From: Marc Zyngier <maz@kernel.org>
To: linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Cc: Marc Zyngier <marc.zyngier@arm.com>,
Andre Przywara <Andre.Przywara@arm.com>,
"Raslan, KarimAllah" <karahmed@amazon.de>,
"Saidi, Ali" <alisaidi@amazon.com>
Subject: [PATCH v3 08/10] KVM: arm/arm64: vgic-its: Cache successful MSI->LPI translation
Date: Thu, 25 Jul 2019 16:35:41 +0100 [thread overview]
Message-ID: <20190725153543.24386-9-maz@kernel.org> (raw)
In-Reply-To: <20190725153543.24386-1-maz@kernel.org>
From: Marc Zyngier <marc.zyngier@arm.com>
On a successful translation, preserve the parameters in the LPI
translation cache. Each translation is reusing the last slot
in the list, naturally evicting the least recently used entry.
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
virt/kvm/arm/vgic/vgic-its.c | 86 ++++++++++++++++++++++++++++++++++++
1 file changed, 86 insertions(+)
diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index d3e90a9d0a7a..e61d3ea0ab40 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -535,6 +535,90 @@ static unsigned long vgic_mmio_read_its_idregs(struct kvm *kvm,
return 0;
}
+static struct vgic_irq *__vgic_its_check_cache(struct vgic_dist *dist,
+ phys_addr_t db,
+ u32 devid, u32 eventid)
+{
+ struct vgic_translation_cache_entry *cte;
+
+ list_for_each_entry(cte, &dist->lpi_translation_cache, entry) {
+ /*
+ * If we hit a NULL entry, there is nothing after this
+ * point.
+ */
+ if (!cte->irq)
+ break;
+
+ if (cte->db != db || cte->devid != devid ||
+ cte->eventid != eventid)
+ continue;
+
+ /*
+ * Move this entry to the head, as it is the most
+ * recently used.
+ */
+ if (!list_is_first(&cte->entry, &dist->lpi_translation_cache))
+ list_move(&cte->entry, &dist->lpi_translation_cache);
+
+ return cte->irq;
+ }
+
+ return NULL;
+}
+
+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;
+ phys_addr_t db;
+
+ /* Do not cache a directly injected interrupt */
+ if (irq->hw)
+ return;
+
+ raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);
+
+ if (unlikely(list_empty(&dist->lpi_translation_cache)))
+ goto out;
+
+ /*
+ * We could have raced with another CPU caching the same
+ * translation behind our back, so let's check it is not in
+ * already
+ */
+ db = its->vgic_its_base + GITS_TRANSLATER;
+ if (__vgic_its_check_cache(dist, db, devid, eventid))
+ goto out;
+
+ /* 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 = db;
+ 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);
+
+out:
+ raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
+}
+
void vgic_its_invalidate_cache(struct kvm *kvm)
{
struct vgic_dist *dist = &kvm->arch.vgic;
@@ -578,6 +662,8 @@ 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;
}
--
2.20.1
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next prev parent reply other threads:[~2019-07-25 15:36 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-25 15:35 [PATCH v3 00/10] KVM: arm/arm64: vgic: ITS translation cache Marc Zyngier
2019-07-25 15:35 ` [PATCH v3 01/10] KVM: arm/arm64: vgic: Add LPI translation cache definition Marc Zyngier
2019-07-25 15:35 ` [PATCH v3 02/10] KVM: arm/arm64: vgic: Add __vgic_put_lpi_locked primitive Marc Zyngier
2019-07-25 15:35 ` [PATCH v3 03/10] KVM: arm/arm64: vgic-its: Add MSI-LPI translation cache invalidation Marc Zyngier
2019-07-25 15:35 ` [PATCH v3 04/10] KVM: arm/arm64: vgic-its: Invalidate MSI-LPI translation cache on specific commands Marc Zyngier
2019-07-25 15:35 ` [PATCH v3 05/10] KVM: arm/arm64: vgic-its: Invalidate MSI-LPI translation cache on disabling LPIs Marc Zyngier
2019-07-25 16:38 ` Auger Eric
2019-07-25 15:35 ` [PATCH v3 06/10] KVM: arm/arm64: vgic-its: Invalidate MSI-LPI translation cache on ITS disable Marc Zyngier
2019-07-25 16:38 ` Auger Eric
2019-07-25 15:35 ` [PATCH v3 07/10] KVM: arm/arm64: vgic-its: Invalidate MSI-LPI translation cache on vgic teardown Marc Zyngier
2019-07-25 16:37 ` Auger Eric
2019-07-25 15:35 ` Marc Zyngier [this message]
2019-07-25 15:35 ` [PATCH v3 09/10] KVM: arm/arm64: vgic-its: Check the LPI translation cache on MSI injection Marc Zyngier
2019-07-25 16:38 ` Auger Eric
2019-07-25 15:35 ` [PATCH v3 10/10] KVM: arm/arm64: vgic-irqfd: Implement kvm_arch_set_irq_inatomic Marc Zyngier
2019-07-30 17:04 ` [PATCH v3 00/10] KVM: arm/arm64: vgic: ITS translation cache Andre Przywara
2019-08-18 17:55 ` Marc Zyngier
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