Re: [PATCH v2 3/5] tpm_tis: Fix interrupts for TIS TPMs without legacy cycles

[Jarkko Sakkinen <jarkko@kernel.org>]

On Sat, Oct 24, 2020 at 03:15:53PM +0300, Jarkko Sakkinen wrote:
> On Mon, Oct 19, 2020 at 05:14:26PM -0700, Jerry Snitselaar wrote:
> > 
> > James Bottomley @ 2020-10-01 11:09 MST:
> > 
> > > If a TIS TPM doesn't have legacy cycles, any write to the interrupt
> > > registers is ignored unless a locality is active.  This means even to
> > > set up the interrupt vectors a locality must first be activated.  Fix
> > > this by activating the 0 locality in the interrupt probe setup.
> > >
> > > Since the TPM_EOI signalling also requires an active locality, the
> > > interrupt routine cannot end an interrupt if the locality is released.
> > > This can lead to a situation where the TPM goes command ready after
> > > locality release and since the interrupt cannot be ended it refires
> > > continuously.  Fix this by disabling all interrupts except locality
> > > change when a locality is released (this only fires when a locality
> > > becomes active, meaning the TPM_EOI should work).
> > >
> > > Finally, since we now disable all status based interrupts in the
> > > locality release, they must be re-enabled before waiting to check the
> > > condition, so add interrupt enabling to the status wait.
> > >
> > > Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
> > >
> > > ---
> > >
> > > v2: renamed functions
> > > ---
> > >  drivers/char/tpm/tpm_tis_core.c | 125 ++++++++++++++++++++++++++------
> > >  1 file changed, 101 insertions(+), 24 deletions(-)
> > >
> > > diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> > > index 431919d5f48a..0c07da8cd680 100644
> > > --- a/drivers/char/tpm/tpm_tis_core.c
> > > +++ b/drivers/char/tpm/tpm_tis_core.c
> > > @@ -29,6 +29,46 @@
> > >  
> > >  static void tpm_tis_clkrun_enable(struct tpm_chip *chip, bool value);
> > >  
> > > +static void tpm_tis_enable_interrupt(struct tpm_chip *chip, u8 mask)
> > > +{
> > > +	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> > > +	u32 intmask;
> > > +
> > > +	/* Take control of the TPM's interrupt hardware and shut it off */
> > 
> > s/shut it off/turn it on/ ?
> > 
> > > +	tpm_tis_read32(priv, TPM_INT_ENABLE(priv->locality), &intmask);
> > > +
> > > +	intmask |= mask | TPM_GLOBAL_INT_ENABLE;
> > > +
> > > +	tpm_tis_write32(priv, TPM_INT_ENABLE(priv->locality), intmask);
> > > +}
> > > +
> > > +static void tpm_tis_disable_interrupt(struct tpm_chip *chip, u8 mask)
> > > +{
> > > +	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> > > +	u32 intmask;
> > > +
> > > +	/* Take control of the TPM's interrupt hardware and shut it off */
> > > +	tpm_tis_read32(priv, TPM_INT_ENABLE(priv->locality), &intmask);
> > > +
> > > +	intmask &= ~mask;
> > > +
> > > +	tpm_tis_write32(priv, TPM_INT_ENABLE(priv->locality), intmask);
> > > +}
> > > +
> > > +static void tpm_tis_enable_stat_interrupts(struct tpm_chip *chip, u8 stat)
> > > +{
> > > +	u32 mask = 0;
> > > +
> > > +	if (stat & TPM_STS_COMMAND_READY)
> > > +		mask |= TPM_INTF_CMD_READY_INT;
> > > +	if (stat & TPM_STS_VALID)
> > > +		mask |= TPM_INTF_STS_VALID_INT;
> > > +	if (stat & TPM_STS_DATA_AVAIL)
> > > +		mask |= TPM_INTF_DATA_AVAIL_INT;
> > > +
> > > +	tpm_tis_enable_interrupt(chip, mask);
> > > +}
> > > +
> > >  static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
> > >  					bool check_cancel, bool *canceled)
> > >  {
> > > @@ -65,11 +105,14 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
> > >  		timeout = stop - jiffies;
> > >  		if ((long)timeout <= 0)
> > >  			return -ETIME;
> > > +		tpm_tis_enable_stat_interrupts(chip, mask);
> > >  		rc = wait_event_interruptible_timeout(*queue,
> > >  			wait_for_tpm_stat_cond(chip, mask, check_cancel,
> > >  					       &canceled),
> > >  			timeout);
> > >  		if (rc > 0) {
> > > +			if (rc == 1)
> > > +				dev_err(&chip->dev, "Lost Interrupt waiting for TPM stat\n");
> > >  			if (canceled)
> > >  				return -ECANCELED;
> > >  			return 0;
> > > @@ -138,6 +181,28 @@ static bool check_locality(struct tpm_chip *chip, int l)
> > >  static int release_locality(struct tpm_chip *chip, int l)
> > >  {
> > >  	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> > > +	u32 int_status;
> > > +	int rc;
> > > +
> > > +	/*
> > > +	 * Note that once we relinquish the locality, all writes to
> > > +	 * the interrupt registers become ineffective meaning we can't
> > > +	 * do a TPM_EOI.  This means we must disable every interrupt
> > > +	 * except the locality change one to avoid interrupt
> > > +	 * storms.
