Received-SPF: pass (google.com: domain of linux-crypto-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Wed, 22 Sep 2021 08:04:39 +0200
From:   Corentin Labbe <clabbe.montjoie@gmail.com>
To:     Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
Cc:     linux-crypto@vger.kernel.org, Ash Logan <ash@heyquark.com>,
        Jonathan =?iso-8859-1?Q?Neusch=E4fer?= <j.ne@posteo.net>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>,
        Rob Herring <robh+dt@kernel.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 1/4] crypto: nintendo-aes - add a new AES driver
Message-ID: <YUrHdxY4EyanC9KR@Red>
References: <20210921213930.10366-1-linkmauve@linkmauve.fr>
 <20210921213930.10366-2-linkmauve@linkmauve.fr>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <20210921213930.10366-2-linkmauve@linkmauve.fr>
Precedence: bulk

Le Tue, Sep 21, 2021 at 11:39:27PM +0200, Emmanuel Gil Peyrot a écrit :
> This engine implements AES in CBC mode, using 128-bit keys only.  It is
> present on both the Wii and the Wii U, and is apparently identical in
> both consoles.
> 
> The hardware is capable of firing an interrupt when the operation is
> done, but this driver currently uses a busy loop, I’m not too sure
> whether it would be preferable to switch, nor how to achieve that.
> 
> It also supports a mode where no operation is done, and thus could be
> used as a DMA copy engine, but I don’t know how to expose that to the
> kernel or whether it would even be useful.
> 
> In my testing, on a Wii U, this driver reaches 80.7 MiB/s, while the
> aes-generic driver only reaches 30.9 MiB/s, so it is a quite welcome
> speedup.
> 
> This driver was written based on reversed documentation, see:
> https://wiibrew.org/wiki/Hardware/AES
> 
> Signed-off-by: Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
> Tested-by: Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>  # on Wii U

[...]

> +static int
> +do_crypt(const void *src, void *dst, u32 len, u32 flags)
> +{
> +	u32 blocks = ((len >> 4) - 1) & AES_CTRL_BLOCK;
> +	u32 status;
> +	u32 counter = OP_TIMEOUT;
> +	u32 i;
> +
> +	/* Flush out all of src, we can’t know whether any of it is in cache */
> +	for (i = 0; i < len; i += 32)
> +		__asm__("dcbf 0, %0" : : "r" (src + i));
> +	__asm__("sync" : : : "memory");
> +
> +	/* Set the addresses for DMA */
> +	iowrite32be(virt_to_phys((void *)src), base + AES_SRC);
> +	iowrite32be(virt_to_phys(dst), base + AES_DEST);

Hello

Since you do DMA operation, I think you should use the DMA-API and call dma_map_xxx()
This will prevent the use of __asm__ and virt_to_phys().

Regards