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.