On Wed, 2021-08-25 at 22:38 -0700, Hao Wu wrote:
> > On Aug 14, 2021, at 3:25 PM, Hao Wu <hao.wu@xxxxxxxxxx> wrote:
> >
> > The Atmel TPM 1.2 chips crash with error
> > `tpm_try_transmit: send(): error -62` since kernel 4.14.
> > It is observed from the kernel log after running `tpm_sealdata -z`.
> > The error thrown from the command is as follows
> > ```
> > $ tpm_sealdata -z
> > Tspi_Key_LoadKey failed: 0x00001087 - layer=tddl,
> > code=0087 (135), I/O error
> > ```
> >
> > The issue was reproduced with the following Atmel TPM chip:
> > ```
> > $ tpm_version
> > T0 TPM 1.2 Version Info:
> > Chip Version: 1.2.66.1
> > Spec Level: 2
> > Errata Revision: 3
> > TPM Vendor ID: ATML
> > TPM Version: 01010000
> > Manufacturer Info: 41544d4c
> > ```
> >
> > The root cause of the issue is due to the TPM calls to msleep()
> > were replaced with usleep_range() [1], which reduces
> > the actual timeout. Via experiments, it is observed that
> > the original msleep(5) actually sleeps for 15ms.
> > Because of a known timeout issue in Atmel TPM 1.2 chip,
> > the shorter timeout than 15ms can cause the error described above.
> >
> > A few further changes in kernel 4.16 [2] and 4.18 [3, 4] further
> > reduced the timeout to less than 1ms. With experiments,
> > the problematic timeout in the latest kernel is the one
> > for `wait_for_tpm_stat`.
> >
> > To fix it, the patch reverts the timeout of `wait_for_tpm_stat`
> > to 15ms for all Atmel TPM 1.2 chips, but leave it untouched
> > for Ateml TPM 2.0 chip, and chips from other vendors.
> > As explained above, the chosen 15ms timeout is
> > the actual timeout before this issue introduced,
> > thus the old value is used here.
> > Particularly, TPM_ATML_TIMEOUT_WAIT_STAT_MIN is set to 14700us,
> > TPM_ATML_TIMEOUT_WAIT_STAT_MIN is set to 15000us according to
> > the existing TPM_TIMEOUT_RANGE_US (300us).
> > The fixed has been tested in the system with the affected Atmel chip
> > with no issues observed after boot up.
> >
> > References:
> > [1] 9f3fc7bcddcb tpm: replace msleep() with usleep_range() in TPM
> > 1.2/2.0 generic drivers
> > [2] cf151a9a44d5 tpm: reduce tpm polling delay in tpm_tis_core
> > [3] 59f5a6b07f64 tpm: reduce poll sleep time in tpm_transmit()
> > [4] 424eaf910c32 tpm: reduce polling time to usecs for even finer
> > granularity
> >
> > Fixes: 9f3fc7bcddcb ("tpm: replace msleep() with usleep_range() in TPM 1.2/2.0 generic drivers")
> > Link: https://patchwork.kernel.org/project/linux-integrity/patch/20200926223150.109645-1-hao.wu@xxxxxxxxxx/
> > Signed-off-by: Hao Wu <hao.wu@xxxxxxxxxx>
> > ---
> > v4:
> > - Move timeout constants to drivers/char/tpm/tpm_tis_core.h
> > - Cleanup unnecessary inline comment
> >
> > v3:
> > - removes unnecessary condition check in `wait_for_tpm_stat`
> >
> > v2:
> > - follow the existing way to define two timeouts (min and max)
> > for ATMEL chip, thus keep the exact timeout logic for
> > non-ATEML chips.
> > - limit the timeout increase to only ATMEL TPM 1.2 chips,
> > because it is not an issue for TPM 2.0 chips yet.
> >
> > Test Plan:
> > - Run fixed kernel with ATMEL TPM chips and see crash
> > has been fixed.
> > - Run fixed kernel with non-ATMEL TPM chips, and confirm
> > the timeout has not been changed.
