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

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Message-Id: <CVABVIQB3858.CWOHMN527J67@suppilovahvero>
Date:   Mon, 04 Sep 2023 21:00:59 +0300
From:   "Jarkko Sakkinen" <jarkko@...nel.org>
To:     "Mario Limonciello" <mario.limonciello@....com>,
        "Paul Menzel" <pmenzel@...gen.mpg.de>
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>
Subject: Re: [PATCH v3] tpm: Enable hwrng only for Pluton on AMD CPUs

On Mon Aug 28, 2023 at 3:35 AM EEST, 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:
> >>>> Dear Jarkko,
> >>>>
> >>>>
> >>>> Thank you for your patch.
> >>>>
> >>>>
> >>>> 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>
> >>>
> >>> The problem here is that checkpatch throws three warnings:
> >>>
> >>> WARNING: Reported-by: should be immediately followed by Closes: with a URL to the report
> >>> #19:
> >>> Reported-by: Patrick Steinhardt <ps@....im>
> >>> Reported-by: Ronan Pigott <ronan@....ie>
> >>>
> >>> WARNING: Reported-by: should be immediately followed by Closes: with a URL to the report
> >>> #20:
> >>> Reported-by: Ronan Pigott <ronan@....ie>
> >>> Reported-by: Raymond Jay Golo <rjgolo@...il.com>
> >>>
> >>> WARNING: Reported-by: should be immediately followed by Closes: with a URL to the report
> >>> #21:
> >>> Reported-by: Raymond Jay Golo <rjgolo@...il.com>
> >>> Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>
> >>>
> >>
> >> FWIW I observed the same checkpatch warning when I submitted my version
> >> of the patch.  I figured it's better to ignore the warning and attribute
> >> everyone who reported the issue affected them.
> > 
> > OK so:
> > 
> > 1. checkpatch.pl is part of the kernel process.
> > 2. Bugzilla is not part of the kernel process.
> > 
> > Why emphasis on 1?
> > 
> > BR, Jarkko
>
> The reason I submitted it this way is because of this quote from the 
> documentation [1].
>
> "Check your patches with the patch style checker prior to submission 
> (scripts/checkpatch.pl). Note, though, that the style checker should be 
> viewed as a guide, not as a replacement for human judgment. If your code 
> looks better with a violation then its probably best left alone."
>
> I wanted the patch to capture and attribute all those that reported it 
> not just the "first one".  Like I said previously, it's better to have a 
> collection of people to ping to notify if something needs to be reverted.
>
> [1] 
> https://www.kernel.org/doc/html/latest/process/submitting-patches.html#style-check-your-changes

Please denote also that kernel bugzilla is not mentioned in the page
that you put as a reference, and only reporter in the LKML has been
Todd.

BR, Jarkko