Hi Peter,

On 7/9/2024 1:29 PM, Peter Gonda wrote:

Regression test for ae20eef5 ("KVM: SVM: Update SEV-ES shutdown intercepts with more metadata"). Test confirms userspace is correctly indicated of a guest shutdown not previous behavior of an EINVAL from KVM_RUN.

Cc: Paolo Bonzini pbonzini@redhat.com Cc: Sean Christopherson seanjc@google.com Cc: Alper Gun alpergun@google.com Cc: Tom Lendacky thomas.lendacky@amd.com Cc: Michael Roth michael.roth@amd.com Cc: kvm@vger.kernel.org Cc: linux-kselftest@vger.kernel.org Signed-off-by: Peter Gonda pgonda@google.com

Tested-by: Pratik R. Sampat pratikrajesh.sampat@amd.com

---

.../selftests/kvm/x86_64/sev_smoke_test.c | 26 +++++++++++++++++++ 1 file changed, 26 insertions(+)

diff --git a/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c b/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c index 7c70c0da4fb74..04f24d5f09877 100644 --- a/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c +++ b/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c @@ -160,6 +160,30 @@ static void test_sev(void *guest_code, uint64_t policy) kvm_vm_free(vm); } +static void guest_shutdown_code(void) +{

• __asm__ __volatile__("ud2");

+}

+static void test_sev_es_shutdown(void) +{

• struct kvm_vcpu *vcpu;
• struct kvm_vm *vm;
• uint32_t type = KVM_X86_SEV_ES_VM;
• vm = vm_sev_create_with_one_vcpu(type, guest_shutdown_code, &vcpu);
• vm_sev_launch(vm, SEV_POLICY_ES, NULL);
• vcpu_run(vcpu);
• TEST_ASSERT(vcpu->run->exit_reason == KVM_EXIT_SHUTDOWN,

•     "Wanted SHUTDOWN, got %s",
  

•     exit_reason_str(vcpu->run->exit_reason));
  

• kvm_vm_free(vm);

+}

I guess this case also applies to SNP. So maybe once this patch is queued up I could spin another patch in my SNP kselftest patch series that parameterizes this function to test SNP as well.

Thanks! Pratik

int main(int argc, char *argv[]) { TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_SEV)); @@ -171,6 +195,8 @@ int main(int argc, char *argv[]) test_sev(guest_sev_es_code, SEV_POLICY_ES | SEV_POLICY_NO_DBG); test_sev(guest_sev_es_code, SEV_POLICY_ES);

• test_sev_es_shutdown();
  

• if (kvm_has_cap(KVM_CAP_XCRS) && (xgetbv(0) & XFEATURE_MASK_X87_AVX) == XFEATURE_MASK_X87_AVX) { test_sync_vmsa(0);

On Tue, Jul 09, 2024, Peter Gonda wrote:

Regression test for ae20eef5 ("KVM: SVM: Update SEV-ES shutdown intercepts with more metadata"). Test confirms userspace is correctly indicated of a guest shutdown not previous behavior of an EINVAL from KVM_RUN.

Cc: Paolo Bonzini pbonzini@redhat.com Cc: Sean Christopherson seanjc@google.com Cc: Alper Gun alpergun@google.com Cc: Tom Lendacky thomas.lendacky@amd.com Cc: Michael Roth michael.roth@amd.com Cc: kvm@vger.kernel.org Cc: linux-kselftest@vger.kernel.org Signed-off-by: Peter Gonda pgonda@google.com

---

.../selftests/kvm/x86_64/sev_smoke_test.c | 26 +++++++++++++++++++ 1 file changed, 26 insertions(+)

diff --git a/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c b/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c index 7c70c0da4fb74..04f24d5f09877 100644 --- a/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c +++ b/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c @@ -160,6 +160,30 @@ static void test_sev(void *guest_code, uint64_t policy) kvm_vm_free(vm); } +static void guest_shutdown_code(void) +{

• __asm__ __volatile__("ud2");

Heh, this passes by dumb luck, not because the #UD itself causes a SHUTDOWN. It _looks_ like the #UD causes a shutdown, because KVM will always see the original guest RIP, but the shutdown actually occurs somewhere in the ucall_assert() in route_exception().

Now that x86 selftests install an IDT and exception handlers by default, it's actually quite hard to induce shutdown. Ok, not "hard", but it requires more work than simply generating a #UD.

I'll add this as fixup when applying:

diff --git a/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c b/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c index 04f24d5f0987..2e9197eb1652 100644 --- a/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c +++ b/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c @@ -162,6 +162,12 @@ static void test_sev(void *guest_code, uint64_t policy)

static void guest_shutdown_code(void) { + struct desc_ptr idt; + + /* Clobber the IDT so that #UD is guaranteed to trigger SHUTDOWN. */ + memset(&idt, 0, sizeof(idt)); + __asm__ __volatile__("lidt %0" :: "m"(idt)); + __asm__ __volatile__("ud2"); }