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Subject[PATCH v3] tpm: check selftest status before retrying full selftest
Date
TPM 2.0 supports TPM2_GetTestResult[1], which can be used to check the
selftest status. This patch implements the tpm2_get_selftest_result()
function to check the selftest status before trying full selftest.

[1] As per TCG Specification, Trusted Platform Module Library,
Part 2 - Commands, Section 10.4:

"This command(TPM2_GetTestResult) returns manufacturer-specific information
regarding the results of a self-test and an indication of the test status.

Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com>
Tested-by: Mimi Zohar <zohar@linux.vnet.ibm.com> (on Pi with TPM 2.0)
Tested-by: Stefan Berger <stefanb@linux.vnet.ibm.com> (With QEMU with
swtpm TPM 2.0)
---

Changelog:

v3:
* modified to check the selftest status before full selftest command is run
* fixed the patch description
* includes Jarkko's feedbacks

v2:
* changed the subject and updated patch description
* removed the logs

drivers/char/tpm/tpm.h | 2 ++
drivers/char/tpm/tpm2-cmd.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 46 insertions(+)

diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index af3bb87d3ea1..1de4240b52c4 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -114,6 +114,7 @@ enum tpm2_return_codes {
TPM2_RC_FAILURE = 0x0101,
TPM2_RC_DISABLED = 0x0120,
TPM2_RC_COMMAND_CODE = 0x0143,
+ TPM2_RC_NEEDS_TEST = 0x0153,
TPM2_RC_TESTING = 0x090A, /* RC_WARN */
TPM2_RC_REFERENCE_H0 = 0x0910,
TPM2_RC_RETRY = 0x0922,
@@ -144,6 +145,7 @@ enum tpm2_command_codes {
TPM2_CC_FLUSH_CONTEXT = 0x0165,
TPM2_CC_GET_CAPABILITY = 0x017A,
TPM2_CC_GET_RANDOM = 0x017B,
+ TPM2_CC_GET_TEST_RESULT = 0x017C,
TPM2_CC_PCR_READ = 0x017E,
TPM2_CC_PCR_EXTEND = 0x0182,
TPM2_CC_LAST = 0x018F,
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 96c77c8e7f40..811bcf221208 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -825,6 +825,43 @@ unsigned long tpm2_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal)
EXPORT_SYMBOL_GPL(tpm2_calc_ordinal_duration);

/**
+ * tpm2_get_selftest_result() - get the status of selftest
+ * @chip: TPM chip to use
+ *
+ * Return: TPM return code, errno otherwise
+ */
+static int tpm2_get_selftest_result(struct tpm_chip *chip)
+{
+ struct tpm_buf buf;
+ int rc;
+ int test_result;
+ uint16_t data_size;
+ int len;
+ const struct tpm_output_header *header;
+
+ rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_TEST_RESULT);
+ if (rc)
+ return rc;
+
+ len = tpm_transmit(chip, NULL, buf.data, PAGE_SIZE, 0);
+ if (len < 0)
+ return len;
+
+ header = (struct tpm_output_header *)buf.data;
+
+ rc = be32_to_cpu(header->return_code);
+ if (rc)
+ return rc;
+
+ data_size = be16_to_cpup((__be16 *)&buf.data[TPM_HEADER_SIZE]);
+
+ test_result = be32_to_cpup((__be32 *)
+ (&buf.data[TPM_HEADER_SIZE + 2 + data_size]));
+
+ return test_result;
+}
+
+/**
* tpm2_do_selftest() - ensure that all self tests have passed
*
* @chip: TPM chip to use
@@ -857,6 +894,13 @@ static int tpm2_do_selftest(struct tpm_chip *chip)
rc = TPM2_RC_SUCCESS;
if (rc == TPM2_RC_INITIALIZE || rc == TPM2_RC_SUCCESS)
return rc;
+
+ rc = tpm2_get_selftest_result(chip);
+ dev_dbg(&chip->dev, "self test result is %04x\n", rc);
+
+ if (rc == TPM2_RC_TESTING || rc == TPM2_RC_SUCCESS)
+ return TPM2_RC_SUCCESS;
+
}

return rc;
--
2.13.6
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