FAILED: patch "[PATCH] KVM: VMX: Preserve negative return value in vmx_handle_exit()" failed to apply to 6.6-stable tree

The patch below does not apply to the 6.6-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-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x cef48693da1e964e9f192bfc16cd0ed287c48337
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026110459-cone-playlist-3832@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

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

From cef48693da1e964e9f192bfc16cd0ed287c48337 Mon Sep 17 00:00:00 2001
From: Xiaoyao Li <[email protected]>
Date: Wed, 19 Aug 2026 17:49:00 +0800
Subject: [PATCH] KVM: VMX: Preserve negative return value in vmx_handle_exit()
with bus lock detected

Preserve the negative return value from __vmx_handle_exit() when a bus lock is detected, instead of always overwriting it with 0.

The purpose of bus_lock_detected handling is to force a userspace exit to inform userspace that a bus lock happened. The negative return value can achieve this purpose, and changing the negative value to 0 fails to return an error to userspace. So, preserve the negative return value.

index 965141e0d4c8..6df390ae8708 100644
@@ -6864,11 +6864,12 @@ int vmx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
 	 * a bus lock in guest.
 	 */
 	if (vmx_get_exit_reason(vcpu).bus_lock_detected) {
-		if (ret > 0)
+		if (ret > 0) {
 			vcpu->run->exit_reason = KVM_EXIT_X86_BUS_LOCK;
+			ret = 0;
+		}
 
 		vcpu->run->flags |= KVM_RUN_X86_BUS_LOCK;
-		return 0;
 	}
 	return ret;
 }

[ Upstream commit cef48693da1e964e9f192bfc16cd0ed287c48337 ]

Preserve the negative return value from __vmx_handle_exit() when a bus lock is detected, instead of always overwriting it with 0.

The purpose of bus_lock_detected handling is to force a userspace exit to inform userspace that a bus lock happened. The negative return value can achieve this purpose, and changing the negative value to 0 fails to return an error to userspace. So, preserve the negative return value.

---
 arch/x86/kvm/vmx/vmx.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

index ebbb9f63beae..1846f8b3c890 100644
@@ -6620,11 +6620,12 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
 	 * a bus lock in guest.
 	 */
 	if (to_vmx(vcpu)->exit_reason.bus_lock_detected) {
-		if (ret > 0)
+		if (ret > 0) {
 			vcpu->run->exit_reason = KVM_EXIT_X86_BUS_LOCK;
+			ret = 0;
+		}
 
 		vcpu->run->flags |= KVM_RUN_X86_BUS_LOCK;
-		return 0;
 	}
 	return ret;
 }

2.53.0

Conflict on the exit_reason field due to lack of 7172c753c26a5 ("KVM: VMX: Move common fields of struct vcpu_{vmx,tdx} to a struct").