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

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Message-ID: <aCVGW7T5Gy5zVkJ-@kernel.org>
Date: Thu, 15 May 2025 04:41:47 +0300
From: Jarkko Sakkinen <jarkko@...nel.org>
To: Michal Suchánek <msuchanek@...e.de>,
	Sasha Levin <sashal@...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

On Wed, May 14, 2025 at 02:10:45PM +0200, Michal Suchánek wrote:
> 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?

Definitely not. I got shifted away with other work early April and
this was left to my TODO folder, apologies.

Sasha, can you also auto-select this to v6.1+? It is in my next
branch now (should be soon'ish mirrored to linux-next).

BR, Jarkko