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

[James Bottomley]

On Fri, 2022-12-16 at 09:55 -0500, Stefan Berger wrote:
> 
> 
> On 12/16/22 09:29, Daniel P. Berrangé wrote:
> 
> > 
> > All the objections you're raising are related to the current
> > specifics of the implementation of the mssim remote server.
> > While valid, this is of no concern to QEMU when deciding whether
> > to require a migration blocker on the client side. This is 3rd
> > party remote service that should be considered a black box from
> > QEMU's POV. It is possible to write a remote server that supports
> > the mssim network protocol, and has the ability to serialize
> > its state. Whether such an impl exists today or not is separate.
> 
> Then let's document the scenarios so someone can repeat them, I think
> this is just fair. James said he tested state migration scenarios and
> it works, so let's enable others to do it as well. I am open to
> someone maintaining just this driver and the dynamics that may
> develop around it.

Well, OK, this is what I think would be appropriate ... I'll fold it in
to the second patch.

James

---

diff --git a/docs/specs/tpm.rst b/docs/specs/tpm.rst
index 535912a92b..985d0775a0 100644
--- a/docs/specs/tpm.rst
+++ b/docs/specs/tpm.rst
@@ -270,6 +270,38 @@ available as a module (assuming a TPM 2 is passed through):
   /sys/devices/LNXSYSTEM:00/LNXSYBUS:00/MSFT0101:00/tpm/tpm0/pcr-sha256/9
   ...
 
+The QEMU TPM Microsoft Simulator Device
+---------------------------------------
+
+The TCG provides a reference implementation for TPM 2.0 written by
+Microsoft (See `ms-tpm-20-ref`_ on github).  The reference implementation
+starts a network server and listens for TPM commands on port 2321 and
+TPM Platform control commands on port 2322, although these can be
+altered.  The QEMU mssim TPM backend talks to this implementation.  By
+default it connects to the default ports on localhost:
+
+.. code-block:: console
+
+  qemu-system-x86_64 <qemu-options> \
+    -tpmdev mssim,id=tpm0 \
+    -device tpm-crb,tpmdev=tpm0
+
+
+Although it can also communicate with a remote host, which must be
+specified as a SocketAddress via json on the command line for each of
+the command and control ports:
+
+.. code-block:: console
+
+  qemu-system-x86_64 <qemu-options> \
+    -tpmdev 
"{'type':'mssim','id':'tpm0','command':{'type':inet,'host':'remote','port':'2321'},'control':{'type':'inet','host':'remote','port':'2322'}}"
 \
+    -device tpm-crb,tpmdev=tpm0
+
+
+The mssim backend supports snapshotting and migration, but the state
+of the Microsoft Simulator server must be preserved (or the server
+kept running) outside of QEMU for restore to be successful.
+
 The QEMU TPM emulator device
 ----------------------------
 
@@ -526,3 +558,6 @@ the following:
 
 .. _SWTPM protocol:
    https://github.com/stefanberger/swtpm/blob/master/man/man3/swtpm_ioctls.pod
+
+.. _ms-tpm-20-ref:
+   https://github.com/microsoft/ms-tpm-20-ref