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