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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: vD9EKBf5CGRbvC3ifO9/h3cno9+9hyamcezOV68Y4GpjH14Z1hJE1I45bA2HBb3LTzjjX27gM/LKMPhIartq2Jc/Ky1rSdRqf0oPf8s2KVW/fHs4fY2zwyuMKT9tgMUMn7SbPQPxHDYhLPYaDh+yms5BsO74pqpmj0PduFrN3uswz6ogZZT1zWsVArJpDYJPAifKr2HiUKEm9dBdnlctmQ+HQk/Ye24Q/n2ZsaJrOVmbWHHLclhZqyW+968hTUtqD8DuRNaf1KVtvCz4hBvkIfRQrlqjHENEI9sBB+85kK4Nq5ErgwPBIT1ByAs2H3EpPGXMDKAYXu6l4BPck71MdAL+ctyoLZc7pqYucryilDZASREq0KPhFMZQKXJUt8MoORoXbtYxLRtwPwf0iA3cK3sHluS4ooStSGbZOsnDR/g4oWGu+lNLHdG0e7mN5r8b X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Mar 2026 04:56:45.3204 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 5ae39774-8868-4a44-30c3-08de7f2a984f X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: SN1PEPF00026367.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB6541 On 3/11/2026 2:48 AM, Sean Christopherson wrote: > Add "do no harm" testing of EFER, CR0, CR4, and CR8 for SEV+ guests to > verify that the guest can read and write the registers, without hitting > e.g. a #VC on SEV-ES guests due to KVM incorrectly trying to intercept a > register. > > Signed-off-by: Sean Christopherson > --- > .../selftests/kvm/include/x86/processor.h | 23 ++++++++++++++ > .../selftests/kvm/x86/sev_smoke_test.c | 30 +++++++++++++++++++ > 2 files changed, 53 insertions(+) > > diff --git a/tools/testing/selftests/kvm/include/x86/processor.h b/tools/testing/selftests/kvm/include/x86/processor.h > index 4ebae4269e68..469a22122157 100644 > --- a/tools/testing/selftests/kvm/include/x86/processor.h > +++ b/tools/testing/selftests/kvm/include/x86/processor.h > @@ -557,6 +557,11 @@ static inline uint64_t get_cr0(void) > return cr0; > } > > +static inline void set_cr0(uint64_t val) > +{ > + __asm__ __volatile__("mov %0, %%cr0" : : "r" (val) : "memory"); > +} > + > static inline uint64_t get_cr3(void) > { > uint64_t cr3; > @@ -566,6 +571,11 @@ static inline uint64_t get_cr3(void) > return cr3; > } > > +static inline void set_cr3(uint64_t val) > +{ > + __asm__ __volatile__("mov %0, %%cr3" : : "r" (val) : "memory"); > +} > + > static inline uint64_t get_cr4(void) > { > uint64_t cr4; > @@ -580,6 +590,19 @@ static inline void set_cr4(uint64_t val) > __asm__ __volatile__("mov %0, %%cr4" : : "r" (val) : "memory"); > } > > +static inline uint64_t get_cr8(void) > +{ > + uint64_t cr8; > + > + __asm__ __volatile__("mov %%cr8, %[cr8]" : [cr8]"=r"(cr8)); > + return cr8; > +} > + > +static inline void set_cr8(uint64_t val) > +{ > + __asm__ __volatile__("mov %0, %%cr8" : : "r" (val) : "memory"); > +} > + > static inline void set_idt(const struct desc_ptr *idt_desc) > { > __asm__ __volatile__("lidt %0"::"m"(*idt_desc)); > diff --git a/tools/testing/selftests/kvm/x86/sev_smoke_test.c b/tools/testing/selftests/kvm/x86/sev_smoke_test.c > index 86ad1c7d068f..8bd37a476f15 100644 > --- a/tools/testing/selftests/kvm/x86/sev_smoke_test.c > +++ b/tools/testing/selftests/kvm/x86/sev_smoke_test.c > @@ -13,6 +13,30 @@ > #include "linux/psp-sev.h" > #include "sev.h" > > +static void guest_sev_test_msr(uint32_t msr) > +{ > + uint64_t val = rdmsr(msr); > + > + wrmsr(msr, val); > + GUEST_ASSERT(val == rdmsr(msr)); > +} > + > +#define guest_sev_test_reg(reg) \ > +do { \ > + uint64_t val = get_##reg(); \ > + \ > + set_##reg(val); \ > + GUEST_ASSERT(val == get_##reg()); \ > +} while (0) > + > +static void guest_sev_test_regs(void) > +{ > + guest_sev_test_msr(MSR_EFER); > + guest_sev_test_reg(cr0); > + guest_sev_test_reg(cr3); > + guest_sev_test_reg(cr4); > + guest_sev_test_reg(cr8); > +} > > #define XFEATURE_MASK_X87_AVX (XFEATURE_MASK_FP | XFEATURE_MASK_SSE | XFEATURE_MASK_YMM) > > @@ -24,6 +48,8 @@ static void guest_snp_code(void) > GUEST_ASSERT(sev_msr & MSR_AMD64_SEV_ES_ENABLED); > GUEST_ASSERT(sev_msr & MSR_AMD64_SEV_SNP_ENABLED); > > + guest_sev_test_regs(); > + > wrmsr(MSR_AMD64_SEV_ES_GHCB, GHCB_MSR_TERM_REQ); > vmgexit(); > } > @@ -34,6 +60,8 @@ static void guest_sev_es_code(void) > GUEST_ASSERT(rdmsr(MSR_AMD64_SEV) & MSR_AMD64_SEV_ENABLED); > GUEST_ASSERT(rdmsr(MSR_AMD64_SEV) & MSR_AMD64_SEV_ES_ENABLED); > > + guest_sev_test_regs(); > + > /* > * TODO: Add GHCB and ucall support for SEV-ES guests. For now, simply > * force "termination" to signal "done" via the GHCB MSR protocol. > @@ -47,6 +75,8 @@ static void guest_sev_code(void) > GUEST_ASSERT(this_cpu_has(X86_FEATURE_SEV)); > GUEST_ASSERT(rdmsr(MSR_AMD64_SEV) & MSR_AMD64_SEV_ENABLED); > > + guest_sev_test_regs(); > + > GUEST_DONE(); > } > Tested this on my machine: # selftests: kvm: sev_smoke_test # Random seed: 0x6b8b4567 ok 81 selftests: kvm: sev_smoke_test Tested-by: Srikanth Aithal