linux-kernel - RE: [tpmdd-devel] [PATCH v2 3/3] tpm_crb: request and relinquish locality 0

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Date:   Mon, 5 Dec 2016 21:51:42 +0000
From:   "Winkler, Tomas" <tomas.winkler@...el.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Peter Huewe <peterhuewe@....de>
CC:     "linux-security-module@...r.kernel.org" 
        <linux-security-module@...r.kernel.org>,
        "moderated list:TPM DEVICE DRIVER" 
        <tpmdd-devel@...ts.sourceforge.net>,
        open list <linux-kernel@...r.kernel.org>
Subject: RE: [tpmdd-devel] [PATCH v2 3/3] tpm_crb: request and relinquish
        locality 0

> 
> CC linux-security-module
> 
> On Sat, Dec 03, 2016 at 07:52:13PM +0200, Jarkko Sakkinen wrote:
> > Request and relinquish locality for the driver use in order to be a
> > better citizen in a multi locality environment like TXT. The locality
> > is requested and relinquished as part of going into and waking up from
> > idle.
> 
This has nothing to do with power management, please note, that this is run via runtime_pm handlers, 
which can be disabled  via sysfs and actually on server platforms runtime pm is not relevant, 
while you cannot disable locality acquire/relinquish flow.

NACK
> > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> > ---
> >  drivers/char/tpm/tpm_crb.c | 36 ++++++++++++++++++++++++------------
> >  1 file changed, 24 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
> > index f986d02..f6e0beb 100644
> > --- a/drivers/char/tpm/tpm_crb.c
> > +++ b/drivers/char/tpm/tpm_crb.c
> > @@ -34,6 +34,15 @@ enum crb_defaults {
> >  	CRB_ACPI_START_INDEX = 1,
> >  };
> >
> > +enum crb_loc_ctrl {
> > +	CRB_LOC_CTRL_REQUEST_ACCESS	= BIT(0),
> > +	CRB_LOC_CTRL_RELINQUISH		= BIT(1),
> > +};
> > +
> > +enum crb_loc_state {
> > +	CRB_LOC_STATE_LOC_ASSIGNED	= BIT(1),
> > +};
> > +
> >  enum crb_ctrl_req {
> >  	CRB_CTRL_REQ_CMD_READY	= BIT(0),
> >  	CRB_CTRL_REQ_GO_IDLE	= BIT(1),
> > @@ -101,12 +110,8 @@ struct crb_priv {
> >   * @dev:  crb device
> >   * @priv: crb private data
> >   *
> > - * Write CRB_CTRL_REQ_GO_IDLE to TPM_CRB_CTRL_REQ
> > - * The device should respond within TIMEOUT_C by clearing the bit.
> > - * Anyhow, we do not wait here as a consequent CMD_READY request
> > - * will be handled correctly even if idle was not completed.
> > - *
> > - * The function does nothing for devices with ACPI-start method.
> > + * Put device to the idle state and relinquish locality. The function
> > + does
> > + * nothing for devices with the ACPI-start method.
> >   *
> >   * Return: 0 always
> >   */
> > @@ -115,6 +120,7 @@ static int __maybe_unused crb_go_idle(struct device
> *dev, struct crb_priv *priv)
> >  	if (priv->flags & CRB_FL_ACPI_START)
> >  		return 0;
> >
> > +	iowrite32(CRB_LOC_CTRL_RELINQUISH, &priv->regs_h->loc_ctrl);	
This is misleading this has nothing to do with go idle,  what is the 
> >  	iowrite32(CRB_CTRL_REQ_GO_IDLE, &priv->regs_t->ctrl_req);
> >  	/* we don't really care when this settles */
> >
> > @@ -146,11 +152,8 @@ static bool crb_wait_for_reg_32(u32 __iomem *reg,
> u32 mask, u32 value,
> >   * @dev:  crb device
> >   * @priv: crb private data
> >   *
> > - * Write CRB_CTRL_REQ_CMD_READY to TPM_CRB_CTRL_REQ
> > - * and poll till the device acknowledge it by clearing the bit.
> > - * The device should respond within TIMEOUT_C.
> > - *
> > - * The function does nothing for devices with ACPI-start method
> > + * Try to wake up the device and request locality. The function does
> > + nothing
> > + * for devices with the ACPI-start method.
> >   *
> >   * Return: 0 on success -ETIME on timeout;
> >   */
> > @@ -165,7 +168,16 @@ static int __maybe_unused crb_cmd_ready(struct
> device *dev,
> >  				 CRB_CTRL_REQ_CMD_READY /* mask */,
> >  				 0, /* value */
> >  				 TPM2_TIMEOUT_C)) {
> > -		dev_warn(dev, "cmdReady timed out\n");
> > +		dev_warn(dev, "TPM_CRB_CTRL_REQ_x.cmdReady timed
> out\n");
We are always in locality 0 here, right?

> > +		return -ETIME;
> > +	}
> > +
> > +	iowrite32(CRB_LOC_CTRL_REQUEST_ACCESS, &priv->regs_h-
> >loc_ctrl);
> > +	if (!crb_wait_for_reg_32(&priv->regs_h->loc_state,
> > +				 CRB_LOC_STATE_LOC_ASSIGNED, /* mask */
> > +				 CRB_LOC_STATE_LOC_ASSIGNED, /* value */
> > +				 TPM2_TIMEOUT_C)) {
> > +		dev_warn(dev, "TPM_LOC_STATE_x.requestAccess timed
> out\n");


> >  		return -ETIME;
> >  	}