Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru> writes:
For now we only log the vhost device error, when virtqueue is actually
stopped. Let's add a QAPI event, which makes possible:
- collect statistics of such errors
- make immediate actions: take core dumps or do some other debugging
- inform the user through a management API or UI, so that (s)he can
react somehow, e.g. reset the device driver in the guest or even
build up some automation to do so
Note that basically every inconsistency discovered during virtqueue
processing results in a silent virtqueue stop. The guest then just
sees the requests getting stuck somewhere in the device for no visible
reason. This event provides a means to inform the management layer of
this situation in a timely fashion.
The event could be reused for some other virtqueue problems (not only
for vhost devices) in future. For this it gets a generic name and
structure.
We keep original VHOST_OPS_DEBUG(), to keep original debug output as is
here, it's not the only call to VHOST_OPS_DEBUG in the file.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Denis Plotnikov <den-plotnikov@yandex-team.ru>
[...]
diff --git a/qapi/qdev.json b/qapi/qdev.json
index 6bc5a733b8..55d6c9018e 100644
--- a/qapi/qdev.json
+++ b/qapi/qdev.json
@@ -161,3 +161,31 @@
##
{ 'event': 'DEVICE_UNPLUG_GUEST_ERROR',
'data': { '*device': 'str', 'path': 'str' } }
+
+##
+# @VirtqueueError:
+#
+# @vhost-vring-error: Vhost device reported failure through
+# through vring error fd.
+#
+# Since: 8.2
+##
+{ 'enum': 'VirtqueueError',
+ 'data': [ 'vhost-vring-error' ] }
+
+##
+# @VIRTQUEUE_ERROR:
+#
+# Emitted when a device virtqueue fails in runtime.
+#
+# @device: the device's ID if it has one
+# @path: the device's QOM path
+# @virtqueue: virtqueue index
+# @error: error identifier
+# @description: human readable description
Please add blank lines between the @argument sections, to blend in with
recent commit a937b6aa739 (qapi: Reformat doc comments to conform to
current conventions).
+#
+# Since: 8.2
+##
+{ 'event': 'VIRTQUEUE_ERROR',
+ 'data': { '*device': 'str', 'path': 'str', 'virtqueue': 'int',
+ 'error': 'VirtqueueError', 'description': 'str'} }
With that:
Acked-by: Markus Armbruster <armbru@redhat.com>