Re: [Qemu-devel] [QAPI+QGA 3/3] QEMU Guest Agent (virtagent) v7

[Luiz Capitulino <lcapitulino@redhat.com>]

On Fri, 15 Jul 2011 09:15:18 +0800
Zhi Yong Wu <zwu.kernel@gmail.com> wrote:

> On Fri, Jul 15, 2011 at 4:00 AM, Michael Roth <mdroth@linux.vnet.ibm.com> wrote:
> > This is Set 3/3 of the QAPI+QGA patchsets.
> >
> > These patches apply on top of qapi-backport-set2-v6, and can also be obtained from:
> > git://repo.or.cz/qemu/mdroth.git qapi-backport-set3-v7
> >
> > (Set1+2 are a backport of some of the QAPI-related work from Anthony's
> > glib tree. The main goal is to get the basic code generation infrastructure in
> > place so that it can be used by the guest agent to implement a QMP-like guest
> > interface, and so that future work regarding the QMP conversion to QAPI can be
> > decoupled from the infrastructure bits. Set3 is the Qemu Guest Agent
> > (virtagent), rebased on the new code QAPI code generation infrastructure. This
> > is the first user of QAPI, QMP will follow.)
> > ___
> >
> > CHANGES SINCE V6:
> >  - Made "/dev/virtio-ports/org.qemu.guest_agent.0" default device path for agent
> >  - Consolidated uneeded fcntl() calls into qemu_open()
> >  - JSON/QMP parse errors now propagated to client
> >  - Replaced non-assertion uses of g_error() with exit()
> >  - Added guest-file-flush
> >  - Removed limit on max read size for guest-file-read
> >  - 'count' parameters to guest-file-read/guest-file-write are now optional (default to 4KB and size of provided buffer, base64-decoded, respectively)
> >  - Removed redundant 'file_' and 'shutdown_' prefixes from guest-file-*/guest-shutdown commands, switched to "-" in place of "_" in parameter names, renamed guest-file-read's "buf" param to "buf-b64" and guest-file-write's "data_b64" param to "buf-b64" for consistency.
> >  - guest-fsfreeze-freeze now returns error objects on error rather as part of it's integer return values, and on error will unfreeze previously frozen filesystems.
> >  - GUEST_FSFREEZE_STATUS_INPROGRESS removed, GUEST_FSFREEZE_STATUS_ERROR now serves the explicit purpose of noting a failure to find a previously mounted filesytem/directory after initial freeze, or failure to unfreeze 1 or more filesystems.
> >  - -c/--channel option to qemu-ga is now -m/--method
> >
> > CHANGES SINCE V5:
> >  - switched to using qemu malloc/list functions where possible
> >  - removed unused proxy_path field in struct GAState
> >  - pid file now opened write-only, removed lockf() in favor of O_EXCL, added SIGINT/SIGTERM signal handlers to handle cleanup
> >  - cleaned up error-handling, switched to asserts where appropriate, removed unecessary gotos and NULL checks for qemu_free()/qobject_decref()
> >  - refactored send_payload() using helper functions
> >  - fixed improper handling of pidfile fd==0
> >  - changed guest-shutdown's "shutdown_mode" param to "mode"
> >  - switched to using kernel-generated FDs for guest-file-open rather than an autoincrement value
> >  - add maximum chunk size of guest-file-read/guest-file-write
> >  - added checks to avoid guest-file-write from writing data beyond the provided data buffer
> >  - made logging best-effort, removed handling of failures to log as errors
> >  - guest-shutdown exec errors now logged to guest syslog, clarified shutdown's asynchronous, no gauruntee nature in schema.
> >
> > CHANGES SINCE V4:
> >  - Removed timeout mechanism via worker thread/pthread_cancel due to potential memory leak. Will re-introduce guest-side timeout support in future version.
> >  - Fixed up fsfreeze code to use enums specified within the guest agent's qapi schema.
> >  - Fixed memory leak due to a log statement, and added missing cleanup functions for heap-allocated g_error objects.
> >  - Made "mode" param to guest-file-open optional, defaults to "r" (read-only)
> >
> > CHANGES SINCE V3:
> >  - Fixed error-handling issues in fsfreeze commands leading to certain mounted directories causing freeze/thaw operations to fail
> >  - Added cleanup hook to thaw filesystems on graceful guest agent exit
> >  - Removed unused enum values and added additional details to schema documentation
> >  - Fixed build issue that was missed due to deprecated files in source tree, removed unused includes
> >
> > CHANGES SINCE V2:
> >  - Rebased on new QAPI code generation framework
> >  - Dropped ability for QMP to act as a proxy for the guest agent, will be added when new QMP server is backported from Anthony's glib tree
> >  - Replaced negotiation/control events with a simple 2-way handshake implemented by a standard RPC (guest-sync)
> >  - Removed enforcement of "pristine" sessions, state is now global/persistant across multiple clients/connections
> >  - Fixed segfault in logging code
> >  - Added Jes' filesystem freeze patches
> >  - General cleanups
> >
> > 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:
> >  - Add unit tests for guest agent wire protocol
> >
> > 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
> HI, Macheal.
> Is qemu-ga built in guest? if yes, it will require the guest to set up
> a gcc environment. Can we make it built on the host?

