Re: [PATCH v11 2/2] tpm: add backend for mssim

[Daniel P . Berrangé]

On Thu, Dec 12, 2024 at 12:05:28PM -0500, James Bottomley wrote:
> The Microsoft Simulator (mssim) is the reference emulation platform
> for the TCG TPM 2.0 specification.
> 
> https://github.com/Microsoft/ms-tpm-20-ref.git
> 
> It exports a fairly simple network socket based protocol on two
> sockets, one for command (default 2321) and one for control (default
> 2322).  This patch adds a simple backend that can speak the mssim
> protocol over the network.  It also allows the two sockets to be
> specified on the command line.  The benefits are twofold: firstly it
> gives us a backend that actually speaks a standard TPM emulation
> protocol instead of the linux specific TPM driver format of the
> current emulated TPM backend and secondly, using the microsoft
> protocol, the end point of the emulator can be anywhere on the
> network, facilitating the cloud use case where a central TPM service
> can be used over a control network.
> 
> The implementation does basic control commands like power off/on, but
> doesn't implement cancellation or startup.  The former because
> cancellation is pretty much useless on a fast operating TPM emulator
> and the latter because this emulator is designed to be used with OVMF
> which itself does TPM startup and I wanted to validate that.
> 
> To run this, simply download an emulator based on the MS specification
> (package ibmswtpm2 on openSUSE) and run it, then add these two lines
> to the qemu command and it will use the emulator.
> 
>     -tpmdev mssim,id=tpm0 \
>     -device tpm-crb,tpmdev=tpm0 \
> 
> to use a remote emulator replace the first line with
> 
>     -tpmdev 
> "{'type':'mssim','id':'tpm0','command':{'type':inet,'host':'remote','port':'2321'}}"
> 
> tpm-tis also works as the backend.
> 
> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
> Acked-by: Markus Armbruster <armbru@redhat.com>
> 
> ---
> 
> v2: convert to SocketAddr json and use qio_channel_socket_connect_sync()
> v3: gate control power off by migration state keep control socket disconnected
>     to test outside influence and add docs.
> v7: TPMmssim -> TPMMssim; doc and json fixes
>     Make command socket open each time (makes OS debugging easier)
> v11: add startup method to make sure TPM is reset on reboot
> ---
>  MAINTAINERS              |   6 +
>  backends/tpm/Kconfig     |   5 +
>  backends/tpm/meson.build |   1 +
>  backends/tpm/tpm_mssim.c | 335 +++++++++++++++++++++++++++++++++++++++
>  backends/tpm/tpm_mssim.h |  44 +++++
>  docs/specs/tpm.rst       |  39 +++++
>  qapi/tpm.json            |  31 +++-
>  system/tpm-hmp-cmds.c    |   9 ++
>  8 files changed, 466 insertions(+), 4 deletions(-)
>  create mode 100644 backends/tpm/tpm_mssim.c
>  create mode 100644 backends/tpm/tpm_mssim.h
> 


> diff --git a/backends/tpm/tpm_mssim.c b/backends/tpm/tpm_mssim.c
> new file mode 100644
> index 0000000000..8f105fc924
> --- /dev/null
> +++ b/backends/tpm/tpm_mssim.c
> @@ -0,0 +1,335 @@
> +/*
> + * Emulator TPM driver which connects over the mssim protocol
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + *
> + * Copyright (c) 2022

Copyright by whom ? I presume yourself, but I wouldn't normally
assume the 'Author' line applies to the Copyright line.

> + * Author: James Bottomley <jejb@linux.ibm.com>
> + */
> +


> diff --git a/backends/tpm/tpm_mssim.h b/backends/tpm/tpm_mssim.h
> new file mode 100644
> index 0000000000..397474e4f6
> --- /dev/null
> +++ b/backends/tpm/tpm_mssim.h
> @@ -0,0 +1,44 @@
> +/*
> + * SPDX-License-Identifier: BSD-2-Clause
> + *
> + * The code below is copied from the Microsoft/TCG Reference implementation
> + *
> + *  https://github.com/Microsoft/ms-tpm-20-ref.git
> + *
> + * In file TPMCmd/Simulator/include/TpmTcpProtocol.h
> + */

That file has a volumous copyright header that I would expect to be
preserved here.


> diff --git a/qapi/tpm.json b/qapi/tpm.json
> index e6345d424b..eed4cb9e82 100644
> --- a/qapi/tpm.json
> +++ b/qapi/tpm.json
> @@ -6,6 +6,8 @@
>  # = TPM (trusted platform module) devices
>  ##
>  
> +{ 'include': 'sockets.json' }
> +
>  ##
>  # @TpmModel:
>  #
> @@ -48,9 +50,11 @@
>  #
>  # @emulator: Software Emulator TPM type (since 2.11)
>  #
> +# @mssim: Microsoft TPM Emulator (since 9.0)

Sorry, this needs a trivial bump to 10.0 now as that's
the current dev cycle

> +##
> +# @TPMMssimOptions:
> +#
> +# Information for the mssim emulator connection
> +#
> +# @command: command socket for the TPM emulator
> +#
> +# @control: control socket for the TPM emulator
> +#
> +# Since: 9.0

Likewise.

> +##
> +{ 'struct': 'TPMMssimOptions',
> +  'data': { '*command': 'SocketAddress',
> +            '*control': 'SocketAddress' },
> +  'if': 'CONFIG_TPM' }
> +
>  ##
>  # @TpmTypeOptions:
>  #


Functionally the code looks mergable with just those bureaucratic changes.

With regards,
Daniel
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