[PATCH 5.14 060/172] KVM: nVMX: Fix nested bus lock VM exit

[Greg Kroah-Hartman]

From: Chenyi Qiang <chenyi.qiang@xxxxxxxxx>

commit 24a996ade34d00deef5dee2c33aacd8fda91ec31 upstream.

Nested bus lock VM exits are not supported yet. If L2 triggers bus lock
VM exit, it will be directed to L1 VMM, which would cause unexpected
behavior. Therefore, handle L2's bus lock VM exits in L0 directly.

Fixes: fe6b6bc802b4 ("KVM: VMX: Enable bus lock VM exit")
Signed-off-by: Chenyi Qiang <chenyi.qiang@xxxxxxxxx>
Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Reviewed-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
Message-Id: <20210914095041.29764-1-chenyi.qiang@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 arch/x86/kvm/vmx/nested.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -5898,6 +5898,12 @@ static bool nested_vmx_l0_wants_exit(str
 	case EXIT_REASON_VMFUNC:
 		/* VM functions are emulated through L2->L0 vmexits. */
 		return true;
+	case EXIT_REASON_BUS_LOCK:
+		/*
+		 * At present, bus lock VM exit is never exposed to L1.
+		 * Handle L2's bus locks in L0 directly.
+		 */
+		return true;
 	default:
 		break;
 	}