On Fri, 2018-02-16 at 12:31 -0800, James Bottomley wrote: > Ever since > > commit 2482b1bba5122b1d5516c909832bdd282015b8e9 > Author: Alexander Steffen <Alexander.Steffen@xxxxxxxxxxxx> > Date: Thu Aug 31 19:18:56 2017 +0200 > > tpm: Trigger only missing TPM 2.0 self tests > > My Nuvoton 6xx in a Dell XPS-13 has been intermittently failing to > work (necessitating a reboot). The problem seems to be that the TPM > gets into a state where the partial self-test doesn't return > TPM_RC_SUCCESS (meaning all tests have run to completion), but > instead > returns TPM_RC_TESTING (meaning some tests are still running in the > background). There are various theories that resending the self-test > command actually causes the tests to restart and thus triggers more > TPM_RC_TESTING returns until the timeout is exceeded. > > There are several issues here: firstly being we shouldn't slow down > the boot sequence waiting for the self test to complete once the TPM > backgrounds them. It will actually make available all functions that > have passed and if it gets a failure return TPM_RC_FAILURE to every > subsequent command. So the fix is to kick off self tests once and if > they return TPM_RC_TESTING log that as a backgrounded self test and > continue on. In order to prevent other tpm users from seeing any > TPM_RC_TESTING returns (which it might if they send a command > that needs a TPM subsystem which is still under test), we loop in > tpm_transmit_cmd until either a timeout or we don't get a > TPM_RC_TESTING return. Having run this through a TPM emulator, there's one additional return that needs to be accounted for: for TPMs that don't get a startup from the BIOS return TPM_RC_INITIALIZE which is used to trigger the startup sequence. I'll send a v3 with this fixed. James
