Message-ID: <20230906214723.4393-6-dakr@redhat.com>
Date:   Wed,  6 Sep 2023 23:47:13 +0200
From:   Danilo Krummrich <dakr@...hat.com>
To:     airlied@...il.com, daniel@...ll.ch, matthew.brost@...el.com,
        thomas.hellstrom@...ux.intel.com, sarah.walker@...tec.com,
        donald.robson@...tec.com, boris.brezillon@...labora.com,
        christian.koenig@....com, faith.ekstrand@...labora.com
Cc:     dri-devel@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, Danilo Krummrich <dakr@...hat.com>
Subject: [PATCH drm-misc-next v2 5/7] drm/gpuvm: add an abstraction for a VM / BO combination

This patch adds an abstraction layer between the drm_gpuva mappings of
a particular drm_gem_object and this GEM object itself. The abstraction
represents a combination of a drm_gem_object and drm_gpuvm. The
drm_gem_object holds a list of drm_gpuvm_bo structures (the structure
representing this abstraction), while each drm_gpuvm_bo contains list of
mappings of this GEM object.

This has multiple advantages:

1) We can use the drm_gpuvm_bo structure to attach it to various lists
   of the drm_gpuvm. This is useful for tracking external and evicted
   objects per VM, which is introduced in subsequent patches.

2) Finding mappings of a certain drm_gem_object mapped in a certain
   drm_gpuvm becomes much cheaper.

3) Drivers can derive and extend the structure to easily represent
   driver specific states of a BO for a certain GPUVM.

The idea of this abstraction was taken from amdgpu, hence the credit for
this idea goes to the developers of amdgpu.

Cc: Christian König <christian.koenig@....com>
Signed-off-by: Danilo Krummrich <dakr@...hat.com>
---
 drivers/gpu/drm/drm_gpuva_mgr.c        | 210 +++++++++++++++++++++++--
 drivers/gpu/drm/nouveau/nouveau_uvmm.c |  77 ++++++---
 include/drm/drm_gem.h                  |  48 ++++--
 include/drm/drm_gpuva_mgr.h            | 153 +++++++++++++++++-
 4 files changed, 437 insertions(+), 51 deletions(-)

diff --git a/drivers/gpu/drm/drm_gpuva_mgr.c b/drivers/gpu/drm/drm_gpuva_mgr.c
index 838277794990..da7a6e1aabe0 100644
--- a/drivers/gpu/drm/drm_gpuva_mgr.c
+++ b/drivers/gpu/drm/drm_gpuva_mgr.c
@@ -723,6 +723,161 @@ drm_gpuvm_destroy(struct drm_gpuvm *gpuvm)
 }
 EXPORT_SYMBOL_GPL(drm_gpuvm_destroy);
 
