diff options
Diffstat (limited to 'drivers/char/tpm/tpm-chip.c')
| -rw-r--r-- | drivers/char/tpm/tpm-chip.c | 60 |
1 files changed, 59 insertions, 1 deletions
diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c index 7c444209a256..29305a0c0d45 100644 --- a/drivers/char/tpm/tpm-chip.c +++ b/drivers/char/tpm/tpm-chip.c @@ -510,6 +510,63 @@ static int tpm_add_legacy_sysfs(struct tpm_chip *chip) return 0; } +/* + * Some AMD fTPM versions may cause stutter + * https://www.amd.com/en/support/kb/faq/pa-410 + * + * Fixes are available in two series of fTPM firmware: + * 6.x.y.z series: 6.0.18.6 + + * 3.x.y.z series: 3.57.y.5 + + */ +static bool tpm_amd_is_rng_defective(struct tpm_chip *chip) +{ + u32 val1, val2; + u64 version; + int ret; + + if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) + return false; + + ret = tpm_request_locality(chip); + if (ret) + return false; + + ret = tpm2_get_tpm_pt(chip, TPM2_PT_MANUFACTURER, &val1, NULL); + if (ret) + goto release; + if (val1 != 0x414D4400U /* AMD */) { + ret = -ENODEV; + goto release; + } + ret = tpm2_get_tpm_pt(chip, TPM2_PT_FIRMWARE_VERSION_1, &val1, NULL); + if (ret) + goto release; + ret = tpm2_get_tpm_pt(chip, TPM2_PT_FIRMWARE_VERSION_2, &val2, NULL); + +release: + tpm_relinquish_locality(chip); + + if (ret) + return false; + + version = ((u64)val1 << 32) | val2; + if ((version >> 48) == 6) { + if (version >= 0x0006000000180006ULL) + return false; + } else if ((version >> 48) == 3) { + if (version >= 0x0003005700000005ULL) + return false; + } else { + return false; + } + + dev_warn(&chip->dev, + "AMD fTPM version 0x%llx causes system stutter; hwrng disabled\n", + version); + + return true; +} + static int tpm_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait) { struct tpm_chip *chip = container_of(rng, struct tpm_chip, hwrng); @@ -519,7 +576,8 @@ static int tpm_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait) static int tpm_add_hwrng(struct tpm_chip *chip) { - if (!IS_ENABLED(CONFIG_HW_RANDOM_TPM) || tpm_is_firmware_upgrade(chip)) + if (!IS_ENABLED(CONFIG_HW_RANDOM_TPM) || tpm_is_firmware_upgrade(chip) || + tpm_amd_is_rng_defective(chip)) return 0; snprintf(chip->hwrng_name, sizeof(chip->hwrng_name), |