linux-kernel - Re: [PATCH] tpm_tis: Add missing start/stop_tpm

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Message-ID: <CAFJ_xboNDcp-XrxfbrBjqTWjLZUdVWe1OJi4KK==ij+yivFeHA@mail.gmail.com>
Date:   Tue, 26 Jan 2021 16:46:07 +0100
From:   Łukasz Majczak <lma@...ihalf.com>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Peter Huewe <peterhuewe@....de>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Jason Gunthorpe <jgg@...pe.ca>,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        Radoslaw Biernacki <rad@...ihalf.com>,
        Marcin Wojtas <mw@...ihalf.com>,
        Alex Levin <levinale@...gle.com>
Subject: Re: [PATCH] tpm_tis: Add missing start/stop_tpm_chip calls

Hi Jarkko, Guenter

Yes, here are the logs when failure occurs -
https://gist.github.com/semihalf-majczak-lukasz/1575461f585f1e7fb1e9366b8eceaab9
Look for a phrase "TPM returned invalid status"

Guenter - good suggestion - I will try to keep it as tight as possible.

Best regards,
Lukasz

pon., 25 sty 2021 o 18:18 Guenter Roeck <linux@...ck-us.net> napisał(a):
>
> Hi Lukasz,
>
> On Sat, Jan 23, 2021 at 02:42:47AM +0100, Lukasz Majczak wrote:
> > There is a missing call to start_tpm_chip before the call to
> > the tpm_get_timeouts() and tpm_tis_probe_irq_single(). As the current
> > approach maight work for tpm2, it fails for tpm1.x - in that case
> > call to tpm_get_timeouts() or tpm_tis_probe_irq_single() tries to
> > transmit TPM commands on a disabled chip what what doesn't succeed
>
> s/what what/what/
>
> > and in turn causes tpm_tis_core_init() to fail.
> > Tested on Samsung Chromebook Pro (Caroline).
> >
> > Signed-off-by: Lukasz Majczak <lma@...ihalf.com>
> > ---
> >  drivers/char/tpm/tpm_tis_core.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> > index 92c51c6cfd1b..ff0e5fe46a9d 100644
> > --- a/drivers/char/tpm/tpm_tis_core.c
> > +++ b/drivers/char/tpm/tpm_tis_core.c
> > @@ -1063,12 +1063,16 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
> >       init_waitqueue_head(&priv->read_queue);
> >       init_waitqueue_head(&priv->int_queue);
> >       if (irq != -1) {
> > +             rc = tpm_chip_start(chip);
>
> Unless I am missing something, the underlying problem seems to be
> the calls to tpm1_getcap(). From other code calling this function,
> it looks like it may only require tpm_clk_enable() to work.
>
> With that in mind, would it possibly be better to call tpm_clk_enable()
> and tpm_clk_disable() around the calls to tpm1_getcap(), ie in
> tpm1_get_timeouts() and in tpm_tis_gen_interrupt() ?
>
> This would avoid the unnecessary calls to tpm_chip_start() and
> tpm_chip_stop() for tpm2 chips.
>
> Thanks,
> Guenter
>
>
> > +             if (rc)
> > +                     goto out_err;
> >               /* Before doing irq testing issue a command to the TPM in polling mode
> >                * to make sure it works. May as well use that command to set the
> >                * proper timeouts for the driver.
> >                */
> >               if (tpm_get_timeouts(chip)) {
> >                       dev_err(dev, "Could not get TPM timeouts and durations\n");
> > +                     tpm_chip_stop(chip);
> >                       rc = -ENODEV;
> >                       goto out_err;
> >               }
> > @@ -1085,6 +1089,7 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
> >               } else {
> >                       tpm_tis_probe_irq(chip, intmask);
> >               }
> > +             tpm_chip_stop(chip);
> >       }
> >
> >       rc = tpm_chip_register(chip);