+/**
+ * drm_gpuvm_bo_create() - create a new instance of struct drm_gpuvm_bo
+ * @gpuvm: The &drm_gpuvm the @obj is mapped in.
+ * @obj: The &drm_gem_object being mapped in the @gpuvm.
+ *
+ * If provided by the driver, this function uses the &drm_gpuvm_ops
+ * vm_bo_alloc() callback to allocate.
+ *
+ * Returns: a pointer to the &drm_gpuvm_bo on success, NULL on failure
+ */
+struct drm_gpuvm_bo *
+drm_gpuvm_bo_create(struct drm_gpuvm *gpuvm,
+		    struct drm_gem_object *obj)
+{
+	const struct drm_gpuvm_ops *ops = gpuvm->ops;
+	struct drm_gpuvm_bo *vm_bo;
+
+	if (ops && ops->vm_bo_alloc)
+		vm_bo = ops->vm_bo_alloc();
+	else
+		vm_bo = kzalloc(sizeof(*vm_bo), GFP_KERNEL);
+
+	if (unlikely(!vm_bo))
+		return NULL;
+
+	vm_bo->vm = gpuvm;
+	vm_bo->obj = obj;
+
+	kref_init(&vm_bo->kref);
+	INIT_LIST_HEAD(&vm_bo->list.gpuva);
+	INIT_LIST_HEAD(&vm_bo->list.entry.gem);
+
+	drm_gem_object_get(obj);
+
+	return vm_bo;
+}
+EXPORT_SYMBOL_GPL(drm_gpuvm_bo_create);
+
+void
+drm_gpuvm_bo_destroy(struct kref *kref)
+{
+	struct drm_gpuvm_bo *vm_bo = container_of(kref, struct drm_gpuvm_bo,
+						  kref);
+	const struct drm_gpuvm_ops *ops = vm_bo->vm->ops;
+
+	drm_gem_object_put(vm_bo->obj);
+
+	if (ops && ops->vm_bo_free)
+		ops->vm_bo_free(vm_bo);
+	else
+		kfree(vm_bo);
+}
+EXPORT_SYMBOL_GPL(drm_gpuvm_bo_destroy);
+
+static struct drm_gpuvm_bo *
+__drm_gpuvm_bo_find(struct drm_gpuvm *gpuvm,
+		    struct drm_gem_object *obj)
+{
+	struct drm_gpuvm_bo *vm_bo;
+
+	drm_gem_gpuva_assert_lock_held(obj);
+
+	drm_gem_for_each_gpuva_gem(vm_bo, obj)
+		if (vm_bo->vm == gpuvm)
+			return vm_bo;
+
+	return NULL;
+}
+
+/**
+ * drm_gpuvm_bo_find() - find the &drm_gpuvm_bo for the given
+ * &drm_gpuvm and &drm_gem_object
+ * @gpuvm: The &drm_gpuvm the @obj is mapped in.
+ * @obj: The &drm_gem_object being mapped in the @gpuvm.
+ *
+ * Find the &drm_gpuvm_bo representing the combination of the given
+ * &drm_gpuvm and &drm_gem_object. If found, increases the reference
+ * count of the &drm_gpuvm_bo accordingly.
+ *
+ * Returns: a pointer to the &drm_gpuvm_bo on success, NULL on failure
+ */
+struct drm_gpuvm_bo *
+drm_gpuvm_bo_find(struct drm_gpuvm *gpuvm,
+		  struct drm_gem_object *obj)
+{
+	struct drm_gpuvm_bo *vm_bo = __drm_gpuvm_bo_find(gpuvm, obj);
+
+	return vm_bo ? drm_gpuvm_bo_get(vm_bo) : NULL;
+}
+EXPORT_SYMBOL_GPL(drm_gpuvm_bo_find);
+
+/**
+ * drm_gpuvm_bo_obtain() - obtains and instance of the &drm_gpuvm_bo for the
+ * given &drm_gpuvm and &drm_gem_object
+ * @gpuvm: The &drm_gpuvm the @obj is mapped in.
+ * @obj: The &drm_gem_object being mapped in the @gpuvm.
+ *
+ * Find the &drm_gpuvm_bo representing the combination of the given
+ * &drm_gpuvm and &drm_gem_object. If found, increases the reference
+ * count of the &drm_gpuvm_bo accordingly. If not found, allocates a new
+ * &drm_gpuvm_bo.
+ *
+ * Returns: a pointer to the &drm_gpuvm_bo on success, an ERR_PTR on failure
+ */
+struct drm_gpuvm_bo *
+drm_gpuvm_bo_obtain(struct drm_gpuvm *gpuvm,
+		    struct drm_gem_object *obj)
+{
+	struct drm_gpuvm_bo *vm_bo;
+
+	vm_bo = drm_gpuvm_bo_find(gpuvm, obj);
+	if (vm_bo)
+		return vm_bo;
+
+	vm_bo = drm_gpuvm_bo_create(gpuvm, obj);
+	if (!vm_bo)
+		return ERR_PTR(-ENOMEM);
+
+	return vm_bo;
+}
+EXPORT_SYMBOL_GPL(drm_gpuvm_bo_obtain);
+
+/**
+ * drm_gpuvm_bo_obtain_prealloc() - obtains and instance of the &drm_gpuvm_bo
+ * for the given &drm_gpuvm and &drm_gem_object
+ * @gpuvm: The &drm_gpuvm the @obj is mapped in.
+ * @obj: The &drm_gem_object being mapped in the @gpuvm.
+ * @__vm_bo: A pre-allocated struct drm_gpuvm_bo.
+ *
+ * Find the &drm_gpuvm_bo representing the combination of the given
+ * &drm_gpuvm and &drm_gem_object. If found, increases the reference
+ * count of the found &drm_gpuvm_bo accordingly, while the @__vm_bo reference
+ * count is decreased. If not found @__vm_bo is returned without further
+ * increase of the reference count.
+ *
+ * Returns: a pointer to the found &drm_gpuvm_bo or @__vm_bo if no existing
+ * &drm_gpuvm_bo was found
+ */
+struct drm_gpuvm_bo *
+drm_gpuvm_bo_obtain_prealloc(struct drm_gpuvm *gpuvm,
+			      struct drm_gem_object *obj,
+			      struct drm_gpuvm_bo *__vm_bo)
+{
+	struct drm_gpuvm_bo *vm_bo;
+
+	vm_bo = drm_gpuvm_bo_find(gpuvm, obj);
+	if (vm_bo) {
+		drm_gpuvm_bo_put(__vm_bo);
+		return vm_bo;
+	}
+
+	return __vm_bo;
+}
+EXPORT_SYMBOL_GPL(drm_gpuvm_bo_obtain_prealloc);
+
 static int
 __drm_gpuva_insert(struct drm_gpuvm *gpuvm,
 		   struct drm_gpuva *va)
@@ -812,15 +967,20 @@ EXPORT_SYMBOL_GPL(drm_gpuva_remove);
 /**
  * drm_gpuva_link() - link a &drm_gpuva
  * @va: the &drm_gpuva to link
+ * @vm_bo: the &drm_gpuvm_bo to add the &drm_gpuva to
  *
- * This adds the given &va to the GPU VA list of the &drm_gem_object it is
- * associated with.
+ * This adds the given &va to the GPU VA list of the &drm_gpuvm_bo and the
+ * &drm_gpuvm_bo to the &drm_gem_object it is associated with.
+ *
+ * For every &drm_gpuva entry added to the &drm_gpuvm_bo an additional
+ * reference of the latter is taken.
  *
  * This function expects the caller to protect the GEM's GPUVA list against
- * concurrent access using the GEMs dma_resv lock.
+ * concurrent access using either the GEMs dma_resv lock or a driver specific
+ * lock set through drm_gem_gpuva_set_lock().
  */
 void
-drm_gpuva_link(struct drm_gpuva *va)
+drm_gpuva_link(struct drm_gpuva *va, struct drm_gpuvm_bo *vm_bo)
 {
 	struct drm_gem_object *obj = va->gem.obj;
 
