FAILED: patch "[PATCH] KVM: SEV: Don't terminate SNP VMs on #VMGEXIT without a" failed to apply to 6.18-stable tree

The patch below does not apply to the 6.18-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y
git checkout FETCH_HEAD
git cherry-pick -x 1797e00bf802d64b859ea18505087daad92019c8
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026071620-sporting-snowdrop-2d52@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 1797e00bf802d64b859ea18505087daad92019c8 Mon Sep 17 00:00:00 2001
From: Sean Christopherson <[email protected]>
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.

Message-ID: <[email protected]>

Message-ID: <[email protected]>

index 6c6a6d663e29..7c2ebc81306f 100644
@@ -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);