linux-kernel - Re: [PATCH 1/2 v4] tpm: cmd_ready command can be issued only after granting locality

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Date:   Sun, 25 Feb 2018 15:40:45 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     "Winkler, Tomas" <tomas.winkler@...el.com>
Cc:     Jason Gunthorpe <jgg@...pe.ca>,
        "Usyskin, Alexander" <alexander.usyskin@...el.com>,
        "linux-integrity@...r.kernel.org" <linux-integrity@...r.kernel.org>,
        "linux-security-module@...r.kernel.org" 
        <linux-security-module@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2 v4] tpm: cmd_ready command can be issued only after
 granting locality

On Sun, Feb 25, 2018 at 10:37:08AM +0000, Winkler, Tomas wrote:
> > 
> > On Sat, Feb 24, 2018 at 05:43:16PM +0200, Tomas Winkler wrote:
> > > The correct sequence is to first request locality and only after that
> > > perform cmd_ready handshake, otherwise the hardware will drop the
> > > subsequent message as from the device point of view the cmd_ready
> > > handshake wasn't performed. Symmetrically locality has to be
> > > relinquished only after going idle handshake has completed, this
> > > requires that go_idle has to poll for the completion and as well
> > > locality relinquish has to poll for completion so it is not overridden
> > > in back to back commands flow.
> > >
> > > The issue is only visible on devices that support multiple localities.
> > >
> > > Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
> > > Tested-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> > > ---
> > > V2: poll for locality relinquish completion
> > > V3: 1. Print error message upon locality relinquish failure
> > >     2. Don't override rc code on error path with locality relinquish
> > > V4: 3. Don't capture locality relinquish error code in rc, just print
> > > 	the error message.
> > >
> > >        return value.
> > >  drivers/char/tpm/tpm-interface.c |  20 +++++---
> > >  drivers/char/tpm/tpm_crb.c       | 108 +++++++++++++++++++++++++++------
> > ------
> > >  drivers/char/tpm/tpm_tis_core.c  |   4 +-
> > >  include/linux/tpm.h              |   2 +-
> > >  4 files changed, 93 insertions(+), 41 deletions(-)
> > >
> > > diff --git a/drivers/char/tpm/tpm-interface.c
> > > b/drivers/char/tpm/tpm-interface.c
> > > index 9e80a953d693..4d74bacca5a1 100644
> > > --- a/drivers/char/tpm/tpm-interface.c
> > > +++ b/drivers/char/tpm/tpm-interface.c
> > > @@ -422,8 +422,6 @@ ssize_t tpm_transmit(struct tpm_chip *chip, struct
> > tpm_space *space,
> > >  	if (!(flags & TPM_TRANSMIT_UNLOCKED))
> > >  		mutex_lock(&chip->tpm_mutex);
> > >
> > > -	if (chip->dev.parent)
> > > -		pm_runtime_get_sync(chip->dev.parent);
> > >
> > >  	if (chip->ops->clk_enable != NULL)
> > >  		chip->ops->clk_enable(chip, true);
> > > @@ -439,6 +437,9 @@ ssize_t tpm_transmit(struct tpm_chip *chip, struct
> > tpm_space *space,
> > >  		chip->locality = rc;
> > >  	}
> > >
> > > +	if (chip->dev.parent)
> > > +		pm_runtime_get_sync(chip->dev.parent);
> > > +
> > >  	rc = tpm2_prepare_space(chip, space, ordinal, buf);
> > >  	if (rc)
> > >  		goto out;
> > > @@ -499,17 +500,24 @@ ssize_t tpm_transmit(struct tpm_chip *chip,
> > struct tpm_space *space,
> > >  	rc = tpm2_commit_space(chip, space, ordinal, buf, &len);
> > >
> > >  out:
> > > +	if (chip->dev.parent)
> > > +		pm_runtime_put_sync(chip->dev.parent);
> > > +
> > >  	if (need_locality && chip->ops->relinquish_locality) {
> > > -		chip->ops->relinquish_locality(chip, chip->locality);
> > > +		/* this coud be on error path, don't override error code */
> > > +		int l_rc = chip->ops->relinquish_locality(chip, chip->locality);
> > 
> > Declaration should be in the beginning of the function.
> 
> No, it shouldn't. I cannot find any reference to this statement, I've already explained my reasoning in a previous mail. 
>   
> > 
> > > +
> > > +		if (l_rc) {
> > > +			dev_err(&chip->dev, "%s: relinquish_locality: error
> > %d\n",
> > > +				__func__, l_rc);
> > > +		}
> > 
> > In kernel coding style, this should be w/o curly braces.
> 
> Yep, missed that, will resubmit
> 
> 
> > I can fix these cosmetic issues
> > 
> > Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> > 
> > Doesn't this need
> > 
> > Fixes: 877c57d0d0ca ("tpm_crb: request and relinquish locality 0")
> > And shouldn't this also have
> > 
> > Cc: stable@...r.kernel.org
> > 
> > ?
> Good points
> Thanks
> Tomas

Tomas, I updated v4 myself and pushed it to master/next. Please tell
me if there is anything wrong and I will fix it.

/Jarkko