Re: tpm device not showing up in /dev anymore

[Jerry Snitselaar <jsnitsel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On Mon Oct 23 17, Jarkko Sakkinen wrote:
>On Sat, Oct 21, 2017 at 10:53:55AM +0200, Laurent Bigonville wrote:
>> Le 14/10/17 à 10:13, Jerry Snitselaar a écrit :
>> > On Wed Sep 06 17, Jarkko Sakkinen wrote:
>> > > On Fri, Sep 01, 2017 at 02:10:18PM +0200, Laurent Bigonville wrote:
>> > > > Le 31/08/17 à 18:40, Jerry Snitselaar a écrit :
>> > > > > On Thu Aug 31 17, Alexander.Steffen-d0qZbvYSIPpWk0Htik3J/w@public.gmane.org wrote:
>> > > > > > > Le 29/08/17 à 18:35, Laurent Bigonville a écrit :
>> > > > > > > > Le 29/08/17 à 18:00, Alexander.Steffen-d0qZbvYSIPpWk0Htik3J/w@public.gmane.org a écrit :
>> > > > > > > >>> An idea how to troubleshoot this?
>> > > > > > > >> Can you run git bisect on the changes between 4.11 and
>> > > > 4.12, so that
>> > > > > > > >> we find the offending commit? It is probably sufficient
>> > > > to limit the
>> > > > > > > >> search to commits that touch something in drivers/char/tpm.
>> > > > > > > >
>> > > > > > > > I'll try and keep you posted.
>> > > > > > >
>> > > > > > > OK I've been able to bisect the problem and the bad commit is:
>> > > > > > >
>> > > > > > > e6aef069b6e97790cb127d5eeb86ae9ff0b7b0e3 is the first bad commit
>> > > > > > > commit e6aef069b6e97790cb127d5eeb86ae9ff0b7b0e3
>> > > > > > > Author: Jerry Snitselaar <jsnitsel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>> > > > > > > Date:   Mon Mar 27 08:46:04 2017 -0700
>> > > > > > >
>> > > > > > >      tpm_tis: convert to using locality callbacks
>> > > > > > >
>> > > > > > >      This patch converts tpm_tis to use of the new tpm class ops
>> > > > > > >      request_locality, and relinquish_locality.
>> > > > > > >
>> > > > > > >      With the move to using the callbacks, release_locality is
>> > > > > > > changed so
>> > > > > > >      that we now release the locality even if there is no
>> > > > > > > request pending.
>> > > > > > >
>> > > > > > >      This required some changes to the tpm_tis_core_init
>> > > > code path to
>> > > > > > >      make sure locality is requested when needed:
>> > > > > > >
>> > > > > > >        - tpm2_probe code path will end up calling
>> > > > > > > request/release through
>> > > > > > >          callbacks, so request_locality prior to
>> > > > tpm2_probe not needed.
>> > > > > > >
>> > > > > > >        - probe_itpm makes calls to tpm_tis_send_data which no
>> > > > > > > longer calls
>> > > > > > >          request_locality, so add request_locality prior to
>> > > > > > > tpm_tis_send_data
>> > > > > > >          calls. Also drop release_locality call in middleof
>> > > > > > > probe_itpm, and
>> > > > > > >          keep locality until release_locality called at end of
>> > > > > > > probe_itpm.
>> > > > > > >
>> > > > > > >      Cc: Peter Huewe <peterhuewe-Mmb7MZpHnFY@public.gmane.org>
>> > > > > > >      Cc: Jarkko Sakkinen <jarkko.sakkinen-VuQAYsv1563N0uC3ymp8PA@public.gmane.orgl.com>
>> > > > > > >      Cc: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
>> > > > > > >      Cc: Marcel Selhorst <tpmdd-yWjUBOtONefk1uMJSBkQmQ@public.gmane.org>
>> > > > > > >      Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>
>> > > > > > >      Reviewed-by: Jarkko Sakkinen
>> > > > <jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
>> > > > > > >      Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
>> > > > > > >      Signed-off-by: Jarkko Sakkinen
>> > > > <jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
>> > > > > > >
>> > > > > > > :040000 040000 70234365da69959d47076ebb40c8d17f520c3e44
>> > > > > > > 72f21b446e45ea1003de75902b0553deb99157fd M drivers
>> > > > > > >
>> > > > > >
>> > > > > > I've looked again at the code in question, but could not find
>> > > > > > anything that is obviously wrong there. Locality is now
>> > > > > > requested/released at slightly different points in the process than
>> > > > > > before, but that's it. It does not seem to cause problems with the
