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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