> > > +	 */
> > > +	tpm_tis_disable_interrupt(chip, TPM_INTF_CMD_READY_INT
> > > +				  | TPM_INTF_STS_VALID_INT
> > > +				  | TPM_INTF_DATA_AVAIL_INT);
> > > +
> > > +	rc = tpm_tis_read32(priv, TPM_INT_STATUS(priv->locality), &int_status);
> > > +	if (rc < 0)
> > > +		return rc;
> > > +
> > > +	/* Clear all pending */
> > > +	rc = tpm_tis_write32(priv, TPM_INT_STATUS(priv->locality), int_status);
> > > +	if (rc < 0)
> > > +		return rc;
> > >  
> > >  	tpm_tis_write8(priv, TPM_ACCESS(l), TPM_ACCESS_ACTIVE_LOCALITY);
> > >  
> > > @@ -164,12 +229,17 @@ static int request_locality(struct tpm_chip *chip, int l)
> > >  		timeout = stop - jiffies;
> > >  		if ((long)timeout <= 0)
> > >  			return -1;
> > > +
> > >  		rc = wait_event_interruptible_timeout(priv->int_queue,
> > >  						      (check_locality
> > >  						       (chip, l)),
> > >  						      timeout);
> > > -		if (rc > 0)
> > > +		if (rc > 1)
> > > +			return l;
> > > +		if (rc == 1) {
> > > +			dev_info(&chip->dev, "Lost Interrupt waiting for locality\n");
> > >  			return l;
> > > +		}
> > >  		if (rc == -ERESTARTSYS && freezing(current)) {
> > >  			clear_thread_flag(TIF_SIGPENDING);
> > >  			goto again;
> > > @@ -465,6 +535,10 @@ static int tpm_tis_send(struct tpm_chip *chip, u8 *buf, size_t len)
> > >  	irq = priv->irq;
> > >  	priv->irq = 0;
> > >  	chip->flags &= ~TPM_CHIP_FLAG_IRQ;
> > > +	tpm_tis_enable_interrupt(chip, TPM_INTF_CMD_READY_INT
> > > +				 | TPM_INTF_LOCALITY_CHANGE_INT
> > > +				 | TPM_INTF_DATA_AVAIL_INT
> > > +				 | TPM_INTF_STS_VALID_INT);
> > >  	rc = tpm_tis_send_main(chip, buf, len);
> > >  	priv->irq = irq;
> > >  	chip->flags |= TPM_CHIP_FLAG_IRQ;
> > > @@ -719,7 +793,7 @@ static int tpm_tis_gen_interrupt(struct tpm_chip *chip)
> > >   * irq is seen then leave the chip setup for IRQ operation, otherwise reverse
> > >   * everything and leave in polling mode. Returns 0 on success.
> > >   */
> > > -static int tpm_tis_probe_irq_single(struct tpm_chip *chip, u32 intmask,
> > > +static int tpm_tis_probe_irq_single(struct tpm_chip *chip,
> > >  				    int flags, int irq)
> > >  {
> > >  	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> > > @@ -753,9 +827,11 @@ static int tpm_tis_probe_irq_single(struct tpm_chip *chip, u32 intmask,
> > >  	if (rc < 0)
> > >  		return rc;
> > >  
> > > -	/* Turn on */
> > > -	rc = tpm_tis_write32(priv, TPM_INT_ENABLE(priv->locality),
> > > -			     intmask | TPM_GLOBAL_INT_ENABLE);
> > > +	/*
> > > +	 * Turn on.  The locality change interrupt is the only one
> > > +	 * always enabled
> > > +	 */
> > > +	tpm_tis_enable_interrupt(chip, TPM_INTF_LOCALITY_CHANGE_INT);
> > >  	if (rc < 0)
> > >  		return rc;
> > >  
> > > @@ -787,7 +863,7 @@ static int tpm_tis_probe_irq_single(struct tpm_chip *chip, u32 intmask,
> > >   * do not have ACPI/etc. We typically expect the interrupt to be declared if
> > >   * present.
