Hi Marc,
On 6/6/19 6:54 PM, Marc Zyngier wrote:
> On a successful translation, preserve the parameters in the LPI
> translation cache. Each translation is reusing the last slot
> in the list, naturally evincting the least recently used entry.
evicting
>
> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
> ---
> virt/kvm/arm/vgic/vgic-its.c | 41 ++++++++++++++++++++++++++++++++++++
> 1 file changed, 41 insertions(+)
>
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index 5758504fd934..bc370b6c5afa 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -538,6 +538,45 @@ static unsigned long vgic_mmio_read_its_idregs(struct kvm *kvm,
> return 0;
> }
>
> +static void vgic_its_cache_translation(struct kvm *kvm, struct vgic_its *its,
> + u32 devid, u32 eventid,
> + struct vgic_irq *irq)
> +{
> + struct vgic_dist *dist = &kvm->arch.vgic;
> + struct vgic_translation_cache_entry *cte;
> + unsigned long flags;
> +
> + /* Do not cache a directly injected interrupt */
> + if (irq->hw)
> + return;
> +
> + raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);
> +
> + /* Always reuse the last entry (LRU policy) */
> + cte = list_last_entry(&dist->lpi_translation_cache,
> + typeof(*cte), entry);
> +
> + /*
> + * Caching the translation implies having an extra reference
> + * to the interrupt, so drop the potential reference on what
> + * was in the cache, and increment it on the new interrupt.
> + */
> + if (cte->irq)
> + __vgic_put_lpi_locked(kvm, cte->irq);
> +
> + vgic_get_irq_kref(irq);
> +
> + cte->db = its->vgic_its_base + GITS_TRANSLATER;
> + cte->devid = devid;
> + cte->eventid = eventid;
> + cte->irq = irq;
> +
> + /* Move the new translation to the head of the list */
> + list_move(&cte->entry, &dist->lpi_translation_cache);
> +
> + raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
> +}
> +
> int vgic_its_resolve_lpi(struct kvm *kvm, struct vgic_its *its,
> u32 devid, u32 eventid, struct vgic_irq **irq)
> {
> @@ -558,6 +597,8 @@ int vgic_its_resolve_lpi(struct kvm *kvm, struct vgic_its *its,
> if (!vcpu->arch.vgic_cpu.lpis_enabled)
> return -EBUSY;
>
> + vgic_its_cache_translation(kvm, its, devid, eventid, ite->irq);
> +
> *irq = ite->irq;
> return 0;
> }
>
Otherwise looks good to me.
Thanks
Eric
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