Re: [Qemu-devel] [PATCH 0/7] VNVRAM persistent storage

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

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

> This patch series provides VNVRAM persistent storage support that
> QEMU can use internally.  The initial target user will be a software
> vTPM 1.2 backend that needs to store keys in VNVRAM and be able to
> reboot/migrate and retain the keys.
>
> This support uses QEMU's block driver to provide persistent storage
> by reading/writing VNVRAM data from/to a drive image.  The VNVRAM
> drive image is provided with the -drive command line option just like
> any other drive image and the vnvram_create() API will find it.
>
> The APIs allow for VNVRAM entries to be registered, one at a time,
> each with a maximum blob size.  Entry blobs can then be read/written
> from/to an entry on the drive.  Here's an example of usage:

I still don't get why this needs to exist.  This doesn't map to any
hardware concept I know of.

Why can't the vTPM manage on it's own how it stores blobs in it's flash
memory?  I think we're adding an unneeded layer of abstraction here.

Regards,

Anthony Liguori

>
> VNVRAM *vnvram;
> int errcode
> const VNVRAMEntryName entry_name;
> const char *blob_w = "blob data";
> char *blob_r;
> uint32_t blob_r_size;
>
> vnvram = vnvram_create("drive-ide0-0-0", false, &errcode);
> strcpy((char *)entry_name, "first-entry");
> vnvram_register_entry(vnvram, &entry_name, 1024);
> vnvram_write_entry(vnvram, &entry_name, (char *)blob_w, strlen(blob_w)+1);
> vnvram_read_entry(vnvram, &entry_name, &blob_r, &blob_r_size);
> vnvram_delete(vnvram);
>
> Thanks,
> Corey
>
> Corey Bryant (7):
>   vnvram: VNVRAM bdrv support
>   vnvram: VNVRAM in-memory support
>   vnvram: VNVRAM bottom-half r/w scheduling support
>   vnvram: VNVRAM internal APIs
>   vnvram: VNVRAM additional debug support
>   main: Initialize VNVRAM
>   monitor: QMP/HMP support for retrieving VNVRAM details
>
>  Makefile.objs    |    2 +
>  hmp.c            |   32 ++
>  hmp.h            |    1 +
>  monitor.c        |    7 +
>  qapi-schema.json |   47 ++
>  qmp-commands.hx  |   41 ++
>  vl.c             |    6 +
>  vnvram.c         | 1254 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  vnvram.h         |   36 ++
>  9 files changed, 1426 insertions(+), 0 deletions(-)
>  create mode 100644 vnvram.c
>  create mode 100644 vnvram.h