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

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

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@xxxxxxxxxx>

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