linux-kernel - Re: [PATCH v2] tpm_tis: reserve chip for duration of tpm_tis_core

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Date:   Tue, 17 Dec 2019 13:29:20 -0700
From:   Jerry Snitselaar <jsnitsel@...hat.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     Dan Williams <dan.j.williams@...el.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Christian Bundy <christianbundy@...ction.io>,
        Peter Huewe <peterhuewe@....de>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Stefan Berger <stefanb@...ux.vnet.ibm.com>,
        stable <stable@...r.kernel.org>, linux-integrity@...r.kernel.org
Subject: Re: [PATCH v2] tpm_tis: reserve chip for duration of
 tpm_tis_core_init

On Tue Dec 17 19, Jarkko Sakkinen wrote:
>On Mon, 2019-12-16 at 18:14 -0800, Dan Williams wrote:
>> On Mon, Dec 16, 2019 at 6:00 PM Jerry Snitselaar <jsnitsel@...hat.com> wrote:
>> > On Mon Dec 16 19, Dan Williams wrote:
>> > > On Mon, Dec 16, 2019 at 4:59 PM Jarkko Sakkinen
>> > > <jarkko.sakkinen@...ux.intel.com> wrote:
>> > > > On Wed, 2019-12-11 at 16:54 -0700, Jerry Snitselaar wrote:
>> > > > > Instead of repeatedly calling tpm_chip_start/tpm_chip_stop when
>> > > > > issuing commands to the tpm during initialization, just reserve the
>> > > > > chip after wait_startup, and release it when we are ready to call
>> > > > > tpm_chip_register.
>> > > > >
>> > > > > Cc: Christian Bundy <christianbundy@...ction.io>
>> > > > > Cc: Dan Williams <dan.j.williams@...el.com>
>> > > > > Cc: Peter Huewe <peterhuewe@....de>
>> > > > > Cc: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
>> > > > > Cc: Jason Gunthorpe <jgg@...pe.ca>
>> > > > > Cc: Stefan Berger <stefanb@...ux.vnet.ibm.com>
>> > > > > Cc: stable@...r.kernel.org
>> > > > > Cc: linux-integrity@...r.kernel.org
>> > > > > Fixes: a3fbfae82b4c ("tpm: take TPM chip power gating out of tpm_transmit()")
>> > > > > Fixes: 5b359c7c4372 ("tpm_tis_core: Turn on the TPM before probing IRQ's")
>> > > > > Signed-off-by: Jerry Snitselaar <jsnitsel@...hat.com>
>> > > >
>> > > > I pushed to my master with minor tweaks and added my tags.
>> > > >
>> > > > Please check before I put it to linux-next.
>> > >
>> > > I don't see it yet here:
>> > >
>> > > http://git.infradead.org/users/jjs/linux-tpmdd.git/shortlog/refs/heads/master
>> > >
>> > > However, I wanted to make sure you captured that this does *not* fix
>> > > the interrupt issue. I.e. make sure you remove the "Fixes:
>> > > 5b359c7c4372 ("tpm_tis_core: Turn on the TPM before probing IRQ's")"
>> > > tag.
>> > >
>> > > With that said, are you going to include the revert of:
>> > >
>> > > 1ea32c83c699 tpm_tis_core: Set TPM_CHIP_FLAG_IRQ before probing for interrupts
>> >
>> > Dan, with the above reverted do you still get the screaming interrupt?
>>
>> Yes, the screaming interrupt goes away, although it is replaced by
>> these messages when the driver starts:
>>
>> [    3.725131] tpm_tis IFX0740:00: 2.0 TPM (device-id 0x1B, rev-id 16)
>> [    3.725358] tpm tpm0: tpm_try_transmit: send(): error -5
>> [    3.725359] tpm tpm0: [Firmware Bug]: TPM interrupt not working,
>> polling instead
>>
>> If the choice is "error message + polled-mode" vs "pinning a cpu with
>> interrupts" I'd accept the former, but wanted Jarkko with his
>> maintainer hat to weigh in.
>>
>> Is there a simple sanity check I can run to see if the TPM is still
>> operational in this state?
>
>What about T490S?
>
>/Jarkko
>

I just heard back from the t490s user, and as expected the problem still exists
there with this patch.

Regards,
Jerry