KVM: arm/arm64: vgic: Add LPI translation cache definition

Add the basic data structure that expresses an MSI to LPI
translation as well as the allocation/release hooks.

The size of the cache is arbitrarily defined as 16*nr_vcpus.
Tested-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>

include/kvm/arm_vgic.h

@@ -249,6 +249,9 @@ struct vgic_dist {
 	struct list_head	lpi_list_head;
 	int			lpi_list_count;
 
+	/* LPI translation cache */
+	struct list_head	lpi_translation_cache;
+
 	/* used by vgic-debug */
 	struct vgic_state_iter *iter;
 

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

@@ -53,6 +53,7 @@ void kvm_vgic_early_init(struct kvm *kvm)
 	struct vgic_dist *dist = &kvm->arch.vgic;
 
 	INIT_LIST_HEAD(&dist->lpi_list_head);
+	INIT_LIST_HEAD(&dist->lpi_translation_cache);
 	raw_spin_lock_init(&dist->lpi_list_lock);
 }
 
@@ -294,6 +295,7 @@ int vgic_init(struct kvm *kvm)
 	}
 
 	if (vgic_has_its(kvm)) {
+		vgic_lpi_translation_cache_init(kvm);
 		ret = vgic_v4_init(kvm);
 		if (ret)
 			goto out;
@@ -335,6 +337,9 @@ static void kvm_vgic_dist_destroy(struct kvm *kvm)
 		INIT_LIST_HEAD(&dist->rd_regions);
 	}
 
+	if (vgic_has_its(kvm))
+		vgic_lpi_translation_cache_destroy(kvm);
+
 	if (vgic_supports_direct_msis(kvm))
 		vgic_v4_teardown(kvm);
 }

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

@@ -138,6 +138,14 @@ struct its_ite {
 	u32 event_id;
 };
 
+struct vgic_translation_cache_entry {
+	struct list_head	entry;
+	phys_addr_t		db;
+	u32			devid;
+	u32			eventid;
+	struct vgic_irq		*irq;
+};
+
 /**
  * struct vgic_its_abi - ITS abi ops and settings
  * @cte_esz: collection table entry size
@@ -1657,6 +1665,45 @@ static int vgic_register_its_iodev(struct kvm *kvm, struct vgic_its *its,
 	return ret;
 }
 
+/* Default is 16 cached LPIs per vcpu */
+#define LPI_DEFAULT_PCPU_CACHE_SIZE	16
+
+void vgic_lpi_translation_cache_init(struct kvm *kvm)
+{
+	struct vgic_dist *dist = &kvm->arch.vgic;
+	unsigned int sz;
+	int i;
+
+	if (!list_empty(&dist->lpi_translation_cache))
+		return;
+
+	sz = atomic_read(&kvm->online_vcpus) * LPI_DEFAULT_PCPU_CACHE_SIZE;
+
+	for (i = 0; i < sz; i++) {
+		struct vgic_translation_cache_entry *cte;
+
+		/* An allocation failure is not fatal */
+		cte = kzalloc(sizeof(*cte), GFP_KERNEL);
+		if (WARN_ON(!cte))
+			break;
+
+		INIT_LIST_HEAD(&cte->entry);
+		list_add(&cte->entry, &dist->lpi_translation_cache);
+	}
+}
+
+void vgic_lpi_translation_cache_destroy(struct kvm *kvm)
+{
+	struct vgic_dist *dist = &kvm->arch.vgic;
+	struct vgic_translation_cache_entry *cte, *tmp;
+
+	list_for_each_entry_safe(cte, tmp,
+				 &dist->lpi_translation_cache, entry) {
+		list_del(&cte->entry);
+		kfree(cte);
+	}
+}
+
 #define INITIAL_BASER_VALUE						  \
 	(GIC_BASER_CACHEABILITY(GITS_BASER, INNER, RaWb)		| \
 	 GIC_BASER_CACHEABILITY(GITS_BASER, OUTER, SameAsInner)		| \
@@ -1685,6 +1732,8 @@ static int vgic_its_create(struct kvm_device *dev, u32 type)
 			kfree(its);
 			return ret;
 		}
+
+		vgic_lpi_translation_cache_init(dev->kvm);
 	}
 
 	mutex_init(&its->its_lock);

virt/kvm/arm/vgic/vgic.h

@@ -307,6 +307,8 @@ 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);
+void vgic_lpi_translation_cache_init(struct kvm *kvm);
+void vgic_lpi_translation_cache_destroy(struct kvm *kvm);
 
 bool vgic_supports_direct_msis(struct kvm *kvm);
 int vgic_v4_init(struct kvm *kvm);