RE: [Xense-devel] Run vTPM in its own VM?

["Fischer, Anna" <anna.fischer@xxxxxx>]

Thanks for your reply.

But do I understand it correctly that in your design you will have a
vTPM manager running in each vTPM BE domain? And you have the vTPM then
talking again through FIFOs to the vTPM manager who talks to the BE? 

However, the code seems to be designed so that the vTPMs talk directly
to the BE. Is that what you mean with that the code for this
configuration is broken? According to the currently implemented design I
don't see how such a direct communication can work as for example
capabilities like saving and loading NVRAM won't work without having the
vTPM manager in between, right?

Anna

-----Original Message-----
From: Scarlata, Vincent R [mailto:vincent.r.scarlata@xxxxxxxxx] 
Sent: Donnerstag, 14. September 2006 17:59
To: Fischer, Anna; Xense-devel@xxxxxxxxxxxxxxxxxxx
Subject: RE: [Xense-devel] Run vTPM in its own VM?

Sorry Anna, the documentation is both slightly out of date, and slightly
ahead of its time. :-)

The vtpm manager was architected to allows each vtpm instance to run in
its own VM, but during the last restructuring of the code, support for
this configuration was broken. It's now incomplete. Due to other
commitments, I won't be able to get back to this immediately, I hope to
submit a patch to re-enable this config options within a month-ish.

The way it looked and will look again is the following. A standard
config would be a Dom0, DomU1 guest, DomU1vTPM vtpm domain, ... DomUn,
DomUnvTPM. DomU1 has a tpm FE, for which DomU1vTPM has the BE. Similarly
DomU2 has a tpm FE, for which DomU2vTPM has the BE. This allows direct
communication between the DomU and it's vTPM, as you mention below. Then
all the DomU*vTPM domains have tpm FEs, for which the domain housing the
vtpm manager is the BE. By default this is Dom0, but provided that the
tpm device can be assigned to a different domain, this can be put in any
domain. The vtpm_manager's domain has the tpm driver.

This is a little heavier weight than running everything in dom0, but it
removes the manager from being a bottle neck in tpm access, since all
DomUs can access their vTPMs simultaneously (though the manager can
still only handle 1 vtpm request at a time to save internal states).
Also isolation between vtpms is established.

Do you need this functionality, or are you just doing thought
experiments?

Hopes this answers your questions,

-Vinnie Scarlata
  Trusted Platform Lab
  Corporate Technology Group
  Intel Corporation

-----Original Message-----
From: xense-devel-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xense-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Fischer,
Anna
Sent: Thursday, September 14, 2006 2:01 AM
To: Xense-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xense-devel] Run vTPM in its own VM?

The README of the current Xen unstable version says that setting
VTPM_MULTI_VM allows running each vTPM in its own VM. However, compiling
with this option doesn't work on my machine and the code doesn't seem to
be complete for this option.

Did I miss to configure something or is the current implementation in
Xen not really ready for running a vTPM in a separate VM?

Can you explain to me how a communication will look like for the planned
implementation in Xen? Will all communication continue to go through the
vTPM manager and the vTPM manager talks to a kind of FE that transmits
TPM commands to a BE running in a separate domain? Or is it possible to
set up direct connections between a user domain TPM FE and the vTPM
running in an isolated VM?

Regards,
Anna

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