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From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: "Winkler, Tomas" <tomas.winkler@intel.com>
Cc: "linux-integrity@vger.kernel.org"
	<linux-integrity@vger.kernel.org>,
	"linux-security-module@vger.kernel.org" 
	<linux-security-module@vger.kernel.org>,
	James Bottomley <James.Bottomley@HansenPartnership.com>,
	"Struk, Tadeusz" <tadeusz.struk@intel.com>,
	Stefan Berger <stefanb@linux.vnet.ibm.com>,
	Nayna Jain <nayna@linux.ibm.com>, Peter Huewe <peterhuewe@gmx.de>,
	Jason Gunthorpe <jgg@ziepe.ca>, Arnd Bergmann <arnd@arndb.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v5 16/17] tpm: take TPM chip power gating out of tpm_transmit()
Date: Tue, 13 Nov 2018 13:12:04 +0200	[thread overview]
Message-ID: <20181113111204.GD10434@linux.intel.com> (raw)
In-Reply-To: <5B8DA87D05A7694D9FA63FD143655C1B9DA190F4@hasmsx108.ger.corp.intel.com>

On Fri, Nov 09, 2018 at 09:37:48PM +0000, Winkler, Tomas wrote:
> > On Thu, Nov 08, 2018 at 06:38:59PM +0000, Winkler, Tomas wrote:
> > > > 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.
> > 
> > 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.

/Jarkko

  reply	other threads:[~2018-11-13 11:12 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-08 14:15 [PATCH v5 00/17] Remove nested TPM operations Jarkko Sakkinen
2018-11-08 14:15 ` Jarkko Sakkinen
2018-11-08 14:15 ` [PATCH v5 01/17] tpm: use tpm_buf in tpm_transmit_cmd() as the IO parameter Jarkko Sakkinen
2018-11-08 14:15 ` [PATCH v5 02/17] tpm: fix invalid return value in pubek_show() Jarkko Sakkinen
2018-11-08 14:15 ` [PATCH v5 03/17] tpm: return 0 from pcrs_show() when tpm1_pcr_read() fails Jarkko Sakkinen
2018-11-08 14:52   ` Stefan Berger
2018-11-08 14:15 ` [PATCH v5 04/17] tpm: call tpm2_flush_space() on error in tpm_try_transmit() Jarkko Sakkinen
2018-11-08 14:55   ` Stefan Berger
2018-11-08 14:15 ` [PATCH v5 05/17] tpm: print tpm2_commit_space() error inside tpm2_commit_space() Jarkko Sakkinen
2018-11-08 14:56   ` Stefan Berger
2018-11-08 14:15 ` [PATCH v5 06/17] tpm: clean up tpm_try_transmit() error handling flow Jarkko Sakkinen
2018-11-08 14:59   ` Stefan Berger
2018-11-08 14:15 ` [PATCH v5 07/17] tpm: declare struct tpm_header Jarkko Sakkinen
2018-11-08 14:15   ` Jarkko Sakkinen
2018-11-08 15:02   ` Stefan Berger
2018-11-08 15:02     ` Stefan Berger
2018-11-08 14:15 ` [PATCH v5 08/17] tpm: access command header through struct in tpm_try_transmit() Jarkko Sakkinen
2018-11-08 15:03   ` Stefan Berger
2018-11-08 14:15 ` [PATCH v5 09/17] tpm: move tpm_validate_commmand() to tpm2-space.c Jarkko Sakkinen
2018-11-08 17:03   ` Winkler, Tomas
2018-11-08 23:07     ` Jarkko Sakkinen
2018-11-08 14:15 ` [PATCH v5 10/17] tpm: encapsulate tpm_dev_transmit() Jarkko Sakkinen
2018-11-08 14:15 ` [PATCH v5 11/17] tpm: move TPM space code out of tpm_transmit() Jarkko Sakkinen
2018-11-08 15:16   ` Stefan Berger
2018-11-08 18:58     ` Jarkko Sakkinen
2018-11-08 14:15 ` [PATCH v5 12/17] tpm: remove @space from tpm_transmit() Jarkko Sakkinen
2018-11-08 15:18   ` Stefan Berger
2018-11-08 14:15 ` [PATCH v5 13/17] tpm: use tpm_try_get_ops() in tpm-sysfs.c Jarkko Sakkinen
2018-11-08 15:26   ` Stefan Berger
2018-11-08 14:15 ` [PATCH v5 14/17] tpm: remove TPM_TRANSMIT_UNLOCKED flag Jarkko Sakkinen
2018-11-08 15:43   ` Stefan Berger
2018-11-08 19:02     ` Jarkko Sakkinen
2018-11-08 14:15 ` [PATCH v5 15/17] tpm: introduce tpm_chip_start() and tpm_chip_stop() Jarkko Sakkinen
2018-11-08 14:15 ` [PATCH v5 16/17] tpm: take TPM chip power gating out of tpm_transmit() Jarkko Sakkinen
2018-11-08 18:38   ` Winkler, Tomas
2018-11-08 23:07     ` Jarkko Sakkinen
2018-11-09 21:37       ` Winkler, Tomas
2018-11-13 11:12         ` Jarkko Sakkinen [this message]
2018-11-13 11:58           ` Winkler, Tomas
2018-11-13 15:52             ` Jarkko Sakkinen
2018-11-08 14:15 ` [PATCH v5 17/17] tpm: remove @flags from tpm_transmit() Jarkko Sakkinen

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