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

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

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);
> +}
> +
>


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