2010-04-01 21:57:12 +04:00
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/*
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2011-07-20 12:05:30 +04:00
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* Generic Balloon handlers and management
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2010-04-01 21:57:12 +04:00
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*
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* Copyright (c) 2003-2008 Fabrice Bellard
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2011-07-20 12:05:30 +04:00
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* Copyright (C) 2011 Red Hat, Inc.
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* Copyright (C) 2011 Amit Shah <amit.shah@redhat.com>
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2010-04-01 21:57:12 +04:00
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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2016-01-29 20:50:05 +03:00
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#include "qemu/osdep.h"
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2018-08-17 18:27:15 +03:00
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#include "qemu/atomic.h"
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2012-12-17 21:20:04 +04:00
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#include "sysemu/kvm.h"
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#include "sysemu/balloon.h"
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2017-01-25 19:14:15 +03:00
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#include "trace-root.h"
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2018-02-01 14:18:31 +03:00
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#include "qapi/error.h"
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2018-02-27 02:13:27 +03:00
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#include "qapi/qapi-commands-misc.h"
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2015-03-17 19:22:46 +03:00
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#include "qapi/qmp/qerror.h"
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2010-04-01 21:57:12 +04:00
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2011-07-20 11:38:46 +04:00
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static QEMUBalloonEvent *balloon_event_fn;
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balloon: Separate out stat and balloon handling
Passing on '0' as ballooning target to indicate retrieval of stats is
bad API. It also makes 'balloon 0' in the monitor cause a segfault.
Have two different functions handle the different functionality instead.
Detailed explanation from Markus's review:
1. do_info_balloon() is an info_async() method. It receives a callback
with argument, to be called exactly once (callback frees the
argument). It passes the callback via qemu_balloon_status() and
indirectly through qemu_balloon_event to virtio_balloon_to_target().
virtio_balloon_to_target() executes its balloon stats half. It
stores the callback in the device state.
If it can't send a stats request, it resets stats and calls the
callback right away.
Else, it sends a stats request. The device model runs the callback
when it receives the answer.
Works.
2. do_balloon() is a cmd_async() method. It receives a callback with
argument, to be called when the command completes. do_balloon()
calls it right before it succeeds. Odd, but should work.
Nevertheless, it passes the callback on via qemu_ballon() and
indirectly through qemu_balloon_event to virtio_balloon_to_target().
a. If the argument is non-zero, virtio_balloon_to_target() executes
its balloon half, which doesn't use the callback in any way.
Odd, but works.
b. If the argument is zero, virtio_balloon_to_target() executes its
balloon stats half, just like in 1. It either calls the callback
right away, or arranges for it to be called later.
Thus, the callback runs twice: use after free and double free.
Test case: start with -S -device virtio-balloon, execute "balloon 0" in
human monitor. Runs the callback first from virtio_balloon_to_target(),
then again from do_balloon().
Reported-by: Mike Cao <bcao@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
2011-07-20 12:00:56 +04:00
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static QEMUBalloonStatus *balloon_stat_fn;
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2011-07-20 11:38:46 +04:00
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static void *balloon_opaque;
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2010-04-01 21:57:12 +04:00
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2015-02-11 01:40:30 +03:00
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static bool have_balloon(Error **errp)
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2015-01-13 19:44:14 +03:00
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{
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if (kvm_enabled() && !kvm_has_sync_mmu()) {
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2015-01-13 19:50:23 +03:00
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error_set(errp, ERROR_CLASS_KVM_MISSING_CAP,
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"Using KVM without synchronous MMU, balloon unavailable");
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2015-01-13 19:44:14 +03:00
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return false;
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}
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if (!balloon_event_fn) {
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2015-01-13 19:50:23 +03:00
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error_set(errp, ERROR_CLASS_DEVICE_NOT_ACTIVE,
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"No balloon device has been activated");
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2015-01-13 19:44:14 +03:00
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return false;
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}
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return true;
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}
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2011-07-27 10:58:19 +04:00
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int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
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QEMUBalloonStatus *stat_func, void *opaque)
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2010-04-01 21:57:12 +04:00
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{
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2011-07-27 10:58:19 +04:00
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if (balloon_event_fn || balloon_stat_fn || balloon_opaque) {
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/* We're already registered one balloon handler. How many can
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* a guest really have?
