linux-kernel - Re: [PATCH v3] tpm: tis: Double the timeout B to 4s

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Message-ID: <aCSIRS1fq_b9sByn@kitsune.suse.cz>
Date: Wed, 14 May 2025 14:10:45 +0200
From: Michal Suchánek <msuchanek@...e.de>
To: Jarkko Sakkinen <jarkko@...nel.org>
Cc: Peter Huewe <peterhuewe@....de>, Jason Gunthorpe <jgg@...pe.ca>,
	linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
	Jonathan McDowell <noodles@...th.li>,
	Paul Menzel <pmenzel@...gen.mpg.de>
Subject: Re: [PATCH v3] tpm: tis: Double the timeout B to 4s

Hello,

On Fri, Apr 04, 2025 at 11:53:00AM +0300, Jarkko Sakkinen wrote:
> On Fri, Apr 04, 2025 at 10:23:14AM +0200, Michal Suchanek wrote:
> > With some Infineon chips the timeouts in tpm_tis_send_data (both B and
> > C) can reach up to about 2250 ms.
> > 
> > Timeout C is retried since
> > commit de9e33df7762 ("tpm, tpm_tis: Workaround failed command reception on Infineon devices")
> > 
> > Timeout B still needs to be extended.
> > 
> > The problem is most commonly encountered with context related operation
> > such as load context/save context. These are issued directly by the
> > kernel, and there is no retry logic for them.
> > 
> > When a filesystem is set up to use the TPM for unlocking the boot fails,
> > and restarting the userspace service is ineffective. This is likely
> > because ignoring a load context/save context result puts the real TPM
> > state and the TPM state expected by the kernel out of sync.
> > 
> > Chips known to be affected:
> > tpm_tis IFX1522:00: 2.0 TPM (device-id 0x1D, rev-id 54)
> > Description: SLB9672
> > Firmware Revision: 15.22
> > 
> > tpm_tis MSFT0101:00: 2.0 TPM (device-id 0x1B, rev-id 22)
> > Firmware Revision: 7.83
> > 
> > tpm_tis MSFT0101:00: 2.0 TPM (device-id 0x1A, rev-id 16)
> > Firmware Revision: 5.63
> > 
> > Link: https://lore.kernel.org/linux-integrity/Z5pI07m0Muapyu9w@kitsune.suse.cz/
> > Signed-off-by: Michal Suchanek <msuchanek@...e.de>
> > ---
> > v2: Only extend timeout B
> > v3: Update commit message
> > ---
> >  drivers/char/tpm/tpm_tis_core.h | 2 +-
> >  include/linux/tpm.h             | 2 +-
> >  2 files changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/char/tpm/tpm_tis_core.h b/drivers/char/tpm/tpm_tis_core.h
> > index 970d02c337c7..6c3aa480396b 100644
> > --- a/drivers/char/tpm/tpm_tis_core.h
> > +++ b/drivers/char/tpm/tpm_tis_core.h
> > @@ -54,7 +54,7 @@ enum tis_int_flags {
> >  enum tis_defaults {
> >  	TIS_MEM_LEN = 0x5000,
> >  	TIS_SHORT_TIMEOUT = 750,	/* ms */
> > -	TIS_LONG_TIMEOUT = 2000,	/* 2 sec */
> > +	TIS_LONG_TIMEOUT = 4000,	/* 4 secs */
> >  	TIS_TIMEOUT_MIN_ATML = 14700,	/* usecs */
> >  	TIS_TIMEOUT_MAX_ATML = 15000,	/* usecs */
> >  };
> > diff --git a/include/linux/tpm.h b/include/linux/tpm.h
> > index 6c3125300c00..3db0b6a87d45 100644
> > --- a/include/linux/tpm.h
> > +++ b/include/linux/tpm.h
> > @@ -224,7 +224,7 @@ enum tpm2_const {
> >  
> >  enum tpm2_timeouts {
> >  	TPM2_TIMEOUT_A          =    750,
> > -	TPM2_TIMEOUT_B          =   2000,
> > +	TPM2_TIMEOUT_B          =   4000,
> >  	TPM2_TIMEOUT_C          =    200,
> >  	TPM2_TIMEOUT_D          =     30,
> >  	TPM2_DURATION_SHORT     =     20,
> > -- 
> > 2.47.1
> > 
> > 
> 
> Cc: stable@...r.kernel.org # v6.1+
> 
> Probably best that I'll piggyback a patch set for stable with the two
> fixes, in order to cause least noise. I need to do this *after* an
> ack'd PR to -rc2.

While there is talk about stable this does not seem to be applied
anywhere I could find. Is that expected?

Thanks

Michal

> 
> Reviewed-by: Jarkko Sakkinen <jarkko@...nel.org>
> 
> BR, Jarkko