Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <CAJKOXPfVXnazraHq-NCCM+h26FFi1U6Z3OSYOX17XH3bj-UDLQ@mail.gmail.com>
 <3053033.se6UkFii4W@tauon.chronox.de> <CGME20180830130922epcas1p35b0395da64de59107a805c6b99d770c2@epcas1p3.samsung.com>
 <CAJKOXPd7JdzM2_PiHkS1ix1yU9hZmMbGDZaL07vbON0XzORH=w@mail.gmail.com> <20180830132732eucas1p12b941ed065276c0cbed6e7b1e01a30dc~PrH1zJtnY2603926039eucas1p1b@eucas1p1.samsung.com>
In-Reply-To: <20180830132732eucas1p12b941ed065276c0cbed6e7b1e01a30dc~PrH1zJtnY2603926039eucas1p1b@eucas1p1.samsung.com>
From:   Krzysztof Kozlowski <krzk@kernel.org>
Date:   Thu, 30 Aug 2018 15:59:51 +0200
Message-ID: <CAJKOXPfNjHRXVic=ycJ3yek-1ufL7v8MkUM9ZBhyOnj0SEaHSw@mail.gmail.com>
Subject: Re: Locking for HW crypto accelerators
To:     k.konieczny@partner.samsung.com
Cc:     smueller@chronox.de, herbert@gondor.apana.org.au,
        davem@davemloft.net, linux-crypto@vger.kernel.org,
        linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Thu, 30 Aug 2018 at 15:27, Kamil Konieczny
<k.konieczny@partner.samsung.com> wrote:
>
> On 30.08.2018 15:09, Krzysztof Kozlowski wrote:
> > [...]
> > Thanks Stephan for hints. Let's assume the each of init, update and
> > final are atomic... but how about the relation between update and
> > final? I have two concurrent users in user-space but only one HW:
> >
> > Process A:             Process B:
> > init() and set_key()
> >                        init() and different key
> > update(some_data)
> >                        update(different_data)
> > final()
> >                        final()
> >
> > The final() from process A will now produce the result of hashing/CRC
> > of some_data and different_data (and even maybe mixed with init() for
> > different key). All because in the meantime process B added its own
> > data to the HW.
> >
> > Best regards,
> > Krzysztof
> Can your hardware do export/import ?
>
> If yes, you can use workqueue and guard HW with spinlock,
> as in exynos hash in s5p-sss.c (or see other drivers).

Yes, workqueue doing all necessary HW initialization would be the
solution here as well. The point is what later Herbert wrote - I need
to take care about the HW state because the requests even for shash
will be coming in random order.

Best regards,
Krzysztof