@@ -829,7 +989,10 @@ drm_gpuva_link(struct drm_gpuva *va)
 
 	drm_gem_gpuva_assert_lock_held(obj);
 
-	list_add_tail(&va->gem.entry, &obj->gpuva.list);
+	drm_gpuvm_bo_get(vm_bo);
+	list_add_tail(&va->gem.entry, &vm_bo->list.gpuva);
+	if (list_empty(&vm_bo->list.entry.gem))
+		list_add_tail(&vm_bo->list.entry.gem, &obj->gpuva.list);
 }
 EXPORT_SYMBOL_GPL(drm_gpuva_link);
 
@@ -840,20 +1003,40 @@ EXPORT_SYMBOL_GPL(drm_gpuva_link);
  * This removes the given &va from the GPU VA list of the &drm_gem_object it is
  * associated with.
  *
+ * This removes the given &va from the GPU VA list of the &drm_gpuvm_bo and
+ * the &drm_gpuvm_bo from the &drm_gem_object it is associated with in case
+ * this call unlinks the last &drm_gpuva from the &drm_gpuvm_bo.
+ *
+ * For every &drm_gpuva entry removed from the &drm_gpuvm_bo a reference of
+ * the latter is dropped.
+ *
  * This function expects the caller to protect the GEM's GPUVA list against
- * concurrent access using the GEMs dma_resv lock.
+ * concurrent access using either the GEMs dma_resv lock or a driver specific
+ * lock set through drm_gem_gpuva_set_lock().
  */
 void
 drm_gpuva_unlink(struct drm_gpuva *va)
 {
 	struct drm_gem_object *obj = va->gem.obj;
+	struct drm_gpuvm_bo *vm_bo;
 
 	if (unlikely(!obj))
 		return;
 
 	drm_gem_gpuva_assert_lock_held(obj);
 
+	vm_bo = __drm_gpuvm_bo_find(va->vm, obj);
+	if (WARN(!vm_bo, "GPUVA doesn't seem to be linked.\n"))
+		return;
+
 	list_del_init(&va->gem.entry);
+
+	/* This is the last mapping being unlinked for this GEM object, hence
+	 * also remove the VM_BO from the GEM's gpuva list.
+	 */
+	if (list_empty(&vm_bo->list.gpuva))
+		list_del_init(&vm_bo->list.entry.gem);
+	drm_gpuvm_bo_put(vm_bo);
 }
 EXPORT_SYMBOL_GPL(drm_gpuva_unlink);
 
