[PATCH 4/6] KVM: SEV: WARN if SEV-ES is marked active but SEV is not

From: Sean Christopherson
Date: Tue Nov 09 2021 - 16:53:27 EST


WARN if the VM is tagged as SEV-ES but not SEV. KVM relies on SEV and
SEV-ES being set atomically, and guards common flows with "is SEV", i.e.
observing SEV-ES without SEV means KVM has a fatal bug.

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/svm/svm.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 0d7bbe548ac3..a345f557be4a 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -242,7 +242,7 @@ static inline bool sev_es_guest(struct kvm *kvm)
#ifdef CONFIG_KVM_AMD_SEV
struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;

- return sev_guest(kvm) && sev->es_active;
+ return sev->es_active && !WARN_ON_ONCE(!sev->active);
#else
return false;
#endif
--
2.34.0.rc0.344.g81b53c2807-goog