Re: [PATCH v3 5/9] xen/gntdev: Allow mappings for DMA buffers

Boris Ostrovsky
2018-06-13T01:27:10Z

On 06/12/2018 09:41 AM, Oleksandr Andrushchenko wrote:

>
> static void gntdev_print_maps(struct gntdev_priv *priv,
> @@ -121,8 +146,27 @@ static void gntdev_free_map(struct grant_map *map)
> if (map == NULL)
> return;
>
> +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
> + if (map->dma_vaddr) {
> + struct gnttab_dma_alloc_args args;
> +
> + args.dev = map->dma_dev;
> + args.coherent = map->dma_flags & GNTDEV_DMA_FLAG_COHERENT;

args.coherent = !!(map->dma_flags & GNTDEV_DMA_FLAG_COHERENT);

> + args.nr_pages = map->count;
> + args.pages = map->pages;
> + args.frames = map->frames;
> + args.vaddr = map->dma_vaddr;
> + args.dev_bus_addr = map->dma_bus_addr;
> +
> + gnttab_dma_free_pages(&args);
> + } else
> +#endif
> if (map->pages)
> gnttab_free_pages(map->count, map->pages);
> +
> +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
> + kfree(map->frames);
> +#endif
> kfree(map->pages);
> kfree(map->grants);
> kfree(map->map_ops);
> @@ -132,7 +176,8 @@ static void gntdev_free_map(struct grant_map *map)
> kfree(map);
> }
>
> -static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count)
> +static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count,
> + int dma_flags)
> {
> struct grant_map *add;
> int i;
> @@ -155,6 +200,37 @@ static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count)
> NULL == add->pages)
> goto err;
>
> +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
> + add->dma_flags = dma_flags;
> +
> + /*
> + * Check if this mapping is requested to be backed
> + * by a DMA buffer.
> + */
> + if (dma_flags & (GNTDEV_DMA_FLAG_WC | GNTDEV_DMA_FLAG_COHERENT)) {
> + struct gnttab_dma_alloc_args args;
> +
> + add->frames = kcalloc(count, sizeof(add->frames[0]),
> + GFP_KERNEL);
> + if (!add->frames)
> + goto err;
> +
> + /* Remember the device, so we can free DMA memory. */
> + add->dma_dev = priv->dma_dev;
> +
> + args.dev = priv->dma_dev;
> + args.coherent = dma_flags & GNTDEV_DMA_FLAG_COHERENT;

And again here.

> + args.nr_pages = count;
> + args.pages = add->pages;
> + args.frames = add->frames;
> +
> + if (gnttab_dma_alloc_pages(&args))
> + goto err;
> +
> + add->dma_vaddr = args.vaddr;
> + add->dma_bus_addr = args.dev_bus_addr;
> + } else
> +#endif
> if (gnttab_alloc_pages(count, add->pages))
> goto err;
>
> @@ -325,6 +401,14 @@ static int map_grant_pages(struct grant_map *map)
> map->unmap_ops[i].handle = map->map_ops[i].handle;
> if (use_ptemod)
> map->kunmap_ops[i].handle = map->kmap_ops[i].handle;
> +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
> + else if (map->dma_vaddr) {
> + unsigned long mfn;

This should be called bfn now.

> +
> + mfn = pfn_to_bfn(page_to_pfn(map->pages[i]));
> + map->unmap_ops[i].dev_bus_addr = __pfn_to_phys(mfn);
> + }
> +#endif
> }
> return err;
> }
> @@ -548,6 +632,17 @@ static int gntdev_open(struct inode *inode, struct file *flip)
> }
>
> flip->private_data = priv;
> +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
> + priv->dma_dev = gntdev_miscdev.this_device;
> +
> + /*
> + * The device is not spawn from a device tree, so arch_setup_dma_ops
> + * is not called, thus leaving the device with dummy DMA ops.
> + * Fix this call of_dma_configure() with a NULL node to set

"Fix this by calling ..." I think.

> + * default DMA ops.
> + */
> + of_dma_configure(priv->dma_dev, NULL);
> +#endif
> pr_debug("priv %p\n", priv);
>
> return 0;

With those fixed,

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>