xref: /openbmc/qemu/system/balloon.c (revision b86c6ba6)
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 value, Error **errp)
94 {
95     if (!have_balloon(errp)) {
96         return;
97     }
98 
99     if (value <= 0) {
100         error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "value", "a size");
101         return;
102     }
103 
104     trace_balloon_event(balloon_opaque, value);
105     balloon_event_fn(balloon_opaque, value);
106 }
107