[PATCH] tpm: fix ATMEL TPM crash caused by too frequent queries

[Hao Wu <hao.wu@rubrik.com>]

This is a fix for the ATMEL TPM crash bug reported in
https://patchwork.kernel.org/project/linux-integrity/patch/20200926223150.109645-1-hao.wu@rubrik.com/

According to the discussions in the original thread,
we don't want to revert the timeout of wait_for_tpm_stat
for non-ATMEL chips, which brings back the performance cost.
For investigation and analysis of why wait_for_tpm_stat
caused the issue, and how the regression was introduced,
please read the original thread above.

Thus the proposed fix here is to only revert the timeout
for ATMEL chips by checking the vendor ID.

Fixes: 9f3fc7bcddcb ("tpm: replace msleep() with usleep_range() in TPM 1.2/2.0 generic drivers")
Signed-off-by: Hao Wu <hao.wu@rubrik.com>
---
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.h          |  6 ++++--
 drivers/char/tpm/tpm_tis_core.c | 23 +++++++++++++++++++++--
 include/linux/tpm.h             |  3 +++
 3 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 283f78211c3a..6de1b44c4aab 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -41,8 +41,10 @@ enum tpm_timeout {
 	TPM_TIMEOUT_RETRY = 100, /* msecs */
 	TPM_TIMEOUT_RANGE_US = 300,	/* usecs */
 	TPM_TIMEOUT_POLL = 1,	/* msecs */
-	TPM_TIMEOUT_USECS_MIN = 100,      /* usecs */
-	TPM_TIMEOUT_USECS_MAX = 500      /* usecs */
+	TPM_TIMEOUT_USECS_MIN = 100,	/* usecs */
+	TPM_TIMEOUT_USECS_MAX = 500,	/* usecs */
+	TPM_ATML_TIMEOUT_WAIT_STAT_MIN = 14700,	/* usecs */
+	TPM_ATML_TIMEOUT_WAIT_STAT_MAX = 15000	/* usecs */
 };
 
 /* TPM addresses */
diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 55b9d3965ae1..ae27d66fdd94 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -80,8 +80,17 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
 		}
 	} else {
 		do {
-			usleep_range(TPM_TIMEOUT_USECS_MIN,
-				     TPM_TIMEOUT_USECS_MAX);
+			/* this code path could be executed before
+			 * timeouts initialized in chip instance.
+			 */
+			if (chip->timeout_wait_stat_min &&
+			    chip->timeout_wait_stat_max)
+				usleep_range(chip->timeout_wait_stat_min,
+					     chip->timeout_wait_stat_max);
+			else
+				usleep_range(TPM_TIMEOUT_USECS_MIN,
+					     TPM_TIMEOUT_USECS_MAX);
+
 			status = chip->ops->status(chip);
 			if ((status & mask) == mask)
 				return 0;
@@ -934,6 +943,9 @@ 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);
+	/* init timeouts for wait_for_tpm_stat */
+	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 +995,13 @@ 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/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