Yes, if the host OS matches the guest OS or if you can cross-compile.

Otherwise I think we'll have to rely on distros making qemu-ga available,
and/or use the guest tools iso Michael is planning. Another option would
be to compile qemu-ga statically, but this is probably unfeasible.

> 
> >
> > 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/qga.sock,server,nowait,id=qga0 \
> >  -device virtio-serial \
> >  -device virtserialport,chardev=qga0,name=org.qemu.guest_agent.0"
> >
> > use guest agent:
> >  ./qemu-ga -h
> >  ./qemu-ga -m virtio-serial -p /dev/virtio-ports/org.qemu.guest_agent.0
> >
> > start/use qmp:
> >  mdroth@illuin:~$ sudo socat unix-connect:/tmp/qga.sock readline
> >  {"execute":"guest-sync", "arguments":{"id":1234}}
> >  {"return": 1234}
> >
> >  {"execute":"guest-ping"}
> >  {"return": {}}
> >
> >  {"execute": "guest-info"}
> >  {"return": {"version": "1.0"}}
> >
> >  // write "hello world!\n" to /tmp/testqga
> >  {"execute":"guest-file-open", "arguments":{"path":"/tmp/testqga","mode":"w+"}}
> >  {"return": 0}
> >  {"execute":"guest-file-write", "arguments":{"handle":0,"buf-b64":"aGVsbG8gd29ybGQhCg=="}}
> >  {"return": {"count": 13, "eof": false}}
> >  {"execute":"guest-file-close", "arguments":{"handle":0}}
> >  {"return": {}}
> >
> >  // read back the "hello world!\n" from /tmp/testqga
> >  {"execute":"guest-file-open", "arguments":{"path":"/tmp/testqga","mode":"r"}}
> >  {"return": 1}
> >  {"execute":"guest-file-read", "arguments":{"handle":1,"count":1024}}
> >  {"return": {"buf-b64": "aGVsbG8gd29ybGQhCg==", "count": 13, "eof": true}}
> >  {"execute":"guest-file-close","arguments":{"handle":1}}
> >  {"return": {}}
> >
> >  Makefile                        |   25 ++-
> >  configure                       |    1 +
> >  qapi-schema-guest.json          |  217 +++++++++++++
> >  qemu-ga.c                       |  671 +++++++++++++++++++++++++++++++++++++++
> >  qerror.c                        |   13 +
> >  qerror.h                        |    6 +
> >  qga/guest-agent-command-state.c |   73 +++++
> >  qga/guest-agent-commands.c      |  512 +++++++++++++++++++++++++++++
> >  qga/guest-agent-core.h          |   31 ++
> >  9 files changed, 1544 insertions(+), 5 deletions(-)
> >
> >
> >
> 
> 
>