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Date:   Wed, 8 Jul 2020 09:53:36 +0200
From:   Corentin Labbe <clabbe.montjoie@gmail.com>
To:     Ard Biesheuvel <ardb@kernel.org>
Cc:     linux-crypto@vger.kernel.org, Corentin Labbe <clabbe@baylibre.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>,
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        Chen-Yu Tsai <wens@csie.org>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        John Allen <john.allen@amd.com>,
        Ayush Sawal <ayush.sawal@chelsio.com>,
        Vinay Kumar Yadav <vinay.yadav@chelsio.com>,
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        Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
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        Fabio Estevam <festevam@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>,
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        linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org,
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Subject: Re: [PATCH v4 05/13] crypto: sun8i-ce - permit asynchronous skcipher
 as fallback
Message-ID: <20200708075336.GB19609@Red>
References: <20200707063203.5018-1-ardb@kernel.org>
 <20200707063203.5018-6-ardb@kernel.org>
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On Tue, Jul 07, 2020 at 09:31:55AM +0300, Ard Biesheuvel wrote:
> Even though the sun8i-ce driver implements asynchronous versions of
> ecb(aes) and cbc(aes), the fallbacks it allocates are required to be
> synchronous. Given that SIMD based software implementations are usually
> asynchronous as well, even though they rarely complete asynchronously
> (this typically only happens in cases where the request was made from
> softirq context, while SIMD was already in use in the task context that
> it interrupted), these implementations are disregarded, and either the
> generic C version or another table based version implemented in assembler
> is selected instead.
> 
> Since falling back to synchronous AES is not only a performance issue, but
> potentially a security issue as well (due to the fact that table based AES
> is not time invariant), let's fix this, by allocating an ordinary skcipher
> as the fallback, and invoke it with the completion routine that was given
> to the outer request.
> 
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> Acked-by: Corentin Labbe <clabbe.montjoie@gmail.com>
> ---
>  drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c | 41 ++++++++++----------
>  drivers/crypto/allwinner/sun8i-ce/sun8i-ce.h        |  8 ++--
>  2 files changed, 25 insertions(+), 24 deletions(-)
> 

I finally took the time to rebase all my hash/xrng serie on top of this change and test this patch.

Tested-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Tested-on: sun50i-h6-pine-h64
Tested-on: sun8i-h3-orangepi-pc