[PATCH 2/4] selftests/kvm: check that SEV-ES VMs are allowed in SEV-SNP mode

[Tycho Andersen]

From: "Tycho Andersen (AMD)" <ty...@kernel.org>

As in the comment, check to make sure that SEV-ES VMs are allowed before
running the test. Otherwise, there is a generic:

    ==== Test Assertion Failure ====
      lib/x86/sev.c:91: !ret
      pid=3678 tid=3678 errno=5 - Input/output error
         1      0x0000000000417000: sev_vm_launch at sev.c:91 (discriminator 4)
         2      0x0000000000417d49: vm_sev_launch at sev.c:191
         3      0x0000000000402a7d: test_sev at sev_smoke_test.c:132
         4      0x000000000040328f: test_sev_smoke at sev_smoke_test.c:198
         5      0x00000000004026c8: main at sev_smoke_test.c:223
         6      0x00007fdde5c2a1c9: ?? ??:0
         7      0x00007fdde5c2a28a: ?? ??:0
         8      0x00000000004027f4: _start at ??:?
      KVM_SEV_LAUNCH_START failed, rc: -1 errno: 5 (Input/output error)

Signed-off-by: Tycho Andersen (AMD) <ty...@kernel.org>
---
 .../selftests/kvm/x86/sev_smoke_test.c        | 37 ++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/x86/sev_smoke_test.c 
b/tools/testing/selftests/kvm/x86/sev_smoke_test.c
index 86ad1c7d068f..c7fda9fc324b 100644
--- a/tools/testing/selftests/kvm/x86/sev_smoke_test.c
+++ b/tools/testing/selftests/kvm/x86/sev_smoke_test.c
@@ -213,13 +213,48 @@ static void test_sev_smoke(void *guest, uint32_t type, 
uint64_t policy)
        }
 }
 
+static bool sev_es_allowed(void)
+{
+       struct kvm_sev_launch_start launch_start = {
+               .policy = SEV_POLICY_ES,
+       };
+       struct kvm_vcpu *vcpu;
+       struct kvm_vm *vm;
+       int firmware_error, ret;
+       bool supported = true;
+
+       if (!kvm_cpu_has(X86_FEATURE_SEV_ES))
+               return false;
+
+       if (!kvm_cpu_has(X86_FEATURE_SEV_SNP))
+               return true;
+
+       /*
+        * In some cases when SEV-SNP is enabled, firmware disallows starting
+        * an SEV-ES VM. When SEV-SNP is enabled try to launch an SEV-ES, and
+        * check the underlying firmware error for this case.
+        */
+       vm = vm_sev_create_with_one_vcpu(KVM_X86_SEV_ES_VM, guest_sev_es_code,
+                                        &vcpu);
+
+       ret = __vm_sev_ioctl(vm, KVM_SEV_LAUNCH_START, &launch_start,
+                            &firmware_error);
+       if (ret == -1 && firmware_error == SEV_RET_UNSUPPORTED) {
+               pr_info("SEV-ES not supported with SNP\n");
+               supported = false;
+       }
+
+       kvm_vm_free(vm);
+       return supported;
+}
+
 int main(int argc, char *argv[])
 {
        TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_SEV));
 
        test_sev_smoke(guest_sev_code, KVM_X86_SEV_VM, 0);
 
-       if (kvm_cpu_has(X86_FEATURE_SEV_ES))
+       if (sev_es_allowed())
                test_sev_smoke(guest_sev_es_code, KVM_X86_SEV_ES_VM, 
SEV_POLICY_ES);
 
        if (kvm_cpu_has(X86_FEATURE_SEV_SNP))
-- 
2.53.0