[PATCH 02/15] KVM: arm64: vgic: Use xarray to find LPI in vgic_get_lpi()

Oliver Upton
2024-01-24T20:49:26Z

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.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
arch/arm64/kvm/vgic/vgic.c | 19 +++++--------------
1 file changed, 5 insertions(+), 14 deletions(-)

diff --git a/arch/arm64/kvm/vgic/vgic.c b/arch/arm64/kvm/vgic/vgic.c
index c126014f8395..d90c42ff051d 100644
--- a/arch/arm64/kvm/vgic/vgic.c
+++ b/arch/arm64/kvm/vgic/vgic.c
@@ -54,8 +54,9 @@ 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)
{
@@ -65,20 +66,10 @@ 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;
--
2.43.0.429.g432eaa2c6b-goog