drm/i915: Convert the dmabuf object to use the new i915_gem_object_ops

By providing a callback for when we need to bind the pages, and then
release them again later, we can shorten the amount of time we hold the
foreign pages mapped and pinned, and importantly the dmabuf objects then
behave as any other normal object with respect to the shrinker and
memory management.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -1012,7 +1012,6 @@ struct drm_i915_gem_object {
 	int pages_pin_count;
 
 	/* prime dma-buf support */
-	struct sg_table *sg_table;
 	void *dma_buf_vmapping;
 	int vmapping_count;
 

drivers/gpu/drm/i915/i915_gem.c

@@ -1692,7 +1692,7 @@ i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
 {
 	const struct drm_i915_gem_object_ops *ops = obj->ops;
 
-	if (obj->sg_table || obj->pages == NULL)
+	if (obj->pages == NULL)
 		return 0;
 
 	BUG_ON(obj->gtt_space);
@@ -1845,7 +1845,7 @@ i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
 	const struct drm_i915_gem_object_ops *ops = obj->ops;
 	int ret;
 
-	if (obj->sg_table || obj->pages)
+	if (obj->pages)
 		return 0;
 
 	BUG_ON(obj->pages_pin_count);
@@ -3738,9 +3738,6 @@ void i915_gem_free_object(struct drm_gem_object *gem_obj)
 
 	trace_i915_gem_object_destroy(obj);
 
-	if (gem_obj->import_attach)
-		drm_prime_gem_destroy(gem_obj, obj->sg_table);
-
 	if (obj->phys_obj)
 		i915_gem_detach_phys_object(dev, obj);
 
@@ -3762,6 +3759,9 @@ void i915_gem_free_object(struct drm_gem_object *gem_obj)
 
 	BUG_ON(obj->pages);
 
+	if (obj->base.import_attach)
+		drm_prime_gem_destroy(&obj->base, NULL);
+
 	drm_gem_object_release(&obj->base);
 	i915_gem_info_remove_obj(dev_priv, obj->base.size);
 

drivers/gpu/drm/i915/i915_gem_dmabuf.c

@@ -82,7 +82,8 @@ out:
 }
 
 static void i915_gem_unmap_dma_buf(struct dma_buf_attachment *attachment,
-			    struct sg_table *sg, enum dma_data_direction dir)
+				   struct sg_table *sg,
+				   enum dma_data_direction dir)
 {
 	dma_unmap_sg(attachment->dev, sg->sgl, sg->nents, dir);
 	sg_free_table(sg);
@@ -228,11 +229,35 @@ struct dma_buf *i915_gem_prime_export(struct drm_device *dev,
 	return dma_buf_export(obj, &i915_dmabuf_ops, obj->base.size, 0600);
 }
 
+static int i915_gem_object_get_pages_dmabuf(struct drm_i915_gem_object *obj)
+{
+	struct sg_table *sg;
+
+	sg = dma_buf_map_attachment(obj->base.import_attach, DMA_BIDIRECTIONAL);
+	if (IS_ERR(sg))
+		return PTR_ERR(sg);
+
+	obj->pages = sg;
+	obj->has_dma_mapping = true;
+	return 0;
+}
+
+static void i915_gem_object_put_pages_dmabuf(struct drm_i915_gem_object *obj)
+{
+	dma_buf_unmap_attachment(obj->base.import_attach,
+				 obj->pages, DMA_BIDIRECTIONAL);
+	obj->has_dma_mapping = false;
+}
+
+static const struct drm_i915_gem_object_ops i915_gem_object_dmabuf_ops = {
+	.get_pages = i915_gem_object_get_pages_dmabuf,
+	.put_pages = i915_gem_object_put_pages_dmabuf,
+};
+
 struct drm_gem_object *i915_gem_prime_import(struct drm_device *dev,
 					     struct dma_buf *dma_buf)
 {
 	struct dma_buf_attachment *attach;
-	struct sg_table *sg;
 	struct drm_i915_gem_object *obj;
 	int ret;
 
@@ -251,34 +276,25 @@ struct drm_gem_object *i915_gem_prime_import(struct drm_device *dev,
 	if (IS_ERR(attach))
 		return ERR_CAST(attach);
 
-	sg = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
-	if (IS_ERR(sg)) {
-		ret = PTR_ERR(sg);
-		goto fail_detach;
-	}
 
 	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
 	if (obj == NULL) {
 		ret = -ENOMEM;
-		goto fail_unmap;
+		goto fail_detach;
 	}
 
 	ret = drm_gem_private_object_init(dev, &obj->base, dma_buf->size);
 	if (ret) {
 		kfree(obj);
-		goto fail_unmap;
+		goto fail_detach;
 	}
 
-	obj->has_dma_mapping = true;
-	obj->sg_table = sg;
+	i915_gem_object_init(obj, &i915_gem_object_dmabuf_ops);
 	obj->base.import_attach = attach;
 
 	return &obj->base;
 
-fail_unmap:
-	dma_buf_unmap_attachment(attach, sg, DMA_BIDIRECTIONAL);
 fail_detach:
 	dma_buf_detach(dma_buf, attach);
 	return ERR_PTR(ret);
 }
-

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -234,7 +234,7 @@ void i915_ppgtt_bind_object(struct i915_hw_ppgtt *ppgtt,
 	}
 
 	i915_ppgtt_insert_sg_entries(ppgtt,
-				     obj->sg_table ?: obj->pages,
+				     obj->pages,
 				     obj->gtt_space->start >> PAGE_SHIFT,
 				     pte_flags);
 }
@@ -325,7 +325,7 @@ void i915_gem_gtt_bind_object(struct drm_i915_gem_object *obj,
 	struct drm_device *dev = obj->base.dev;
 	unsigned int agp_type = cache_level_to_agp_type(dev, cache_level);
 
-	intel_gtt_insert_sg_entries(obj->sg_table ?: obj->pages,
+	intel_gtt_insert_sg_entries(obj->pages,
 				    obj->gtt_space->start >> PAGE_SHIFT,
 				    agp_type);
 	obj->has_global_gtt_mapping = 1;