[Skiboot] NX crypto on POWER9

George Wilson gcwilson at us.ibm.com
Tue Mar 9 06:49:00 AEDT 2021

"Klaus Heinrich Kiwi" <klaus at linux.vnet.ibm.com> wrote on 03/08/2021
12:48:28 PM:

> From: "Klaus Heinrich Kiwi" <klaus at linux.vnet.ibm.com>
> To: Haren Myneni/Beaverton/IBM at IBM
> Cc: skiboot at lists.ozlabs.org, George Wilson/Austin/IBM at IBM
> Date: 03/08/2021 12:48 PM
> Subject: Re: [Skiboot] NX crypto on POWER9
> On 3/8/2021 3:39 PM, Haren Myneni wrote:
> > Klaus,
> >
> > NX crypto is not enabled and supported on P9 due to performance issues.
Instead use SW instructions.
> >
> > George Wilson can give more information.

We consider NX crypto deprecated in favor of the VMX crypto instructions.
The Linux device driver
for NX crypto hasn't been updated on many years.  NX crypto has a number of
characteristics that
make it difficult or impossible achieve the theoretical performance levels
from it.  Our team is
neither the first nor the last to arrive at that conclusion.  I'd strongly
recommend using the
vector instructions rather than NX.

> >
> > Thanks
> > haren
> Haren,
>   thanks for your answer, but perhaps we need a bit more to go on?
>  From what I could understand, Léo is really looking for the
specification for NX crypto? Sometimes the use-case he
> has has better performance characteristics using those.. I don't think
anyone is requesting Official IBM support here..
>   -Klaus
> --
> Klaus Heinrich Kiwi <klaus at linux.vnet.ibm.com>
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