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 "qemu-common.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/qerror.h"
  34 #include "qapi/qmp/qjson.h"
  35
  36 static QEMUBalloonEvent *balloon_event_fn;
  37 static QEMUBalloonStatus *balloon_stat_fn;
  38 static void *balloon_opaque;
  39 static bool balloon_inhibited;
  40
  41 bool qemu_balloon_is_inhibited(void)
  42 {
  43     return balloon_inhibited;
  44 }
  45
  46 void qemu_balloon_inhibit(bool state)
  47 {
  48     balloon_inhibited = state;
  49 }
  50
  51 static bool have_balloon(Error **errp)
  52 {
  53     if (kvm_enabled() && !kvm_has_sync_mmu()) {
  54         error_set(errp, ERROR_CLASS_KVM_MISSING_CAP,
  55                   "Using KVM without synchronous MMU, balloon unavailable");
  56         return false;
  57     }
  58     if (!balloon_event_fn) {
  59         error_set(errp, ERROR_CLASS_DEVICE_NOT_ACTIVE,
  60                   "No balloon device has been activated");
  61         return false;
  62     }
  63     return true;
  64 }
  65
  66 int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
  67                              QEMUBalloonStatus *stat_func, void *opaque)
  68 {
  69     if (balloon_event_fn || balloon_stat_fn || balloon_opaque) {
  70         /* We're already registered one balloon handler.  How many can
  71          * a guest really have?
  72          */
  73         return -1;
  74     }
  75     balloon_event_fn = event_func;
  76     balloon_stat_fn = stat_func;
  77     balloon_opaque = opaque;
  78     return 0;
  79 }
  80
  81 void qemu_remove_balloon_handler(void *opaque)
  82 {
  83     if (balloon_opaque != opaque) {
  84         return;
  85     }
  86     balloon_event_fn = NULL;
  87     balloon_stat_fn = NULL;
  88     balloon_opaque = NULL;
  89 }
  90
  91 BalloonInfo *qmp_query_balloon(Error **errp)
  92 {
  93     BalloonInfo *info;
  94
  95     if (!have_balloon(errp)) {
  96         return NULL;
  97     }
  98
  99     info = g_malloc0(sizeof(*info));
 100     balloon_stat_fn(balloon_opaque, info);
 101     return info;
 102 }
 103
 104 void qmp_balloon(int64_t target, Error **errp)
 105 {
 106     if (!have_balloon(errp)) {
 107         return;
 108     }
 109
 110     if (target <= 0) {
 111         error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "target", "a size");
 112         return;
 113     }
 114
 115     trace_balloon_event(balloon_opaque, target);
 116     balloon_event_fn(balloon_opaque, target);
 117 }