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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
36static QEMUBalloonEvent *balloon_event_fn;
37static QEMUBalloonStatus *balloon_stat_fn;
38static void *balloon_opaque;
39
40static 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
55int 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
60
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
70void 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
80BalloonInfo *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
93void 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}
107