From: Jarkko Sakkinen <jarkko@kernel.org>
To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Linux regressions mailing list <regressions@lists.linux.dev>,
Peter Huewe <peterhuewe@gmx.de>, Jason Gunthorpe <jgg@ziepe.ca>,
linux-integrity@vger.kernel.org,
LKML <linux-kernel@vger.kernel.org>,
reach622@mailcuk.com, 1138267643@qq.com,
"Jason A. Donenfeld" <Jason@zx2c4.com>
Subject: Re: [regression] Bug 216989 - since 6.1 systems with AMD Ryzen stutter when fTPM is enabled
Date: Wed, 8 Feb 2023 04:13:37 +0200 [thread overview]
Message-ID: <Y+MFUZ7WD0rX2rU9@kernel.org> (raw)
In-Reply-To: <Y+MFNvr2deX7+Mxa@kernel.org>
On Wed, Feb 08, 2023 at 04:13:16AM +0200, Jarkko Sakkinen wrote:
> On Thu, Feb 02, 2023 at 07:57:37AM -0500, James Bottomley wrote:
> > On Thu, 2023-02-02 at 11:28 +0100, Linux kernel regression tracking
> > (Thorsten Leemhuis) wrote:
> > [...]
> > > So it's a firmware problem, but apparently one that Linux only
> > > triggers since 6.1.
> > >
> > > Jason, could the hwrng changes have anything to do with this?
> > >
> > > A bisection really would be helpful, but I guess that is not easy as
> > > the problem apparently only shows up after some time...
> >
> > the problem description says the fTPM causes system stutter when it
> > writes to NVRAM. Since an fTPM is a proprietary implementation, we
> > don't know what it does. The ms TPM implementation definitely doesn't
> > trigger NV writes on rng requests, but it is plausible this fTPM does
> > ... particularly if they have a time based input to the DRNG. Even if
> > this speculation is true, there's not much we can do about it, since
> > it's a firmware bug and AMD should have delivered the BIOS update that
> > fixes it.
> >
> > The way to test this would be to set the config option
> >
> > CONFIG_HW_RANDOM_TPM=n
> >
> > and see if the stutter goes away. I suppose if someone could quantify
> > the bad bioses, we could warn, but that's about it.
> >
> > James
> >
>
> And e.g. I do not have a Ryzen CPU so pretty hard to answer such question.
... about hwrng
BR, Jarkko
next prev parent reply other threads:[~2023-02-08 2:14 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-02 10:28 [regression] Bug 216989 - since 6.1 systems with AMD Ryzen stutter when fTPM is enabled Linux kernel regression tracking (Thorsten Leemhuis)
2023-02-02 12:57 ` James Bottomley
2023-02-08 2:13 ` Jarkko Sakkinen
2023-02-08 2:13 ` Jarkko Sakkinen [this message]
2023-02-08 2:31 ` Jason A. Donenfeld
2023-02-08 2:52 ` Jarkko Sakkinen
2023-02-05 17:38 ` Linux kernel regression tracking (Thorsten Leemhuis)
2023-02-07 22:13 ` Jason A. Donenfeld
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