Re: [Xen-devel] [PATCH v3 2/2] swiotlb-xen: implement xen_swiotlb_get_sgtable callback

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Tue, Jan 31, 2017 at 08:30:26PM +0200, Andrii Anisov wrote:
> From: Andrii Anisov <andrii_anisov@xxxxxxxx>
> 
> Signed-off-by: Andrii Anisov <andrii_anisov@xxxxxxxx>
> Signed-off-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> ---
>  arch/arm/xen/mm.c         |  1 +
>  drivers/xen/swiotlb-xen.c | 22 ++++++++++++++++++++++
>  include/xen/swiotlb-xen.h |  6 ++++++
>  3 files changed, 29 insertions(+)
> 
> diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
> index cd1684e..76ea48a 100644
> --- a/arch/arm/xen/mm.c
> +++ b/arch/arm/xen/mm.c
> @@ -199,6 +199,7 @@ static struct dma_map_ops xen_swiotlb_dma_ops = {
>       .dma_supported = xen_swiotlb_dma_supported,
>       .set_dma_mask = xen_swiotlb_set_dma_mask,
>       .mmap = xen_swiotlb_dma_mmap,
> +     .get_sgtable = xen_swiotlb_get_sgtable,
>  };
>  
>  int __init xen_mm_init(void)
> diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> index 8ac36b4..a809d43 100644
> --- a/drivers/xen/swiotlb-xen.c
> +++ b/drivers/xen/swiotlb-xen.c
> @@ -699,3 +699,25 @@ xen_swiotlb_dma_mmap(struct device *dev, struct 
> vm_area_struct *vma,
>       return dma_common_mmap(dev, vma, cpu_addr, dma_addr, size);
>  }
>  EXPORT_SYMBOL_GPL(xen_swiotlb_dma_mmap);
> +
> +/*
> + * Following function should be called with the local pages only.

What does 'local pages' mean?

> + */
> +int
> +xen_swiotlb_get_sgtable(struct device *dev, struct sg_table *sgt,
> +                     void *cpu_addr, dma_addr_t handle, size_t size,
> +                     unsigned long attrs)
> +{
> +#if defined(CONFIG_ARM) || defined(CONFIG_ARM64)
> +     if (__generic_dma_ops(dev)->get_sgtable) {
> +#ifdef DEBUG
> +             unsigned long bfn = PHYS_PFN(dma_to_phys(dev, handle));
> +             BUG_ON (!page_is_ram(bfn));
> +#endif

Could you remove the above please?

> +             return __generic_dma_ops(dev)->get_sgtable(dev, sgt, cpu_addr,
> +                                                        handle, size, attrs);
> +     }
> +#endif
> +     return dma_common_get_sgtable(dev, sgt, cpu_addr, handle, size);
> +}
> +EXPORT_SYMBOL_GPL(xen_swiotlb_get_sgtable);
> diff --git a/include/xen/swiotlb-xen.h b/include/xen/swiotlb-xen.h
> index 5c8f4c8..c554c23 100644
> --- a/include/xen/swiotlb-xen.h
> +++ b/include/xen/swiotlb-xen.h
> @@ -60,4 +60,10 @@ 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,
>                       unsigned long attrs);
> +
> +extern int
> +xen_swiotlb_get_sgtable(struct device *dev, struct sg_table *sgt,
> +                     void *cpu_addr, dma_addr_t handle, size_t size,
> +                     unsigned long attrs);

And perhaps fix this to be aligned properly?
> +
>  #endif /* __LINUX_SWIOTLB_XEN_H */
> -- 
> 2.7.4
> 

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