KVM: arm64: vgic: Get rid of the LPI linked-list

All readers of LPI configuration have been transitioned to use the LPI
xarray. Get rid of the linked-list altogether.
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240221054253.3848076-6-oliver.upton@linux.devSigned-off-by: Oliver Upton <oliver.upton@linux.dev>

arch/arm64/kvm/vgic/vgic-init.c

@@ -53,7 +53,6 @@ void kvm_vgic_early_init(struct kvm *kvm)
 {
 	struct vgic_dist *dist = &kvm->arch.vgic;
 
-	INIT_LIST_HEAD(&dist->lpi_list_head);
 	INIT_LIST_HEAD(&dist->lpi_translation_cache);
 	raw_spin_lock_init(&dist->lpi_list_lock);
 	xa_init_flags(&dist->lpi_xa, XA_FLAGS_LOCK_IRQ);

arch/arm64/kvm/vgic/vgic-its.c

@@ -58,7 +58,6 @@ static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid,
 		return ERR_PTR(ret);
 	}
 
-	INIT_LIST_HEAD(&irq->lpi_list);
 	INIT_LIST_HEAD(&irq->ap_list);
 	raw_spin_lock_init(&irq->irq_lock);
 
@@ -74,10 +73,8 @@ static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid,
 	 * There could be a race with another vgic_add_lpi(), so we need to
 	 * check that we don't add a second list entry with the same LPI.
 	 */
-	list_for_each_entry(oldirq, &dist->lpi_list_head, lpi_list) {
-		if (oldirq->intid != intid)
-			continue;
-
+	oldirq = xa_load(&dist->lpi_xa, intid);
+	if (oldirq) {
 		/* Someone was faster with adding this LPI, lets use that. */
 		kfree(irq);
 		irq = oldirq;
@@ -99,7 +96,6 @@ static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid,
 		goto out_unlock;
 	}
 
-	list_add_tail(&irq->lpi_list, &dist->lpi_list_head);
 	dist->lpi_list_count++;
 
 out_unlock:

arch/arm64/kvm/vgic/vgic.c

@@ -122,7 +122,6 @@ void __vgic_put_lpi_locked(struct kvm *kvm, struct vgic_irq *irq)
 	if (!kref_put(&irq->refcount, vgic_irq_release))
 		return;
 
-	list_del(&irq->lpi_list);
 	xa_erase(&dist->lpi_xa, irq->intid);
 	dist->lpi_list_count--;
 

include/kvm/arm_vgic.h

@@ -117,7 +117,6 @@ struct irq_ops {
 
 struct vgic_irq {
 	raw_spinlock_t irq_lock;	/* Protects the content of the struct */
-	struct list_head lpi_list;	/* Used to link all LPIs together */
 	struct list_head ap_list;
 
 	struct kvm_vcpu *vcpu;		/* SGIs and PPIs: The VCPU
@@ -277,7 +276,6 @@ struct vgic_dist {
 	/* Protects the lpi_list and the count value below. */
 	raw_spinlock_t		lpi_list_lock;
 	struct xarray		lpi_xa;
-	struct list_head	lpi_list_head;
 	int			lpi_list_count;
 
 	/* LPI translation cache */