vhost-user interrupt management fixes

Since guest_mask_notifier can not be used in vhost-user mode due
to buffering implied by unix control socket, force
use_mask_notifier on virtio devices of vhost-user interfaces, and
send correct callfd to the guest at vhost start.

Using guest_notifier_mask function in vhost-user case may
break interrupt mask paradigm, because mask/unmask is not
really done when returning from guest_notifier_mask call, instead
message is posted in a unix socket, and processed later.

Add an option boolean flag 'use_mask_notifier' to disable the use
of guest_notifier_mask in virtio pci.

Signed-off-by: Didier Pallard <didier.pallard@6wind.com>
Signed-off-by: Victor Kaplansky <victork@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 13 insertions, 2 deletions

diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
index b242832..6e1032f 100644
--- a/hw/net/vhost_net.c
+++ b/hw/net/vhost_net.c
@@ -284,8 +284,19 @@ int vhost_net_start(VirtIODevice *dev, NetClientState *ncs,
     }
 
     for (i = 0; i < total_queues; i++) {
-        vhost_net_set_vq_index(get_vhost_net(ncs[i].peer), i * 2);
-    }
+        struct vhost_net *net;
+
+        net = get_vhost_net(ncs[i].peer);
+        vhost_net_set_vq_index(net, i * 2);
+
+        /* Suppress the masking guest notifiers on vhost user
+         * because vhost user doesn't interrupt masking/unmasking
+         * properly.
+         */
+        if (net->nc->info->type == NET_CLIENT_OPTIONS_KIND_VHOST_USER) {
+                dev->use_guest_notifier_mask = false;
+        }
+     }
 
     r = k->set_guest_notifiers(qbus->parent, total_queues * 2, true);
     if (r < 0) {