@@ -998,10 +1181,10 @@ drm_gpuva_remap(struct drm_gpuva *prev,
 		struct drm_gpuva *next,
 		struct drm_gpuva_op_remap *op)
 {
-	struct drm_gpuva *curr = op->unmap->va;
-	struct drm_gpuvm *gpuvm = curr->vm;
+	struct drm_gpuva *va = op->unmap->va;
+	struct drm_gpuvm *gpuvm = va->vm;
 
-	drm_gpuva_remove(curr);
+	drm_gpuva_remove(va);
 
 	if (op->prev) {
 		drm_gpuva_init_from_op(prev, op->prev);
@@ -1645,7 +1828,7 @@ drm_gpuva_prefetch_ops_create(struct drm_gpuvm *gpuvm,
 EXPORT_SYMBOL_GPL(drm_gpuva_prefetch_ops_create);
 
 /**
- * drm_gpuva_gem_unmap_ops_create() - creates the &drm_gpuva_ops to unmap a GEM
+ * drm_gpuvm_bo_unmap_ops_create() - creates the &drm_gpuva_ops to unmap a GEM
  * @gpuvm: the &drm_gpuvm representing the GPU VA space
  * @obj: the &drm_gem_object to unmap
  *
@@ -1664,11 +1847,12 @@ EXPORT_SYMBOL_GPL(drm_gpuva_prefetch_ops_create);
  * Returns: a pointer to the &drm_gpuva_ops on success, an ERR_PTR on failure
  */
 struct drm_gpuva_ops *
-drm_gpuva_gem_unmap_ops_create(struct drm_gpuvm *gpuvm,
+drm_gpuvm_bo_unmap_ops_create(struct drm_gpuvm *gpuvm,
 			       struct drm_gem_object *obj)
 {
 	struct drm_gpuva_ops *ops;
 	struct drm_gpuva_op *op;
+	struct drm_gpuvm_bo *vm_bo;
 	struct drm_gpuva *va;
 	int ret;
 
@@ -1680,7 +1864,7 @@ drm_gpuva_gem_unmap_ops_create(struct drm_gpuvm *gpuvm,
 
 	INIT_LIST_HEAD(&ops->list);
 
-	drm_gem_for_each_gpuva(va, obj) {
+	drm_gem_for_each_gpuva(va, vm_bo, gpuvm, obj) {
 		op = gpuva_op_alloc(gpuvm);
 		if (!op) {
 			ret = -ENOMEM;
@@ -1698,7 +1882,7 @@ drm_gpuva_gem_unmap_ops_create(struct drm_gpuvm *gpuvm,
 	drm_gpuva_ops_free(gpuvm, ops);
 	return ERR_PTR(ret);
 }
-EXPORT_SYMBOL_GPL(drm_gpuva_gem_unmap_ops_create);
+EXPORT_SYMBOL_GPL(drm_gpuvm_bo_unmap_ops_create);
 
 /**
  * drm_gpuva_ops_free() - free the given &drm_gpuva_ops
diff --git a/drivers/gpu/drm/nouveau/nouveau_uvmm.c b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
index 21d5a06241ae..a93483a4ceb5 100644
--- a/drivers/gpu/drm/nouveau/nouveau_uvmm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
@@ -71,6 +71,7 @@ struct bind_job_op {
 		u32 handle;
 		u64 offset;
 		struct drm_gem_object *obj;
+		struct drm_gpuvm_bo *vm_bo;
 	} gem;
 
 	struct nouveau_uvma_region *reg;
@@ -1113,22 +1114,34 @@ bind_validate_region(struct nouveau_job *job)
 }
 
 static void
-bind_link_gpuvas(struct drm_gpuva_ops *ops, struct nouveau_uvma_prealloc *new)
+bind_link_gpuvas(struct bind_job_op *bop)
 {
+	struct nouveau_uvma_prealloc *new = &bop->new;
+	struct drm_gpuvm_bo *vm_bo = bop->gem.vm_bo;
+	struct drm_gpuva_ops *ops = bop->ops;
 	struct drm_gpuva_op *op;
 
