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973603a813
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>
133 lines
3.7 KiB
C
133 lines
3.7 KiB
C
/*
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* Generic Balloon handlers and management
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*
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* Copyright (c) 2003-2008 Fabrice Bellard
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* Copyright (C) 2011 Red Hat, Inc.
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* Copyright (C) 2011 Amit Shah <amit.shah@redhat.com>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "monitor.h"
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#include "cpu-common.h"
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#include "kvm.h"
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#include "balloon.h"
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#include "trace.h"
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#include "qmp-commands.h"
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#include "qjson.h"
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static QEMUBalloonEvent *balloon_event_fn;
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static QEMUBalloonStatus *balloon_stat_fn;
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static void *balloon_opaque;
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int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
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QEMUBalloonStatus *stat_func, void *opaque)
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{
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if (balloon_event_fn || balloon_stat_fn || balloon_opaque) {
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/* We're already registered one balloon handler. How many can
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* a guest really have?
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*/
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error_report("Another balloon device already registered");
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return -1;
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}
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balloon_event_fn = event_func;
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balloon_stat_fn = stat_func;
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balloon_opaque = opaque;
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return 0;
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}
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void qemu_remove_balloon_handler(void *opaque)
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{
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if (balloon_opaque != opaque) {
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return;
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}
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balloon_event_fn = NULL;
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balloon_stat_fn = NULL;
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balloon_opaque = NULL;
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}
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static int qemu_balloon(ram_addr_t target)
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{
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if (!balloon_event_fn) {
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return 0;
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}
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trace_balloon_event(balloon_opaque, target);
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balloon_event_fn(balloon_opaque, target);
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return 1;
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}
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static int qemu_balloon_status(BalloonInfo *info)
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{
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if (!balloon_stat_fn) {
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return 0;
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}
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balloon_stat_fn(balloon_opaque, info);
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return 1;
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}
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void qemu_balloon_changed(int64_t actual)
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{
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QObject *data;
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data = qobject_from_jsonf("{ 'actual': %" PRId64 " }",
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actual);
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monitor_protocol_event(QEVENT_BALLOON_CHANGE, data);
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qobject_decref(data);
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}
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BalloonInfo *qmp_query_balloon(Error **errp)
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{
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BalloonInfo *info;
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if (kvm_enabled() && !kvm_has_sync_mmu()) {
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error_set(errp, QERR_KVM_MISSING_CAP, "synchronous MMU", "balloon");
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return NULL;
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}
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info = g_malloc0(sizeof(*info));
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if (qemu_balloon_status(info) == 0) {
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error_set(errp, QERR_DEVICE_NOT_ACTIVE, "balloon");
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qapi_free_BalloonInfo(info);
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return NULL;
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}
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return info;
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}
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void qmp_balloon(int64_t value, Error **errp)
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{
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if (kvm_enabled() && !kvm_has_sync_mmu()) {
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error_set(errp, QERR_KVM_MISSING_CAP, "synchronous MMU", "balloon");
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return;
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}
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if (value <= 0) {
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error_set(errp, QERR_INVALID_PARAMETER_VALUE, "target", "a size");
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return;
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}
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if (qemu_balloon(value) == 0) {
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error_set(errp, QERR_DEVICE_NOT_ACTIVE, "balloon");
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}
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}
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