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

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Date:   Mon, 16 Dec 2019 18:14:54 -0800
From:   Dan Williams <dan.j.williams@...el.com>
To:     Jerry Snitselaar <jsnitsel@...hat.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.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 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?