Re: [PATCH 07/10] crypto: Use ARCH_DMA_MINALIGN instead of ARCH_KMALLOC_MINALIGN

Arnd Bergmann
2022-04-21T07:38:15Z

On Thu, Apr 21, 2022 at 9:20 AM Christoph Hellwig <hch@infradead.org> wrote:
>
> Btw, there is another option: Most real systems already require having
> swiotlb to bounce buffer in some cases. We could simply force bounce
> buffering in the dma mapping code for too small or not properly aligned
> transfers and just decrease the dma alignment.

I like the idea because these days we already rely on bounce buffering
for sub-page buffers in many iommu based cases for strict isolation
purposes, as well as most 64-bit machines that lack an iommu.

Does this work on all 32-bit architectures as well? I see that you added
swiotlb for ARM LPASE systems in 2019, but I don't know if that has any
additional requirements for the other 32-bit architectures that don't
select SWIOTLB today.

Arnd