KVM: arm64: vgic-its: Walk the LPI xarray in vgic_copy_lpi_list()

Start iterating the LPI xarray in anticipation of removing the LPI
linked-list.

Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240221054253.3848076-5-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c
index fb2d3c3569848bf8e6cb3a617f1800e38dc92eb7..b9874dc046088572498141686767880f5f46c8c5 100644 (file)
--- a/arch/arm64/kvm/vgic/vgic-its.c
+++ b/arch/arm64/kvm/vgic/vgic-its.c
@@ -327,6 +327,8 @@ static int update_lpi_config(struct kvm *kvm, struct vgic_irq *irq,
        return 0;
 }
 
+#define GIC_LPI_MAX_INTID      ((1 << INTERRUPT_ID_BITS_ITS) - 1)
+
 /*
  * Create a snapshot of the current LPIs targeting @vcpu, so that we can
  * enumerate those LPIs without holding any lock.
@@ -335,6 +337,7 @@ static int update_lpi_config(struct kvm *kvm, struct vgic_irq *irq,
 int vgic_copy_lpi_list(struct kvm *kvm, struct kvm_vcpu *vcpu, u32 **intid_ptr)
 {
        struct vgic_dist *dist = &kvm->arch.vgic;
+       XA_STATE(xas, &dist->lpi_xa, GIC_LPI_OFFSET);
        struct vgic_irq *irq;
        unsigned long flags;
        u32 *intids;
@@ -353,7 +356,9 @@ int vgic_copy_lpi_list(struct kvm *kvm, struct kvm_vcpu *vcpu, u32 **intid_ptr)
                return -ENOMEM;
 
        raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);
-       list_for_each_entry(irq, &dist->lpi_list_head, lpi_list) {
+       rcu_read_lock();
+
+       xas_for_each(&xas, irq, GIC_LPI_MAX_INTID) {
                if (i == irq_count)
                        break;
                /* We don't need to "get" the IRQ, as we hold the list lock. */
@@ -361,6 +366,8 @@ int vgic_copy_lpi_list(struct kvm *kvm, struct kvm_vcpu *vcpu, u32 **intid_ptr)
                        continue;
                intids[i++] = irq->intid;
        }
+
+       rcu_read_unlock();
        raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
 
        *intid_ptr = intids;