-----Original Message-----
From: Jarkko Sakkinen [mailto:jarkko.sakkinen@linux.intel.com]
Sent: Tuesday, November 13, 2018 13:12
To: Winkler, Tomas <redacted>
Cc: linux-integrity@vger.kernel.org; linux-security-module@vger.kernel.org;
James Bottomley [off-list ref]; Struk,
Tadeusz [off-list ref]; Stefan Berger
[off-list ref]; Nayna Jain [off-list ref]; Peter
Huewe [off-list ref]; Jason Gunthorpe [off-list ref]; Arnd
Bergmann [off-list ref]; Greg Kroah-Hartman
[off-list ref]; open list [off-list ref]
Subject: Re: [PATCH v5 16/17] tpm: take TPM chip power gating out of
tpm_transmit()

On Fri, Nov 09, 2018 at 09:37:48PM +0000, Winkler, Tomas wrote:

quoted

quoted

On Thu, Nov 08, 2018 at 06:38:59PM +0000, Winkler, Tomas wrote:

quoted

quoted

Call tpm_chip_start() and tpm_chip_stop() in

* tpm_try_get_ops() and tpm_put_ops()
* tpm_chip_register()
* tpm2_del_space()

And remove these calls from tpm_transmit(). The core reason for
this change is that in tpm_vtpm_proxy a locality change requires
a virtual TPM command (a command made up just for that driver).

I don't think you can do that,  locality has to be request for
each command, as  for example tboot can request higher locality any

time.

quoted

quoted

That could be a potential problem. How tboot intervention gets
prevented without this patch?

As it was said, need to request locality and relinquish it for each
command, I believe thought this is not required for client platforms
only for servers.

And what I'm trying to under is why so.

If the intervention can happen at any time that would imply that even if you
would request and relinquish locality for a single TPM command, the
intervention could happen in the middle. That is why I'm asking why without
this patch things are just fine.

Yes, w/o this constrain it would be okay to request locality only once, 
we can ask tboot ask again but at the time the requirement was that locality can be taken of at any point, 
I believe that the locality won't be granted till a single command is completed.

Anyhow still the power gating is wrong in this patch do not ignore that part.

Thanks
Tomas