Re: [EXT] Re: [PATCH v4 5/5] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys

Ahmad Fatoum
2022-02-22T11:25:27Z

Hello Pankaj,

On 22.02.22 05:30, Pankaj Gupta wrote:
> Hi Ahmad,
>
>
>> -----Original Message-----
>> From: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
>> Sent: Monday, December 13, 2021 7:11 PM
>> To: Ahmad Fatoum <a.fatoum@pengutronix.de>
>>
>>> For now, this is pointed out in the documentation. If you have a
>>> suggestion on a specific condition we should check and issue a
>>> diagnostic on, I can incorporate it. An exhaustive if
>>> WARN_ON(!secure()) is impossible, but having some warning for
>>> unsuspecting users would indeed be nice.
>>
>> I don't know of any condition that doesn't involve looking at SoC- specific OTP
>> registers - that's what U-Boot does to determine whether HAB is enabled...
>>
>
> Check the value fetched from the SEC Status Register (SSTA) (Offset 0xFD4h, bit 8,9 => 00b - Non-Secure, 01b - Secure, 10b - Trusted, 11b - Fail), for MOO (Mode of Operation).
> And the warning can be issued accordingly.
>
> It is to be noted that this register is part of CAAM page0, which might not be accessible to Linux, for all the iMX SoC(s).
>
> For other SoC(s), this can be added.

Thanks for the pointer. I am only testing this with i.MX, so I'd prefer this
be left as a future exercise for a Layerscape user.

Thanks for your reviews. I collected them on Patches 2/5 and 4/5 for v5.

Cheers,
Ahmad

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