On Wed, Jul 01, 2020 at 10:34:53AM -0700, Stefano Stabellini wrote:

Would you be in favor of a more flexible check along the lines of the
one proposed in the patch that started this thread:

    if (xen_vring_use_dma())
            return true;


xen_vring_use_dma would be implemented so that it returns true when
xen_swiotlb is required and false otherwise.

Just to stress - with a patch like this virtio can *still* use DMA API
if PLATFORM_ACCESS is set. So if DMA API is broken on some platforms
as you seem to be saying, you guys should fix it before doing something
like this..

-- 
MST