qemu-kvm/kvm-virtio-net-setup-vhost_dev-and-notifiers-for-cvq-onl.patch

From bc307149fe4e3fe2a3e0ac52534383c955051e7e Mon Sep 17 00:00:00 2001
From: Si-Wei Liu <si-wei.liu@oracle.com>
Date: Fri, 6 May 2022 19:28:12 -0700
Subject: [PATCH 14/24] virtio-net: setup vhost_dev and notifiers for cvq only
 when feature is negotiated
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RH-Author: Jason Wang <jasowang@redhat.com>
RH-MergeRequest: 187: Multiqueue fixes for vhost-vDPA
RH-Commit: [1/7] 38bcfaa661f437b3dfa6b6f152dffd60073dc054
RH-Bugzilla: 2069946
RH-Acked-by: Eugenio Pérez <eperezma@redhat.com>
RH-Acked-by: Cindy Lu <lulu@redhat.com>
RH-Acked-by: Laurent Vivier <lvivier@redhat.com>

When the control virtqueue feature is absent or not negotiated,
vhost_net_start() still tries to set up vhost_dev and install
vhost notifiers for the control virtqueue, which results in
erroneous ioctl calls with incorrect queue index sending down
to driver. Do that only when needed.

Fixes: 22288fe ("virtio-net: vhost control virtqueue support")
Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <1651890498-24478-2-git-send-email-si-wei.liu@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit aa8581945a13712ff3eed0ad3ba7a9664fc1604b)
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 hw/net/virtio-net.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index e1f4748831..ec045c3f41 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -244,7 +244,8 @@ static void virtio_net_vhost_status(VirtIONet *n, uint8_t status)
     VirtIODevice *vdev = VIRTIO_DEVICE(n);
     NetClientState *nc = qemu_get_queue(n->nic);
     int queue_pairs = n->multiqueue ? n->max_queue_pairs : 1;
-    int cvq = n->max_ncs - n->max_queue_pairs;
+    int cvq = virtio_vdev_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ) ?
+              n->max_ncs - n->max_queue_pairs : 0;
 
     if (!get_vhost_net(nc->peer)) {
         return;
-- 
2.35.3