 	drm_gpuva_for_each_op(op, ops) {
 		switch (op->op) {
 		case DRM_GPUVA_OP_MAP:
-			drm_gpuva_link(&new->map->va);
+			drm_gpuva_link(&new->map->va, vm_bo);
 			break;
-		case DRM_GPUVA_OP_REMAP:
+		case DRM_GPUVA_OP_REMAP: {
+			struct drm_gpuva *va = op->remap.unmap->va;
+			struct drm_gpuvm_bo *vm_bo;
+
+			vm_bo = drm_gpuvm_bo_find(va->vm, va->gem.obj);
+			BUG_ON(!vm_bo);
+
 			if (op->remap.prev)
-				drm_gpuva_link(&new->prev->va);
+				drm_gpuva_link(&new->prev->va, vm_bo);
 			if (op->remap.next)
-				drm_gpuva_link(&new->next->va);
-			drm_gpuva_unlink(op->remap.unmap->va);
+				drm_gpuva_link(&new->next->va, vm_bo);
+			drm_gpuva_unlink(va);
+
+			drm_gpuvm_bo_put(vm_bo);
 			break;
+		}
 		case DRM_GPUVA_OP_UNMAP:
 			drm_gpuva_unlink(op->unmap.va);
 			break;
@@ -1150,10 +1163,22 @@ nouveau_uvmm_bind_job_submit(struct nouveau_job *job)
 
 	list_for_each_op(op, &bind_job->ops) {
 		if (op->op == OP_MAP) {
-			op->gem.obj = drm_gem_object_lookup(job->file_priv,
-							    op->gem.handle);
-			if (!op->gem.obj)
+			struct drm_gem_object *obj;
+
+			obj = drm_gem_object_lookup(job->file_priv,
+						    op->gem.handle);
+			if (!obj)
 				return -ENOENT;
+
+			dma_resv_lock(obj->resv, NULL);
+			op->gem.vm_bo = drm_gpuvm_bo_obtain(&uvmm->base, obj);
+			dma_resv_unlock(obj->resv);
+			if (IS_ERR(op->gem.vm_bo)) {
+				drm_gem_object_put(obj);
+				return PTR_ERR(op->gem.vm_bo);
+			}
+
+			op->gem.obj = obj;
 		}
 
 		ret = bind_validate_op(job, op);
@@ -1364,7 +1389,7 @@ nouveau_uvmm_bind_job_submit(struct nouveau_job *job)
 		case OP_UNMAP_SPARSE:
 		case OP_MAP:
 		case OP_UNMAP:
-			bind_link_gpuvas(op->ops, &op->new);
+			bind_link_gpuvas(op);
 			break;
 		default:
 			break;
@@ -1511,6 +1536,12 @@ nouveau_uvmm_bind_job_free_work_fn(struct work_struct *work)
 		if (!IS_ERR_OR_NULL(op->ops))
 			drm_gpuva_ops_free(&uvmm->base, op->ops);
 
+		if (!IS_ERR_OR_NULL(op->gem.vm_bo)) {
+			dma_resv_lock(obj->resv, NULL);
+			drm_gpuvm_bo_put(op->gem.vm_bo);
+			dma_resv_unlock(obj->resv);
+		}
+
 		if (obj)
 			drm_gem_object_put(obj);
 	}
@@ -1776,15 +1807,18 @@ void
 nouveau_uvmm_bo_map_all(struct nouveau_bo *nvbo, struct nouveau_mem *mem)
 {
 	struct drm_gem_object *obj = &nvbo->bo.base;
+	struct drm_gpuvm_bo *vm_bo;
 	struct drm_gpuva *va;
 
 	dma_resv_assert_held(obj->resv);
 
-	drm_gem_for_each_gpuva(va, obj) {
-		struct nouveau_uvma *uvma = uvma_from_va(va);
+	drm_gem_for_each_gpuva_gem(vm_bo, obj) {
+		drm_gpuvm_bo_for_each_va(va, vm_bo) {
+			struct nouveau_uvma *uvma = uvma_from_va(va);
 
-		nouveau_uvma_map(uvma, mem);
-		drm_gpuva_invalidate(va, false);
+			nouveau_uvma_map(uvma, mem);
+			drm_gpuva_invalidate(va, false);
+		}
 	}
 }
 
@@ -1792,15 +1826,18 @@ void
 nouveau_uvmm_bo_unmap_all(struct nouveau_bo *nvbo)
 {
 	struct drm_gem_object *obj = &nvbo->bo.base;
+	struct drm_gpuvm_bo *vm_bo;
 	struct drm_gpuva *va;
 
 	dma_resv_assert_held(obj->resv);
 
-	drm_gem_for_each_gpuva(va, obj) {
-		struct nouveau_uvma *uvma = uvma_from_va(va);
+	drm_gem_for_each_gpuva_gem(vm_bo, obj) {
+		drm_gpuvm_bo_for_each_va(va, vm_bo) {
+			struct nouveau_uvma *uvma = uvma_from_va(va);
 
-		nouveau_uvma_unmap(uvma);
-		drm_gpuva_invalidate(va, true);
+			nouveau_uvma_unmap(uvma);
+			drm_gpuva_invalidate(va, true);
+		}
 	}
 }
 
