Commit Graph

9 Commits

Author SHA1 Message Date
Amit Shah 6c6ec1821a balloon: Don't allow multiple balloon handler registrations
Multiple balloon devices don't make sense; disallow more than one
registration attempt to register handlers.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
2011-08-04 16:43:09 -05:00
Amit Shah 30fb2ca603 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>
2011-08-04 16:43:09 -05:00
Amit Shah 0a2a30d5ad balloon: Make functions, local vars static
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: Amit Shah <amit.shah@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
2011-08-04 16:43:08 -05:00
Paolo Bonzini 28c2897373 move balloon handling to balloon.c
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
2010-04-09 18:55:56 +02:00
Blue Swirl 1c14f162dd Allow various header files to be included from non-CPU code
Allow balloon.h, gdbstub.h and kvm.h to be included from
non-CPU code.

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2010-03-29 19:23:47 +00:00
Adam Litke 625a5befc2 virtio: Add memory statistics reporting to the balloon driver
When using ballooning to manage overcommitted memory on a host, a system for
guests to communicate their memory usage to the host can provide information
that will minimize the impact of ballooning on the guests.  The current method
employs a daemon running in each guest that communicates memory statistics to a
host daemon at a specified time interval.  The host daemon aggregates this
information and inflates and/or deflates balloons according to the level of
host memory pressure.  This approach is effective but overly complex since a
daemon must be installed inside each guest and coordinated to communicate with
the host.  A simpler approach is to collect memory statistics in the virtio
balloon driver and communicate them directly to the hypervisor.

Signed-off-by: Adam Litke <agl@us.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2010-01-26 17:08:03 -06:00
Anthony Liguori c227f0995e Revert "Get rid of _t suffix"
In the very least, a change like this requires discussion on the list.

The naming convention is goofy and it causes a massive merge problem.  Something
like this _must_ be presented on the list first so people can provide input
and cope with it.

This reverts commit 99a0949b72.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-10-01 16:12:16 -05:00
malc 99a0949b72 Get rid of _t suffix
Some not so obvious bits, slirp and Xen were left alone for the time
being.

Signed-off-by: malc <av1474@comtv.ru>
2009-10-01 22:45:02 +04:00
aliguori d096ab91c9 Add missing file from previous commit.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>



git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5875 c046a42c-6fe2-441c-8c8c-71466251a162
2008-12-04 20:35:16 +00:00