The previous submission was missing the subject, please disregard it.
This set of patches is meant to be applied on top of the recently submitted
Virtproxy v2 patchset. It can also be obtained at:
git://repo.or.cz/qemu/mdroth.git virtproxy_v2
OVERVIEW:
There are a wide range of use cases motivating the need for a guest agent of
some sort to extend the functionality/usability/control offered by QEMU. Some
examples include graceful guest shutdown/reboot and notifications thereof,
copy/paste syncing between host/guest, guest statistics gathering, file access,
etc.
Ideally these would all be served by a single, easilly extensible agent that
can be deployed in a wide range of guests. Virtagent is an XMLRPC server
integrated into the Virtproxy guest daemon and aimed at providing this type of
functionality.
CHANGES IN V3:
- Integrated virtagent server into virtproxy chardev. Usage examples below.
- Consolidated RPC server/client setup into a pair of init routines
- Fixed buffer overflow in agent_viewfile() and various memory leaks
CHANGES IN V2:
- All RPC communication is now done using asynchronous/non-blocking read/write
handlers
- Previously fork()'d RPC server loop is now integrated into qemu-vp/virtproxy
i/o loop
- Cleanups/suggestions from previous RFC
DESIGN:
There are actually 2 RPC servers:
1) a server in the guest integrated into qemu-vp, the Virtproxy guest daemon,
which handles RPC requests from QEMU
2) a server in the host, integrated into the virtproxy chardev, to handle RPC
requests sent by the guest agent (mainly for handling asynchronous events
reported by the agent).
At the Virtagent level, communication is done via standard RPCs (HTTP between
host and guest). Virtproxy transparently handles transport over a network or
isa/virtio serial channel, allowing the agent to be deployed on older guests
which may not support virtio-serial.
Currently there are only 2 RPCs implemented for the guest server (getfile and
getdmesg), and 0 for the host. Additional RPCs can be added fairly easily, but
are dependent on feedback from here and elsewhere. ping/status, shutdown, and
reboot are likely candidates (although the latter 2 will likely require
asynchronous notifications to the host RPC server to implement reliably).
EXAMPLE USAGE:
The commandline options are a little convoluted right now; this will addressed
in later revisions.
- Configure guest agent to talk to host via virtio-serial
# start guest with virtio-serial/virtproxy/virtagent. for example
(RHEL6rc1):
qemu \
-chardev virtproxy,id=test0,virtagent=on \
-device virtio-serial \
-device virtserialport,chardev=test0,name=virtagent0 \
-monitor stdio
...
# in the guest:
./qemu-vp -c virtserial-open:/dev/virtio-ports/virtagent0:- -g
...
# monitor commands
(qemu) agent_viewdmesg
[139311.710326] wlan0: deauthenticating from 00:30:bd:f7:12:d5 by local
choice (reason=3)
[139323.469857] wlan0: deauthenticating from 00:21:29:cd:41:ee by local
choice (reason=3)
...
[257683.375646] wlan0: authenticated
[257683.375684] wlan0: associate with AP 00:30:bd:f7:12:d5 (try 1)
[257683.377932] wlan0: RX AssocResp from 00:30:bd:f7:12:d5 (capab=0x411
status=0 aid=4)
[257683.377940] wlan0: associated
(qemu) agent_viewfile /proc/meminfo
MemTotal: 3985488 kB
MemFree: 400524 kB
Buffers: 220556 kB
Cached: 2073160 kB
SwapCached: 0 kB
...
Hugepagesize: 2048 kB
DirectMap4k: 8896 kB
DirectMap2M: 4110336 kB
KNOWN ISSUES/PLANS:
- the client socket that qemu connects to send RPCs is a hardcoded filepath.
This is unacceptable as the socket is channel/process specific and things will
break when multiple guests are started.
- capability negotiation will be needed to handle version/architecture
differences.
- proper channel negotiation is needed to avoid hung monitors and such when a
guest reboots or the guest agent is stopped for whatever reason. additionally,
a timeout may need to be imposed on the amount of time the http read handler
can block the monitor.
- additional host-to-guest RPCs as well as asynchronous notifications via
guest-to-host RPCs for events such as shutdown/reboot/agent up/agent down
Makefile | 2 +-
Makefile.target | 2 +-
configure | 25 +++
hmp-commands.hx | 32 ++++
monitor.c | 1 +
qemu-char.c | 24 +++
qemu-config.c | 3 +
qemu-vp.c | 94 ++++++++++-
qerror.c | 4 +
qerror.h | 3 +
qmp-commands.hx | 68 ++++++++
roms/seabios | 2 +-
virtagent-common.c | 431 ++++++++++++++++++++++++++++++++++++++++++++++++++++
virtagent-common.h | 73 +++++++++
virtagent-daemon.c | 291 +++++++++++++++++++++++++++++++++++
virtagent-daemon.h | 23 +++
virtagent.c | 345 +++++++++++++++++++++++++++++++++++++++++
virtagent.h | 33 ++++
18 files changed, 1444 insertions(+), 12 deletions(-)
