Re: [Xen-devel] [PATCH 2/3] x86: allow dma_get_required_mask() to be overridden

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Wed, 12 Nov 2014, David Vrabel wrote:
> Use dma_ops->get_required_mask() if provided, defaulting to
> dma_get_requried_mask_from_max_pfn().
> 
> This is needed on systems (such as Xen PV guests) where the DMA
> address and the physical address are not equal.
> 
> Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>

Reviewed-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>


>  arch/x86/include/asm/device.h |    2 ++
>  arch/x86/kernel/pci-dma.c     |    8 ++++++++
>  2 files changed, 10 insertions(+)
> 
> diff --git a/arch/x86/include/asm/device.h b/arch/x86/include/asm/device.h
> index 03dd729..10bc628 100644
> --- a/arch/x86/include/asm/device.h
> +++ b/arch/x86/include/asm/device.h
> @@ -13,4 +13,6 @@ struct dev_archdata {
>  struct pdev_archdata {
>  };
>  
> +#define ARCH_HAS_DMA_GET_REQUIRED_MASK
> +
>  #endif /* _ASM_X86_DEVICE_H */
> diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
> index a25e202..5154400 100644
> --- a/arch/x86/kernel/pci-dma.c
> +++ b/arch/x86/kernel/pci-dma.c
> @@ -140,6 +140,14 @@ void dma_generic_free_coherent(struct device *dev, 
> size_t size, void *vaddr,
>               free_pages((unsigned long)vaddr, get_order(size));
>  }
>  
> +u64 dma_get_required_mask(struct device *dev)
> +{
> +     if (dma_ops->get_required_mask)
> +             return dma_ops->get_required_mask(dev);
> +     return dma_get_required_mask_from_max_pfn(dev);
> +}
> +EXPORT_SYMBOL_GPL(dma_get_required_mask);
> +
>  /*
>   * See <Documentation/x86/x86_64/boot-options.txt> for the iommu kernel
>   * parameter documentation.
> -- 
> 1.7.10.4
> 
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