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Re: [Qemu-devel] [PATCH v3 0/3] TPM NVRAM persistent storage


From: Corey Bryant
Subject: Re: [Qemu-devel] [PATCH v3 0/3] TPM NVRAM persistent storage
Date: Fri, 14 Jun 2013 12:21:09 -0400
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130514 Thunderbird/17.0.6



On 06/14/2013 11:56 AM, Anthony Liguori wrote:
Corey Bryant <address@hidden> writes:

On 06/14/2013 11:38 AM, Anthony Liguori wrote:
Corey Bryant <address@hidden> writes:

On 06/14/2013 10:01 AM, Anthony Liguori wrote:
Corey Bryant <address@hidden> writes:

This patch series provides persistent storage support that a TPM
can use to store NVRAM data.  It uses QEMU's block driver to store
data on a drive image.  The libtpms TPM 1.2 backend will be the
initial user of this functionality to store data that must persist
through a reboot or migration.  A sample command line may look like
this:

This should be folded into the libtpms backend series.

There are no users for this so this would just be untestable code in the
tree subject to bitrot.

Regards,

Anthony Liguori


Fair enough.  I assume you're ok with this code though?

I don't understand why it's needed to be honest.  I suspect this has to
do with the fact that the libtpms implementation will need significant
reworking.

Regards,

Anthony Liguori


In regards to why it is needed..  The QEMU software-emulated vTPM
backend will pass callback functions to libtpms for writing/reading
nvram data.  Those callbacks will use the code in this patch series to
do the writing/reading of nvram data to/from image files so that the
data persists through migration/reboot.

I'm not sure I completely understand your second sentence, but yes the
software-emulated vTPM backend code for QEMU will certainly need rework
to use the code in this patch series.

I think it's easiest to discuss this in the context of the actual patch
series.

Regards,

Anthony Liguori


I suppose, but the earlier we can get feedback the better so that we don't waste any more time. This NVRAM code alone has gone through far too many iterations as folks have asked for it to go in different directions, and we went in those directions to find that they were the wrong directions. Anyway, for the record, this latest patch series adheres to the direction you suggested we take last month: http://lists.nongnu.org/archive/html/qemu-devel/2013-05/msg04275.html

--
Regards,
Corey Bryant


--
Regards,
Corey Bryant


--
Regards,
Corey Bryant


qemu-system-x86_64 ...
-drive file=/path/to/nvram.qcow2,id=drive-nvram0-0-0
-tpmdev libtpms,id=tpm-tpm0
-device tpm-tis,tpmdev=tpm-tpm0,id=tpm0,drive=drive-nvram0-0-0

Thanks,
Corey

Corey Bryant (3):
     nvram: Add TPM NVRAM implementation
     nvram: Add tpm-tis drive support
     TPM NVRAM test

    hw/tpm/Makefile.objs     |    1 +
    hw/tpm/tpm_int.h         |    2 +
    hw/tpm/tpm_nvram.c       |  324 
++++++++++++++++++++++++++++++++++++++++++++++
    hw/tpm/tpm_nvram.h       |   25 ++++
    hw/tpm/tpm_passthrough.c |   85 ++++++++++++
    hw/tpm/tpm_tis.c         |    8 +
    6 files changed, 445 insertions(+), 0 deletions(-)
    create mode 100644 hw/tpm/tpm_nvram.c
    create mode 100644 hw/tpm/tpm_nvram.h














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