Re: [PATCH 1/2] xen/swiotlb: relax alignment requirements

[Jan Beulich]

On 11.02.2025 13:04, Juergen Gross wrote:
> When mapping a buffer for DMA via .map_page or .map_sg DMA operations,
> there is no need to check the machine frames to be aligned according
> to the mapped areas size. All what is needed in these cases is that the
> buffer is contiguous at machine level.

Is this really true in all cases? Can't e.g. compound pages make it here,
with the caller then still being permitted to assume higher than page
alignment? Alignment checking in xen_swiotlb_map_page() would perhaps
need doing with the base address of the incoming page, i.e. excluding
the incoming offset.

Jan