@@ -1847,14 +1884,14 @@ nouveau_uvmm_init(struct nouveau_uvmm *uvmm, struct nouveau_cli *cli,
 			    kernel_managed_addr, kernel_managed_size,
 			    NULL, 0, &cli->uvmm.vmm.vmm);
 	if (ret)
-		goto out_free_gpuva_mgr;
+		goto out_free_gpuvm;
 
 	cli->uvmm.vmm.cli = cli;
 	mutex_unlock(&cli->mutex);
 
 	return 0;
 
-out_free_gpuva_mgr:
+out_free_gpuvm:
 	drm_gpuvm_destroy(&uvmm->base);
 out_unlock:
 	mutex_unlock(&cli->mutex);
diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
index bc9f6aa2f3fe..7f591e76d74d 100644
--- a/include/drm/drm_gem.h
+++ b/include/drm/drm_gem.h
@@ -571,7 +571,7 @@ int drm_gem_evict(struct drm_gem_object *obj);
  * drm_gem_gpuva_init() - initialize the gpuva list of a GEM object
  * @obj: the &drm_gem_object
  *
- * This initializes the &drm_gem_object's &drm_gpuva list.
+ * This initializes the &drm_gem_object's &drm_gpuvm_bo list.
  *
  * Calling this function is only necessary for drivers intending to support the
  * &drm_driver_feature DRIVER_GEM_GPUVA.
@@ -584,28 +584,44 @@ static inline void drm_gem_gpuva_init(struct drm_gem_object *obj)
 }
 
 /**
- * drm_gem_for_each_gpuva() - iternator to walk over a list of gpuvas
- * @entry__: &drm_gpuva structure to assign to in each iteration step
- * @obj__: the &drm_gem_object the &drm_gpuvas to walk are associated with
+ * drm_gem_for_each_gpuva_gem() - iterator to walk over a list of &drm_gpuvm_bo
+ * @entry__: &drm_gpuvm_bo structure to assign to in each iteration step
+ * @obj__: the &drm_gem_object the &drm_gpuvm_bo to walk are associated with
  *
- * This iterator walks over all &drm_gpuva structures associated with the
- * &drm_gpuva_manager.
+ * This iterator walks over all &drm_gpuvm_bo structures associated with the
+ * &drm_gem_object.
  */
-#define drm_gem_for_each_gpuva(entry__, obj__) \
-	list_for_each_entry(entry__, &(obj__)->gpuva.list, gem.entry)
+#define drm_gem_for_each_gpuva_gem(entry__, obj__) \
+	list_for_each_entry(entry__, &(obj__)->gpuva.list, list.entry.gem)
 
 /**
- * drm_gem_for_each_gpuva_safe() - iternator to safely walk over a list of
- * gpuvas
- * @entry__: &drm_gpuva structure to assign to in each iteration step
- * @next__: &next &drm_gpuva to store the next step
- * @obj__: the &drm_gem_object the &drm_gpuvas to walk are associated with
+ * drm_gem_for_each_gpuva_gem_safe() - iterator to safely walk over a list of
+ * &drm_gpuvm_bo
+ * @entry__: &drm_gpuvm_bostructure to assign to in each iteration step
+ * @next__: &next &drm_gpuvm_bo to store the next step
+ * @obj__: the &drm_gem_object the &drm_gpuvm_bo to walk are associated with
  *
- * This iterator walks over all &drm_gpuva structures associated with the
+ * This iterator walks over all &drm_gpuvm_bo structures associated with the
  * &drm_gem_object. It is implemented with list_for_each_entry_safe(), hence
  * it is save against removal of elements.
  */
-#define drm_gem_for_each_gpuva_safe(entry__, next__, obj__) \
-	list_for_each_entry_safe(entry__, next__, &(obj__)->gpuva.list, gem.entry)
+#define drm_gem_for_each_gpuva_gem_safe(entry__, next__, obj__) \
+	list_for_each_entry_safe(entry__, next__, &(obj__)->gpuva.list, list.entry.gem)
+
+/**
+ * drm_gem_for_each_gpuva() - iterator to walk over a list of &drm_gpuva
+ * @va__: &drm_gpuva structure to assign to in each iteration step
+ * @vm_bo__: the &drm_gpuvm_bo representing the @gpuvm__ and @obj__ combination
+ * @gpuvm__: the &drm_gpuvm the &drm_gpuvas to walk are associated with
+ * @obj__: the &drm_gem_object the &drm_gpuvas to walk are associated with
+ *
+ * This iterator walks over all &drm_gpuva structures associated with the
+ * &drm_gpuvm and &drm_gem_object.
+ */
+#define drm_gem_for_each_gpuva(va__, vm_bo__, gpuvm__, obj__) \
+	for (vm_bo__ = drm_gpuvm_bo_find(gpuvm__, obj__), \
+	     va__ = vm_bo__ ? list_first_entry(&vm_bo__->list.gpuva, typeof(*va__), gem.entry) : NULL; \
+	     va__ && !list_entry_is_head(va__, &vm_bo__->list.gpuva, gem.entry); \
+	     va__ = list_next_entry(va__, gem.entry))
 
