Re: [Qemu-devel] Regression: virtio-pci: convert to ioeventfd callbacks

[Cornelia Huck]

On Tue, 28 Jun 2016 09:47:01 +0200
Peter Lieven <address@hidden> wrote:

> The problem goes away, but its horribly slow. Maybe the lost notifications
> you were thinking off.

I have the following patch (works for me on ccw as well). I'm worried
about the slowness you're seeing, though. Is this just with an iscsi
backing?

From a62e1518fa9c8a68c27d6997d8ca8fccf6152d1e Mon Sep 17 00:00:00 2001
From: Cornelia Huck <address@hidden>
Date: Tue, 28 Jun 2016 10:04:52 +0200
Subject: [PATCH] virtio: deassign ioeventfd before resetting handler

We should unassign the transport's ioeventfd backing before
resetting the handler, or we may use notifications.

Pointed-out-by: Michael S. Tsirkin <address@hidden>
Reported-by: Peter Lieven <address@hidden>
Signed-off-by: Cornelia Huck <address@hidden>
---
 hw/virtio/virtio-bus.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/virtio/virtio-bus.c b/hw/virtio/virtio-bus.c
index 1313760..32fcc64 100644
--- a/hw/virtio/virtio-bus.c
+++ b/hw/virtio/virtio-bus.c
@@ -176,8 +176,8 @@ static int set_host_notifier_internal(DeviceState *proxy, 
VirtioBusState *bus,
             return r;
         }
     } else {
-        virtio_queue_set_host_notifier_fd_handler(vq, false, false);
         k->ioeventfd_assign(proxy, notifier, n, assign);
+        virtio_queue_set_host_notifier_fd_handler(vq, false, false);
         event_notifier_cleanup(notifier);
     }
     return r;
-- 
2.9.0