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KVM: arm64: vgic-its: Maintain a translation cache per ITS

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Within the context of a single ITS, it is possible to use an xarray to
cache the device ID & event ID translation to a particular irq
descriptor. Take advantage of this to build a translation cache capable
of fitting all valid translations for a given ITS.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240422200158.2606761-9-oliver.upton@linux.dev
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Oliver Upton 2024-04-22 20:01:47 +00:00 committed by Marc Zyngier
parent c09c8ab99a
commit 8201d1028c
2 changed files with 42 additions and 1 deletions
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37
arch/arm64/kvm/vgic/vgic-its.c
View file

@ -511,6 +511,11 @@ static unsigned long vgic_mmio_read_its_idregs(struct kvm *kvm,
return 0;
}
static unsigned long vgic_its_cache_key(u32 devid, u32 eventid)
{
return (((unsigned long)devid) << VITS_TYPER_IDBITS) | eventid;
}
static struct vgic_irq *__vgic_its_check_cache(struct vgic_dist *dist,
phys_addr_t db,
u32 devid, u32 eventid)
@ -564,8 +569,10 @@ static void vgic_its_cache_translation(struct kvm *kvm, struct vgic_its *its,
u32 devid, u32 eventid,
struct vgic_irq *irq)
{
unsigned long cache_key = vgic_its_cache_key(devid, eventid);
struct vgic_dist *dist = &kvm->arch.vgic;
struct vgic_translation_cache_entry *cte;
struct vgic_irq *old;
unsigned long flags;
phys_addr_t db;
@ -604,6 +611,15 @@ static void vgic_its_cache_translation(struct kvm *kvm, struct vgic_its *its,
* its_lock, as the ITE (and the reference it holds) cannot be freed.
*/
lockdep_assert_held(&its->its_lock);
/*
* Yes, two references are necessary at the moment:
* - One for the global LPI translation cache
* - Another for the translation cache belonging to @its
*
* This will soon disappear.
*/
vgic_get_irq_kref(irq);
vgic_get_irq_kref(irq);
cte->db = db;
@ -613,6 +629,16 @@ static void vgic_its_cache_translation(struct kvm *kvm, struct vgic_its *its,
/* 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);
/*
* The per-ITS cache is a perfect cache, so it may already have an
* identical translation even if it were missing from the global
* cache. Ensure we don't leak a reference if that is the case.
*/
old = xa_store(&its->translation_cache, cache_key, irq, GFP_KERNEL_ACCOUNT);
if (old)
vgic_put_irq(kvm, old);
out:
raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
@ -623,7 +649,8 @@ static void vgic_its_invalidate_cache(struct vgic_its *its)
struct kvm *kvm = its->dev->kvm;
struct vgic_dist *dist = &kvm->arch.vgic;
struct vgic_translation_cache_entry *cte;
unsigned long flags;
unsigned long flags, idx;
struct vgic_irq *irq;
raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);
@ -640,6 +667,11 @@ static void vgic_its_invalidate_cache(struct vgic_its *its)
}
raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
xa_for_each(&its->translation_cache, idx, irq) {
xa_erase(&its->translation_cache, idx);
vgic_put_irq(kvm, irq);
}
}
void vgic_its_invalidate_all_caches(struct kvm *kvm)
@ -1962,6 +1994,7 @@ static int vgic_its_create(struct kvm_device *dev, u32 type)
INIT_LIST_HEAD(&its->device_list);
INIT_LIST_HEAD(&its->collection_list);
xa_init(&its->translation_cache);
dev->kvm->arch.vgic.msis_require_devid = true;
dev->kvm->arch.vgic.has_its = true;
@ -1992,6 +2025,8 @@ static void vgic_its_destroy(struct kvm_device *kvm_dev)
vgic_its_free_device_list(kvm, its);
vgic_its_free_collection_list(kvm, its);
vgic_its_invalidate_cache(its);
xa_destroy(&its->translation_cache);
mutex_unlock(&its->its_lock);
kfree(its);

6
include/kvm/arm_vgic.h
View file

@ -210,6 +210,12 @@ struct vgic_its {
struct mutex its_lock;
struct list_head device_list;
struct list_head collection_list;
/*
* Caches the (device_id, event_id) -> vgic_irq translation for
* LPIs that are mapped and enabled.
*/
struct xarray translation_cache;
};
struct vgic_state_iter;