Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <Y7dPV5BK6jk1KvX+@zx2c4.com> <20230106030156.3258307-1-Jason@zx2c4.com>
 <Y7hF5vG8rWjbCLyL@zx2c4.com> <CAA25o9RGVbiXS6ne53gdM1K706zT=hm5c-KuMWrCA_CJtJDXdw@mail.gmail.com>
In-Reply-To: <CAA25o9RGVbiXS6ne53gdM1K706zT=hm5c-KuMWrCA_CJtJDXdw@mail.gmail.com>
From:   "Jason A. Donenfeld" <Jason@zx2c4.com>
Date:   Fri, 6 Jan 2023 18:16:19 +0100
Message-ID: <CAHmME9pwUZ+rOLEB=zLTUObAv0At=_n5vs=xQfB=Kw_hwA03Tg@mail.gmail.com>
Subject: Re: [PATCH v2] tpm: Allow system suspend to continue when TPM suspend fails
To:     Luigi Semenzato <semenzato@chromium.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,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Vlastimil Babka <vbabka@suse.cz>, tbroch@chromium.org,
        dbasehore@chromium.org, keescook@chromium.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Fri, Jan 6, 2023 at 6:04 PM Luigi Semenzato <semenzato@chromium.org> wro=
te:
>
> I worked a fair amount on TPM 1.0 about 10 years ago and I even vaguely r=
emember suspend-related problems.  I'd be happy to take a look.  The linked=
 thread shows that Peter Huewe was copied.  I know Peter well, his opinion =
can be trusted.  Unfortunately I don't immediately see a link to a patch, c=
an you help?

Sorry, I should have included that:
https://lore.kernel.org/lkml/20230106030156.3258307-1-Jason@zx2c4.com/
Instead of blocking system suspend when TPM_ORD_SAVESTATE fails, it
just lets the system sleep anyway. This means that presumably the
system might sleep without having called TPM_ORD_SAVESTATE. Trying to
figure out how bad that is.

And yes, Peter Huewe certainly knows about TPMs, especially as he
maintains the code in Linux, but the maintainers haven't been so much
available, unfortunately. This bug happens to intersect with something
mostly related that I work on (the rng), so I'm motivated to at least
prevent the worst of the breakage, but I otherwise don't know anything
about the Linux TPM driver.

Jason