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[thirdparty/qemu.git] / balloon.c
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28c28973 1/*
73428a8e 2 * Generic Balloon handlers and management
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3 *
4 * Copyright (c) 2003-2008 Fabrice Bellard
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5 * Copyright (C) 2011 Red Hat, Inc.
6 * Copyright (C) 2011 Amit Shah <amit.shah@redhat.com>
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7 *
8 * Permission is hereby granted, free of charge, to any person obtaining a copy
9 * of this software and associated documentation files (the "Software"), to deal
10 * in the Software without restriction, including without limitation the rights
11 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
12 * copies of the Software, and to permit persons to whom the Software is
13 * furnished to do so, subject to the following conditions:
14 *
15 * The above copyright notice and this permission notice shall be included in
16 * all copies or substantial portions of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
21 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
23 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
24 * THE SOFTWARE.
25 */
26
d38ea87a 27#include "qemu/osdep.h"
01ccbec7 28#include "qemu/atomic.h"
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29#include "sysemu/kvm.h"
30#include "sysemu/balloon.h"
0ab8ed18 31#include "trace-root.h"
e688df6b 32#include "qapi/error.h"
112ed241 33#include "qapi/qapi-commands-misc.h"
cc7a8ea7 34#include "qapi/qmp/qerror.h"
28c28973 35
0a2a30d5 36static QEMUBalloonEvent *balloon_event_fn;
30fb2ca6 37static QEMUBalloonStatus *balloon_stat_fn;
0a2a30d5 38static void *balloon_opaque;
01ccbec7 39static int balloon_inhibit_count;
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40
41bool qemu_balloon_is_inhibited(void)
42{
01ccbec7 43 return atomic_read(&balloon_inhibit_count) > 0;
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44}
45
46void qemu_balloon_inhibit(bool state)
47{
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48 if (state) {
49 atomic_inc(&balloon_inhibit_count);
50 } else {
51 atomic_dec(&balloon_inhibit_count);
52 }
53
54 assert(atomic_read(&balloon_inhibit_count) >= 0);
371ff5a3 55}
28c28973 56
438e8289 57static bool have_balloon(Error **errp)
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58{
59 if (kvm_enabled() && !kvm_has_sync_mmu()) {
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60 error_set(errp, ERROR_CLASS_KVM_MISSING_CAP,
61 "Using KVM without synchronous MMU, balloon unavailable");
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62 return false;
63 }
64 if (!balloon_event_fn) {
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65 error_set(errp, ERROR_CLASS_DEVICE_NOT_ACTIVE,
66 "No balloon device has been activated");
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67 return false;
68 }
69 return true;
70}
71
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72int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
73 QEMUBalloonStatus *stat_func, void *opaque)
28c28973 74{
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75 if (balloon_event_fn || balloon_stat_fn || balloon_opaque) {
76 /* We're already registered one balloon handler. How many can
77 * a guest really have?
78 */
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79 return -1;
80 }
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81 balloon_event_fn = event_func;
82 balloon_stat_fn = stat_func;
0a2a30d5 83 balloon_opaque = opaque;
6c6ec182 84 return 0;
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85}
86
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87void qemu_remove_balloon_handler(void *opaque)
88{
89 if (balloon_opaque != opaque) {
90 return;
91 }
92 balloon_event_fn = NULL;
93 balloon_stat_fn = NULL;
94 balloon_opaque = NULL;
95}
96
96637bcd 97BalloonInfo *qmp_query_balloon(Error **errp)
28c28973 98{
96637bcd 99 BalloonInfo *info;
28c28973 100
438e8289 101 if (!have_balloon(errp)) {
96637bcd 102 return NULL;
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103 }
104
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105 info = g_malloc0(sizeof(*info));
106 balloon_stat_fn(balloon_opaque, info);
96637bcd 107 return info;
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108}
109
6502a147 110void qmp_balloon(int64_t target, Error **errp)
28c28973 111{
438e8289 112 if (!have_balloon(errp)) {
d72f3264 113 return;
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114 }
115
6502a147 116 if (target <= 0) {
c6bd8c70 117 error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "target", "a size");
d72f3264 118 return;
514e73ec 119 }
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120
121 trace_balloon_event(balloon_opaque, target);
122 balloon_event_fn(balloon_opaque, target);
28c28973 123}