The TPM RNG functionality is not necessary for entropy when the CPU already supports the RDRAND instruction. The TPM RNG functionality was previously disabled on a subset of AMD fTPM series, but reports continue to show problems on some systems causing stutter root caused to TPM RNG functionality.
Expand disabling TPM RNG use for all AMD fTPMs whether they have versions that claim to have fixed or not. To accomplish this, move the detection into part of the TPM CRB registration and add a flag indicating that the TPM should opt-out of registration to hwrng.
Cc: stable@vger.kernel.org # 6.1.y+ Fixes: b006c439d58d ("hwrng: core - start hwrng kthread also for untrusted sources") Fixes: f1324bbc4011 ("tpm: disable hwrng for fTPM on some AMD designs") Reported-by: daniil.stas@posteo.net Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217719 Reported-by: bitlord0xff@gmail.com Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217212 Signed-off-by: Mario Limonciello mario.limonciello@amd.com --- v1->v2: * switch from callback to everything in tpm_crb * switch to open coded flags check instead of new inline --- drivers/char/tpm/tpm-chip.c | 68 ++----------------------------------- drivers/char/tpm/tpm_crb.c | 30 ++++++++++++++++ include/linux/tpm.h | 1 + 3 files changed, 33 insertions(+), 66 deletions(-)
diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c index cf5499e51999b..e904aae9771be 100644 --- a/drivers/char/tpm/tpm-chip.c +++ b/drivers/char/tpm/tpm-chip.c @@ -510,70 +510,6 @@ 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 + - */ -#ifdef CONFIG_X86 -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; -} -#else -static inline bool tpm_amd_is_rng_defective(struct tpm_chip *chip) -{ - return false; -} -#endif /* CONFIG_X86 */ - 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); @@ -588,7 +524,7 @@ 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) || - tpm_amd_is_rng_defective(chip)) + chip->flags & TPM_CHIP_FLAG_HWRNG_DISABLED) return 0;
snprintf(chip->hwrng_name, sizeof(chip->hwrng_name), @@ -719,7 +655,7 @@ void tpm_chip_unregister(struct tpm_chip *chip) { tpm_del_legacy_sysfs(chip); if (IS_ENABLED(CONFIG_HW_RANDOM_TPM) && !tpm_is_firmware_upgrade(chip) && - !tpm_amd_is_rng_defective(chip)) + !(chip->flags & TPM_CHIP_FLAG_HWRNG_DISABLED)) hwrng_unregister(&chip->hwrng); tpm_bios_log_teardown(chip); if (chip->flags & TPM_CHIP_FLAG_TPM2 && !tpm_is_firmware_upgrade(chip)) diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c index 1a5d09b185134..9eb1a18590123 100644 --- a/drivers/char/tpm/tpm_crb.c +++ b/drivers/char/tpm/tpm_crb.c @@ -463,6 +463,28 @@ static bool crb_req_canceled(struct tpm_chip *chip, u8 status) return (cancel & CRB_CANCEL_INVOKE) == CRB_CANCEL_INVOKE; }
+static int crb_check_flags(struct tpm_chip *chip) +{ + u32 val; + int ret; + + ret = crb_request_locality(chip, 0); + if (ret) + return ret; + + ret = tpm2_get_tpm_pt(chip, TPM2_PT_MANUFACTURER, &val, NULL); + if (ret) + goto release; + + if (val == 0x414D4400U /* AMD */) + chip->flags |= TPM_CHIP_FLAG_HWRNG_DISABLED; + +release: + crb_relinquish_locality(chip, 0); + + return ret; +} + static const struct tpm_class_ops tpm_crb = { .flags = TPM_OPS_AUTO_STARTUP, .status = crb_status, @@ -800,6 +822,14 @@ static int crb_acpi_add(struct acpi_device *device) chip->acpi_dev_handle = device->handle; chip->flags = TPM_CHIP_FLAG_TPM2;
+ rc = tpm_chip_bootstrap(chip); + if (rc) + goto out; + + rc = crb_check_flags(chip); + if (rc) + goto out; + rc = tpm_chip_register(chip);
out: diff --git a/include/linux/tpm.h b/include/linux/tpm.h index 6a1e8f1572551..4ee9d13749adc 100644 --- a/include/linux/tpm.h +++ b/include/linux/tpm.h @@ -283,6 +283,7 @@ enum tpm_chip_flags { TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED = BIT(6), TPM_CHIP_FLAG_FIRMWARE_UPGRADE = BIT(7), TPM_CHIP_FLAG_SUSPENDED = BIT(8), + TPM_CHIP_FLAG_HWRNG_DISABLED = BIT(9), };
#define to_tpm_chip(d) container_of(d, struct tpm_chip, dev)
On Wed Aug 2, 2023 at 3:25 PM EEST, Mario Limonciello wrote:
The TPM RNG functionality is not necessary for entropy when the CPU already supports the RDRAND instruction. The TPM RNG functionality was previously disabled on a subset of AMD fTPM series, but reports continue to show problems on some systems causing stutter root caused to TPM RNG functionality.
