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 "exec/cpu-common.h"
  30#include "sysemu/kvm.h"
  31#include "sysemu/balloon.h"
  32#include "trace-root.h"
  33#include "qapi/error.h"
  34#include "qapi/qapi-commands-misc.h"
  35#include "qapi/qmp/qerror.h"
  36
  37static QEMUBalloonEvent *balloon_event_fn;
  38static QEMUBalloonStatus *balloon_stat_fn;
  39static void *balloon_opaque;
  40static int balloon_inhibit_count;
  41
  42bool qemu_balloon_is_inhibited(void)
  43{
  44    return atomic_read(&balloon_inhibit_count) > 0;
  45}
  46
  47void qemu_balloon_inhibit(bool state)
  48{
  49    if (state) {
  50        atomic_inc(&balloon_inhibit_count);
  51    } else {
  52        atomic_dec(&balloon_inhibit_count);
  53    }
  54
  55    assert(atomic_read(&balloon_inhibit_count) >= 0);
  56}
  57
  58static bool have_balloon(Error **errp)
  59{
  60    if (kvm_enabled() && !kvm_has_sync_mmu()) {
  61        error_set(errp, ERROR_CLASS_KVM_MISSING_CAP,
  62                  "Using KVM without synchronous MMU, balloon unavailable");
  63        return false;
  64    }
  65    if (!balloon_event_fn) {
  66        error_set(errp, ERROR_CLASS_DEVICE_NOT_ACTIVE,
  67                  "No balloon device has been activated");
  68        return false;
  69    }
  70    return true;
  71}
  72
  73int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
  74                             QEMUBalloonStatus *stat_func, void *opaque)
  75{
  76    if (balloon_event_fn || balloon_stat_fn || balloon_opaque) {
  77        /* We're already registered one balloon handler.  How many can
  78         * a guest really have?
  79         */
  80        return -1;
  81    }
  82    balloon_event_fn = event_func;
  83    balloon_stat_fn = stat_func;
  84    balloon_opaque = opaque;
  85    return 0;
  86}
  87
  88void qemu_remove_balloon_handler(void *opaque)
  89{
  90    if (balloon_opaque != opaque) {
  91        return;
  92    }
  93    balloon_event_fn = NULL;
  94    balloon_stat_fn = NULL;
  95    balloon_opaque = NULL;
  96}
  97
  98BalloonInfo *qmp_query_balloon(Error **errp)
  99{
 100    BalloonInfo *info;
 101
 102    if (!have_balloon(errp)) {
 103        return NULL;
 104    }
 105
 106    info = g_malloc0(sizeof(*info));
 107    balloon_stat_fn(balloon_opaque, info);
 108    return info;
 109}
 110
 111void qmp_balloon(int64_t target, Error **errp)
 112{
 113    if (!have_balloon(errp)) {
 114        return;
 115    }
 116
 117    if (target <= 0) {
 118        error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "target", "a size");
 119        return;
 120    }
 121
 122    trace_balloon_event(balloon_opaque, target);
 123    balloon_event_fn(balloon_opaque, target);
 124}
 125