KVM: arm/arm64: vgic-v4: Only perform an unmap for valid vLPIs

Before performing an unmap, let's check that what we have was
really mapped the first place.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

virt/kvm/arm/vgic/vgic-v4.c

@@ -337,8 +337,10 @@ int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int virq,
 		goto out;
 
 	WARN_ON(!(irq->hw && irq->host_irq == virq));
+	if (irq->hw) {
 		irq->hw = false;
 		ret = its_unmap_vlpi(virq);
+	}
 
 out:
 	mutex_unlock(&its->its_lock);