On Thu, Aug 24, 2017 at 10:34:10AM +0200, Alexander Steffen wrote:
> The TPM can choose one of two ways to react to the TPM2_SelfTest command.
> It can either run all self tests synchronously and then return RC_SUCCESS
> once all tests were successful. Or it can choose to run the tests
> asynchronously and return RC_TESTING immediately while the self tests still
> execute in the background.
>
> The previous implementation apparently was not aware of those possibilities
> and attributed RC_TESTING to some prototype chips instead. With this change
> the return code of TPM2_SelfTest is interpreted correctly, i.e. the self
> test result is polled if and only if RC_TESTING is received.
>
> Unfortunately, the polling cannot be done in the most straightforward way.
> If RC_TESTING is received, ideally the code should now poll the
> selfTestDone bit in the STS register, as this avoids sending more commands,
> that might interrupt self tests executing in the background and thus
> prevent them from ever completing. But it cannot be guaranteed that this
> bit is correctly implemented for all devices, so the next best thing would
> be to use TPM2_GetTestResult to query the test result. But the response to
> that command can be very long, and the code currently lacks the
> capabilities for efficient unmarshalling, so it is difficult to execute
> this command.
>
> Therefore, we simply run the TPM2_SelfTest command in a loop, which should
> complete eventually, since we only request the execution of self tests that
> have not yet been done.
>
> Signed-off-by: Alexander Steffen <alexander.stef...@infineon.com>
> ---
> drivers/char/tpm/tpm2-cmd.c | 52
> ++++++++++-----------------------------------
> 1 file changed, 11 insertions(+), 41 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> index 2178437..70ee328 100644
> --- a/drivers/char/tpm/tpm2-cmd.c
> +++ b/drivers/char/tpm/tpm2-cmd.c
> @@ -834,64 +834,34 @@ static const struct tpm_input_header
> tpm2_selftest_header = {
> };
>
> /**
> - * tpm2_continue_selftest() - start a self test
> - *
> - * @chip: TPM chip to use
> - * @full: test all commands instead of testing only those that were not
> - * previously tested.
> - *
> - * Return: Same as with tpm_transmit_cmd with exception of RC_TESTING.
> - */
> -static int tpm2_start_selftest(struct tpm_chip *chip, bool full)
> -{
> - int rc;
> - struct tpm2_cmd cmd;
> -
> - cmd.header.in = tpm2_selftest_header;
> - cmd.params.selftest_in.full_test = full;
> -
> - rc = tpm_transmit_cmd(chip, NULL, &cmd, TPM2_SELF_TEST_IN_SIZE, 0, 0,
> - "continue selftest");
> -
> - /* At least some prototype chips seem to give RC_TESTING error
> - * immediately. This is a workaround for that.
> - */
> - if (rc == TPM2_RC_TESTING) {
> - dev_warn(&chip->dev, "Got RC_TESTING, ignoring\n");
> - rc = 0;
> - }
> -
> - return rc;
> -}
> -
> -/**
> * tpm2_do_selftest() - ensure that all self tests have passed
> *
> * @chip: TPM chip to use
> *
> * Return: Same as with tpm_transmit_cmd.
> *
> - * During the self test TPM2 commands return with the error code RC_TESTING.
> - * Waiting is done by issuing PCR read until it executes successfully.
> + * The TPM can either run all self tests synchronously and then return
> + * RC_SUCCESS once all tests were successful. Or it can choose to run the
> tests
> + * asynchronously and return RC_TESTING immediately while the self tests
> still
> + * execute in the background. This function handles both cases and waits
> until
> + * all tests have completed.
> */
> 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));
>
> - rc = tpm2_start_selftest(chip, false);
> - if (rc)
> - return rc;
> -
> while (duration > 0) {
> - /* Attempt to read a PCR value */
> - rc = tpm2_pcr_read(chip, 0, NULL);
> - if (rc < 0)
> - break;
> + 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;
> --
> 2.7.4
>
Much better! Thank you.
Reviewed-by: Jarkko Sakkinen <jarkko.sakki...@linux.intel.com>
PS. I'm not subscribed at the moment to tpmdd mailing list because SF
kicked me out of the list. I've been trying to contact vger.kernel.org
to create a new ML there but haven't received any response. I just saw
your resends so it might have something to do with this. Also, patchwork
is broken ATM:
https://patchwork.kernel.org/project/tpmdd-devel/list/
/Jarkko
------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
tpmdd-devel mailing list
tpmdd-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/tpmdd-devel
