h-61-{\narch/x86/kvm/vmx/common.h:62:\treturn kvm-\u003earch.vm_type == KVM_X86_TDX_VM;\narch/x86/kvm/vmx/common.h-63-}\n--\narch/x86/kvm/vmx/main.c=1058=static int __init vt_init(void)\n--\narch/x86/kvm/vmx/main.c-1078-\t\t\t\t__alignof__(struct vcpu_tdx));\narch/x86/kvm/vmx/main.c:1079:\t\tkvm_caps.supported_vm_types \|= BIT(KVM_X86_TDX_VM);\narch/x86/kvm/vmx/main.c-1080-\t}\n--\narch/x86/kvm/x86.c=2171=static int kvm_ioctl_get_supported_hv_cpuid(struct kvm_vcpu vcpu,\n--\narch/x86/kvm/x86.c-2192-\narch/x86/kvm/x86.c:2193:static bool kvm_is_vm_type_supported(unsigned long type)\narch/x86/kvm/x86.c-2194-{\narch/x86/kvm/x86.c:2195:\treturn type \u003c 32 \u0026\u0026 (kvm_caps.supported_vm_types \u0026 BIT(type));\narch/x86/kvm/x86.c-2196-}\n--\narch/x86/kvm/x86.c=2203=int kvm_vm_ioctl_check_extension(struct kvm kvm, long ext)\n--\narch/x86/kvm/x86.c-2404-\tcase KVM_CAP_VM_TYPES:\narch/x86/kvm/x86.c:2405:\t\tr = kvm_caps.supported_vm_types;\narch/x86/kvm/x86.c-2406-\t\tbreak;\n--\narch/x86/kvm/x86.c=6999=int kvm_x86_vendor_init(struct kvm_x86_init_ops ops)\n--\narch/x86/kvm/x86.c-7062-\narch/x86/kvm/x86.c:7063:\tkvm_caps.supported_vm_types = BIT(KVM_X86_DEFAULT_VM);\narch/x86/kvm/x86.c-7064-\tkvm_caps.supported_mce_cap = MCG_CTL_P \| MCG_SER_P;\n--\narch/x86/kvm/x86.c-7124-\tif (IS_ENABLED(CONFIG_KVM_SW_PROTECTED_VM) \u0026\u0026 tdp_mmu_enabled)\narch/x86/kvm/x86.c:7125:\t\tkvm_caps.supported_vm_types \|= BIT(KVM_X86_SW_PROTECTED_VM);\narch/x86/kvm/x86.c-7126-\n--\narch/x86/kvm/x86.c=9843=int kvm_arch_init_vm(struct kvm kvm, unsigned long type)\n--\narch/x86/kvm/x86.c-9847-\narch/x86/kvm/x86.c:9848:\tif (!kvm_is_vm_type_supported(type))\narch/x86/kvm/x86.c-9849-\t\treturn -EINVAL;\narch/x86/kvm/x86.c-9850-\narch/x86/kvm/x86.c:9851:\tkvm-\u003earch.vm_type = type;\narch/x86/kvm/x86.c-9852-\tkvm-\u003earch.has_private_mem =\n" }
25/2	2026/09/10 22:53	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 36428 output: 187 thoughts: 1587 Thoughts: Analysis of Reachability in Standard Virtualized Environments Okay, let's break this down. My initial assessment is that this patch introduces code that's fundamentally unreachable in the standard virtualized environments we're typically working with, like QEMU and Google Compute Engine (GCE). Here's the reasoning: First, the code touches `kvm_arch_init_vm` and `kvm_caps.supported_vm_types`. The inclusion of `KVM_X86_SNP_VM` – which is key here – is contingent on `sev_snp_supported` being true. And `sev_snp_supported` is directly linked to `cc_platform_has(CC_ATTR_HOST_SEV_SNP)`. This, in turn, requires bare-metal AMD hardware with SEV-SNP support, and explicitly excludes the hypervisor case (`!cpu_has(c, X86_FEATURE_HYPERVISOR)`). Then there's the `RMPOPT` stuff – all those changes around `X86_FEATURE_RMPOPT`, `snp_setup_rmpopt`, etc. These are also tightly coupled to bare-metal hardware with `CC_ATTR_HOST_SEV_SNP` and specific CPU features like `X86_FEATURE_RMPOPT` and Segmented RMP support (which appears to be Zen 5/Zen 6 specific). Executing the binutils RMPOPT opcode and having physical AMD IOMMU / CCP co-processor hardware is another requirement. Now, let's walk through the files and functions I've looked at: 1. `arch/x86/include/asm/cpufeatures.h`, `arch/x86/include/asm/msr-index.h`, `arch/x86/include/asm/sev.h`: Just definitions and headers. No execution path. 2. `arch/x86/kernel/cpu/scattered.c`: CPUID detection code; that's fine, but requires the underlying CPU to have RMPOPT, which in a hypervisor environment, it won't. 3. `arch/x86/kvm/svm/sev.c`: `sev_vm_destroy` calls `snp_rmpopt_all_physmem` only if it's an SNP guest VM. An SNP guest is unreachable without `CC_ATTR_HOST_SEV_SNP`. 