KVM: arm/arm64: vgic: Add __vgic_put_lpi_locked primitive

Our LPI translation cache needs to be able to drop the refcount
on an LPI whilst already holding the lpi_list_lock.

Let's add a new primitive for this.
Tested-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>

virt/kvm/arm/vgic/vgic.c

@@ -119,6 +119,22 @@ static void vgic_irq_release(struct kref *ref)
 {
 }
 
+/*
+ * Drop the refcount on the LPI. Must be called with lpi_list_lock held.
+ */
+void __vgic_put_lpi_locked(struct kvm *kvm, struct vgic_irq *irq)
+{
+	struct vgic_dist *dist = &kvm->arch.vgic;
+
+	if (!kref_put(&irq->refcount, vgic_irq_release))
+		return;
+
+	list_del(&irq->lpi_list);
+	dist->lpi_list_count--;
+
+	kfree(irq);
+}
+
 void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq)
 {
 	struct vgic_dist *dist = &kvm->arch.vgic;
@@ -128,16 +144,8 @@ void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq)
 		return;
 
 	raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);
-	if (!kref_put(&irq->refcount, vgic_irq_release)) {
-		raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
-		return;
-	};
-
-	list_del(&irq->lpi_list);
-	dist->lpi_list_count--;
+	__vgic_put_lpi_locked(kvm, irq);
 	raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
-
-	kfree(irq);
 }
 
 void vgic_flush_pending_lpis(struct kvm_vcpu *vcpu)

virt/kvm/arm/vgic/vgic.h

@@ -161,6 +161,7 @@ vgic_get_mmio_region(struct kvm_vcpu *vcpu, struct vgic_io_device *iodev,
 		     gpa_t addr, int len);
 struct vgic_irq *vgic_get_irq(struct kvm *kvm, struct kvm_vcpu *vcpu,
 			      u32 intid);
+void __vgic_put_lpi_locked(struct kvm *kvm, struct vgic_irq *irq);
 void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq);
 bool vgic_get_phys_line_level(struct vgic_irq *irq);
 void vgic_irq_set_phys_pending(struct vgic_irq *irq, bool pending);