Re: swiotlb-xen question

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Fri, Apr 04, 2014 at 02:30:22PM +0300, Oleksandr Dmytryshyn wrote:
> >From f52bafc1ba51324ca5044df22778aacf815c59bf Mon Sep 17 00:00:00 2001
> From: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> Date: Fri, 4 Apr 2014 12:16:27 +0300
> Subject: [PATCH] swiotlb-xen: implement xen_swiotlb_dma_mmap callback
> 
> This function creates userspace mapping for the DMA-coherent memory.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> Signed-off-by: Oleksandr Dmytryshyn <oleksandr.dmytryshyn@globallogic.com>
> 
> diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
> index b0e77de..91408b1 100644
> --- a/arch/arm/xen/mm.c
> +++ b/arch/arm/xen/mm.c
> @@ -48,6 +48,7 @@ static struct dma_map_ops xen_swiotlb_dma_ops = {
>   .sync_sg_for_device = xen_swiotlb_sync_sg_for_device,
>   .map_sg = xen_swiotlb_map_sg_attrs,
>   .unmap_sg = xen_swiotlb_unmap_sg_attrs,
> + .mmap = xen_swiotlb_dma_mmap,
>   .map_page = xen_swiotlb_map_page,
>   .unmap_page = xen_swiotlb_unmap_page,
>   .dma_supported = xen_swiotlb_dma_supported,
> diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> index 5403855..acf0c06 100644
> --- a/drivers/xen/swiotlb-xen.c
> +++ b/drivers/xen/swiotlb-xen.c
> @@ -407,6 +407,42 @@ dma_addr_t xen_swiotlb_map_page(struct device
> *dev, struct page *page,
>  EXPORT_SYMBOL_GPL(xen_swiotlb_map_page);
> 
>  /*
> + * Create userspace mapping for the DMA-coherent memory.
> + */
> +int xen_swiotlb_dma_mmap(struct device *dev, struct vm_area_struct *vma,
> + void *cpu_addr, dma_addr_t dma_addr, size_t size,
> + struct dma_attrs *attrs)

Wow. Your editor ate all the nice tabs and spaces. Could you
please also run

scripts/checkpatch.pl on the patch and fix the issues it would
complain about.

Thank you!
> +{
> + int ret = -ENXIO;
> +#ifdef CONFIG_MMU
> + unsigned long nr_vma_pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
> + unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
> + unsigned long pfn = PFN_DOWN(xen_bus_to_phys(dma_addr));
> + unsigned long off = vma->vm_pgoff;
> + pgprot_t prot = vma->vm_page_prot;
> +
> + prot = dma_get_attr(DMA_ATTR_WRITE_COMBINE, attrs) ?
> +    pgprot_writecombine(prot) :
> +    pgprot_dmacoherent(prot);
> +
> + vma->vm_page_prot = prot;
> +
> + if (dma_mmap_from_coherent(dev, vma, cpu_addr, size, &ret))
> + return ret;
> +
> + if (off < nr_pages && nr_vma_pages <= (nr_pages - off)) {
> + ret = remap_pfn_range(vma, vma->vm_start,
> + pfn + off,
> + vma->vm_end - vma->vm_start,
> + vma->vm_page_prot);
> + }
> +#endif  /* CONFIG_MMU */
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(xen_swiotlb_dma_mmap);
> +
> +/*
>   * Unmap a single streaming mode DMA translation.  The dma_addr and size must
>   * match what was provided for in a previous xen_swiotlb_map_page call.  All
>   * other usages are undefined.
> diff --git a/include/xen/swiotlb-xen.h b/include/xen/swiotlb-xen.h
> index 7b64465..930fa94 100644
> --- a/include/xen/swiotlb-xen.h
> +++ b/include/xen/swiotlb-xen.h
> @@ -15,6 +15,11 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t size,
>    void *vaddr, dma_addr_t dma_handle,
>    struct dma_attrs *attrs);
> 
> +extern int
> +xen_swiotlb_dma_mmap(struct device *dev, struct vm_area_struct *vma,
> +     void *cpu_addr, dma_addr_t dma_addr, size_t size,
> +     struct dma_attrs *attrs);
> +
>  extern dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
>         unsigned long offset, size_t size,
>         enum dma_data_direction dir,