tests/qapi/doc-good.json: Prepare for qapi-doc Sphinx extension
[qemu.git] / softmmu / 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 "qapi/error.h"
32 #include "qapi/qapi-commands-machine.h"
33 #include "qapi/qmp/qerror.h"
34 #include "trace.h"
35
36 static QEMUBalloonEvent *balloon_event_fn;
37 static QEMUBalloonStatus *balloon_stat_fn;
38 static void *balloon_opaque;
39
40 static bool have_balloon(Error **errp)
41 {
42 if (kvm_enabled() && !kvm_has_sync_mmu()) {
43 error_set(errp, ERROR_CLASS_KVM_MISSING_CAP,
44 "Using KVM without synchronous MMU, balloon unavailable");
45 return false;
46 }
47 if (!balloon_event_fn) {
48 error_set(errp, ERROR_CLASS_DEVICE_NOT_ACTIVE,
49 "No balloon device has been activated");
50 return false;
51 }
52 return true;
53 }
54
55 int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
56 QEMUBalloonStatus *stat_func, void *opaque)
57 {
58 if (balloon_event_fn || balloon_stat_fn || balloon_opaque) {
59 /* We're already registered one balloon handler. How many can
60 * a guest really have?
61 */
62 return -1;
63 }
64 balloon_event_fn = event_func;
65 balloon_stat_fn = stat_func;
66 balloon_opaque = opaque;
67 return 0;
68 }
69
70 void qemu_remove_balloon_handler(void *opaque)
71 {
72 if (balloon_opaque != opaque) {
73 return;
74 }
75 balloon_event_fn = NULL;
76 balloon_stat_fn = NULL;
77 balloon_opaque = NULL;
78 }
79
80 BalloonInfo *qmp_query_balloon(Error **errp)
81 {
82 BalloonInfo *info;
83
84 if (!have_balloon(errp)) {
85 return NULL;
86 }
87
88 info = g_malloc0(sizeof(*info));
89 balloon_stat_fn(balloon_opaque, info);
90 return info;
91 }
92
93 void qmp_balloon(int64_t target, Error **errp)
94 {
95 if (!have_balloon(errp)) {
96 return;
97 }
98
99 if (target <= 0) {
100 error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "target", "a size");
101 return;
102 }
103
104 trace_balloon_event(balloon_opaque, target);
105 balloon_event_fn(balloon_opaque, target);
106 }