Merge remote-tracking branch 'remotes/bonzini/tags/for-upstream' into staging
[qemu.git] / balloon.c
1 /*
2 * Generic Balloon handlers and management
3 *
4 * Copyright (c) 2003-2008 Fabrice Bellard
5 * Copyright (C) 2011 Red Hat, Inc.
6 * Copyright (C) 2011 Amit Shah <amit.shah@redhat.com>
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
27 #include "qemu/osdep.h"
28 #include "qemu/atomic.h"
29 #include "sysemu/kvm.h"
30 #include "sysemu/balloon.h"
31 #include "trace-root.h"
32 #include "qapi/error.h"
33 #include "qapi/qapi-commands-misc.h"
34 #include "qapi/qmp/qerror.h"
35
36 static QEMUBalloonEvent *balloon_event_fn;
37 static QEMUBalloonStatus *balloon_stat_fn;
38 static void *balloon_opaque;
39 static int balloon_inhibit_count;
40
41 bool qemu_balloon_is_inhibited(void)
42 {
43 return atomic_read(&balloon_inhibit_count) > 0;
44 }
45
46 void qemu_balloon_inhibit(bool state)
47 {
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);
55 }
56
57 static bool have_balloon(Error **errp)
58 {
59 if (kvm_enabled() && !kvm_has_sync_mmu()) {
60 error_set(errp, ERROR_CLASS_KVM_MISSING_CAP,
61 "Using KVM without synchronous MMU, balloon unavailable");
62 return false;
63 }
64 if (!balloon_event_fn) {
65 error_set(errp, ERROR_CLASS_DEVICE_NOT_ACTIVE,
66 "No balloon device has been activated");
67 return false;
68 }
69 return true;
70 }
71
72 int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
73 QEMUBalloonStatus *stat_func, void *opaque)
74 {
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 */
79 return -1;
80 }
81 balloon_event_fn = event_func;
82 balloon_stat_fn = stat_func;
83 balloon_opaque = opaque;
84 return 0;
85 }
86
87 void 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
97 BalloonInfo *qmp_query_balloon(Error **errp)
98 {
99 BalloonInfo *info;
100
101 if (!have_balloon(errp)) {
102 return NULL;
103 }
104
105 info = g_malloc0(sizeof(*info));
106 balloon_stat_fn(balloon_opaque, info);
107 return info;
108 }
109
110 void qmp_balloon(int64_t target, Error **errp)
111 {
112 if (!have_balloon(errp)) {
113 return;
114 }
115
116 if (target <= 0) {
117 error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "target", "a size");
118 return;
119 }
120
121 trace_balloon_event(balloon_opaque, target);
122 balloon_event_fn(balloon_opaque, target);
123 }