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 "qemu/atomic.h"
  30#include "exec/cpu-common.h"
  31#include "sysemu/kvm.h"
  32#include "sysemu/balloon.h"
  33#include "trace-root.h"
  34#include "qapi/error.h"
  35#include "qapi/qapi-commands-misc.h"
  36#include "qapi/qmp/qerror.h"
  37
  38static QEMUBalloonEvent *balloon_event_fn;
  39static QEMUBalloonStatus *balloon_stat_fn;
  40static void *balloon_opaque;
  41static int balloon_inhibit_count;
  42
  43bool qemu_balloon_is_inhibited(void)
  44{
  45    return atomic_read(&balloon_inhibit_count) > 0;
  46}
  47
  48void qemu_balloon_inhibit(bool state)
  49{
  50    if (state) {
  51        atomic_inc(&balloon_inhibit_count);
  52    } else {
  53        atomic_dec(&balloon_inhibit_count);
  54    }
  55
  56    assert(atomic_read(&balloon_inhibit_count) >= 0);
  57}
  58
  59static bool have_balloon(Error **errp)
  60{
  61    if (kvm_enabled() && !kvm_has_sync_mmu()) {
  62        error_set(errp, ERROR_CLASS_KVM_MISSING_CAP,
  63                  "Using KVM without synchronous MMU, balloon unavailable");
  64        return false;
  65    }
  66    if (!balloon_event_fn) {
  67        error_set(errp, ERROR_CLASS_DEVICE_NOT_ACTIVE,
  68                  "No balloon device has been activated");
  69        return false;
  70    }
  71    return true;
  72}
  73
  74int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
  75                             QEMUBalloonStatus *stat_func, void *opaque)
  76{
  77    if (balloon_event_fn || balloon_stat_fn || balloon_opaque) {
  78        /* We're already registered one balloon handler.  How many can
  79         * a guest really have?
  80         */
  81        return -1;
  82    }
  83    balloon_event_fn = event_func;
  84    balloon_stat_fn = stat_func;
  85    balloon_opaque = opaque;
  86    return 0;
  87}
  88
  89void qemu_remove_balloon_handler(void *opaque)
  90{
  91    if (balloon_opaque != opaque) {
  92        return;
  93    }
  94    balloon_event_fn = NULL;
  95    balloon_stat_fn = NULL;
  96    balloon_opaque = NULL;
  97}
  98
  99BalloonInfo *qmp_query_balloon(Error **errp)
 100{
 101    BalloonInfo *info;
 102
 103    if (!have_balloon(errp)) {
 104        return NULL;
 105    }
 106
 107    info = g_malloc0(sizeof(*info));
 108    balloon_stat_fn(balloon_opaque, info);
 109    return info;
 110}
 111
 112void qmp_balloon(int64_t target, Error **errp)
 113{
 114    if (!have_balloon(errp)) {
 115        return;
 116    }
 117
 118    if (target <= 0) {
 119        error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "target", "a size");
 120        return;
 121    }
 122
 123    trace_balloon_event(balloon_opaque, target);
 124    balloon_event_fn(balloon_opaque, target);
 125}
 126