Message-ID: <20230319135338.c7k6r3ws6lby5qgv@kernel.org>
Date:   Sun, 19 Mar 2023 15:53:38 +0200
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Michael Niewöhner <linux@...ewoehner.de>
Cc:     Lino Sanfilippo <LinoSanfilippo@....de>, peterhuewe@....de,
        jgg@...pe.ca, stefanb@...ux.vnet.ibm.com,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        jandryuk@...il.com, pmenzel@...gen.mpg.de, l.sanfilippo@...bus.com,
        lukas@...ner.de, p.rosenberger@...bus.com
Subject: Re: [PATCH v11 00/14] TPM IRQ fixes

On Thu, Mar 16, 2023 at 06:18:11PM +0100, Michael Niewöhner wrote:
> On Fri, 2023-02-24 at 15:48 +0100, Lino Sanfilippo wrote:
> > On 24.11.22 at 14:55, Lino Sanfilippo wrote:
> > > From: Lino Sanfilippo <l.sanfilippo@...bus.com>
> > > 
> > > This series enables IRQ support for the TPM TIS core. For this reason a
> > > number of bugfixes around the interrupt handling are required (patches 1 to
> > > 5).
> > > 
> > > Patch 6 takes into account that according to the TPM Interface
> > > Specification stsValid and commandRead interrupts might not be supported
> > > by the hardware. For this reason the supported interrupts are first queried
> > > and stored. Then wait_for_tpm_stat() is adjusted to not wait for status
> > > changes that are not reported by interrupts.
> > > 
> > > Patch 7 moves the interrupt flag checks into an own function as suggested
> > > by Jarkko.
> > > 
> > > Patch 8 Removes the possibility that tpm_tis_data->locality can be changed
> > > at driver runtime so this variable can be read without the need to protect
> > > it against concurrent modification.
> > > 
> > > Patch 9 addresses the issue with concurrent locality handling:
> > > Since the interrupt handler writes the interrupt status registers it needs
> > > to hold the locality. However it runs concurrently to the thread which
> > > triggered the interrupt (e.g. by reading or writing data to the TPM). So
> > > it must take care when claiming and releasing the locality itself,
> > > because it may race with the concurrent running thread which also claims
> > > and releases the locality.
> > > To avoid that both interrupt and concurrent running thread interfere with
> > > each other a locality counter is used which guarantees that at any time
> > > the locality is held as long as it is required by one of both execution
> > > paths.
> > > 
> > > Patch 10 implements the request of a threaded interrupt handler. This is
> > > needed since SPI uses a mutex for data transmission and since we access the
> > > interrupt status register via SPI in the irq handler we need a sleepable
> > > context.
> > > 
> > > Patch 11 makes sure that writes to the interrupt register are effective if
> > > done in the interrupt handler.
> > > 
> > > Patch 12 makes sure that writes to the interrupt and INTERRUPT_VECTOR
> > > and INTERRUPT_ENABLE registers are effective by holding the locality.
> > > 
> > > Patch 13 makes sure that the TPM is properly initialized after power cycle
> > > before the irq test is done.
> > > 
> > > Patch 14 enables the test for interrupts by setting the required flag
> > > before the test is executed.
> > > 
> > > Changes in v11:
> > > - adjust patches 4,5 and 14 slightly to void the consecutive removal and
> > >   re-addition of the "ret" variable in tpm_tis_gen_interrupt()
> > > 
> > > Changes in v10:
> > > - fix typo in subject line as pointed out by Jason Andryuk
> > > - improve patch "tpm, tpm_tis: Claim locality before writing interrupt
> > >   registers" by extending the scope with held locality". For this reason
> > >   the "Reviewed-by" tag by Jarko and the "Tested-by" tag by Michael have
> > >   been removed.
> > > - add fix to avoid TPM_RC_INITIALIZE after power cycle when testing irqs
> > >   (PATCH 13)
> > > - add fix to restore the old interrupt vector at error (PATCH 4)
> > > 
> > > 
> > > Changes in v9:
> > > - add a fix for an issue when interrupts are reenabled on resume (PATCH 11)
> > > - improve the commit message for patch 8 as requested by Jarkko
> > > - improved functions naming
