Hi Steffen,

On Wed, Jan 31, 2018 at 12:13 AM, Steffen Klassert
<steffen.klass...@secunet.com> wrote:
>
> I wonder which special usecase you have in mind that will be improved
> by your patches.
>

This is not related to IPsec. We have an internal use case where the
data buffer itself is a single memory page but the authentication tag
needs to be in a separate buffer. This patch set allows us to have
zero copy in that case.

>
> Maybe it would be better to investigate in the direction to
> support SG operations with gcm-aesni instead of trying to
> find all corner cases where the existing implementation can
> do zero-copy.
>

Yes, if gcm-aesni could be implemented to handle arbitrarily
fragmented buffers, that would be better, but it would likely be a
much bigger and more complicated change. Just handling the case where
the AAD/data/authtag are separate contiguous buffers is relatively
simpler but still useful.

Thanks,
Junaid

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