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