From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander Steffen Subject: [PATCH 3/3] tpm2-cmd: React correctly to RC_TESTING from self tests Date: Fri, 18 Aug 2017 14:15:32 +0200 Message-ID: <20170818121532.5764-3-Alexander.Steffen@infineon.com> References: <20170818121532.5764-1-Alexander.Steffen@infineon.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170818121532.5764-1-Alexander.Steffen-d0qZbvYSIPpWk0Htik3J/w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: tpmdd-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org, tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: tpmdd-devel@lists.sourceforge.net 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, so the solution is explained with a comment in the code. Signed-off-by: Alexander Steffen --- drivers/char/tpm/tpm2-cmd.c | 68 ++++++++++++++++++--------------------------- 1 file changed, 27 insertions(+), 41 deletions(-) diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c index e3d4cc3..d09032f 100644 --- a/drivers/char/tpm/tpm2-cmd.c +++ b/drivers/char/tpm/tpm2-cmd.c @@ -834,68 +834,54 @@ 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; + /* 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. + * Unfortunately, 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. + */ + msleep(delay_msec); duration -= delay_msec; -- 2.7.4 ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot