Re: [Qemu-devel] [PATCH V8 07/14] Implementation of the libtpms-based backend

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Aug 31, 2011 at 10:35:58AM -0400, Stefan Berger wrote:
> This patch provides the glue for the TPM TIS interface (frontend) to
> the libtpms that provides the actual TPM functionality.
> 
> Some details:
> 
> This part of the patch provides support for the spawning of a thread
> that will interact with the libtpms-based TPM. It expects a signal
> from the frontend to wake and pick up the TPM command that is supposed
> to be processed and delivers the response packet using a callback
> function provided by the frontend.
> 
> The backend connects itself to the frontend by filling out an interface
> structure with pointers to the function implementing support for various
> operations.
> 
> In this part a structure with callback functions is registered with
> libtpms. Those callback functions are invoked by libtpms for example to
> store the TPM's state.
> 
> The libtpms-based backend implements functionality to write into a 
> Qemu block storage device rather than to plain files. With that we
> can support VM snapshotting and we also get the possibility to use
> encrypted QCoW2 for free. Thanks to Anthony for pointing this out.
> The storage part of the driver has been split off into its own patch.
> 
> v6:
>   - cache a copy of the last permanent state blob
>   - move some functions into tpm_builtin.h
>   - reworked parts of the error path handling where the TPM is
>     now used to process commands under error conditions and the callbacks
>     make the TPM aware of the error conditions. Only as the last resort
>     fault messages are sent by the backend driver circumventing the TPM.
>   - add out_len variable used in the thread
> 
> v5:
>   - check access() to TPM's state file and report error if file is not
>     accessible
> 
> v3:
>   - temporarily deactivate the building of the tpm_builtin.c until
>     subsequent patch completely converts it to the libtpms based driver
> 
> v2:
>   - fixes to adhere to the qemu coding style
> 
> 
> Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
> 
> ---
>  configure        |    1 
>  hw/tpm_builtin.c |  450 ++++++++++++++++++++++++++++++++++++++++++++++++++++---
>  hw/tpm_builtin.h |   56 ++++++
>  3 files changed, 482 insertions(+), 25 deletions(-)
> 
> Index: qemu-git/hw/tpm_builtin.c
> ===================================================================
> --- qemu-git.orig/hw/tpm_builtin.c
> +++ qemu-git/hw/tpm_builtin.c
> @@ -1,5 +1,5 @@
>  /*
> - *  builtin 'null' TPM driver
> + *  builtin TPM driver based on libtpms

Just wondering - might a stub driver be useful for
basic testing on systems without TPM hardware?

The namespace comment applies to this and all other patches.