[regression] virtio net locks up

[Bernd Schubert <bernd.schubert@itwm.fraunhofer.de>]

No idea what is going on, but recent kernels lock up here after 
transferring some amount of data. So far I only know that 2.6.32 is the 
last working kernel I have tested and 3.0 is the first non-working 
version I tested.

How to reproduce:

vm1: iperf  -c vm2
vm2: iperf -s vm1

After some time either of both VMs cannot be pinged anymore, neither 
from host nor from the other (still working) VM. Direct access of the 
non-net-working vm via console still works fine.


Also not important if I run with vhost on or off, in both modes it fails.

qemu-kvm version is 1.0.

Here's my qemu-kvm start-up script:

> #! /bin/bash
>
> source  ~/bin/kvm-config.sh
>
> iface=`sudo tunctl -b -u $USER`
> FILE=${IMAGE_DIR}/squeeze1.img
> #NICMODEL=e1000
> NICMODEL=virtio
>
>
> DISKIF=virtio
> #DISKIF=ide
> #DISKIF=scsi
>
> ${kvm}                                                                  \
>         -m 4096                                                         \
>         -net nic,macaddr=52:54:00:12:34:11,model=${NICMODEL}            \
>         -net tap,id=foo,script=${HOME}/bin/kvm-ifup,downscript=${HOME}/bin/kvm-ifdown,ifname=$iface,vhost=on                    \
>         -boot c                                                         \
>         -drive file=${FILE},if=${DISKIF},boot=on,cache=writeback        \
>         ${common_opts}                                                  \
>         "$@"
>
> sudo /usr/sbin/tunctl -d $iface



Any idea what is going on or how to debug it?


Thanks,
Bernd