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Subject: Re: Locking for HW crypto accelerators
To:     Krzysztof Kozlowski <krzk@kernel.org>, smueller@chronox.de
Cc:     herbert@gondor.apana.org.au, davem@davemloft.net,
        linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org
From:   Kamil Konieczny <k.konieczny@partner.samsung.com>
Date:   Thu, 30 Aug 2018 15:27:31 +0200
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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).

-- 
Best regards,
Kamil Konieczny
Samsung R&D Institute Poland