[RFC PATCH] crypto: flush poison data

[Christoph Hellwig]

On Tue, Jul 05, 2022 at 07:56:11PM +0200, LABBE Corentin wrote:
> My problem is that a dma_sync on the data buffer corrupt the poison buffer as collateral dommage.
> Probably because the sync operate on a larger region than the requested dma_sync length.
> So I try to flush poison data in the cryptoAPI.

Data structures that are DMAed to must be aligned to
the value returned by dma_get_cache_alignment(), as non-coherent DMA
by definition can disturb the data inside that boundary.  That is not
a bug but fundamentally part of how DMA works when the device attachment
is not cache coherent.