[BUG] vhost-vdpa: qemu-system-s390x crashes with second virtio-net-ccw device

[Cornelia Huck]

When I start qemu with a second virtio-net-ccw device (i.e. adding
-device virtio-net-ccw in addition to the autogenerated device), I get
a segfault. gdb points to

#0  0x000055d6ab52681d in virtio_net_get_config (vdev=<optimized out>, 
    config=0x55d6ad9e3f80 "RT") at /home/cohuck/git/qemu/hw/net/virtio-net.c:146
146         if (nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_VDPA) {

(backtrace doesn't go further)

Starting qemu with no additional "-device virtio-net-ccw" (i.e., only
the autogenerated virtio-net-ccw device is present) works. Specifying
several "-device virtio-net-pci" works as well.

Things break with 1e0a84ea49b6 ("vhost-vdpa: introduce vhost-vdpa net
client"), 38140cc4d971 ("vhost_net: introduce set_config & get_config")
works (in-between state does not compile).

This is reproducible with tcg as well. Same problem both with
--enable-vhost-vdpa and --disable-vhost-vdpa.

Have not yet tried to figure out what might be special with
virtio-ccw... anyone have an idea?

[This should probably be considered a blocker?]