> > > - changed patch 12 (tpm, tpm_tis: Enable interrupt test) to not delete the
> > >   TPM_CHIP_FLAG_IRQ flag any more when tpm2_get_tpm_pt() fails. Due to this
> > >   change the 'Tested-by' tag from Michael and the 'Reviewed-by:' tag from
> > >   Jarko has been removed
> > > 
> > > Changes in v8:
> > > - tpm_tis_data->locality is not changed at runtime any more so that it can
> > > be read without any protection against concurrent modification.
> > > - add missing brackets as pointed out by Jason Andryuk
> > > 
> > > Changes in v7:
> > > - moved interrupt flag checks into an own function as suggested by Jarkko
> > > - added "Tested-by" tags for Tests from Michael Niewöhner
> > > - fixed one comment
> > > 
> > > Changes in v6:
> > > - set TPM_TIS_IRQ_TESTED in flag member of the tpm_tis_data struct instead
> > > in an own bitfield
> > > - improve commit messages
> > > - use int_mask instead of irqs_in_use as variable name
> > > - use sts_mask instead of active_irqs as variable name
> > > - squash patch 5 and 6
> > > - prefix functions with tpm_tis_
> > > - remove "fixes" tag
> > > 
> > > Changes in v5:
> > > - improve commit message of patch 1 as requested by Jarko
> > > - drop patch that makes locality handling simpler by only claiming it at
> > >   driver startup and releasing it at driver shutdown (requested by Jarko)
> > > - drop patch that moves the interrupt test from tpm_tis_send()
> > >   to tmp_tis_probe_irq_single() as requested by Jarko
> > > - add patch to make locality handling threadsafe so that it can also be
> > >   done by the irq handler
> > > - separate logical changes into own patches
> > > - always request threaded interrupt handler
> > > 
> > > Changes in v4:
> > > - only request threaded irq in case of SPI as requested by Jarko.
> > > - reimplement patch 2 to limit locality handling changes to the TIS core.
> > > - separate fixes from cleanups as requested by Jarko.
> > > - rephrase commit messages
> > > 
> > > Changes in v3:
> > > - fixed compiler error reported by kernel test robot
> > > - rephrased commit message as suggested by Jarko Sakkinen
> > > - added Reviewed-by tag
> > > 
> > > Changes in v2:
> > > - rebase against 5.12
> > > - free irq on error path
> > > 
> > > 
> > > Lino Sanfilippo (14):
> > >   tpm, tpm_tis: Avoid cache incoherency in test for interrupts
> > >   tpm, tpm_tis: Claim locality before writing TPM_INT_ENABLE register
> > >   tpm, tpm_tis: Disable interrupts if tpm_tis_probe_irq() failed
> > >   tpm, tpm_tis: Do not skip reset of original interrupt vector
> > >   tpm, tpm_tis: Claim locality before writing interrupt registers
> > >   tpm, tpm_tis: Only handle supported interrupts
> > >   tpm, tpm_tis: Move interrupt mask checks into own function
> > >   tpm, tpm_tis: do not check for the active locality in interrupt
> > >     handler
> > >   tpm, tpm: Implement usage counter for locality
> > >   tpm, tpm_tis: Request threaded interrupt handler
> > >   tpm, tpm_tis: Claim locality in interrupt handler
> > >   tpm, tpm_tis: Claim locality when interrupts are reenabled on resume
> > >   tpm, tpm_tis: startup chip before testing for interrupts
> > >   tpm, tpm_tis: Enable interrupt test
> > > 
> > >  drivers/char/tpm/tpm-chip.c     |  38 ++--
> > >  drivers/char/tpm/tpm.h          |   1 +
> > >  drivers/char/tpm/tpm_tis.c      |   2 +-
> > >  drivers/char/tpm/tpm_tis_core.c | 299 ++++++++++++++++++++------------
> > >  drivers/char/tpm/tpm_tis_core.h |   5 +-
> > >  5 files changed, 214 insertions(+), 131 deletions(-)
> > > 
> > 
> > Hi Jarkko,
> > 
> > its been a while now since the review of this series has been completed. Will
> > it be merged in the
> > near future? Or is there anything left to do (from my side)?
> > 
> > Regards,
> > Lino
> > 
> 
> @Jarkko ping ;)
> 

Thanks for reminding. I was wondering this week what was the situation
but latest version I had bookmarked from lore was 10.

Please ping earlier! I'll get on testing this, apologies.

BR, Jarkko

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