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.h"
  28 #include "cpu-common.h"
  29 #include "kvm.h"
  30 #include "balloon.h"
  31 #include "trace.h"
  32 #include "qmp-commands.h"
  33
  34 static QEMUBalloonEvent *balloon_event_fn;
  35 static QEMUBalloonStatus *balloon_stat_fn;
  36 static void *balloon_opaque;
  37
  38 int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
  39                              QEMUBalloonStatus *stat_func, void *opaque)
  40 {
  41     if (balloon_event_fn || balloon_stat_fn || balloon_opaque) {
  42         /* We're already registered one balloon handler.  How many can
  43          * a guest really have?
  44          */
  45         error_report("Another balloon device already registered");
  46         return -1;
  47     }
  48     balloon_event_fn = event_func;
  49     balloon_stat_fn = stat_func;
  50     balloon_opaque = opaque;
  51     return 0;
  52 }
  53
  54 void qemu_remove_balloon_handler(void *opaque)
  55 {
  56     if (balloon_opaque != opaque) {
  57         return;
  58     }
  59     balloon_event_fn = NULL;
  60     balloon_stat_fn = NULL;
  61     balloon_opaque = NULL;
  62 }
  63
  64 static int qemu_balloon(ram_addr_t target)
  65 {
  66     if (!balloon_event_fn) {
  67         return 0;
  68     }
  69     trace_balloon_event(balloon_opaque, target);
  70     balloon_event_fn(balloon_opaque, target);
  71     return 1;
  72 }
  73
  74 static int qemu_balloon_status(BalloonInfo *info)
  75 {
  76     if (!balloon_stat_fn) {
  77         return 0;
  78     }
  79     balloon_stat_fn(balloon_opaque, info);
  80     return 1;
  81 }
  82
  83 BalloonInfo *qmp_query_balloon(Error **errp)
  84 {
  85     BalloonInfo *info;
  86
  87     if (kvm_enabled() && !kvm_has_sync_mmu()) {
  88         error_set(errp, QERR_KVM_MISSING_CAP, "synchronous MMU", "balloon");
  89         return NULL;
  90     }
  91
  92     info = g_malloc0(sizeof(*info));
  93
  94     if (qemu_balloon_status(info) == 0) {
  95         error_set(errp, QERR_DEVICE_NOT_ACTIVE, "balloon");
  96         qapi_free_BalloonInfo(info);
  97         return NULL;
  98     }
  99
 100     return info;
 101 }
 102
 103 /**
 104  * do_balloon(): Request VM to change its memory allocation
 105  */
 106 int do_balloon(Monitor *mon, const QDict *params,
 107                MonitorCompletion cb, void *opaque)
 108 {
 109     int64_t target;
 110     int ret;
 111
 112     if (kvm_enabled() && !kvm_has_sync_mmu()) {
 113         qerror_report(QERR_KVM_MISSING_CAP, "synchronous MMU", "balloon");
 114         return -1;
 115     }
 116
 117     target = qdict_get_int(params, "value");
 118     if (target <= 0) {
 119         qerror_report(QERR_INVALID_PARAMETER_VALUE, "target", "a size");
 120         return -1;
 121     }
 122     ret = qemu_balloon(target);
 123     if (ret == 0) {
 124         qerror_report(QERR_DEVICE_NOT_ACTIVE, "balloon");
 125         return -1;
 126     }
 127
 128     cb(opaque, NULL);
 129     return 0;
 130 }