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

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Message-ID: <5B8DA87D05A7694D9FA63FD143655C1B94228C1A@hasmsx108.ger.corp.intel.com>
Date:   Sun, 25 Feb 2018 10:37:08 +0000
From:   "Winkler, Tomas" <tomas.winkler@...el.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.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 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