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

[Corey Bryant <coreyb@linux.vnet.ibm.com>]

On 06/14/2013 11:38 AM, Anthony Liguori wrote:
> Corey Bryant <coreyb@linux.vnet.ibm.com> writes:
>
>> On 06/14/2013 10:01 AM, Anthony Liguori wrote:
>>> Corey Bryant <coreyb@linux.vnet.ibm.com> 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.

-- 
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
>>>
>>>
>>>
>>>
>
>
>