FAILED: patch "[PATCH] KVM: SVM: Process ICR on AVIC IPI delivery failure due to" failed to apply to 5.15-stable tree

[<gregkh@xxxxxxxxxxxxxxxxxxx>]

The patch below does not apply to the 5.15-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 <stable@xxxxxxxxxxxxxxx>.

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-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 5aede752a839904059c2b5d68be0dc4501c6c15f
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@xxxxxxxxxxxxxxx>' --in-reply-to '167812341322173@xxxxxxxxx' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

5aede752a839 ("KVM: SVM: Process ICR on AVIC IPI delivery failure due to invalid target")
b51818afdc1d ("KVM: SVM: Don't rewrite guest ICR on AVIC IPI virtualization failure")
dd4589eee99d ("Revert "svm: Add warning message for AVIC IPI invalid target"")

thanks,

greg k-h

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

>From 5aede752a839904059c2b5d68be0dc4501c6c15f Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@xxxxxxxxxx>
Date: Fri, 6 Jan 2023 01:12:37 +0000
Subject: [PATCH] KVM: SVM: Process ICR on AVIC IPI delivery failure due to
 invalid target

Emulate ICR writes on AVIC IPI failures due to invalid targets using the
same logic as failures due to invalid types.  AVIC acceleration fails if
_any_ of the targets are invalid, and crucially VM-Exits before sending
IPIs to targets that _are_ valid.  In logical mode, the destination is a
bitmap, i.e. a single IPI can target multiple logical IDs.  Doing nothing
causes KVM to drop IPIs if at least one target is valid and at least one
target is invalid.

Fixes: 18f40c53e10f ("svm: Add VMEXIT handlers for AVIC")
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Message-Id: <20230106011306.85230-5-seanjc@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>

diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 712330b80891..3b2c88b168ba 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -502,14 +502,18 @@ int avic_incomplete_ipi_interception(struct kvm_vcpu *vcpu)
 	trace_kvm_avic_incomplete_ipi(vcpu->vcpu_id, icrh, icrl, id, index);
 
 	switch (id) {
+	case AVIC_IPI_FAILURE_INVALID_TARGET:
 	case AVIC_IPI_FAILURE_INVALID_INT_TYPE:
 		/*
 		 * Emulate IPIs that are not handled by AVIC hardware, which
-		 * only virtualizes Fixed, Edge-Triggered INTRs.  The exit is
-		 * a trap, e.g. ICR holds the correct value and RIP has been
-		 * advanced, KVM is responsible only for emulating the IPI.
-		 * Sadly, hardware may sometimes leave the BUSY flag set, in
-		 * which case KVM needs to emulate the ICR write as well in
+		 * only virtualizes Fixed, Edge-Triggered INTRs, and falls over
+		 * if _any_ targets are invalid, e.g. if the logical mode mask
+		 * is a superset of running vCPUs.
+		 *
+		 * The exit is a trap, e.g. ICR holds the correct value and RIP
+		 * has been advanced, KVM is responsible only for emulating the
+		 * IPI.  Sadly, hardware may sometimes leave the BUSY flag set,
+		 * in which case KVM needs to emulate the ICR write as well in
 		 * order to clear the BUSY flag.
 		 */
 		if (icrl & APIC_ICR_BUSY)
@@ -525,8 +529,6 @@ int avic_incomplete_ipi_interception(struct kvm_vcpu *vcpu)
 		 */
 		avic_kick_target_vcpus(vcpu->kvm, apic, icrl, icrh, index);
 		break;
-	case AVIC_IPI_FAILURE_INVALID_TARGET:
-		break;
 	case AVIC_IPI_FAILURE_INVALID_BACKING_PAGE:
 		WARN_ONCE(1, "Invalid backing page\n");
 		break;