Bail early from svm_enable_nmi_window() for SEV-ES guests without trying
to enable single-step of the guest, as single-stepping an SEV-ES guest is
impossible and the guest is responsible for *telling* KVM when it is ready
for an new NMI to be injected.
Functionally, setting TF and RF in svm->vmcb->save.rflags is benign as the
field is ignored by hardware, but it's all kinds of confusing.
Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
Link: https://lore.kernel.org/r/20230615063757.3039121-10-aik@amd.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
if (svm_get_nmi_mask(vcpu) && !svm->awaiting_iret_completion)
return; /* IRET will cause a vm exit */
+ /*
+ * SEV-ES guests are responsible for signaling when a vCPU is ready to
+ * receive a new NMI, as SEV-ES guests can't be single-stepped, i.e.
+ * KVM can't intercept and single-step IRET to detect when NMIs are
+ * unblocked (architecturally speaking). See SVM_VMGEXIT_NMI_COMPLETE.
+ *
+ * Note, GIF is guaranteed to be '1' for SEV-ES guests as hardware
+ * ignores SEV-ES guest writes to EFER.SVME *and* CLGI/STGI are not
+ * supported NAEs in the GHCB protocol.
+ */
+ if (sev_es_guest(vcpu->kvm))
+ return;
+
if (!gif_set(svm)) {
if (vgif)
svm_set_intercept(svm, INTERCEPT_STGI);