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Subject: Re: [PATCH v2 1/3] crypto: mxs-dcp: Add support for hardware provided
 keys
From:   David Gstir <david@sigma-star.at>
In-Reply-To: <CVH49V57VE6R.2488KOQMR5AKQ@suppilovahvero>
Date:   Wed, 13 Sep 2023 10:36:11 +0200
Cc:     Mimi Zohar <zohar@linux.ibm.com>,
        James Bottomley <jejb@linux.ibm.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>,
        Shawn Guo <shawnguo@kernel.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        "kernel@pengutronix.de" <kernel@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        Ahmad Fatoum <a.fatoum@pengutronix.de>,
        sigma star Kernel Team <upstream+dcp@sigma-star.at>,
        David Howells <dhowells@redhat.com>,
        Li Yang <leoyang.li@nxp.com>, Paul Moore <paul@paul-moore.com>,
        James Morris <jmorris@namei.org>,
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References: <20230912111115.24274-1-david@sigma-star.at>
 <20230912111115.24274-2-david@sigma-star.at>
 <CVH49V57VE6R.2488KOQMR5AKQ@suppilovahvero>
To:     Jarkko Sakkinen <jarkko@kernel.org>
Precedence: bulk

Hi Jarkko,

thanks for the review!

> On 12.09.2023, at 19:32, Jarkko Sakkinen <jarkko@kernel.org> wrote:
>=20
> On Tue Sep 12, 2023 at 2:11 PM EEST, David Gstir wrote:

[...]

>> - /* Payload contains the key. */
>> - desc->control0 |=3D MXS_DCP_CONTROL0_PAYLOAD_KEY;
>> + if (key_referenced) {
>> + /* Set OTP key bit to select the key via KEY_SELECT. */
>> + desc->control0 |=3D MXS_DCP_CONTROL0_OTP_KEY;
>> + } else {
>> + /* Payload contains the key. */
>> + desc->control0 |=3D MXS_DCP_CONTROL0_PAYLOAD_KEY;
>> + }
>=20
> Remove curly braces (coding style).

Will fix that and all similar cases for v3.


>> +static int mxs_dcp_aes_setrefkey(struct crypto_skcipher *tfm, const =
u8 *key,
>> + unsigned int len)
>> +{
>> + struct dcp_async_ctx *actx =3D crypto_skcipher_ctx(tfm);
>> +
>> + if (len !=3D DCP_PAES_KEYSIZE)
>> + return -EINVAL;
>> +
>> + switch (key[0]) {
>> + case DCP_PAES_KEY_SLOT0:
>> + case DCP_PAES_KEY_SLOT1:
>> + case DCP_PAES_KEY_SLOT2:
>> + case DCP_PAES_KEY_SLOT3:
>> + case DCP_PAES_KEY_UNIQUE:
>> + case DCP_PAES_KEY_OTP:
>> + memcpy(actx->key, key, len);
>> + break;
>=20
> I don't understand why the "commit" is split into two parts
> (memcpy and assignments in different code blocks). You should
> probably rather:
>=20
> switch (key[0]) {
> case DCP_PAES_KEY_SLOT0:
> case DCP_PAES_KEY_SLOT1:
> case DCP_PAES_KEY_SLOT2:
> case DCP_PAES_KEY_SLOT3:
> case DCP_PAES_KEY_UNIQUE:
> case DCP_PAES_KEY_OTP:
> memcpy(actx->key, key, len);
> actx->key_len =3D len;
> actx->refkey =3D true;
> return 0;
>=20
> default:
> return -EINVAL;
> }
> }
>=20
> Or alternatively you can move all operations after the switch-case
> statement. IMHO, any state change is better to put into a singular
> location.

Makes sense. I=E2=80=99ll change that.


>> diff --git a/include/soc/fsl/dcp.h b/include/soc/fsl/dcp.h
>> new file mode 100644
>> index 000000000000..df6678ee10a1
>> --- /dev/null
>> +++ b/include/soc/fsl/dcp.h
>> @@ -0,0 +1,19 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/*
>> + * Copyright (C) 2021 sigma star gmbh
>> + * Authors: David Gstir <david@sigma-star.at>
>> + *          Richard Weinberger <richard@sigma-star.at>
>=20
> Git already has author-field and commit can have co-developed-by so
> this is totally obsolete.

Also noted for v3.

Thanks,
- David

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