>From 8f147e6a9a8e08433d6c1836afbf030598d26e9e Mon Sep 17 00:00:00 2001
From: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
Date: Thu, 8 Feb 2018 12:33:47 -0800
Subject: [PATCH] tpm: fix intermittent failure with self tests
Ever since
commit 2482b1bba5122b1d5516c909832bdd282015b8e9
Author: Alexander Steffen <Alexander.Steffen@xxxxxxxxxxxx>
Date: Thu Aug 31 19:18:56 2017 +0200
tpm: Trigger only missing TPM 2.0 self tests
My Nuvoton 6xx in a Dell XPS-13 has been intermittently failing to
work (necessitating a reboot). The problem seems to be that the TPM
gets into a state where the partial self-test doesn't return
TPM_RC_SUCCESS (meaning all tests have run to completion), but instead
returns TPM_RC_TESTING (meaning some tests are still running in the
background). There are various theories that resending the self-test
command actually causes the tests to restart and thus triggers more
TPM_RC_TESTING returns until the timeout is exceeded.
There are several issues here: firstly being we shouldn't slow down
the boot sequence waiting for the self test to complete once the TPM
backgrounds them. It will actually make available all functions that
have passed and if it gets a failure return TPM_RC_FAILURE to every
subsequent command. So the fix is to kick off self tests once and if
they return TPM_RC_TESTING log that as a backgrounded self test and
continue on. In order to prevent userspace from seeing any
TPM_RC_TESTING returns (which it might if userspace sends a command
that needs a TPM subsystem which is still under test), we loop in
tpm_transmit_cmd until either a timeout or we don't get a
TPM_RC_TESTING return.
Signed-off-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
Fixes: 2482b1bba5122b1d5516c909832bdd282015b8e9
---
drivers/char/tpm/tpm-interface.c | 28 ++++++++++++++++++++++++----
drivers/char/tpm/tpm.h | 1 +
drivers/char/tpm/tpm2-cmd.c | 36 ++++++++++++++++--------------------
3 files changed, 41 insertions(+), 24 deletions(-)
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 3cec403a80b3..c3e6d0248af8 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -521,12 +521,32 @@ ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_space *space,
const struct tpm_output_header *header = buf;
int err;
ssize_t len;
+ unsigned int delay_msec = 20;
- len = tpm_transmit(chip, space, (u8 *)buf, bufsiz, flags);
- if (len < 0)
- return len;
+ /*
+ * on first probe we kick off a TPM self test in the
+ * background This means the TPM may return RC_TESTING to any
+ * command that tries to use a subsystem under test, so do an
+ * exponential backoff wait if that happens
+ */
+ for (;;) {
+ len = tpm_transmit(chip, space, (u8 *)buf, bufsiz, flags);
+ if (len < 0)
+ return len;
+
+ err = be32_to_cpu(header->return_code);
+ if (err != TPM2_RC_TESTING ||
+ (flags & TPM_TRANSMIT_NOWAIT))
+ break;
+
+ delay_msec *= 2;
+ if (delay_msec > TPM2_DURATION_LONG) {
+ dev_err(&chip->dev,"TPM: still running self tests, giving up waiting\n");
+ break;
+ }
+ tpm_msleep(delay_msec);
+ }
- err = be32_to_cpu(header->return_code);
if (err != 0 && desc)
dev_err(&chip->dev, "A TPM error (%d) occurred %s\n", err,
desc);
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 528cffbd49d3..47c5a5206325 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -495,6 +495,7 @@ extern struct idr dev_nums_idr;
enum tpm_transmit_flags {
TPM_TRANSMIT_UNLOCKED = BIT(0),
TPM_TRANSMIT_RAW = BIT(1),
+ TPM_TRANSMIT_NOWAIT = BIT(2),
};
ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space,
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index f6be08483ae6..169232179182 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -853,28 +853,24 @@ static const struct tpm_input_header tpm2_selftest_header = {
static int tpm2_do_selftest(struct tpm_chip *chip)
{
int rc;
- unsigned int delay_msec = 20;
- long duration;
struct tpm2_cmd cmd;
- duration = jiffies_to_msecs(
- tpm2_calc_ordinal_duration(chip, TPM2_CC_SELF_TEST));
-
- while (duration > 0) {
- cmd.header.in = tpm2_selftest_header;
- cmd.params.selftest_in.full_test = 0;
-
- rc = tpm_transmit_cmd(chip, NULL, &cmd, TPM2_SELF_TEST_IN_SIZE,
- 0, 0, "continue selftest");
-
- if (rc != TPM2_RC_TESTING)
- break;
-
- tpm_msleep(delay_msec);
- duration -= delay_msec;
-
- /* wait longer the next round */
- delay_msec *= 2;
+ cmd.header.in = tpm2_selftest_header;
+ cmd.params.selftest_in.full_test = 0;
+
+ rc = tpm_transmit_cmd(chip, NULL, &cmd, TPM2_SELF_TEST_IN_SIZE,
+ 0, TPM_TRANSMIT_NOWAIT, "continue selftest");
+
+ if (rc == TPM2_RC_TESTING) {
+ /*
+ * A return of RC_TESTING means the TPM is still
+ * running self tests. If one fails it will go into
+ * failure mode and return RC_FAILED to every command,
+ * so treat a still in testing return as a success
+ * rather than causing a driver detach.
+ */
+ dev_info(&chip->dev,"TPM: Running self test in background\n");
+ rc = TPM2_RC_SUCCESS;
}
return rc;
--
2.12.3
