[Qemu-devel] [PATCH] virtio-net: unbreak the minix guest

[Jason Wang]

Multiqueue patchset conditionally add control vq only when guest negotiate the
feature. Though the spec is not clear on this but it breaks the minix guest
since it will identify the ctrl vq even if it does not support it. Though this
behavior seems a violation on the spec "If the VIRTIO_NET_F_CTRL_VQ feature bit
is negotiated, identify the control virtqueue.", to keep the backward
compatibility, always add the ctrl vq at end of the queues.

Also remove the meaningless ctrl_vq initialization and vq deletion.

Reported-by: Aurelien Jarno <address@hidden>
Cc: Aurelien Jarno <address@hidden>
Signed-off-by: Jason Wang <address@hidden>
---
 hw/net/virtio-net.c |    9 ++++-----
 1 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 4d2cdd2..1068f4e 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -1045,7 +1045,7 @@ static void virtio_net_set_multiqueue(VirtIONet *n, int 
multiqueue, int ctrl)
 
     n->multiqueue = multiqueue;
 
-    for (i = 2; i <= n->max_queues * 2 + 1; i++) {
+    for (i = 2; i <= n->max_queues * 2; i++) {
         virtio_del_queue(vdev, i);
     }
 
@@ -1067,9 +1067,9 @@ static void virtio_net_set_multiqueue(VirtIONet *n, int 
multiqueue, int ctrl)
         n->vqs[i].n = n;
     }
 
-    if (ctrl) {
-        n->ctrl_vq = virtio_add_queue(vdev, 64, virtio_net_handle_ctrl);
-    }
+    /* Some guest (e.g minix) may identifiy ctrl vq even if it does not
+     * support. */
+    n->ctrl_vq = virtio_add_queue(vdev, 64, virtio_net_handle_ctrl);
 
     virtio_net_set_queues(n);
 }
@@ -1317,7 +1317,6 @@ static int virtio_net_device_init(VirtIODevice *vdev)
                                            virtio_net_handle_tx_bh);
         n->vqs[0].tx_bh = qemu_bh_new(virtio_net_tx_bh, &n->vqs[0]);
     }
-    n->ctrl_vq = virtio_add_queue(vdev, 64, virtio_net_handle_ctrl);
     qemu_macaddr_default_if_unset(&n->nic_conf.macaddr);
     memcpy(&n->mac[0], &n->nic_conf.macaddr, sizeof(n->mac));
     n->status = VIRTIO_NET_S_LINK_UP;
-- 
1.7.1