keep the PID file locked for the lifetime of the process
[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 "monitor.h"
28 #include "cpu-common.h"
29 #include "kvm.h"
30 #include "balloon.h"
31 #include "trace.h"
32 #include "qmp-commands.h"
33
34 static QEMUBalloonEvent *balloon_event_fn;
35 static QEMUBalloonStatus *balloon_stat_fn;
36 static void *balloon_opaque;
37
38 int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
39 QEMUBalloonStatus *stat_func, void *opaque)
40 {
41 if (balloon_event_fn || balloon_stat_fn || balloon_opaque) {
42 /* We're already registered one balloon handler. How many can
43 * a guest really have?
44 */
45 error_report("Another balloon device already registered");
46 return -1;
47 }
48 balloon_event_fn = event_func;
49 balloon_stat_fn = stat_func;
50 balloon_opaque = opaque;
51 return 0;
52 }
53
54 void qemu_remove_balloon_handler(void *opaque)
55 {
56 if (balloon_opaque != opaque) {
57 return;
58 }
59 balloon_event_fn = NULL;
60 balloon_stat_fn = NULL;
61 balloon_opaque = NULL;
62 }
63
64 static int qemu_balloon(ram_addr_t target)
65 {
66 if (!balloon_event_fn) {
67 return 0;
68 }
69 trace_balloon_event(balloon_opaque, target);
70 balloon_event_fn(balloon_opaque, target);
71 return 1;
72 }
73
74 static int qemu_balloon_status(BalloonInfo *info)
75 {
76 if (!balloon_stat_fn) {
77 return 0;
78 }
79 balloon_stat_fn(balloon_opaque, info);
80 return 1;
81 }
82
83 BalloonInfo *qmp_query_balloon(Error **errp)
84 {
85 BalloonInfo *info;
86
87 if (kvm_enabled() && !kvm_has_sync_mmu()) {
88 error_set(errp, QERR_KVM_MISSING_CAP, "synchronous MMU", "balloon");
89 return NULL;
90 }
91
92 info = g_malloc0(sizeof(*info));
93
94 if (qemu_balloon_status(info) == 0) {
95 error_set(errp, QERR_DEVICE_NOT_ACTIVE, "balloon");
96 qapi_free_BalloonInfo(info);
97 return NULL;
98 }
99
100 return info;
101 }
102
103 void qmp_balloon(int64_t value, Error **errp)
104 {
105 if (kvm_enabled() && !kvm_has_sync_mmu()) {
106 error_set(errp, QERR_KVM_MISSING_CAP, "synchronous MMU", "balloon");
107 return;
108 }
109
110 if (value <= 0) {
111 qerror_report(QERR_INVALID_PARAMETER_VALUE, "target", "a size");
112 return;
113 }
114
115 if (qemu_balloon(value) == 0) {
116 error_set(errp, QERR_DEVICE_NOT_ACTIVE, "balloon");
117 }
118 }