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

[Anthony Liguori <aliguori@us.ibm.com>]

Corey Bryant <coreyb@linux.vnet.ibm.com> writes:

> 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.

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

Regards,

Anthony Liguori

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