On Fri, Aug 18, 2017 at 02:15:32PM +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, so the solution > is explained with a comment in the code. > > Signed-off-by: Alexander Steffen <[email protected]> > --- > 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. > + */
This should be part of the commit message, not part of the code. /Jarkko > + > 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 _______________________________________________ tpmdd-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/tpmdd-devel
