From 1797e00bf802d64b859ea18505087daad92019c8 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 29 May 2026 20:35:43 +0200 Subject: [PATCH] KVM: SEV: Don't terminate SNP VMs on #VMGEXIT without a registered GHCB If the guest attempts a non-MSR #VMGEXIT without the registered GHCB, return a GHCB_HV_RESP_MALFORMED_INPUT+GHCB_ERR_NOT_REGISTERED error to the guest instead of exiting KVM_RUN with -EINVAL (and in likelihood killing the VM). KVM has already mapped the requested GHCB, i.e. can cleanly report an error, and so exiting with -EINVAL is completely unjustified. Fixes: 0c76b1d08280 ("KVM: SEV: Add support to handle GHCB GPA register VMGEXIT") Cc: stable@vger.kernel.org Reviewed-by: Tom Lendacky Reviewed-by: Michael Roth Signed-off-by: Sean Christopherson Message-ID: <20260501202250.2115252-19-seanjc@google.com> Signed-off-by: Paolo Bonzini Message-ID: <20260529183549.1104619-19-pbonzini@redhat.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/sev.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 6c6a6d663e296..7c2ebc81306f2 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -4520,9 +4520,12 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu) sev_es_sync_from_ghcb(svm); /* SEV-SNP guest requires that the GHCB GPA must be registered */ - if (is_sev_snp_guest(vcpu) && !ghcb_gpa_is_registered(svm, ghcb_gpa)) { - vcpu_unimpl(&svm->vcpu, "vmgexit: GHCB GPA [%#llx] is not registered.\n", ghcb_gpa); - return -EINVAL; + if (is_sev_snp_guest(vcpu) && + !ghcb_gpa_is_registered(svm, control->ghcb_gpa)) { + vcpu_unimpl(vcpu, "vmgexit: GHCB GPA [%#llx] is not registered.\n", + control->ghcb_gpa); + svm_vmgexit_bad_input(svm, GHCB_ERR_NOT_REGISTERED); + return 1; } ret = sev_es_validate_vmgexit(svm); -- 2.47.3