[PATCH v4 6/9] KVM: VMX: Preserve negative return value in vmx_handle_exit() with bus lock detected

[Xiaoyao Li <xiaoyao.li@intel.com>]

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.

Fixes: fe6b6bc802b4 ("KVM: VMX: Enable bus lock VM exit")
Cc: stable@vger.kernel.org
Reported-by: sashiko-bot@kernel.org
Closes: https://lore.kernel.org/all/20260805034602.5B2BB1F000E9@smtp.kernel.org/
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
---
I'm not sure on the Closes: link, since Sashiko didn't find the VMX
issue directly.

Changes in v4
- grabbed from https://lore.kernel.org/all/20260806111923.1990562-2-xiaoyao.li@intel.com/
---
 arch/x86/kvm/vmx/vmx.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 35ac9ddffaf4..d302d0ce47f1 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6860,11 +6860,12 @@ 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;
 }
-- 
2.43.0