--- /dev/null
+From f1324bbc4011ed8aef3f4552210fc429bcd616da Mon Sep 17 00:00:00 2001
+From: Mario Limonciello <mario.limonciello@amd.com>
+Date: Mon, 27 Feb 2023 20:44:39 -0600
+Subject: tpm: disable hwrng for fTPM on some AMD designs
+
+From: Mario Limonciello <mario.limonciello@amd.com>
+
+commit f1324bbc4011ed8aef3f4552210fc429bcd616da upstream.
+
+AMD has issued an advisory indicating that having fTPM enabled in
+BIOS can cause "stuttering" in the OS. This issue has been fixed
+in newer versions of the fTPM firmware, but it's up to system
+designers to decide whether to distribute it.
+
+This issue has existed for a while, but is more prevalent starting
+with kernel 6.1 because commit b006c439d58db ("hwrng: core - start
+hwrng kthread also for untrusted sources") started to use the fTPM
+for hwrng by default. However, all uses of /dev/hwrng result in
+unacceptable stuttering.
+
+So, simply disable registration of the defective hwrng when detecting
+these faulty fTPM versions. As this is caused by faulty firmware, it
+is plausible that such a problem could also be reproduced by other TPM
+interactions, but this hasn't been shown by any user's testing or reports.
+
+It is hypothesized to be triggered more frequently by the use of the RNG
+because userspace software will fetch random numbers regularly.
+
+Intentionally continue to register other TPM functionality so that users
+that rely upon PCR measurements or any storage of data will still have
+access to it. If it's found later that another TPM functionality is
+exacerbating this problem a module parameter it can be turned off entirely
+and a module parameter can be introduced to allow users who rely upon
+fTPM functionality to turn it on even though this problem is present.
+
+Link: https://www.amd.com/en/support/kb/faq/pa-410
+Link: https://bugzilla.kernel.org/show_bug.cgi?id=216989
+Link: https://lore.kernel.org/all/20230209153120.261904-1-Jason@zx2c4.com/
+Fixes: b006c439d58d ("hwrng: core - start hwrng kthread also for untrusted sources")
+Cc: stable@vger.kernel.org
+Cc: Jarkko Sakkinen <jarkko@kernel.org>
+Cc: Thorsten Leemhuis <regressions@leemhuis.info>
+Cc: James Bottomley <James.Bottomley@hansenpartnership.com>
+Tested-by: reach622@mailcuk.com
+Tested-by: Bell <1138267643@qq.com>
+Co-developed-by: Jason A. Donenfeld <Jason@zx2c4.com>
+Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
+Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
+Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
+Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/char/tpm/tpm-chip.c | 60 +++++++++++++++++++++++++++++++++++-
+ drivers/char/tpm/tpm.h | 73 ++++++++++++++++++++++++++++++++++++++++++++
+ 2 files changed, 132 insertions(+), 1 deletion(-)
+
+--- a/drivers/char/tpm/tpm-chip.c
++++ b/drivers/char/tpm/tpm-chip.c
+@@ -507,6 +507,63 @@ static int tpm_add_legacy_sysfs(struct t
+ 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);
+@@ -516,7 +573,8 @@ static int tpm_hwrng_read(struct hwrng *
+
+ 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),
+--- a/drivers/char/tpm/tpm.h
++++ b/drivers/char/tpm/tpm.h
+@@ -150,6 +150,79 @@ enum tpm_sub_capabilities {
+ TPM_CAP_PROP_TIS_DURATION = 0x120,
+ };
+
++enum tpm2_pt_props {
++ TPM2_PT_NONE = 0x00000000,
++ TPM2_PT_GROUP = 0x00000100,
++ TPM2_PT_FIXED = TPM2_PT_GROUP * 1,
