KVM: x86: ignore SIPIs that are received while not in wait-for-sipi state

In the commit 1c96dcce
("KVM: x86: fix apic_accept_events vs check_nested_events"),

we accidently started latching SIPIs that are received while the cpu is not
waiting for them.

This causes vCPUs to never enter a halted state.

Fixes: 1c96dcce ("KVM: x86: fix apic_accept_events vs check_nested_events")
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20201203143319.159394-2-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/lapic.c

@@ -2892,14 +2892,15 @@ void kvm_apic_accept_events(struct kvm_vcpu *vcpu)
 		else
 			vcpu->arch.mp_state = KVM_MP_STATE_INIT_RECEIVED;
 	}
-	if (test_bit(KVM_APIC_SIPI, &pe) &&
-	    vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED) {
+	if (test_bit(KVM_APIC_SIPI, &pe)) {
 		clear_bit(KVM_APIC_SIPI, &apic->pending_events);
-		/* evaluate pending_events before reading the vector */
-		smp_rmb();
-		sipi_vector = apic->sipi_vector;
-		kvm_vcpu_deliver_sipi_vector(vcpu, sipi_vector);
-		vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
+		if (vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED) {
+			/* evaluate pending_events before reading the vector */
+			smp_rmb();
+			sipi_vector = apic->sipi_vector;
+			kvm_vcpu_deliver_sipi_vector(vcpu, sipi_vector);
+			vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
+		}
 	}
 }