qemu

FORK: QEMU emulator
git clone https://git.neptards.moe/neptards/qemu.git
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balloon.c (3230B)

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