Re: [PATCH v3 04/10] KVM: arm64: vgic-its: Walk the LPI xarray in vgic_copy_lpi_list()

Zenghui Yu
2024-02-18T08:47:07Z

On 2024/2/17 2:41, Oliver Upton wrote:
> Start iterating the LPI xarray in anticipation of removing the LPI
> linked-list.
>
> Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
> ---
> arch/arm64/kvm/vgic/vgic-its.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c
> index fb2d3c356984..9ce2edfadd11 100644
> --- a/arch/arm64/kvm/vgic/vgic-its.c
> +++ b/arch/arm64/kvm/vgic/vgic-its.c
> @@ -335,6 +335,7 @@ 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 +354,9 @@ 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, INTERRUPT_ID_BITS_ITS) {

We should use '1 << INTERRUPT_ID_BITS_ITS - 1' to represent the maximum
LPI interrupt ID.

> if (i == irq_count)
> break;
> /* We don't need to "get" the IRQ, as we hold the list lock. */
> @@ -361,6 +364,8 @@ 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;

Thanks,
Zenghui