Re: intermittent hang, s390x host, bios-tables-test test, TPM

["Daniel P. Berrangé" <berrange@redhat.com>]

On Tue, Jan 10, 2023 at 01:50:26PM -0500, Stefan Berger wrote:
> 
> 
> On 1/6/23 10:16, Stefan Berger wrote:
>> This here seems to be the root cause. An unknown control channel
>> command was received from the TPM emulator backend by the control channel thread and we end up in g_assert_not_reached().
> > 
> > https://github.com/qemu/qemu/blob/master/tests/qtest/tpm-emu.c#L189
> > 
> > 
> > 
> >          ret = qio_channel_read(ioc, (char *)&cmd, sizeof(cmd), NULL);
> >          if (ret <= 0) {
> >              break;
> >          }
> > 
> >          cmd = be32_to_cpu(cmd);
> >          switch (cmd) {
> >   [...]
> >          default:
> >              g_debug("unimplemented %u", cmd);
> >              g_assert_not_reached();                <------------------
> >          }
> > 
> > I will run this test case in an endless loop on an x86_64 host and see what we get there ...
> 
> I could not recreate the issue running the  test on a ppc64 and x86_64
> host. There we like >100k test runs on ppc64 and >40k on x86_64. Also
> simulating the reception of an unsupported command did not lead to a
> hang like shown here.

Assuming your ppc64 host is running an little endian OS, and
we're only seeing the test failure on s390x, then it points towards
the problem being an endianness issue in the TPM code. Something
missing a byteswap somewhere along the way ?


With regards,
Daniel
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