From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thorsten Leemhuis <regressions@leemhuis.info>,
James Bottomley <James.Bottomley@hansenpartnership.com>,
Peter Huewe <peterhuewe@gmx.de>,
Jarkko Sakkinen <jarkko@kernel.org>,
Jason Gunthorpe <jgg@ziepe.ca>, Jan Dabros <jsd@semihalf.com>,
regressions@lists.linux.dev, LKML <linux-kernel@vger.kernel.org>,
linux-integrity@vger.kernel.org,
Dominik Brodowski <linux@dominikbrodowski.net>,
Herbert Xu <herbert@gondor.apana.org.au>,
Johannes Altmanninger <aclopte@gmail.com>,
stable@vger.kernel.org
Subject: Re: [PATCH] tpm: Disable hwrng for TPM 1 if PM_SLEEP is enabled
Date: Thu, 5 Jan 2023 23:29:43 +0100 [thread overview]
Message-ID: <Y7dPV5BK6jk1KvX+@zx2c4.com> (raw)
In-Reply-To: <CAHk-=whxaSHcHeo10JGz3EMJZBfC1LarcrerLos7uHbE1URhtQ@mail.gmail.com>
On Thu, Jan 05, 2023 at 01:58:48PM -0800, Linus Torvalds wrote:
> On Thu, Jan 5, 2023 at 6:48 AM Jason A. Donenfeld <Jason@zx2c4.com> wrote:
> >
> > TPM 1's support for its hardware RNG is broken across system suspends,
> > due to races or locking issues or something else that haven't been
> > diagnosed or fixed yet. These issues prevent the system from actually
> > suspending. So disable the driver in this case. Later, when this is
> > fixed properly, we can remove this.
>
> How about just keeping it enabled, but not making it a fatal error if
> the TPM saving doesn't work? IOW, just print the warning, and then
> "return 0" from the suspend function.
You're right that returning 0 from the pm notifier would make the
problem that users actually care about -- laptop doesn't sleep when you
close the lid -- go away.
From a random.c perspective, the RNG is already initialized when the
driver loads, which will be before suspend bricks the driver. So even if
the behavior afterwards is a buggy driver handing all zeros to random.c,
it won't really matter much; random.c can deal with that
cryptographically. I have no idea if this is actually the case with the
driver's error condition. But if it is, it's good that it doesn't
matter.
So okay, I'll roll a patch to do that when I get home. I'm writing on my
phone now, but from memory it's just changing a 'return rc;' into
'return 0;'.
Then the TPM folks can fix the underlying issue at their leisure
whenever.
Jason
next prev parent reply other threads:[~2023-01-05 22:29 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-28 20:22 [REGRESSION] suspend to ram fails in 6.2-rc1 due to tpm errors Vlastimil Babka
2022-12-28 23:07 ` James Bottomley
2022-12-29 4:03 ` Jason A. Donenfeld
2022-12-29 4:16 ` Jason A. Donenfeld
2023-01-05 13:59 ` Thorsten Leemhuis
2023-01-05 14:25 ` Vlastimil Babka
2023-01-05 14:47 ` [PATCH] tpm: Disable hwrng for TPM 1 if PM_SLEEP is enabled Jason A. Donenfeld
2023-01-05 14:53 ` Jason A. Donenfeld
2023-01-05 21:58 ` Linus Torvalds
2023-01-05 22:29 ` Jason A. Donenfeld [this message]
2023-01-06 3:01 ` [PATCH v2] tpm: Allow system suspend to continue when TPM suspend fails Jason A. Donenfeld
2023-01-06 16:01 ` Jason A. Donenfeld
[not found] ` <CAA25o9RGVbiXS6ne53gdM1K706zT=hm5c-KuMWrCA_CJtJDXdw@mail.gmail.com>
2023-01-06 17:16 ` Jason A. Donenfeld
2023-01-06 18:59 ` Linus Torvalds
2023-01-06 20:04 ` Luigi Semenzato
2023-01-06 22:28 ` Linus Torvalds
2023-01-09 16:05 ` Jason A. Donenfeld
2023-01-16 8:12 ` Jarkko Sakkinen
2023-01-16 14:03 ` Jason A. Donenfeld
2023-01-21 0:07 ` Jarkko Sakkinen
2023-01-16 11:44 ` Jarkko Sakkinen
2023-01-16 14:00 ` Vlastimil Babka
2023-01-21 0:03 ` Jarkko Sakkinen
2023-01-05 15:17 ` [REGRESSION] suspend to ram fails in 6.2-rc1 due to tpm errors James Bottomley
2023-01-05 15:27 ` Jason A. Donenfeld
2023-01-05 15:32 ` Jason A. Donenfeld
2023-01-09 16:08 ` Jason A. Donenfeld
2023-01-10 17:19 ` Vlastimil Babka
2023-01-20 23:47 ` Jarkko Sakkinen
2023-03-14 9:35 ` Thorsten Leemhuis
2023-03-14 12:19 ` Jarkko Sakkinen
2023-03-14 12:47 ` Jason A. Donenfeld
2023-03-14 13:05 ` Jarkko Sakkinen
2023-03-14 13:08 ` Jarkko Sakkinen
2023-03-14 13:53 ` Jason A. Donenfeld
2023-03-14 14:23 ` Jarkko Sakkinen
2023-04-21 15:03 ` Jarkko Sakkinen
2023-04-21 18:27 ` Jason A. Donenfeld
2023-04-23 15:34 ` Jarkko Sakkinen
2023-04-25 23:34 ` Jarkko Sakkinen
2023-04-26 1:32 ` Jason A. Donenfeld
2023-04-26 16:07 ` Jarkko Sakkinen
2023-04-26 17:00 ` Jarkko Sakkinen
2023-01-04 9:10 ` Johannes Altmanninger
2023-01-16 11:30 ` Jarkko Sakkinen
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