qxl: check release info object
[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-common.h"
29 #include "qemu/atomic.h"
30 #include "exec/cpu-common.h"
31 #include "sysemu/kvm.h"
32 #include "sysemu/balloon.h"
33 #include "trace-root.h"
34 #include "qapi/error.h"
35 #include "qapi/qapi-commands-misc.h"
36 #include "qapi/qmp/qerror.h"
37
38 static QEMUBalloonEvent *balloon_event_fn;
39 static QEMUBalloonStatus *balloon_stat_fn;
40 static void *balloon_opaque;
41 static int balloon_inhibit_count;
42
43 bool qemu_balloon_is_inhibited(void)
44 {
45 return atomic_read(&balloon_inhibit_count) > 0;
46 }
47
48 void qemu_balloon_inhibit(bool state)
49 {
50 if (state) {
51 atomic_inc(&balloon_inhibit_count);
52 } else {
53 atomic_dec(&balloon_inhibit_count);
54 }
55
56 assert(atomic_read(&balloon_inhibit_count) >= 0);
57 }
58
59 static bool have_balloon(Error **errp)
60 {
61 if (kvm_enabled() && !kvm_has_sync_mmu()) {
62 error_set(errp, ERROR_CLASS_KVM_MISSING_CAP,
63 "Using KVM without synchronous MMU, balloon unavailable");
64 return false;
65 }
66 if (!balloon_event_fn) {
67 error_set(errp, ERROR_CLASS_DEVICE_NOT_ACTIVE,
68 "No balloon device has been activated");
69 return false;
70 }
71 return true;
72 }
73
74 int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
75 QEMUBalloonStatus *stat_func, void *opaque)
76 {
77 if (balloon_event_fn || balloon_stat_fn || balloon_opaque) {
78 /* We're already registered one balloon handler. How many can
79 * a guest really have?
80 */
81 return -1;
82 }
83 balloon_event_fn = event_func;
84 balloon_stat_fn = stat_func;
85 balloon_opaque = opaque;
86 return 0;
87 }
88
89 void qemu_remove_balloon_handler(void *opaque)
90 {
91 if (balloon_opaque != opaque) {
92 return;
93 }
94 balloon_event_fn = NULL;
95 balloon_stat_fn = NULL;
96 balloon_opaque = NULL;
97 }
98
99 BalloonInfo *qmp_query_balloon(Error **errp)
100 {
101 BalloonInfo *info;
102
103 if (!have_balloon(errp)) {
104 return NULL;
105 }
106
107 info = g_malloc0(sizeof(*info));
108 balloon_stat_fn(balloon_opaque, info);
109 return info;
110 }
111
112 void qmp_balloon(int64_t target, Error **errp)
113 {
114 if (!have_balloon(errp)) {
115 return;
116 }
117
118 if (target <= 0) {
119 error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "target", "a size");
120 return;
121 }
122
123 trace_balloon_event(balloon_opaque, target);
124 balloon_event_fn(balloon_opaque, target);
125 }