++ TPM2_PT_FAMILY_INDICATOR = TPM2_PT_FIXED + 0,
++ TPM2_PT_LEVEL = TPM2_PT_FIXED + 1,
++ TPM2_PT_REVISION = TPM2_PT_FIXED + 2,
++ TPM2_PT_DAY_OF_YEAR = TPM2_PT_FIXED + 3,
++ TPM2_PT_YEAR = TPM2_PT_FIXED + 4,
++ TPM2_PT_MANUFACTURER = TPM2_PT_FIXED + 5,
++ TPM2_PT_VENDOR_STRING_1 = TPM2_PT_FIXED + 6,
++ TPM2_PT_VENDOR_STRING_2 = TPM2_PT_FIXED + 7,
++ TPM2_PT_VENDOR_STRING_3 = TPM2_PT_FIXED + 8,
++ TPM2_PT_VENDOR_STRING_4 = TPM2_PT_FIXED + 9,
++ TPM2_PT_VENDOR_TPM_TYPE = TPM2_PT_FIXED + 10,
++ TPM2_PT_FIRMWARE_VERSION_1 = TPM2_PT_FIXED + 11,
++ TPM2_PT_FIRMWARE_VERSION_2 = TPM2_PT_FIXED + 12,
++ TPM2_PT_INPUT_BUFFER = TPM2_PT_FIXED + 13,
++ TPM2_PT_HR_TRANSIENT_MIN = TPM2_PT_FIXED + 14,
++ TPM2_PT_HR_PERSISTENT_MIN = TPM2_PT_FIXED + 15,
++ TPM2_PT_HR_LOADED_MIN = TPM2_PT_FIXED + 16,
++ TPM2_PT_ACTIVE_SESSIONS_MAX = TPM2_PT_FIXED + 17,
++ TPM2_PT_PCR_COUNT = TPM2_PT_FIXED + 18,
++ TPM2_PT_PCR_SELECT_MIN = TPM2_PT_FIXED + 19,
++ TPM2_PT_CONTEXT_GAP_MAX = TPM2_PT_FIXED + 20,
++ TPM2_PT_NV_COUNTERS_MAX = TPM2_PT_FIXED + 22,
++ TPM2_PT_NV_INDEX_MAX = TPM2_PT_FIXED + 23,
++ TPM2_PT_MEMORY = TPM2_PT_FIXED + 24,
++ TPM2_PT_CLOCK_UPDATE = TPM2_PT_FIXED + 25,
++ TPM2_PT_CONTEXT_HASH = TPM2_PT_FIXED + 26,
++ TPM2_PT_CONTEXT_SYM = TPM2_PT_FIXED + 27,
++ TPM2_PT_CONTEXT_SYM_SIZE = TPM2_PT_FIXED + 28,
++ TPM2_PT_ORDERLY_COUNT = TPM2_PT_FIXED + 29,
++ TPM2_PT_MAX_COMMAND_SIZE = TPM2_PT_FIXED + 30,
++ TPM2_PT_MAX_RESPONSE_SIZE = TPM2_PT_FIXED + 31,
++ TPM2_PT_MAX_DIGEST = TPM2_PT_FIXED + 32,
++ TPM2_PT_MAX_OBJECT_CONTEXT = TPM2_PT_FIXED + 33,
++ TPM2_PT_MAX_SESSION_CONTEXT = TPM2_PT_FIXED + 34,
++ TPM2_PT_PS_FAMILY_INDICATOR = TPM2_PT_FIXED + 35,
++ TPM2_PT_PS_LEVEL = TPM2_PT_FIXED + 36,
++ TPM2_PT_PS_REVISION = TPM2_PT_FIXED + 37,
++ TPM2_PT_PS_DAY_OF_YEAR = TPM2_PT_FIXED + 38,
++ TPM2_PT_PS_YEAR = TPM2_PT_FIXED + 39,
++ TPM2_PT_SPLIT_MAX = TPM2_PT_FIXED + 40,
++ TPM2_PT_TOTAL_COMMANDS = TPM2_PT_FIXED + 41,
++ TPM2_PT_LIBRARY_COMMANDS = TPM2_PT_FIXED + 42,
++ TPM2_PT_VENDOR_COMMANDS = TPM2_PT_FIXED + 43,
++ TPM2_PT_NV_BUFFER_MAX = TPM2_PT_FIXED + 44,
++ TPM2_PT_MODES = TPM2_PT_FIXED + 45,
++ TPM2_PT_MAX_CAP_BUFFER = TPM2_PT_FIXED + 46,
++ TPM2_PT_VAR = TPM2_PT_GROUP * 2,
++ TPM2_PT_PERMANENT = TPM2_PT_VAR + 0,
++ TPM2_PT_STARTUP_CLEAR = TPM2_PT_VAR + 1,
++ TPM2_PT_HR_NV_INDEX = TPM2_PT_VAR + 2,
++ TPM2_PT_HR_LOADED = TPM2_PT_VAR + 3,
++ TPM2_PT_HR_LOADED_AVAIL = TPM2_PT_VAR + 4,
++ TPM2_PT_HR_ACTIVE = TPM2_PT_VAR + 5,
++ TPM2_PT_HR_ACTIVE_AVAIL = TPM2_PT_VAR + 6,
++ TPM2_PT_HR_TRANSIENT_AVAIL = TPM2_PT_VAR + 7,
++ TPM2_PT_HR_PERSISTENT = TPM2_PT_VAR + 8,
++ TPM2_PT_HR_PERSISTENT_AVAIL = TPM2_PT_VAR + 9,
++ TPM2_PT_NV_COUNTERS = TPM2_PT_VAR + 10,
++ TPM2_PT_NV_COUNTERS_AVAIL = TPM2_PT_VAR + 11,
++ TPM2_PT_ALGORITHM_SET = TPM2_PT_VAR + 12,
++ TPM2_PT_LOADED_CURVES = TPM2_PT_VAR + 13,
++ TPM2_PT_LOCKOUT_COUNTER = TPM2_PT_VAR + 14,
++ TPM2_PT_MAX_AUTH_FAIL = TPM2_PT_VAR + 15,
++ TPM2_PT_LOCKOUT_INTERVAL = TPM2_PT_VAR + 16,
++ TPM2_PT_LOCKOUT_RECOVERY = TPM2_PT_VAR + 17,
++ TPM2_PT_NV_WRITE_RECOVERY = TPM2_PT_VAR + 18,
++ TPM2_PT_AUDIT_COUNTER_0 = TPM2_PT_VAR + 19,
++ TPM2_PT_AUDIT_COUNTER_1 = TPM2_PT_VAR + 20,
++};
+
+ /* 128 bytes is an arbitrary cap. This could be as large as TPM_BUFSIZE - 18
+ * bytes, but 128 is still a relatively large number of random bytes and
projects / thirdparty / kernel / stable-queue.git / commitdiff
