KVM: arm64: vgic: Use xarray to find LPI in vgic_get_lpi()

Iterating over the LPI linked-list is less than ideal when the desired
index is already known. Use the INTID to index the LPI xarray instead.

Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240221054253.3848076-3-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

diff --git a/arch/arm64/kvm/vgic/vgic.c b/arch/arm64/kvm/vgic/vgic.c
index 92e4d2fea3652e391d678e887e33edbf032cc503..7d17dbc8f5dcaaa23c41f5c53e9714d394015b15 100644 (file)
--- a/arch/arm64/kvm/vgic/vgic.c
+++ b/arch/arm64/kvm/vgic/vgic.c
@@ -55,8 +55,9 @@ struct vgic_global kvm_vgic_global_state __ro_after_init = {
  */
 
 /*
- * Iterate over the VM's list of mapped LPIs to find the one with a
- * matching interrupt ID and return a reference to the IRQ structure.
+ * Index the VM's xarray of mapped LPIs and return a reference to the IRQ
+ * structure. The caller is expected to call vgic_put_irq() later once it's
+ * finished with the IRQ.
  */
 static struct vgic_irq *vgic_get_lpi(struct kvm *kvm, u32 intid)
 {
@@ -66,20 +67,10 @@ static struct vgic_irq *vgic_get_lpi(struct kvm *kvm, u32 intid)
 
        raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);
 
-       list_for_each_entry(irq, &dist->lpi_list_head, lpi_list) {
-               if (irq->intid != intid)
-                       continue;
-
-               /*
-                * This increases the refcount, the caller is expected to
-                * call vgic_put_irq() later once it's finished with the IRQ.
-                */
+       irq = xa_load(&dist->lpi_xa, intid);
+       if (irq)
                vgic_get_irq_kref(irq);
-               goto out_unlock;
-       }
-       irq = NULL;
 
-out_unlock:
        raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
 
        return irq;