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/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
  36static QEMUBalloonEvent *balloon_event_fn;
  37static QEMUBalloonStatus *balloon_stat_fn;
  38static void *balloon_opaque;
  39static int balloon_inhibit_count;
  40
  41bool qemu_balloon_is_inhibited(void)
  42{
  43    return atomic_read(&balloon_inhibit_count) > 0;
  44}
  45
  46void qemu_balloon_inhibit(bool state)
  47{
  48    if (state) {
  49        atomic_inc(&balloon_inhibit_count);
  50    } else {
  51        atomic_dec(&balloon_inhibit_count);
  52    }
  53
  54    assert(atomic_read(&balloon_inhibit_count) >= 0);
  55}
  56
  57static bool have_balloon(Error **errp)
  58{
  59    if (kvm_enabled() && !kvm_has_sync_mmu()) {
  60        error_set(errp, ERROR_CLASS_KVM_MISSING_CAP,
  61                  "Using KVM without synchronous MMU, balloon unavailable");
  62        return false;
  63    }
  64    if (!balloon_event_fn) {
  65        error_set(errp, ERROR_CLASS_DEVICE_NOT_ACTIVE,
  66                  "No balloon device has been activated");
  67        return false;
  68    }
  69    return true;
  70}
  71
  72int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
  73                             QEMUBalloonStatus *stat_func, void *opaque)
  74{
  75    if (balloon_event_fn || balloon_stat_fn || balloon_opaque) {
  76        /* We're already registered one balloon handler.  How many can
  77         * a guest really have?
  78         */
  79        return -1;
  80    }
  81    balloon_event_fn = event_func;
  82    balloon_stat_fn = stat_func;
  83    balloon_opaque = opaque;
  84    return 0;
  85}
  86
  87void qemu_remove_balloon_handler(void *opaque)
  88{
  89    if (balloon_opaque != opaque) {
  90        return;
  91    }
  92    balloon_event_fn = NULL;
  93    balloon_stat_fn = NULL;
  94    balloon_opaque = NULL;
  95}
  96
  97BalloonInfo *qmp_query_balloon(Error **errp)
  98{
  99    BalloonInfo *info;
 100
 101    if (!have_balloon(errp)) {
 102        return NULL;
 103    }
 104
 105    info = g_malloc0(sizeof(*info));
 106    balloon_stat_fn(balloon_opaque, info);
 107    return info;
 108}
 109
 110void qmp_balloon(int64_t target, Error **errp)
 111{
 112    if (!have_balloon(errp)) {
 113        return;
 114    }
 115
 116    if (target <= 0) {
 117        error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "target", "a size");
 118        return;
 119    }
 120
 121    trace_balloon_event(balloon_opaque, target);
 122    balloon_event_fn(balloon_opaque, target);
 123}
 124