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*/
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return -1;
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}
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balloon: Separate out stat and balloon handling
Passing on '0' as ballooning target to indicate retrieval of stats is
bad API. It also makes 'balloon 0' in the monitor cause a segfault.
Have two different functions handle the different functionality instead.
Detailed explanation from Markus's review:
1. do_info_balloon() is an info_async() method. It receives a callback
with argument, to be called exactly once (callback frees the
argument). It passes the callback via qemu_balloon_status() and
indirectly through qemu_balloon_event to virtio_balloon_to_target().
virtio_balloon_to_target() executes its balloon stats half. It
stores the callback in the device state.
If it can't send a stats request, it resets stats and calls the
callback right away.
Else, it sends a stats request. The device model runs the callback
when it receives the answer.
Works.
2. do_balloon() is a cmd_async() method. It receives a callback with
argument, to be called when the command completes. do_balloon()
calls it right before it succeeds. Odd, but should work.
Nevertheless, it passes the callback on via qemu_ballon() and
indirectly through qemu_balloon_event to virtio_balloon_to_target().
a. If the argument is non-zero, virtio_balloon_to_target() executes
its balloon half, which doesn't use the callback in any way.
Odd, but works.
b. If the argument is zero, virtio_balloon_to_target() executes its
balloon stats half, just like in 1. It either calls the callback
right away, or arranges for it to be called later.
Thus, the callback runs twice: use after free and double free.
Test case: start with -S -device virtio-balloon, execute "balloon 0" in
human monitor. Runs the callback first from virtio_balloon_to_target(),
then again from do_balloon().
Reported-by: Mike Cao <bcao@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
2011-07-20 12:00:56 +04:00
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balloon_event_fn = event_func;
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balloon_stat_fn = stat_func;
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2011-07-20 11:38:46 +04:00
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balloon_opaque = opaque;
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2011-07-27 10:58:19 +04:00
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return 0;
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2010-04-01 21:57:12 +04:00
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}
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2011-09-09 13:00:39 +04:00
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void qemu_remove_balloon_handler(void *opaque)
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{
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if (balloon_opaque != opaque) {
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return;
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}
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balloon_event_fn = NULL;
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balloon_stat_fn = NULL;
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balloon_opaque = NULL;
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}
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2011-10-21 17:41:37 +04:00
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BalloonInfo *qmp_query_balloon(Error **errp)
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2010-04-01 21:57:12 +04:00
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{
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2011-10-21 17:41:37 +04:00
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BalloonInfo *info;
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2010-04-01 21:57:12 +04:00
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2015-02-11 01:40:30 +03:00
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if (!have_balloon(errp)) {
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2011-10-21 17:41:37 +04:00
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return NULL;
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2010-04-01 21:57:12 +04:00
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}
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2015-01-13 19:43:25 +03:00
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info = g_malloc0(sizeof(*info));
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balloon_stat_fn(balloon_opaque, info);
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2011-10-21 17:41:37 +04:00
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return info;
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2010-04-01 21:57:12 +04:00
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}
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2015-01-13 19:43:25 +03:00
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void qmp_balloon(int64_t target, Error **errp)
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2010-04-01 21:57:12 +04:00
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{
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2015-02-11 01:40:30 +03:00
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if (!have_balloon(errp)) {
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2011-11-25 20:38:09 +04:00
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return;
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2010-04-01 21:57:12 +04:00
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}
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2015-01-13 19:43:25 +03:00
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if (target <= 0) {
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2015-03-17 13:54:50 +03:00
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error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "target", "a size");
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2011-11-25 20:38:09 +04:00
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return;
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2011-07-27 15:20:54 +04:00
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}
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2015-01-13 19:43:25 +03:00
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trace_balloon_event(balloon_opaque, target);
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balloon_event_fn(balloon_opaque, target);
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2010-04-01 21:57:12 +04:00
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}
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