> 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 */
> };
>
> /* 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 */
>
> 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
Thanks
Hao