> > >   */
> > > -static void tpm_tis_probe_irq(struct tpm_chip *chip, u32 intmask)
> > > +static void tpm_tis_probe_irq(struct tpm_chip *chip)
> > >  {
> > >  	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> > >  	u8 original_int_vec;
> > > @@ -801,11 +877,9 @@ static void tpm_tis_probe_irq(struct tpm_chip *chip, u32 intmask)
> > >  	if (!original_int_vec) {
> > >  		if (IS_ENABLED(CONFIG_X86))
> > >  			for (i = 3; i <= 15; i++)
> > > -				if (!tpm_tis_probe_irq_single(chip, intmask, 0,
> > > -							      i))
> > > +				if (!tpm_tis_probe_irq_single(chip, 0, i))
> > >  					return;
> > > -	} else if (!tpm_tis_probe_irq_single(chip, intmask, 0,
> > > -					     original_int_vec))
> > > +	} else if (!tpm_tis_probe_irq_single(chip, 0, original_int_vec))
> > >  		return;
> > >  }
> > >  
> > > @@ -1030,8 +1104,7 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
> > >  		}
> > >  
> > >  		if (irq) {
> > > -			tpm_tis_probe_irq_single(chip, intmask, IRQF_SHARED,
> > > -						 irq);
> > > +			tpm_tis_probe_irq_single(chip, IRQF_SHARED, irq);
> > >  			if (!(chip->flags & TPM_CHIP_FLAG_IRQ)) {
> > >  				dev_err(&chip->dev, FW_BUG
> > >  					"TPM interrupt not working, polling instead\n");
> > > @@ -1039,7 +1112,7 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
> > >  				disable_interrupts(chip);
> > >  			}
> > >  		} else {
> > > -			tpm_tis_probe_irq(chip, intmask);
> > > +			tpm_tis_probe_irq(chip);
> > >  		}
> > >  	}
> > >  
> > > @@ -1065,12 +1138,23 @@ EXPORT_SYMBOL_GPL(tpm_tis_core_init);
> > >  static void tpm_tis_reenable_interrupts(struct tpm_chip *chip)
> > >  {
> > >  	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> > > -	u32 intmask;
> > >  	int rc;
> > >  
> > >  	if (chip->ops->clk_enable != NULL)
> > >  		chip->ops->clk_enable(chip, true);
> > >  
> > > +	/*
> > > +	 * must have the locality before we can enable interrupts, so
> > > +	 * poll for the locality being ready
> > > +	 */
> > > +	chip->flags &= ~TPM_CHIP_FLAG_IRQ;
> > > +	if (request_locality(chip, 0) != 0) {
> > > +		dev_err(&chip->dev, "Failed to enable interrupts after suspend\n");
> > > +		goto out;
> > > +	}
> > > +	chip->flags |= TPM_CHIP_FLAG_IRQ;
> > > +
> > > +
> > >  	/* reenable interrupts that device may have lost or
> > >  	 * BIOS/firmware may have disabled
> > >  	 */
> > > @@ -1078,17 +1162,10 @@ static void tpm_tis_reenable_interrupts(struct tpm_chip *chip)
> > >  	if (rc < 0)
> > >  		goto out;
> > >  
> > > -	rc = tpm_tis_read32(priv, TPM_INT_ENABLE(priv->locality), &intmask);
> > > -	if (rc < 0)
> > > -		goto out;
> > > -
> > > -	intmask |= TPM_INTF_CMD_READY_INT
> > > -	    | TPM_INTF_LOCALITY_CHANGE_INT | TPM_INTF_DATA_AVAIL_INT
> > > -	    | TPM_INTF_STS_VALID_INT | TPM_GLOBAL_INT_ENABLE;
> > > +	tpm_tis_enable_interrupt(chip, TPM_INTF_LOCALITY_CHANGE_INT);
> > >  
> > > -	tpm_tis_write32(priv, TPM_INT_ENABLE(priv->locality), intmask);
> > > -
> > > -out:
> > > + out:
> > > +	release_locality(chip, 0);
> > >  	if (chip->ops->clk_enable != NULL)
> > >  		chip->ops->clk_enable(chip, false);
> > 
> > Other than the question about the comment in tpm_tis_enable_interrupt
> > 
> > Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
> 
> Should this have
> 
>   Fixes: e6aef069b6e9 ("tpm_tis: convert to using locality callbacks")
> 
> ?

?

/Jarkko