Re: [PATCH 8/9] drm/xen-front: Implement GEM operations

On 02/21/2018 03:03 AM, Oleksandr Andrushchenko wrote:

+static struct xen_gem_object *gem_create(struct drm_device *dev, size_t size) +{

• struct xen_drm_front_drm_info *drm_info = dev->dev_private;
• struct xen_gem_object *xen_obj;
• int ret;
• size = round_up(size, PAGE_SIZE);
• xen_obj = gem_create_obj(dev, size);
• if (IS_ERR_OR_NULL(xen_obj))

• return xen_obj;
  

• if (drm_info->cfg->be_alloc) {

• /*
  

•  * backend will allocate space for this buffer, so
  

•  * only allocate array of pointers to pages
  

•  */
  

• xen_obj->be_alloc = true;
  

If be_alloc is a flag (which I am not sure about) --- should it be set to true *after* you've successfully allocated your things?

• ret = gem_alloc_pages_array(xen_obj, size);
  

• if (ret < 0) {
  

• 	gem_free_pages_array(xen_obj);
  

• 	goto fail;
  

• }
  

• ret = alloc_xenballooned_pages(xen_obj->num_pages,
  

• 		xen_obj->pages);
  

Why are you allocating balloon pages?

-boris

• if (ret < 0) {
  

• 	DRM_ERROR("Cannot allocate %zu ballooned pages: %d\n",
  

• 			xen_obj->num_pages, ret);
  

• 	goto fail;
  

• }
  

• return xen_obj;
  

• }
• /*

• * need to allocate backing pages now, so we can share those
  

• * with the backend
  

• */
  

• xen_obj->num_pages = DIV_ROUND_UP(size, PAGE_SIZE);
• xen_obj->pages = drm_gem_get_pages(&xen_obj->base);
• if (IS_ERR_OR_NULL(xen_obj->pages)) {

• ret = PTR_ERR(xen_obj->pages);
  

• xen_obj->pages = NULL;
  

• goto fail;
  

• }
• return xen_obj;

+fail:

• DRM_ERROR("Failed to allocate buffer with size %zu\n", size);
• return ERR_PTR(ret);

+}