linux-kernel - Re: [PATCH] crypto: caam: disable pkc for non-E SoCs

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Date:   Wed, 22 Sep 2021 18:51:23 +0300
From:   Horia Geantă <horia.geanta@....com>
To:     Michael Walle <michael@...le.cc>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc:     Pankaj Gupta <pankaj.gupta@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S . Miller" <davem@...emloft.net>
Subject: Re: [PATCH] crypto: caam: disable pkc for non-E SoCs

On 9/16/2021 1:03 AM, Michael Walle wrote:
> On newer CAAM versions, not all accelerators are disabled if the SoC is
> a non-E variant. While the driver checks most of the modules for
> availability, there is one - PKHA - which sticks out. On non-E variants
Currently there's no dedicated support for "partially disabled" non-E
(export-controlled) parts in Linux kernel caam driver(s).

Up until recently firmware (U-boot) was deleting the "crypto" DT node
for all non-E parts [1].
Modifying the f/w indeed triggers changes across the s/w stack.

Since you are modifying only the caam code handling PKHA, is it correct
to assume that everything else is working fine?
For example: is the number of AES accelerators (AESA_VERSION[AESA_NUM])
being reported as 0 on non-E parts?

> it is still reported as available, that is the number of instances is
> non-zero, but it has limited functionality. In particular it doesn't
> support encryption and decryption, but just signing and verifying. This
> is indicated by a bit in the PKHA_MISC field. Take this bit into account
> if we are checking for availablitly.
typo:			 ^ availability
> 
> This will the following error:
> [    8.167817] caam_jr 8020000.jr: 20000b0f: CCB: desc idx 11: : Invalid CHA selected.
> 
> Tested on an NXP LS1028A (non-E) SoC.
Thanks.
Unfortunately I don't have a non-E part to test on.

Horia

[1] https://lore.kernel.org/u-boot/ff146322-e8c7-2418-ceb1-a3c0d4cee1a1@nxp.com
4eecc6f1a104 ("armv8: layerscape: don't remove crypto node if just partially disabled")