 #endif /* __DRM_GEM_H__ */
diff --git a/include/drm/drm_gpuva_mgr.h b/include/drm/drm_gpuva_mgr.h
index e09e3e3ac5b2..f8f29c1c858d 100644
--- a/include/drm/drm_gpuva_mgr.h
+++ b/include/drm/drm_gpuva_mgr.h
@@ -32,6 +32,7 @@
 #include <drm/drm_gem.h>
 
 struct drm_gpuvm;
+struct drm_gpuvm_bo;
 struct drm_gpuvm_ops;
 
 /**
@@ -140,7 +141,7 @@ struct drm_gpuva {
 int drm_gpuva_insert(struct drm_gpuvm *gpuvm, struct drm_gpuva *va);
 void drm_gpuva_remove(struct drm_gpuva *va);
 
-void drm_gpuva_link(struct drm_gpuva *va);
+void drm_gpuva_link(struct drm_gpuva *va, struct drm_gpuvm_bo *vm_bo);
 void drm_gpuva_unlink(struct drm_gpuva *va);
 
 struct drm_gpuva *drm_gpuva_find(struct drm_gpuvm *gpuvm,
@@ -339,6 +340,130 @@ __drm_gpuva_next(struct drm_gpuva *va)
 #define drm_gpuvm_for_each_va_safe(va__, next__, gpuvm__) \
 	list_for_each_entry_safe(va__, next__, &(gpuvm__)->rb.list, rb.entry)
 
