Re: TPM selftest failure in 4.15

Nayna Jain
2018-02-09T10:31:49Z

On 02/09/2018 03:32 PM, Jarkko Sakkinen wrote:
> On Thu, Feb 08, 2018 at 09:02:00AM -0800, James Bottomley wrote:
>> There is an identified regression: the TPM driver will now periodically
>> fail to attach. However, there's no point reviewing until we agree
>> what the fix is. I was just waiting to verify this fixed my problem
>> (which means seeing the messages it spits out proving the TPM has
>> remained in self test). I have now seen this and the driver still
>> works, so I can submit a formal patch.
> For the self-test the duration falls down to 2 seconds as the specs do
> not contain any well-defined duration for it, or at least I haven't
> found it.
>
> I see three alternative ways the fix the self-test:
>
> 1. Execute self-test with fullTest = YES.
> 2. Have a flag TPM_CHIP_TESTING that is set when the self-test is
> started. Issue a warning on time-out. Check for this flag in
> tpm_transmit_cmd() and tpm_write() and resend self-test command
> if the flag is stil test before the actual command. Return -EBUSY
> and print a warning if self-test is still active.
> 3. Increase the duration to the "correct" value if we have one.
>
> /Jarkko

IIUC, I see the duration and timeout specified in
TCG_PC_Client_Platform_TPM_Profile_PTP_Specification_Family_2.0_Revision:
Section 5.5.1.3 Command Timing: Table 15

For selftest it is given as:

Command | Duration[ms] |
Timeout[ms]

TPM2_SelfTest(fullTest=YES) 1000 2000
TPM2_SelfTest(fullTest=NO) 20 750

With that I think, TPM is expected to complete the selftest in max 2000 ms.

Thanks & Regards,
- Nayna