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

[Oleksandr Andrushchenko <Oleksandr_Andrushchenko@xxxxxxxx>]

On 06/13/2018 04:26 AM, Boris Ostrovsky wrote:
> 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);
Will fix
> > +        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.
Will fix
> > +        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.
Of course
> > +
> > +            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.
Will fix
> > +     * 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>
Thank you,
Oleksandr

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