linux-kernel - Re: [PATCH v3] tpm: Enable hwrng only for Pluton on AMD CPUs

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Message-ID: <116dd56f-695f-4ecd-dace-805db83f5c3e@leemhuis.info>
Date:   Fri, 1 Sep 2023 10:49:17 +0200
From:   Thorsten Leemhuis <regressions@...mhuis.info>
To:     Mario Limonciello <mario.limonciello@....com>,
        Jarkko Sakkinen <jarkko@...nel.org>
Cc:     linux-integrity@...r.kernel.org,
        Jerry Snitselaar <jsnitsel@...hat.com>, stable@...r.kernel.org,
        Todd Brandt <todd.e.brandt@...el.com>,
        Peter Huewe <peterhuewe@....de>,
        Jason Gunthorpe <jgg@...pe.ca>, linux-kernel@...r.kernel.org,
        Patrick Steinhardt <ps@....im>, Ronan Pigott <ronan@....ie>,
        Raymond Jay Golo <rjgolo@...il.com>,
        Linux kernel regressions list <regressions@...ts.linux.dev>,
        Dusty Mabe <dusty@...tymabe.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Jerry Snitselaar <jsnitsel@...hat.com>,
        Paul Menzel <pmenzel@...gen.mpg.de>
Subject: Re: [PATCH v3] tpm: Enable hwrng only for Pluton on AMD CPUs

[CCing Linus, as this triggered my "this is moving to slowly" threshold,
as (a) the initial report was two weeks ago by now (b) a fix seems
within reach for nearly as long (c) the problem seems to annoy quite a
few people, as the culprit of this regression made it into 6.5 and was
picked up for 6.1.y and 6.4.y (rightfully so I'd say, as it fixes an
earlier regression)]

On 29.08.23 10:38, Linux regression tracking (Thorsten Leemhuis) wrote:
> On 28.08.23 02:35, Mario Limonciello wrote:
>> On 8/27/2023 13:12, Jarkko Sakkinen wrote:
>>> On Wed Aug 23, 2023 at 9:58 PM EEST, Mario Limonciello wrote:
>>>> On 8/23/2023 12:40, Jarkko Sakkinen wrote:
>>>>> On Wed Aug 23, 2023 at 11:23 AM EEST, Paul Menzel wrote:
>>>>>> Am 23.08.23 um 01:15 schrieb Jarkko Sakkinen:
>>>>>>> The vendor check introduced by commit 554b841d4703 ("tpm: Disable
>>>>>>> RNG for
>>>>>>> all AMD fTPMs") doesn't work properly on a number of Intel fTPMs. 
>>>>>>> On the
>>>>>>> reported systems the TPM doesn't reply at bootup and returns back the
>>>>>>> command code. This makes the TPM fail probe.
>>>>>>>
>>>>>>> Since only Microsoft Pluton is the only known combination of AMD
>>>>>>> CPU and
>>>>>>> fTPM from other vendor, disable hwrng otherwise. In order to make
>>>>>>> sysadmin
>>>>>>> aware of this, print also info message to the klog.
>>>>>>>
>>>>>>> Cc: stable@...r.kernel.org
>>>>>>> Fixes: 554b841d4703 ("tpm: Disable RNG for all AMD fTPMs")
>>>>>>> Reported-by: Todd Brandt <todd.e.brandt@...el.com>
>>>>>>> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217804
>>>>>>> Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>
>>>>>>
>>>>>> Mario’s patch also had the three reporters below listed:
>>>>>>
>>>>>> Reported-by: Patrick Steinhardt <ps@....im>
>>>>>> Reported-by: Ronan Pigott <ronan@....ie>
>>>>>> Reported-by: Raymond Jay Golo <rjgolo@...il.com>
>
> [...] this seems to become a regression
> that is annoying quite a few people (in 6.5 and 6.4.y afaics), so it
> would be good to get the fix merged to mainline rather sooner than
> later. Are these warnings and the mentioning of affected machines in the
> patch descriptions the only remaining problems, or is there anything
> else that needs to be addressed?

Hmmm. Quite a bit progress to fix the issue was made in the first week
after Todd's report; Jarkko apparently even applied the earlier patch
from Mario to his master branch:
https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd.git/commit/?id=b1a62d41bdc1d15b0641759717e8c3651f0a810c
But since then (aka in the past week) there was not much progress.

Wondering what's up here -- and if both patches are needed or just one
of them (I suspect it's the latter).

Checked lore and noticed that Jarkko was not much active in kernel land
during the past few days; happens, *no worries at all*. But still would
be good if this could be resolved rather sooner that later. Just not
sure how to achieve that.

Mario, could you maybe pick this up in case Jarkko doesn't show up soon
soon? From an earlier message in the thread it sounded like all that was
missing was a slightly improved patch description? Or am I missing
something?

Ciao, Thorsten (who feels bad that he's putting pressure on people;
sorry for that, but that duty comes with the "regression tracker" hat)
--
Everything you wanna know about Linux kernel regression tracking:
https://linux-regtracking.leemhuis.info/about/#tldr
If I did something stupid, please tell me, as explained on that page.

#regzbot poke