Messages in this thread | | | Date | Sun, 14 Dec 2014 15:40:05 -0500 | From | Stefan Berger <> | Subject | Re: [PATCH v10 8/8] tpm: TPM 2.0 FIFO Interface |
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On 12/14/2014 01:27 PM, Scot Doyle wrote: > On Sun, 14 Dec 2014, Stefan Berger wrote: >> On 12/14/2014 10:40 AM, Jarkko Sakkinen wrote: >>> On Sun, Dec 14, 2014 at 09:48:26AM -0500, Stefan Berger wrote: >>>> On 12/12/2014 02:46 PM, Jarkko Sakkinen wrote: >>>>> Detect TPM 2.0 by sending idempotent TPM 2.x command. Ordinals for >>>>> TPM 2.0 are higher than TPM 1.x commands so this should be fail-safe. >>>>> Using STS3 is unreliable because some chips just report 0xff and not >>>>> what the spec says. >>>> TPM TIS 1.2 can report either 0xff or 0x00 for sts3 since that part of >>>> register was not defined for this version but only for a later version. >>>> So, >>>> unless the TIS 1.3 for TPM 2.0 is broken, it should report a bit _pattern_ >>>> (not plain 0x00 or 0xff) that you could apply the suggested mask to and >>>> check then. >>> I propose this: lets keep the bit ugly but approach for now and when >>> there are TPM2 FIFOs available in the market move to your workaround. >>> I think that would be the most reasonable middle road here. >> You are now calling tpm2_gen_interrupt and are looking at the rc, which is the >> rc from tpm_transmit_cmd, which seems to make sure that the sending of the >> command went alright and the reception of the response. Is this good enough to >> distinguish between a TPM 2 and a TPM 1.2? If you send a valid TPM 2 command >> to a TPM 1.2 this will at least transmit the data ok, but the TPM will respond >> with a TPM 1.2 tag in the response. The way I understand the code, the rc does >> not include whether the response packet is a valid TPM 2 response packet and >> lets you conclude to a TPM2. I do something similar in upcoming QEMU patches >> where I send a valid TPM2 command for probing and if the tag(!) in the >> response is a TPM2 tag (0x8001 = TPM_ST_NO_SESSIONS), then it's a TPM 2, >> otherwise a TPM 1.2. >> >> Did you test this with a TPM 1.2 ? >> >> Stefan > One system's output, with a dev_info call to show the value of rc: > [ 0.223837] tpm_tis 00:08: tpm2_gen_interrupt(chip, true) -> 0xa > [ 0.223847] tpm_tis 00:08: 1.2 TPM (device-id 0xB, rev-id 16) > [ 0.280468] tpm_tis 00:08: [Firmware Bug]: TPM interrupt not working, polling instead >
Ok, good.
[We won't be able to use STS3 if the TIS of Jarkko's TPM2 is broken...]
Stefan
Stefan
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