KVM: arm/arm64: vITS: Add a helper to update the affinity of an LPI

In order to help integrating the vITS code with GICv4, let's add
a new helper that deals with updating the affinity of an LPI,
which will later be augmented with super duper extra GICv4
goodness.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

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

@@ -336,6 +336,15 @@ static int vgic_copy_lpi_list(struct kvm_vcpu *vcpu, u32 **intid_ptr)
 	return i;
 }
 
+static int update_affinity(struct vgic_irq *irq, struct kvm_vcpu *vcpu)
+{
+	spin_lock(&irq->irq_lock);
+	irq->target_vcpu = vcpu;
+	spin_unlock(&irq->irq_lock);
+
+	return 0;
+}
+
 /*
  * Promotes the ITS view of affinity of an ITTE (which redistributor this LPI
  * is targeting) to the VGIC's view, which deals with target VCPUs.
@@ -350,10 +359,7 @@ static void update_affinity_ite(struct kvm *kvm, struct its_ite *ite)
 		return;
 
 	vcpu = kvm_get_vcpu(kvm, ite->collection->target_addr);
-
-	spin_lock(&ite->irq->irq_lock);
-	ite->irq->target_vcpu = vcpu;
-	spin_unlock(&ite->irq->irq_lock);
+	update_affinity(ite->irq, vcpu);
 }
 
 /*
@@ -696,11 +702,7 @@ static int vgic_its_cmd_handle_movi(struct kvm *kvm, struct vgic_its *its,
 	ite->collection = collection;
 	vcpu = kvm_get_vcpu(kvm, collection->target_addr);
 
-	spin_lock(&ite->irq->irq_lock);
-	ite->irq->target_vcpu = vcpu;
-	spin_unlock(&ite->irq->irq_lock);
-
-	return 0;
+	return update_affinity(ite->irq, vcpu);
 }
 
 /*