Merge branch 'for-6.4/amd-sfh' into for-linus

- assorted functional fixes for amd-sfh driver (Basavaraj Natikar)

1 files changed, 59 insertions, 1 deletions

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index b99f55f2d4fd..0601e6e5e326 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -511,6 +511,63 @@ 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);
@@ -520,7 +577,8 @@ 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),