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/osdep.h"
  28 #include "qemu/atomic.h"
  29 #include "sysemu/kvm.h"
  30 #include "sysemu/balloon.h"
  31 #include "trace-root.h"
  32 #include "qapi/error.h"
  33 #include "qapi/qapi-commands-misc.h"
  34 #include "qapi/qmp/qerror.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 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 }