> >
> > drivers/char/tpm/tpm_tis_core.c | 13 +++++++++++--
> > drivers/char/tpm/tpm_tis_core.h | 2 ++
> > include/linux/tpm.h | 3 +++
> > 3 files changed, 16 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> > index 55b9d3965ae1..24605f100e96 100644
> > --- a/drivers/char/tpm/tpm_tis_core.c
> > +++ b/drivers/char/tpm/tpm_tis_core.c
> > @@ -80,8 +80,8 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
> > }
> > } else {
> > do {
> > - usleep_range(TPM_TIMEOUT_USECS_MIN,
> > - TPM_TIMEOUT_USECS_MAX);
> > + usleep_range(chip->timeout_wait_stat_min,
> > + chip->timeout_wait_stat_max);
> > status = chip->ops->status(chip);
> > if ((status & mask) == mask)
> > return 0;
> > @@ -934,6 +934,8 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
> > chip->timeout_b = msecs_to_jiffies(TIS_TIMEOUT_B_MAX);
> > chip->timeout_c = msecs_to_jiffies(TIS_TIMEOUT_C_MAX);
> > chip->timeout_d = msecs_to_jiffies(TIS_TIMEOUT_D_MAX);
> > + chip->timeout_wait_stat_min = TPM_TIMEOUT_USECS_MIN;
> > + chip->timeout_wait_stat_max = TPM_TIMEOUT_USECS_MAX;
> > priv->phy_ops = phy_ops;
> > dev_set_drvdata(&chip->dev, priv);
> >
> > @@ -983,6 +985,13 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
> >
> > priv->manufacturer_id = vendor;
> >
> > + if (priv->manufacturer_id == TPM_VID_ATML &&
> > + !(chip->flags & TPM_CHIP_FLAG_TPM2)) {
> > + /* If TPM chip is 1.2 ATMEL chip, timeout need to be relaxed*/
> > + chip->timeout_wait_stat_min = TPM_ATML_TIMEOUT_WAIT_STAT_MIN;
> > + chip->timeout_wait_stat_max = TPM_ATML_TIMEOUT_WAIT_STAT_MAX;
> > + }
> > +
> > rc = tpm_tis_read8(priv, TPM_RID(0), &rid);
> > if (rc < 0)
> > goto out_err;
> > diff --git a/drivers/char/tpm/tpm_tis_core.h b/drivers/char/tpm/tpm_tis_core.h
> > index 9b2d32a59f67..2e431beb44f7 100644
> > --- a/drivers/char/tpm/tpm_tis_core.h
> > +++ b/drivers/char/tpm/tpm_tis_core.h
> > @@ -54,6 +54,8 @@ enum tis_defaults {
> > TIS_MEM_LEN = 0x5000,
> > TIS_SHORT_TIMEOUT = 750, /* ms */
> > TIS_LONG_TIMEOUT = 2000, /* 2 sec */
> > + TPM_ATML_TIMEOUT_WAIT_STAT_MIN = 14700, /* usecs */
> > + TPM_ATML_TIMEOUT_WAIT_STAT_MAX = 15000, /* usecs */
> > };
I'd prefer TIS_TIMEOUT_{MIN, MAX}_ATML. I.e. no "WAIT_STAT" and without "TPM_"
to be consistent with other constants here.
> >
> > /* Some timeout values are needed before it is known whether the chip is
> > diff --git a/include/linux/tpm.h b/include/linux/tpm.h
> > index aa11fe323c56..171b9102c976 100644
> > --- a/include/linux/tpm.h
> > +++ b/include/linux/tpm.h
> > @@ -150,6 +150,8 @@ struct tpm_chip {
> > bool timeout_adjusted;
> > unsigned long duration[TPM_NUM_DURATIONS]; /* jiffies */
> > bool duration_adjusted;
> > + unsigned int timeout_wait_stat_min; /* usecs */
> > + unsigned int timeout_wait_stat_max; /* usecs */
Please rename as timeout_{min, max}.
And I think tpm_chip is wrong place to put them as they are TIS
specific, i.e. they should be in tpm_tis_data.
> >
> > struct dentry *bios_dir[TPM_NUM_EVENT_LOG_FILES];
> >
> > @@ -269,6 +271,7 @@ enum tpm2_cc_attrs {
> > #define TPM_VID_INTEL 0x8086
> > #define TPM_VID_WINBOND 0x1050
> > #define TPM_VID_STM 0x104A
> > +#define TPM_VID_ATML 0x1114
> >
> > enum tpm_chip_flags {
> > TPM_CHIP_FLAG_TPM2 = BIT(1),
> > --
> > 2.29.0.vfs.0.0
> >
>
> Just kindly remind this code review in case it has been missed somehow
I'm sorry, my bad. I managed to somehow miss this. Might be because
I've been recently reorganizing my email accounts. And thanks for
pinging so that I spotted it.
> Thanks
> Hao
/Jarkko
