linux-kernel - Re: [PATCH v8 16/17] tpm: take TPM chip power gating out of tpm

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Date:   Sun, 18 Nov 2018 09:37:44 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Stefan Berger <stefanb@...ux.ibm.com>
Cc:     linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        James Bottomley <James.Bottomley@...senPartnership.com>,
        Tomas Winkler <tomas.winkler@...el.com>,
        Tadeusz Struk <tadeusz.struk@...el.com>,
        Stefan Berger <stefanb@...ux.vnet.ibm.com>,
        Nayna Jain <nayna@...ux.ibm.com>,
        Peter Huewe <peterhuewe@....de>,
        Jason Gunthorpe <jgg@...pe.ca>, Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v8 16/17] tpm: take TPM chip power gating out of
 tpm_transmit()

On Fri, Nov 16, 2018 at 12:02:17PM -0500, Stefan Berger wrote:
> On 11/16/18 7:38 AM, Jarkko Sakkinen wrote:
> > Call tpm_chip_start() and tpm_chip_stop() in
> > 
> > * tpm_try_get_ops() and tpm_put_ops()
> > * tpm_chip_register()
> > * tpm2_del_space()
> > 
> > And remove these calls from tpm_transmit(). The core reason for this
> > change is that in tpm_vtpm_proxy a locality change requires a virtual
> > TPM command (a command made up just for that driver).
> > 
> > The consequence of this is that this commit removes the remaining nested
> > calls.
> > 
> > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> > ---
> >   drivers/char/tpm/tpm-chip.c       | 21 ++++++++-------------
> >   drivers/char/tpm/tpm-interface.c  |  4 ----
> >   drivers/char/tpm/tpm.h            |  9 ---------
> >   drivers/char/tpm/tpm2-space.c     |  5 ++++-
> >   drivers/char/tpm/tpm_vtpm_proxy.c |  3 +--
> >   5 files changed, 13 insertions(+), 29 deletions(-)
> > 
> > diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> > index 65f1561eba81..837d44fa0797 100644
> > --- a/drivers/char/tpm/tpm-chip.c
> > +++ b/drivers/char/tpm/tpm-chip.c
> > @@ -41,9 +41,6 @@ static int tpm_request_locality(struct tpm_chip *chip, unsigned int flags)
> >   {
> >   	int rc;
> > 
> > -	if (flags & TPM_TRANSMIT_NESTED)
> > -		return 0;
> > -
> >   	if (!chip->ops->request_locality)
> >   		return 0;
> > 
> > @@ -59,9 +56,6 @@ static void tpm_relinquish_locality(struct tpm_chip *chip, unsigned int flags)
> >   {
> >   	int rc;
> > 
> > -	if (flags & TPM_TRANSMIT_NESTED)
> > -		return;
> > -
> >   	if (!chip->ops->relinquish_locality)
> >   		return;
> > 
> > @@ -74,9 +68,6 @@ static void tpm_relinquish_locality(struct tpm_chip *chip, unsigned int flags)
> > 
> >   static int tpm_cmd_ready(struct tpm_chip *chip, unsigned int flags)
> >   {
> > -	if (flags & TPM_TRANSMIT_NESTED)
> > -		return 0;
> > -
> >   	if (!chip->ops->cmd_ready)
> >   		return 0;
> > 
> > @@ -85,9 +76,6 @@ static int tpm_cmd_ready(struct tpm_chip *chip, unsigned int flags)
> > 
> >   static int tpm_go_idle(struct tpm_chip *chip, unsigned int flags)
> >   {
> > -	if (flags & TPM_TRANSMIT_NESTED)
> > -		return 0;
> > -
> >   	if (!chip->ops->go_idle)
> >   		return 0;
> > 
> > @@ -169,7 +157,9 @@ int tpm_try_get_ops(struct tpm_chip *chip)
> >   		goto out_lock;
> > 
> >   	mutex_lock(&chip->tpm_mutex);
> > -	return 0;
> > +	rc = tpm_chip_start(chip, 0);
> > +	if (rc)
> > +		mutex_unlock(&chip->tpm_mutex);
> 
> This cannot be right to fall through to up_read() etc.

Ouch! It is not and I had a fixup for it that was not applied to the
resulting patch set :-/

/Jarkko