KVM: arm/arm64: vgic-its: Check the LPI translation cache on MSI injection

When performing an MSI injection, let's first check if the translation
is already in the cache. If so, let's inject it quickly without
going through the whole translation process.
Tested-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>

virt/kvm/arm/vgic/vgic-its.c

@@ -566,6 +566,20 @@ static struct vgic_irq *__vgic_its_check_cache(struct vgic_dist *dist,
 	return NULL;
 }
 
+static struct vgic_irq *vgic_its_check_cache(struct kvm *kvm, phys_addr_t db,
+					     u32 devid, u32 eventid)
+{
+	struct vgic_dist *dist = &kvm->arch.vgic;
+	struct vgic_irq *irq;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);
+	irq = __vgic_its_check_cache(dist, db, devid, eventid);
+	raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
+
+	return irq;
+}
+
 static void vgic_its_cache_translation(struct kvm *kvm, struct vgic_its *its,
 				       u32 devid, u32 eventid,
 				       struct vgic_irq *irq)
@@ -725,6 +739,25 @@ static int vgic_its_trigger_msi(struct kvm *kvm, struct vgic_its *its,
 	return 0;
 }
 
+int vgic_its_inject_cached_translation(struct kvm *kvm, struct kvm_msi *msi)
+{
+	struct vgic_irq *irq;
+	unsigned long flags;
+	phys_addr_t db;
+
+	db = (u64)msi->address_hi << 32 | msi->address_lo;
+	irq = vgic_its_check_cache(kvm, db, msi->devid, msi->data);
+
+	if (!irq)
+		return -1;
+
+	raw_spin_lock_irqsave(&irq->irq_lock, flags);
+	irq->pending_latch = true;
+	vgic_queue_irq_unlock(kvm, irq, flags);
+
+	return 0;
+}
+
 /*
  * Queries the KVM IO bus framework to get the ITS pointer from the given
  * doorbell address.
@@ -736,6 +769,9 @@ int vgic_its_inject_msi(struct kvm *kvm, struct kvm_msi *msi)
 	struct vgic_its *its;
 	int ret;
 
+	if (!vgic_its_inject_cached_translation(kvm, msi))
+		return 1;
+
 	its = vgic_msi_to_its(kvm, msi);
 	if (IS_ERR(its))
 		return PTR_ERR(its);

virt/kvm/arm/vgic/vgic.h

@@ -308,6 +308,7 @@ int vgic_copy_lpi_list(struct kvm *kvm, struct kvm_vcpu *vcpu, u32 **intid_ptr);
 int vgic_its_resolve_lpi(struct kvm *kvm, struct vgic_its *its,
 			 u32 devid, u32 eventid, struct vgic_irq **irq);
 struct vgic_its *vgic_msi_to_its(struct kvm *kvm, struct kvm_msi *msi);
+int vgic_its_inject_cached_translation(struct kvm *kvm, struct kvm_msi *msi);
 void vgic_lpi_translation_cache_init(struct kvm *kvm);
 void vgic_lpi_translation_cache_destroy(struct kvm *kvm);
 void vgic_its_invalidate_cache(struct kvm *kvm);