Expand disabling TPM RNG use for all AMD fTPMs whether they have versions that claim to have fixed or not. To accomplish this, move the detection into part of the TPM CRB registration and add a flag indicating that the TPM should opt-out of registration to hwrng.
Cc: stable@vger.kernel.org # 6.1.y+ Fixes: b006c439d58d ("hwrng: core - start hwrng kthread also for untrusted sources") Fixes: f1324bbc4011 ("tpm: disable hwrng for fTPM on some AMD designs") Reported-by: daniil.stas@posteo.net Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217719 Reported-by: bitlord0xff@gmail.com Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217212 Signed-off-by: Mario Limonciello mario.limonciello@amd.com
v1->v2:
- switch from callback to everything in tpm_crb
- switch to open coded flags check instead of new inline
drivers/char/tpm/tpm-chip.c | 68 ++----------------------------------- drivers/char/tpm/tpm_crb.c | 30 ++++++++++++++++ include/linux/tpm.h | 1 + 3 files changed, 33 insertions(+), 66 deletions(-)
diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c index cf5499e51999b..e904aae9771be 100644 --- a/drivers/char/tpm/tpm-chip.c +++ b/drivers/char/tpm/tpm-chip.c @@ -510,70 +510,6 @@ static int tpm_add_legacy_sysfs(struct tpm_chip *chip) return 0; } -/*
- Some AMD fTPM versions may cause stutter
- 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 +
- */
-#ifdef CONFIG_X86 -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;
-} -#else -static inline bool tpm_amd_is_rng_defective(struct tpm_chip *chip) -{
- return false;
-} -#endif /* CONFIG_X86 */
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); @@ -588,7 +524,7 @@ 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) ||
tpm_amd_is_rng_defective(chip))
chip->flags & TPM_CHIP_FLAG_HWRNG_DISABLED)snprintf(chip->hwrng_name, sizeof(chip->hwrng_name), @@ -719,7 +655,7 @@ void tpm_chip_unregister(struct tpm_chip *chip) { tpm_del_legacy_sysfs(chip); if (IS_ENABLED(CONFIG_HW_RANDOM_TPM) && !tpm_is_firmware_upgrade(chip) &&
!tpm_amd_is_rng_defective(chip))
!(chip->flags & TPM_CHIP_FLAG_HWRNG_DISABLED))diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c index 1a5d09b185134..9eb1a18590123 100644 --- a/drivers/char/tpm/tpm_crb.c +++ b/drivers/char/tpm/tpm_crb.c @@ -463,6 +463,28 @@ static bool crb_req_canceled(struct tpm_chip *chip, u8 status) return (cancel & CRB_CANCEL_INVOKE) == CRB_CANCEL_INVOKE; } +static int crb_check_flags(struct tpm_chip *chip) +{
- u32 val;
- int ret;
- ret = crb_request_locality(chip, 0);
- if (ret)
return ret;- ret = tpm2_get_tpm_pt(chip, TPM2_PT_MANUFACTURER, &val, NULL);
- if (ret)
goto release;- if (val == 0x414D4400U /* AMD */)
chip->flags |= TPM_CHIP_FLAG_HWRNG_DISABLED;+release:
- crb_relinquish_locality(chip, 0);
- return ret;
+}
static const struct tpm_class_ops tpm_crb = { .flags = TPM_OPS_AUTO_STARTUP, .status = crb_status, @@ -800,6 +822,14 @@ static int crb_acpi_add(struct acpi_device *device) chip->acpi_dev_handle = device->handle; chip->flags = TPM_CHIP_FLAG_TPM2;
- rc = tpm_chip_bootstrap(chip);
- if (rc)
goto out;- rc = crb_check_flags(chip);
- if (rc)
goto out;- rc = tpm_chip_register(chip);
out: diff --git a/include/linux/tpm.h b/include/linux/tpm.h index 6a1e8f1572551..4ee9d13749adc 100644 --- a/include/linux/tpm.h +++ b/include/linux/tpm.h @@ -283,6 +283,7 @@ enum tpm_chip_flags { TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED = BIT(6), TPM_CHIP_FLAG_FIRMWARE_UPGRADE = BIT(7), TPM_CHIP_FLAG_SUSPENDED = BIT(8),
- TPM_CHIP_FLAG_HWRNG_DISABLED = BIT(9),
};
#define to_tpm_chip(d) container_of(d, struct tpm_chip, dev)
2.34.1
Reviewed-by: Jarkko Sakkinen jarkko@kernel.org
Thank you, great work.