>> > > > > > majority of TPMs, since you are the first to report any, so
>> > > > maybe it
>> > > > > > is a quirk that only affects this device.
>> > > > > >
>> > > > > > Perhaps Jerry can help, since this is his change?
>> > > > > >
>> > > > > > Alexander
>> > > > >
>> > > > > Getting some caffeine in me, and starting to take a look. Adding
>> > > > > Jarkko as well since this might involve the general locality changes.
>> > > > >
>> > > > > Laurent, if I send you a patch with some debugging code added, would
>> > > > > you be able to run it on that system? I wasn't running into issues
>> > > > > on the system I had with a 1.2 device, but I no longer have access
>> > > > > to it. I'll see if I can find one in our labs and reproduce it there.
>> > > >
>> > > > Yes I should be able to do that
>> > >
>> > > Any findings?
>> > >
>> > > /Jarkko
>> >
>> > Okay, finally getting back to this. Looking at the code it isn't clear
>> > to me
>> > why the change is causing this. So while I stare at this some more
>> > Laurent
>> > could you reproduce it with this patch so I can see what the status and
>> > access registers look like? Does anyone else on here happen to have a
>> > Sinosun
>> > tpm device? The systems I have access to with TPM1.2 devices don't have
>> > this
>> > issue.
>> >
>> > --8<--
>> >
>> > diff --git a/drivers/char/tpm/tpm_tis_core.c
>> > b/drivers/char/tpm/tpm_tis_core.c
>> > index fdde971bc810..7d60a7e4b50a 100644
>> > --- a/drivers/char/tpm/tpm_tis_core.c
>> > +++ b/drivers/char/tpm/tpm_tis_core.c
>> > @@ -258,6 +258,7 @@ static int tpm_tis_send_data(struct tpm_chip *chip,
>> > const u8 *buf, size_t len)
>> >     int rc, status, burstcnt;
>> >     size_t count = 0;
>> >     bool itpm = priv->flags & TPM_TIS_ITPM_WORKAROUND;
>> > +    u8 access;
>> >
>> >     status = tpm_tis_status(chip);
>> >     if ((status & TPM_STS_COMMAND_READY) == 0) {
>> > @@ -292,6 +293,11 @@ static int tpm_tis_send_data(struct tpm_chip *chip,
>> > const u8 *buf, size_t len)
>> >         }
>> >         status = tpm_tis_status(chip);
>> >         if (!itpm && (status & TPM_STS_DATA_EXPECT) == 0) {
>> > +            rc = tpm_tis_read8(priv, TPM_ACCESS(priv->locality),
>> > &access);
>> > +            if (rc < 0)
>> > +                dev_info(&chip->dev, "TPM_STS_DATA_EXPECT == 0: read
>> > failure TPM_ACCESS(%d)\n", priv->locality);
>> > +            else
>> > +                dev_info(&chip->dev, "TPM_STS_DATA_EXPECT == 0:
>> > locality: %d status: %x access: %x\n", priv->locality, status, access);
>> >             rc = -EIO;
>> >             goto out_err;
>> >         }
>> > @@ -309,6 +315,11 @@ static int tpm_tis_send_data(struct tpm_chip *chip,
>> > const u8 *buf, size_t len)
>> >     }
>> >     status = tpm_tis_status(chip);
>> >     if (!itpm && (status & TPM_STS_DATA_EXPECT) != 0) {
>> > +        rc = tpm_tis_read8(priv, TPM_ACCESS(priv->locality), &access);
>> > +        if (rc < 0)
>> > +            dev_info(&chip->dev, "TPM_STS_DATA_EXPECT != 0: read
>> > failure TPM_ACCESS(%d)\n", priv->locality);
>> > +        else
>> > +            dev_info(&chip->dev, "TPM_STS_DATA_EXPECT != 0: locality:
>> > %d status: %x access: %x\n", priv->locality, status, access);
>> >         rc = -EIO;
>> >         goto out_err;
>> >     }
>>
>> Please find here the dmesg output of the patched kernel
>
>At least 0xff is corrupted value in senseful way. CPU fills the read
>with ones for example for unaligned bus read. See table 19 in PC client
>spec. This can happen when you do unaligned read for example.
>
>Maybe TPM is unreachable i.e. powered off. Bit busy with stuff ATM but
>would probably make sense to compare that 0x81 to table 18 in the same
>spec.
>
>/Jarkko

0x81 is saying the access register status is valid, and the locality
is not active. That first bit means A Dynamic OS has not been previously
established on the platform. Normally we would see 0xa1, which would
mean valid register status, and the locality is active.

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