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Message-ID: <20180319205717.GC13178@linux.intel.com>
Date: Mon, 19 Mar 2018 22:57:17 +0200
From: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To: Nayna Jain <nayna@...ux.vnet.ibm.com>
Cc: linux-integrity@...r.kernel.org, zohar@...ux.vnet.ibm.com,
linux-security-module@...r.kernel.org,
linux-kernel@...r.kernel.org, peterhuewe@....de,
tpmdd@...horst.net, jgunthorpe@...idianresearch.com
Subject: Re: [PATCH] tpm: TPM 2.0 selftest performance improvement
Hi
On Fri, Mar 16, 2018 at 11:15:28PM +0530, Nayna Jain wrote:
> For selftest being run in the background, the TCG 2.0 Specification
> provides the command TPM2_GetTestResult to check the status of selftest
> completion.
>
> When the partial selftest command is sent just after TPM initialization,
> it is observed that it returns RC_COMMAND_CODE error, which as per TPM 2.0
When does it return RC_COMMAND_COMMAND return code? Who is observing
this? Please, do not use passive form.
> Specification, indicates "the response code that is returned if the TPM is
> unmarshalling a value that it expects to be a TPM_CC and the input value is
> not in the table." This doesn't indicate the exact status of selftest
> command on TPM. But, it can be verified by sending the TPM2_GetTestResult.
Where did you draw the conclusion that it doesn not indicate the
exact status? What does RC_COMMAND_CODE anyway indicate then? Just
trying to understand.
Also, please check the grammar in last two sentences (the second one
should probably be a subordinate clause).
> This patch implements the TPM2_GetTestResult command and uses it to check
> the selftest status, before sending the full selftest command after partial
> selftest returns RC_COMMAND_CODE.
Isn't that command implemented inside the TPM? You are implementing
tpm2_get_selftest_result().
> With this change, dmesg shows the TPM selftest completed at 1.243864
> compared with the previous 1.939667 time.
These numbers mean *absolutely nothing* to me as they are not
connected to *anything*.
>
> Signed-off-by: Nayna Jain <nayna@...ux.vnet.ibm.com>
> Tested-by: Mimi Zohar <zohar@...ux.vnet.ibm.com> (on Pi with TPM 2.0)
> Signed-off-by: Mimi Zohar <zohar@...ux.vnet.ibm.com>
> ---
> drivers/char/tpm/tpm.h | 2 ++
> drivers/char/tpm/tpm2-cmd.c | 59 +++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 61 insertions(+)
>
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index 82ae7b722161..d95eeb7c002a 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -107,6 +107,7 @@ 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,
> };
> @@ -135,6 +136,7 @@ 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 89a5397b18d2..494f6dfbc65d 100644
> --- a/drivers/char/tpm/tpm2-cmd.c
> +++ b/drivers/char/tpm/tpm2-cmd.c
> @@ -823,6 +823,50 @@ 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 self tests
> + *
> + * @chip: TPM chip to use
> + *
> + * Return: If error return rc, else return the result of the self tests.
> + * TPM_RC_NEEDS_TESTING: No self tests are done. Needs testing.
> + * TPM_RC_TESTING: Self tests are in progress.
> + * TPM_RC_SUCCESS: Self tests completed successfully.
> + * TPM_RC_FAILURE: Self tests completed failure.
> + *
> + * This function can be used to check the status of self tests on the TPM.
> + */
> +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
> @@ -851,10 +895,25 @@ static int tpm2_do_selftest(struct tpm_chip *chip)
> "attempting the self test");
> tpm_buf_destroy(&buf);
>
> + dev_dbg(&chip->dev, "tpm selftest command returned %04x\n", rc);
> if (rc == TPM2_RC_TESTING)
> rc = TPM2_RC_SUCCESS;
> if (rc == TPM2_RC_INITIALIZE || rc == TPM2_RC_SUCCESS)
> return rc;
> +
> + if (rc == TPM2_RC_COMMAND_CODE) {
> +
> + dev_info(&chip->dev, "Check TPM Test Results\n");
> + rc = tpm2_get_selftest_result(chip);
> +
> + dev_info(&chip->dev, "tpm self test result is %04x\n",
> + rc);
> + if (rc == TPM2_RC_TESTING)
> + rc = TPM2_RC_SUCCESS;
> + if (rc == TPM2_RC_INITIALIZE || rc == TPM2_RC_SUCCESS
> + || TPM2_RC_FAILURE)
> + return rc;
> + }
> }
>
> return rc;
> --
> 2.13.6
>
The log messages do not have consistent wording and they are
prefixed with "tpm" for no reason. I would advice to just remove
them.
You could probably measure the durations with ftrace by using
the function_graph tracer...
/Jarkko
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