I pushed the patch to my next branch:
https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd.git/log/?...
I'll hold on for tested-by's from AMD users, and send a pull request tomorrow afternoon (GMT+3).
BR, Jarkko
On Wed, Aug 02, 2023 at 07:25:33AM -0500, Mario Limonciello wrote:
The TPM RNG functionality is not necessary for entropy when the CPU already supports the RDRAND instruction. The TPM RNG functionality was previously disabled on a subset of AMD fTPM series, but reports continue to show problems on some systems causing stutter root caused to TPM RNG functionality.
Expand disabling TPM RNG use for all AMD fTPMs whether they have versions that claim to have fixed or not. To accomplish this, move the detection into part of the TPM CRB registration and add a flag indicating that the TPM should opt-out of registration to hwrng.
Cc: stable@vger.kernel.org # 6.1.y+ Fixes: b006c439d58d ("hwrng: core - start hwrng kthread also for untrusted sources") Fixes: f1324bbc4011 ("tpm: disable hwrng for fTPM on some AMD designs")
Users can trigger this by reading from /dev/hwrng, which some userspace daemons are known to do. So I think the proper fixes tag and stable@ version range actually begins with whenever fTPM support was introduced.
Reported-by: daniil.stas@posteo.net Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217719 Reported-by: bitlord0xff@gmail.com Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217212 Signed-off-by: Mario Limonciello mario.limonciello@amd.com
Hopefully future AMD hardware won't be broken and we can revisit this. Until then, LGTM:
Reviewed-by: Jason A. Donenfeld Jason@zx2c4.com
On Thu Aug 3, 2023 at 4:45 PM EEST, Jason A. Donenfeld wrote:
On Wed, Aug 02, 2023 at 07:25:33AM -0500, Mario Limonciello wrote:
The TPM RNG functionality is not necessary for entropy when the CPU already supports the RDRAND instruction. The TPM RNG functionality was previously disabled on a subset of AMD fTPM series, but reports continue to show problems on some systems causing stutter root caused to TPM RNG functionality.
Expand disabling TPM RNG use for all AMD fTPMs whether they have versions that claim to have fixed or not. To accomplish this, move the detection into part of the TPM CRB registration and add a flag indicating that the TPM should opt-out of registration to hwrng.
Cc: stable@vger.kernel.org # 6.1.y+ Fixes: b006c439d58d ("hwrng: core - start hwrng kthread also for untrusted sources") Fixes: f1324bbc4011 ("tpm: disable hwrng for fTPM on some AMD designs")
Users can trigger this by reading from /dev/hwrng, which some userspace daemons are known to do. So I think the proper fixes tag and stable@ version range actually begins with whenever fTPM support was introduced.
Reported-by: daniil.stas@posteo.net Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217719 Reported-by: bitlord0xff@gmail.com Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217212 Signed-off-by: Mario Limonciello mario.limonciello@amd.com
Hopefully future AMD hardware won't be broken and we can revisit this. Until then, LGTM:
Reviewed-by: Jason A. Donenfeld Jason@zx2c4.com
Thanks. I'll add your tag.
BR, Jarkko
linux-stable-mirror@lists.linaro.org
-
Jarkko Sakkinen -
Jason A. Donenfeld -
Mario Limonciello