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 "monitor/monitor.h"
  28#include "exec/cpu-common.h"
  29#include "sysemu/kvm.h"
  30#include "sysemu/balloon.h"
  31#include "trace.h"
  32#include "qmp-commands.h"
  33#include "qapi/qmp/qjson.h"
  34
  35static QEMUBalloonEvent *balloon_event_fn;
  36static QEMUBalloonStatus *balloon_stat_fn;
  37static void *balloon_opaque;
  38
  39static bool have_balloon(Error **errp)
  40{
  41    if (kvm_enabled() && !kvm_has_sync_mmu()) {
  42        error_set(errp, ERROR_CLASS_KVM_MISSING_CAP,
  43                  "Using KVM without synchronous MMU, balloon unavailable");
  44        return false;
  45    }
  46    if (!balloon_event_fn) {
  47        error_set(errp, ERROR_CLASS_DEVICE_NOT_ACTIVE,
  48                  "No balloon device has been activated");
  49        return false;
  50    }
  51    return true;
  52}
  53
  54int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
  55                             QEMUBalloonStatus *stat_func, void *opaque)
  56{
  57    if (balloon_event_fn || balloon_stat_fn || balloon_opaque) {
  58        /* We're already registered one balloon handler.  How many can
  59         * a guest really have?
  60         */
  61        error_report("Another balloon device already registered");
  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
  70void 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
  80BalloonInfo *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
  93void qmp_balloon(int64_t target, Error **errp)
  94{
  95    if (!have_balloon(errp)) {
  96        return;
  97    }
  98
  99    if (target <= 0) {
 100        error_set(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}
 107