+/**
+ * struct drm_gpuvm_bo - structure representing a &drm_gpuvm and
+ * &drm_gem_object combination
+ *
+ * This structure is an abstraction representing a &drm_gpuvm and
+ * &drm_gem_object combination. It serves as an indirection to accelerate
+ * iterating all &drm_gpuvas within a &drm_gpuvm backed by the same
+ * &drm_gem_object.
+ *
+ * Furthermore it is used cache evicted GEM objects for a certain GPU-VM to
+ * accelerate validation.
+ *
+ * Typically, drivers want to create an instance of a struct drm_gpuvm_bo once
+ * a GEM object is mapped first in a GPU-VM and release the instance once the
+ * last mapping of the GEM object in this GPU-VM is unmapped.
+ */
+struct drm_gpuvm_bo {
+
+	/**
+	 * @gpuvm: The &drm_gpuvm the @obj is mapped in.
+	 */
+	struct drm_gpuvm *vm;
+
+	/**
+	 * @obj: The &drm_gem_object being mapped in the @gpuvm.
+	 */
+	struct drm_gem_object *obj;
+
+	/**
+	 * @kref: The reference count for this &drm_gpuvm_bo.
+	 */
+	struct kref kref;
+
+	/**
+	 * @list: Structure containing all &list_heads.
+	 */
+	struct {
+		/**
+		 * @gpuva: The list of linked &drm_gpuvas.
+		 */
+		struct list_head gpuva;
+
+		/**
+		 * @entry: Structure containing all &list_heads serving as
+		 * entry.
+		 */
+		struct {
+			/**
+			 * @gem: List entry to attach to the &drm_gem_objects
+			 * gpuva list.
+			 */
+			struct list_head gem;
+		} entry;
+	} list;
+};
+
+struct drm_gpuvm_bo *
+drm_gpuvm_bo_obtain(struct drm_gpuvm *gpuvm,
+		    struct drm_gem_object *obj);
+struct drm_gpuvm_bo *
+drm_gpuvm_bo_obtain_prealloc(struct drm_gpuvm *gpuvm,
+			      struct drm_gem_object *obj,
+			      struct drm_gpuvm_bo *__vm_bo);
+
+struct drm_gpuvm_bo *
+drm_gpuvm_bo_find(struct drm_gpuvm *gpuvm,
+		  struct drm_gem_object *obj);
+
+struct drm_gpuvm_bo *
+drm_gpuvm_bo_create(struct drm_gpuvm *gpuvm,
+		    struct drm_gem_object *obj);
+void drm_gpuvm_bo_destroy(struct kref *kref);
+
+/**
+ * drm_gpuvm_bo_get() - acquire a struct drm_gpuvm_bo reference
+ * @vm_bo: the &drm_gpuvm_bo to acquire the reference of
+ *
+ * This function acquires an additional reference to @vm_bo. It is illegal to
+ * call this without already holding a reference. No locks required.
+ */
+static inline struct drm_gpuvm_bo *
+drm_gpuvm_bo_get(struct drm_gpuvm_bo *vm_bo)
+{
+	kref_get(&vm_bo->kref);
+	return vm_bo;
+}
+
+/**
+ * drm_gpuvm_bo_put() - drop a struct drm_gpuvm_bo reference
+ * @vm_bo: the &drm_gpuvm_bo to release the reference of
+ *
+ * This releases a reference to @vm_bo.
+ */
+static inline void
+drm_gpuvm_bo_put(struct drm_gpuvm_bo *vm_bo)
+{
+	kref_put(&vm_bo->kref, drm_gpuvm_bo_destroy);
+}
+
+/**
+ * drm_gpuvm_bo_for_each_va() - iterator to walk over a list of &drm_gpuva
+ * @va__: &drm_gpuva structure to assign to in each iteration step
+ * @vm_bo__: the &drm_gpuvm_bo the &drm_gpuva to walk are associated with
+ *
+ * This iterator walks over all &drm_gpuva structures associated with the
+ * &drm_gpuvm_bo.
+ */
+#define drm_gpuvm_bo_for_each_va(va__, vm_bo__) \
+	list_for_each_entry(va__, &(vm_bo)->list.gpuva, gem.entry)
+
+/**
+ * drm_gpuvm_bo_for_each_va_safe() - iterator to safely walk over a list of
+ * &drm_gpuva
+ * @va__: &drm_gpuva structure to assign to in each iteration step
+ * @next__: &next &drm_gpuva to store the next step
+ * @vm_bo__: the &drm_gpuvm_bo the &drm_gpuva to walk are associated with
+ *
+ * This iterator walks over all &drm_gpuva structures associated with the
+ * &drm_gpuvm_bo. It is implemented with list_for_each_entry_safe(), hence
+ * it is save against removal of elements.
+ */
+#define drm_gpuvm_bo_for_each_va_safe(va__, next__, vm_bo__) \
+	list_for_each_entry_safe(va__, next__, &(vm_bo)->list.gpuva, gem.entry)
+
 /**
  * enum drm_gpuva_op_type - GPU VA operation type
  *
@@ -608,7 +733,7 @@ drm_gpuva_prefetch_ops_create(struct drm_gpuvm *gpuvm,
 				 u64 addr, u64 range);
 
 struct drm_gpuva_ops *
-drm_gpuva_gem_unmap_ops_create(struct drm_gpuvm *gpuvm,
+drm_gpuvm_bo_unmap_ops_create(struct drm_gpuvm *gpuvm,
 			       struct drm_gem_object *obj);
 
 void drm_gpuva_ops_free(struct drm_gpuvm *gpuvm,
@@ -653,6 +778,30 @@ struct drm_gpuvm_ops {
 	 */
 	void (*op_free)(struct drm_gpuva_op *op);
 
+	/**
+	 * @vm_bo_alloc: called when the &drm_gpuvm allocates
+	 * a struct drm_gpuvm_bo
+	 *
+	 * Some drivers may want to embed struct drm_gpuvm_bo into driver
+	 * specific structures. By implementing this callback drivers can
+	 * allocate memory accordingly.
+	 *
+	 * This callback is optional.
+	 */
+	struct drm_gpuvm_bo *(*vm_bo_alloc)(void);
+
+	/**
+	 * @vm_bo_free: called when the &drm_gpuvm frees a
+	 * struct drm_gpuvm_bo
+	 *
+	 * Some drivers may want to embed struct drm_gpuvm_bo into driver
+	 * specific structures. By implementing this callback drivers can
+	 * free the previously allocated memory accordingly.
+	 *
+	 * This callback is optional.
+	 */
+	void (*vm_bo_free)(struct drm_gpuvm_bo *vm_bo);
+
 	/**
 	 * @sm_step_map: called from &drm_gpuva_sm_map to finally insert the
 	 * mapping once all previous steps were completed
-- 
2.41.0

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