[Qemu-devel] [RFC][PATCH v2 00/11] QEMU Guest Agent: QMP-based host/guest communication (virtagent)

[Michael Roth <mdroth@linux.vnet.ibm.com>]

These apply on top of Anthony's glib tree, commit 03d5927deb5e6baebaade1b4c8ff2428a85e125c currently, and can also be obtained from:
git://repo.or.cz/qemu/mdroth.git qga_v2

Patches 1-8 are general json/QAPI-related fixes. Anthony, please consider pulling these into your glib tree. The json fix-ups may need further evaluation, but I'm confident they're at least an improvement. The QAPI ones are mostly trivial fix-ups.

Changes since V1:

- Added guest agent worker thread to execute RPCs in the guest. With this in place we have a reliable timeout mechanism for hung commands, currently set at 30 seconds.
- Add framework for registering init/cleanup routines for stateful RPCs to clean up after themselves after a timeout.
- Added the following RPCs: guest-file-{open,close,read,write,seek}, guest-shutdown, guest-info, and removed stubs for guest-view-file (now deprecated)
- Added GUEST_AGENT_UP/GUEST_AGENT_DOWN QMP events
- Switched to a TCP-style host-initiated 3-way handshake for channel negotiation, this simplifies client negotiation/interaction over the wire
- Added configurable log level/log file/pid file options for guest agent
- Various fixes for bugs/memory leaks and checkpatch.pl fixups

ISSUES/TODOS:

- Fix QMP proxy handling of error responses sent by guest agent, currently ignored
- Add unit tests for guest agent wire protocol
- Add unit tests for QMP interfaces
- Add host-side timeout mechanism for async QMP commands
- Return error for guest commands if guest up event has not yet been recieved
- Make QMP param names more consistent between related commands
- Clean up logging

OVERVIEW

For a better overview of what these patches are meant to accomplish, please reference the RFC for virtagent:

http://comments.gmane.org/gmane.comp.emulators.qemu/96096

These patches integrate the previous virtagent guest agent work directly in QAPI/QMP to leverage it's auto-generated marshalling code. This has numerous benefits:

 - addresses previous concerns over relying on external libraries to handle data encapsulation
 - reduces the need for manual unmarshalling of requests/responses, which makes adding new RPCs much safer/less error-prone, as well as cutting down on redundant code
 - QAPI documentation aligns completely with guest-side RPC implementation
 - is Just Better (TM)

BUILD/USAGE

build:
  ./configure --target-list=x86_64-softmmu
  make
  make qemu-ga #should be built on|for target guest

start guest:
  qemu \
  -drive file=/home/mdroth/vm/rhel6_64_base.raw,snapshot=off,if=virtio \
  -net nic,model=virtio,macaddr=52:54:00:12:34:00 \
  -net tap,script=/etc/qemu-ifup \
  -vnc :1 -m 1024 --enable-kvm \
  -chardev socket,path=/tmp/mon-qmp.sock,server,nowait,id=mon-qmp \
  -qmp mon-qmp \
  -chardev qmp_proxy,id=qmp_proxy \ 
  -device virtio-serial \
  -device virtserialport,chardev=qmp_proxy,name=qcg"

use guest agent:
  ./qemu-ga -h
  ./qemu-ga -c virtio-serial -p /dev/virtio-ports/qcg

start/use qmp:
  mdroth@illuin:~$ sudo socat unix-connect:/tmp/mon-qmp.sock readline
  {"QMP": {"version": {"qemu": {"micro": 50, "minor": 13, "major": 0}, "package": ""}, "capabilities": []}}

  {"execute":"guest-info"}
  {"return": {}}

  {"execute": "guest-info"}
  {"return": {"version": "1.0", "timeout_ms": 30000}}

  {"execute":"guest-file-open", "arguments":{"filename":"/tmp/testqga","mode":"w+"}}
  {"return": 0}
  {"execute":"guest-file-write", "arguments":{"filehandle":0,"data_b64":"aGVsbG8gd29ybGQhCg==","count":13}} // writes "hello world!\n"
  {"return": {"count": 13, "eof": false}}

  {"execute":"guest-file-open", "arguments":{"filename":"/tmp/testqga","mode":"r"}}
  {"return": 1}
  {"execute":"guest-file-read", "arguments":{"filehandle":1,"count":1024}}
  {"return": {"buf": "aGVsbG8gd29ybGQhCg==", "count": 13, "eof": true}}
  {"execute":"guest-file-close","arguments":{"filehandle":1}}
  {"return": {}}

 Makefile                        |   15 +-
 Makefile.objs                   |    1 +
 configure                       |    6 +-
 json-lexer.c                    |   33 ++-
 json-lexer.h                    |    1 +
 json-parser.c                   |    6 +-
 json-streamer.c                 |   35 ++-
 qapi-schema.json                |  140 ++++++++-
 qemu-char.c                     |   55 +++
 qemu-ga.c                       |  711 +++++++++++++++++++++++++++++++++++++++
 qemu-sockets.c                  |    2 +-
 qga/guest-agent-command-state.c |   73 ++++
 qga/guest-agent-commands.c      |  284 ++++++++++++++++
 qga/guest-agent-core.c          |  139 ++++++++
 qga/guest-agent-core.h          |   40 +++
 qga/guest-agent-worker.c        |  173 ++++++++++
 qmp-core.c                      |   13 +-
 qmp-core.h                      |    7 +-
 qmp-gen.py                      |   15 +-
 qmp-proxy-core.h                |   21 ++
 qmp-proxy.c                     |  294 ++++++++++++++++
 vl.c                            |    1 +
 22 files changed, 2023 insertions(+), 42 deletions(-)