KVM: Fix race between APIC TMR and IRR

Commit Message

Avi Kivity Dec. 29, 2009, 10:42 a.m. UTC

None

Patch

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 3063a0c..ba8c045 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -373,6 +373,12 @@  static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
 		if (unlikely(!apic_enabled(apic)))
 			break;
 
+		if (trig_mode) {
+			apic_debug("level trig mode for vector %d", vector);
+			apic_set_vector(vector, apic->regs + APIC_TMR);
+		} else
+			apic_clear_vector(vector, apic->regs + APIC_TMR);
+
 		result = !apic_test_and_set_irr(vector, apic);
 		trace_kvm_apic_accept_irq(vcpu->vcpu_id, delivery_mode,
 					  trig_mode, vector, !result);
@@ -383,11 +389,6 @@  static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
 			break;
 		}
 
-		if (trig_mode) {
-			apic_debug("level trig mode for vector %d", vector);
-			apic_set_vector(vector, apic->regs + APIC_TMR);
-		} else
-			apic_clear_vector(vector, apic->regs + APIC_TMR);
 		kvm_vcpu_kick(vcpu);
 		break;