qemu/balloon.c
Daniel P. Berrange 973603a813 Add event notification for guest balloon changes
After setting a balloon target value, applications have to
continually poll 'query-balloon' to determine whether the
guest has reacted to this request. The virtio-balloon backend
knows exactly when the guest has reacted though, and thus it
is possible to emit a JSON event to tell the mgmt application
whenever the guest balloon changes.

This introduces a new 'qemu_balloon_changed()' API which is
to be called by balloon driver backends, whenever they have
a change in balloon value. This takes the 'actual' balloon
value, as would be found in the BalloonInfo struct.

The qemu_balloon_change API emits a JSON monitor event which
looks like:

  {"timestamp": {"seconds": 1337162462, "microseconds": 814521},
   "event": "BALLOON_CHANGE", "data": {"actual": 944766976}}

* balloon.c, balloon.h: Introduce qemu_balloon_changed() for
  emitting balloon change events on the monitor
* hw/virtio-balloon.c: Invoke qemu_balloon_changed() whenever
  the guest changes the balloon actual value
* monitor.c, monitor.h: Define QEVENT_BALLOON_CHANGE

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Acked-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2012-06-15 13:34:50 -03:00

133 lines
3.7 KiB
C

/*
* Generic Balloon handlers and management
*
* Copyright (c) 2003-2008 Fabrice Bellard
* Copyright (C) 2011 Red Hat, Inc.
* Copyright (C) 2011 Amit Shah <amit.shah@redhat.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "monitor.h"
#include "cpu-common.h"
#include "kvm.h"
#include "balloon.h"
#include "trace.h"
#include "qmp-commands.h"
#include "qjson.h"
static QEMUBalloonEvent *balloon_event_fn;
static QEMUBalloonStatus *balloon_stat_fn;
static void *balloon_opaque;
int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
QEMUBalloonStatus *stat_func, void *opaque)
{
if (balloon_event_fn || balloon_stat_fn || balloon_opaque) {
/* We're already registered one balloon handler. How many can
* a guest really have?
*/
error_report("Another balloon device already registered");
return -1;
}
balloon_event_fn = event_func;
balloon_stat_fn = stat_func;
balloon_opaque = opaque;
return 0;
}
void qemu_remove_balloon_handler(void *opaque)
{
if (balloon_opaque != opaque) {
return;
}
balloon_event_fn = NULL;
balloon_stat_fn = NULL;
balloon_opaque = NULL;
}
static int qemu_balloon(ram_addr_t target)
{
if (!balloon_event_fn) {
return 0;
}
trace_balloon_event(balloon_opaque, target);
balloon_event_fn(balloon_opaque, target);
return 1;
}
static int qemu_balloon_status(BalloonInfo *info)
{
if (!balloon_stat_fn) {
return 0;
}
balloon_stat_fn(balloon_opaque, info);
return 1;
}
void qemu_balloon_changed(int64_t actual)
{
QObject *data;
data = qobject_from_jsonf("{ 'actual': %" PRId64 " }",
actual);
monitor_protocol_event(QEVENT_BALLOON_CHANGE, data);
qobject_decref(data);
}
BalloonInfo *qmp_query_balloon(Error **errp)
{
BalloonInfo *info;
if (kvm_enabled() && !kvm_has_sync_mmu()) {
error_set(errp, QERR_KVM_MISSING_CAP, "synchronous MMU", "balloon");
return NULL;
}
info = g_malloc0(sizeof(*info));
if (qemu_balloon_status(info) == 0) {
error_set(errp, QERR_DEVICE_NOT_ACTIVE, "balloon");
qapi_free_BalloonInfo(info);
return NULL;
}
return info;
}
void qmp_balloon(int64_t value, Error **errp)
{
if (kvm_enabled() && !kvm_has_sync_mmu()) {
error_set(errp, QERR_KVM_MISSING_CAP, "synchronous MMU", "balloon");
return;
}
if (value <= 0) {
error_set(errp, QERR_INVALID_PARAMETER_VALUE, "target", "a size");
return;
}
if (qemu_balloon(value) == 0) {
error_set(errp, QERR_DEVICE_NOT_ACTIVE, "balloon");
}
}