Re: [RFC PATCH] gcm - fix setkey cache coherence issues

[Radu Solea <radu.solea@nxp.com>]

On Vi, 2017-06-23 at 14:31 +0800, Herbert Xu wrote:
> 
> The crypto API cannot rely on users providing aligned buffers.  So
> if your driver has an alignment requirement, it either has to use
> the existing crypto API alignmask setting which can cope with some
> unaligned inputs, e.g., the IV if you use the skcipher walk
> mechanism,
> or you must copy unaligned data yourself before performing DMA on
> them.
> 
> Cheers,

Normally I would agree with you, if it's a weird requirement coming
from hardware or driver. In this case I think it's different. This is
not a limitation coming from one driver or one particular hardware
variety. It applies to all platforms that do not have hw cache
coherence and a large enough cacheline.
 
A couple of lines below the allocation hash is linked into a
scatterlist, a data structure with remarkably high chances of ending up
in a DMA endpoint, yet we choose to ignore all other DMA requirements?

Cheers,
Radu.