Commit 8201d102 authored by Oliver Upton's avatar Oliver Upton Committed by Marc Zyngier
Browse files

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



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: default avatarOliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240422200158.2606761-9-oliver.upton@linux.dev


Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent c09c8ab9

arch/arm64/kvm/vgic/vgic-its.c

+36 −1
Original line number Diff line number Diff line
@@ -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);

include/kvm/arm_vgic.h

+6 −0
Original line number Diff line number Diff line
@@ -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;