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