diff options
| author | Daniel P. Berrange <berrange@redhat.com> | 2012-06-14 18:12:56 +0100 |
|---|---|---|
| committer | Luiz Capitulino <lcapitulino@redhat.com> | 2012-06-15 13:34:50 -0300 |
| commit | 973603a813c5d60534b4fa0313f83be40e2b9c47 (patch) | |
| tree | d9b07f5d7457b67b309537884c3b80de3a8022cc /hw | |
| parent | 395c3b80bb48c0e1cbce3436e63af3650cc46d1a (diff) | |
Add event notification for guest balloon changes
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: Daniel P. Berrange <berrange@redhat.com>
Acked-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Diffstat (limited to 'hw')
| -rw-r--r-- | hw/virtio-balloon.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/hw/virtio-balloon.c b/hw/virtio-balloon.c index 075ed87e37..d048cef50f 100644 --- a/hw/virtio-balloon.c +++ b/hw/virtio-balloon.c @@ -146,8 +146,13 @@ static void virtio_balloon_set_config(VirtIODevice *vdev, { VirtIOBalloon *dev = to_virtio_balloon(vdev); struct virtio_balloon_config config; + uint32_t oldactual = dev->actual; memcpy(&config, config_data, 8); dev->actual = le32_to_cpu(config.actual); + if (dev->actual != oldactual) { + qemu_balloon_changed(ram_size - + (dev->actual << VIRTIO_BALLOON_PFN_SHIFT)); + } } static uint32_t virtio_balloon_get_features(VirtIODevice *vdev, uint32_t f) |