Re: [PATCH v9 16/17] tpm: take TPM chip power gating out of tpm_transmit()

Jarkko Sakkinen
2018-11-19T15:55:38Z

On Mon, Nov 19, 2018 at 01:17:56PM +0000, Winkler, Tomas wrote:
> > On Sun, Nov 18, 2018 at 10:52:46PM +0000, Winkler, Tomas wrote:
> > > This is still NACK from my side
> >
> > Last time you spoke about tboot intervention but I don't see why as even
> > sending a single command is not atomic in the true sense of the word i.e. if
> > there was a problem that would already affect the existing code and would
> > essentially mean that tboot itself is broken.
> So I've consulted the issue, I wasn't not correct in the description.
> Tboot cannot acquire the locality, unless the host driver relinquish
> it, so the issue is opposite, driver is expected to relinquish the
> locality for tboot to work correctly. This is current status, other
> behavior will need a different implementation on both sides.

The locality is reliquished after the command sequence (load and save
TPM space + command in /dev/tpmX case).

Is this really such a big issue? The intention is not keep the locality
reserved by the driver.

/Jarkko