On Fri, Mar 07, 2025 at 04:36:12PM +0000, Jonathan McDowell wrote:
> On Fri, Mar 07, 2025 at 12:23:11AM +0200, Jarkko Sakkinen wrote:
> > On Thu, Mar 06, 2025 at 09:00:56AM +0000, Jonathan McDowell wrote:
> > > From: Jonathan McDowell <nood...@meta.com>
> > >
> > > Some Infineon devices have a issue where the status register will get
> > > stuck with a quick REQUEST_USE / COMMAND_READY sequence. This is not
> > > simply a matter of requiring a longer timeout; the work around is to
> > > retry the command submission. Add appropriate logic to do this in the
> > > send path.
> > >
> > > This is fixed in later firmware revisions, but those are not always
> > > available, and cannot generally be easily updated from outside a
> > > firmware environment.
> > >
> > > Testing has been performed with a simple repeated loop of doing a
> > > TPM2_CC_GET_CAPABILITY for TPM_CAP_PROP_MANUFACTURER using the Go code
> > > at:
> > >
> > > https://the.earth.li/~noodles/tpm-stuff/timeout-reproducer-simple.go
> > >
> > > It can take several hours to reproduce, and millions of operations.
> > >
> > > Signed-off-by: Jonathan McDowell <nood...@meta.com>
> > > ---
> > > drivers/char/tpm/tpm_tis_core.c | 17 ++++++++++++++---
> > > drivers/char/tpm/tpm_tis_core.h | 1 +
> > > include/linux/tpm.h | 1 +
> > > 3 files changed, 16 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/char/tpm/tpm_tis_core.c
> > > b/drivers/char/tpm/tpm_tis_core.c
> > > index 167d71747666..e4eae206a353 100644
> > > --- a/drivers/char/tpm/tpm_tis_core.c
> > > +++ b/drivers/char/tpm/tpm_tis_core.c
> > > @@ -464,7 +464,10 @@ static int tpm_tis_send_data(struct tpm_chip *chip,
> > > const u8 *buf, size_t len)
> > >
> > > if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
> > > &priv->int_queue, false) < 0) {
> > > - rc = -ETIME;
> > > + if (test_bit(TPM_TIS_STATUS_WORKAROUND, &priv->flags))
> > > + rc = -EAGAIN;
> > > + else
> > > + rc = -ETIME;
> > > goto out_err;
> > > }
> > > status = tpm_tis_status(chip);
> > > @@ -481,7 +484,10 @@ static int tpm_tis_send_data(struct tpm_chip *chip,
> > > const u8 *buf, size_t len)
> > >
> > > if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
> > > &priv->int_queue, false) < 0) {
> > > - rc = -ETIME;
> > > + if (test_bit(TPM_TIS_STATUS_WORKAROUND, &priv->flags))
> > > + rc = -EAGAIN;
> > > + else
> > > + rc = -ETIME;
> >
> > I'd encapsulate this inside wait_for_tpm_stat().
>
> I think that gets a bit more complicated; this is an errata in the send
> command path, for a stuck VALID bit, and the fix is to restart the whole
> command send (i.e. we need to kick the TPM with tpm_tis_ready() etc).
> I'm not sure returning EAGAIN in wait_for_tpm_stat() then makes
> tpm_tis_send_data() any simpler.
OK, it is a fair argument. Let's keep it as it is.
>
> > > goto out_err;
> > > }
> > > status = tpm_tis_status(chip);
> > > @@ -546,9 +552,11 @@ static int tpm_tis_send_main(struct tpm_chip *chip,
> > > const u8 *buf, size_t len)
> > > if (rc >= 0)
> > > /* Data transfer done successfully */
> > > break;
> > > - else if (rc != -EIO)
> > > + else if (rc != EAGAIN && rc != -EIO)
> > > /* Data transfer failed, not recoverable */
> > > return rc;
> > > +
> > > + usleep_range(priv->timeout_min, priv->timeout_max);
> > > }
> > >
> > > /* go and do it */
> > > @@ -1144,6 +1152,9 @@ int tpm_tis_core_init(struct device *dev, struct
> > > tpm_tis_data *priv, int irq,
> > > priv->timeout_max = TIS_TIMEOUT_MAX_ATML;
> > > }
> > >
> > > + if (priv->manufacturer_id == TPM_VID_IFX)
> > > + set_bit(TPM_TIS_STATUS_WORKAROUND, &priv->flags);
> > > +
> > > if (is_bsw()) {
> > > priv->ilb_base_addr = ioremap(INTEL_LEGACY_BLK_BASE_ADDR,
> > > ILB_REMAP_SIZE);
> > > diff --git a/drivers/char/tpm/tpm_tis_core.h
> > > b/drivers/char/tpm/tpm_tis_core.h
> > > index 690ad8e9b731..ce97b58dc005 100644
> > > --- a/drivers/char/tpm/tpm_tis_core.h
> > > +++ b/drivers/char/tpm/tpm_tis_core.h
> > > @@ -89,6 +89,7 @@ enum tpm_tis_flags {
> > > TPM_TIS_INVALID_STATUS = 1,
> > > TPM_TIS_DEFAULT_CANCELLATION = 2,
> > > TPM_TIS_IRQ_TESTED = 3,
> > > + TPM_TIS_STATUS_WORKAROUND = 4,
> >
> > TPM_TIS_TIMEOUT_AGAIN or maybe *_REPEAT? The current name does
> > not tell anything.
>
> Yeah, TPM_TIS_STATUS_VALID_RETRY is perhaps clearer; it's not a timeout,
> and we're looking to do a retry based on STS_VALID.
WFM
>
> > > };
> > >
> > > struct tpm_tis_data {
> > > diff --git a/include/linux/tpm.h b/include/linux/tpm.h
> > > index 20a40ade8030..6c3125300c00 100644
> > > --- a/include/linux/tpm.h
> > > +++ b/include/linux/tpm.h
> > > @@ -335,6 +335,7 @@ enum tpm2_cc_attrs {
> > > #define TPM_VID_WINBOND 0x1050
> > > #define TPM_VID_STM 0x104A
> > > #define TPM_VID_ATML 0x1114
> > > +#define TPM_VID_IFX 0x15D1
> > >
> > > enum tpm_chip_flags {
> > > TPM_CHIP_FLAG_BOOTSTRAPPED = BIT(0),
>
> J.
>
> --
> ... "What's the philosophical difference between a killfile and the
> automoderation?" "A killfile throws away good posts. Automoderation
> throws away bad posts." -- Jonathan H N Chin to Calle Dybedahl
BR, Jarkko