4. `arch/x86/virt/svm/sev.c`: Functions like `snp_prepare`, `snp_shutdown`, and others are guarded by `cc_platform_has(CC_ATTR_HOST_SEV_SNP)` or `X86_FEATURE_RMPOPT`, or they are called from AMD IOMMU init, which also checks `!cc_platform_has(CC_ATTR_HOST_SEV_SNP)`. `snp_probe_rmptable_info()` also needs a physical AMD Zen3+ CPU. 5. `drivers/crypto/ccp/sev-dev.c`: `__sev_snp_init_locked` immediately checks for `cc_platform_has(CC_ATTR_HOST_SEV_SNP)` and bails out if it's not present. The crucial point is that none of this code can execute because the core prerequisites are absent in a standard QEMU or GCE environment. QEMU and GCE explicitly expose `X86_FEATURE_HYPERVISOR`, which disables the necessary AMD SNP host platform support. Therefore, given the guidelines, this is structurally unreachable hardware. It requires specific, physical AMD hardware that is not emulated in these standard virtualized environments. So, setting the parameters for our tool: * WorthFuzzing: `false` * EnableConfigs: `null` or `[]` * FocusSymbols: `null` or `[]` * Reasoning: "Modified code is structurally unreachable in standard virtualized fuzzing environments (QEMU/GCE). RMPOPT and SEV-SNP host functionality require bare-metal AMD physical hardware with SEV-SNP and RMPOPT support. `CC_ATTR_HOST_SEV_SNP` is explicitly disabled when running under a hypervisor (`X86_FEATURE_HYPERVISOR`)."
26/2	2026/09/10 22:54	tool	set-results	0m Args: { "EnableConfigs": [], "FocusSymbols": [], "Reasoning": "The patch adds kernel support for the AMD RMPOPT (RMP optimization) instruction and updates SEV-SNP host initialization/teardown paths. All modified code paths require AMD SEV-SNP host support (CC_ATTR_HOST_SEV_SNP) and hardware-specific CPU/firmware capabilities (such as X86_FEATURE_RMPOPT and Segmented RMP). In standard virtualized fuzzing environments (QEMU/GCE), X86_FEATURE_HYPERVISOR is present which prevents CC_ATTR_HOST_SEV_SNP from being enabled (in bsp_determine_snp()), making all modified logic structurally unreachable without physical bare-metal AMD hardware supporting SEV-SNP and RMPOPT.", "WorthFuzzing": false } Results: { "EnableConfigs": null, "FocusSymbols": [], "Reasoning": "The patch adds kernel support for the AMD RMPOPT (RMP optimization) instruction and updates SEV-SNP host initialization/teardown paths. All modified code paths require AMD SEV-SNP host support (CC_ATTR_HOST_SEV_SNP) and hardware-specific CPU/firmware capabilities (such as X86_FEATURE_RMPOPT and Segmented RMP). In standard virtualized fuzzing environments (QEMU/GCE), X86_FEATURE_HYPERVISOR is present which prevents CC_ATTR_HOST_SEV_SNP from being enabled (in bsp_determine_snp()), making all modified logic structurally unreachable without physical bare-metal AMD hardware supporting SEV-SNP and RMPOPT.", "WorthFuzzing": false }
27/1	2026/09/10 22:54	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)