Commit 422e0501 introduced a typo (unless removing an 'o' from
balloon is how you deflate it?)
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

The QERR_ macros are leftovers from the days of "rich" error objects.
They're used with error_set() and qerror_report(), and expand into the
first *two* arguments.  This trickiness has become pointless.  Clean
up the balloon ones.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

... and simplify a bit.  Permits factoring out common error checks in
the next commit.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

Signed-off-by: NWenchao Xia <wenchaoqemu@gmail.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

After setting a balloon target value, applications have to
continually poll 'query-balloon' to determine whether the
guest has reacted to this request. The virtio-balloon backend
knows exactly when the guest has reacted though, and thus it
is possible to emit a JSON event to tell the mgmt application
whenever the guest balloon changes.

This introduces a new 'qemu_balloon_changed()' API which is
to be called by balloon driver backends, whenever they have
a change in balloon value. This takes the 'actual' balloon
value, as would be found in the BalloonInfo struct.

The qemu_balloon_change API emits a JSON monitor event which
looks like:

  {"timestamp": {"seconds": 1337162462, "microseconds": 814521},
   "event": "BALLOON_CHANGE", "data": {"actual": 944766976}}

* balloon.c, balloon.h: Introduce qemu_balloon_changed() for
  emitting balloon change events on the monitor
* hw/virtio-balloon.c: Invoke qemu_balloon_changed() whenever
  the guest changes the balloon actual value
* monitor.c, monitor.h: Define QEVENT_BALLOON_CHANGE
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Acked-by: NAmit Shah <amit.shah@redhat.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

Commit d72f3264 forgot to convert a call from qerror_report() to
error_set(). Fix it.
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: NMichael Roth <mdroth@linux.vnet.ibm.com>

Note that the command being dropped uses the deprecated MONITOR_CMD_ASYNC
API, but the new command is a regular synchronous command. There shouldn't
be visible differences though, as MONITOR_CMD_ASYNC is internal only.
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

Please, note that some of the code supporting memory statistics is
still around (eg. virtio_balloon_receive_stats() and reset_stats()).

Also, the qmp_query_balloon() function is synchronous and thus doesn't
make any use of the (not fully working) monitor's asynchronous command
support (the old non-qapi implementation did).
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

When a balloon device gets unplugged, allow the balloon handlers to be
freed.
Reported-by: NShaolong Hu <shu@redhat.com>
Signed-off-by: NAmit Shah <amit.shah@redhat.com>
Signed-off-by: NAmit Shah <amit.shah@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Negative balloon values don't make sense, reject them and throw a qerror
with QERR_INVALID_PARAMETER_VALUE.
Reported-by: NMike Cao <bcao@redhat.com>
Signed-off-by: NAmit Shah <amit.shah@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>

Multiple balloon devices don't make sense; disallow more than one
registration attempt to register handlers.
Signed-off-by: NAmit Shah <amit.shah@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>

Signed-off-by: NAmit Shah <amit.shah@redhat.com>

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: NMike Cao <bcao@redhat.com>
Signed-off-by: NAmit Shah <amit.shah@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>

Replace:
  if (foo) {
    ...
  } else {
    return 0;
  }

by

  if (!foo) {
    return 0;
  }
  ...
Signed-off-by: NAmit Shah <amit.shah@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>

Signed-off-by: NAmit Shah <amit.shah@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>

balloon.h had function declarations for a couple of functions that are
local to balloon.c.  Make them static.

Drop the 'qemu_' prefix for balloon.c-local variables, and make them
static.
Signed-off-by: NAmit Shah <amit.shah@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>

Remove unused sysemu.h include directives to speed up build
with the following patches.
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

Signed-off-by: NPrerna Saxena <prerna@linux.vnet.ibm.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>