KVM: Don't mistreat edge-triggered INIT IPI as INIT de-assert. (LAPIC)

If the guest programs an IPI with level=0 (de-assert) and trig_mode=0 (edge),
it is erroneously treated as INIT de-assert and ignored, but to quote the
spec: "For this delivery mode [INIT de-assert], the level flag must be set to
0 and trigger mode flag to 1."
Signed-off-by: Julian Stecklina <js@alien8.de>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/x86/kvm/lapic.c

@@ -433,7 +433,7 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
 		break;
 
 	case APIC_DM_INIT:
-		if (level) {
+		if (!trig_mode || level) {
 			result = 1;
 			vcpu->arch.mp_state = KVM_MP_STATE_INIT_RECEIVED;
 			kvm_make_request(KVM_REQ_EVENT, vcpu);