Re: [PATCH v3 09/11] swiotlb-xen: introduce phys_to_dma/dma_to_phys translations

[Jürgen Groß <jgross@xxxxxxxx>]

On 11.07.20 00:34, Stefano Stabellini wrote:
> From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
>
> With some devices physical addresses are different than dma addresses.
> To be able to deal with these cases, we need to call phys_to_dma on
> physical addresses (including machine addresses in Xen terminology)
> before returning them from xen_swiotlb_alloc_coherent and
> xen_swiotlb_map_page.
>
> We also need to convert dma addresses back to physical addresses using
> dma_to_phys in xen_swiotlb_free_coherent and xen_swiotlb_unmap_page if
> we want to do any operations on them.
>
> Call dma_to_phys in is_xen_swiotlb_buffer.
> Introduce xen_phys_to_dma and call phys_to_dma in its implementation.
> Introduce xen_dma_to_phys and call dma_to_phys in its implementation.
> Call xen_phys_to_dma/xen_dma_to_phys instead of
> xen_phys_to_bus/xen_bus_to_phys through swiotlb-xen.c.
>
> Everything is taken care of by these changes except for
> xen_swiotlb_alloc_coherent and xen_swiotlb_free_coherent, which need a
> few explicit phys_to_dma/dma_to_phys calls.
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
> Tested-by: Corey Minyard <cminyard@xxxxxxxxxx>
> Tested-by: Roman Shaposhnik <roman@xxxxxxxxxx>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>


Juergen