[PATCH v5 9/9] KVM: selftests: Add a basic SEV-SNP smoke test

Pratik R. Sampat
2025-01-23T22:02:56Z

Extend sev_smoke_test to also run a minimal SEV-SNP smoke test that
initializes and sets up private memory regions required to run a simple
SEV-SNP guest.

Similar to its SEV-ES smoke test counterpart, this also does not
support GHCB and ucall yet and uses the GHCB MSR protocol to trigger an
exit of the type KVM_EXIT_SYSTEM_EVENT.

Signed-off-by: Pratik R. Sampat <prsampat@amd.com>
---
.../selftests/kvm/x86/sev_smoke_test.c | 42 +++++++++++++++++++
1 file changed, 42 insertions(+)

diff --git a/tools/testing/selftests/kvm/x86/sev_smoke_test.c b/tools/testing/selftests/kvm/x86/sev_smoke_test.c
index 3a36cd3ca151..4fcd0f6290ae 100644
--- a/tools/testing/selftests/kvm/x86/sev_smoke_test.c
+++ b/tools/testing/selftests/kvm/x86/sev_smoke_test.c
@@ -16,6 +16,18 @@

#define XFEATURE_MASK_X87_AVX (XFEATURE_MASK_FP | XFEATURE_MASK_SSE | XFEATURE_MASK_YMM)

+static void guest_snp_code(void)
+{
+ uint64_t sev_msr = rdmsr(MSR_AMD64_SEV);
+
+ GUEST_ASSERT(sev_msr & MSR_AMD64_SEV_ENABLED);
+ GUEST_ASSERT(sev_msr & MSR_AMD64_SEV_ES_ENABLED);
+ GUEST_ASSERT(sev_msr & MSR_AMD64_SEV_SNP_ENABLED);
+
+ wrmsr(MSR_AMD64_SEV_ES_GHCB, GHCB_MSR_TERM_REQ);
+ VMGEXIT();
+}
+
static void guest_sev_es_code(void)
{
/* TODO: Check CPUID after GHCB-based hypercall support is added. */
@@ -157,11 +169,21 @@ static void test_sev_es(uint64_t policy)
__test_sev(guest_sev_es_code, KVM_X86_SEV_ES_VM, policy);
}

+static void test_snp(uint64_t policy)
+{
+ __test_sev(guest_snp_code, KVM_X86_SNP_VM, policy);
+}
+
static void test_sync_vmsa_sev_es(uint64_t policy)
{
__test_sync_vmsa(KVM_X86_SEV_ES_VM, policy);
}

+static void test_sync_vmsa_snp(uint64_t policy)
+{
+ __test_sync_vmsa(KVM_X86_SNP_VM, policy);
+}
+
static void guest_shutdown_code(void)
{
struct desc_ptr idt;
@@ -195,6 +217,11 @@ static void test_sev_es_shutdown(uint64_t policy)
__test_sev_shutdown(KVM_X86_SEV_ES_VM, SEV_POLICY_ES);
}

+static void test_snp_shutdown(uint64_t policy)
+{
+ __test_sev_shutdown(KVM_X86_SNP_VM, policy);
+}
+
int main(int argc, char *argv[])
{
const u64 xf_mask = XFEATURE_MASK_X87_AVX;
@@ -217,5 +244,20 @@ int main(int argc, char *argv[])
}
}

+ if (kvm_cpu_has(X86_FEATURE_SNP)) {
+ uint64_t snp_policy = snp_default_policy();
+
+ test_snp(snp_policy);
+ /* Test minimum firmware level */
+ test_snp(snp_policy | SNP_FW_VER_MAJOR(SNP_MIN_API_MAJOR) |
+ SNP_FW_VER_MINOR(SNP_MIN_API_MINOR));
+
+ test_snp_shutdown(snp_policy);
+
+ if (kvm_has_cap(KVM_CAP_XCRS) &&
+ (xgetbv(0) & kvm_cpu_supported_xcr0() & xf_mask) == xf_mask)
+ test_sync_vmsa_snp(snp_policy);
+ }
+
return 0;
}
--
2.43.0