virtio_net hang

[Emmanuel Lacour <elacour@easter-eggs.com>]

Dear kvm users/developpers,

I have a problem here where the network interface of a guest hang
2 or 3 times a day. No more packets can be sent out or received, no
error in guest or host logs. I have to stop networking, remove module,
then modprobe again and start the network to get back connection.

My setup:
host: debian etch, kernel 2.6.26 amd64 (etch backports), kvm 73, using
libvirt
guest: debian sarge, kernel 2.6.26 686 (from etch backports)


I looked at changelogs for userspace kvm tools as well as kernel but didn't
found something relevant to this problem.


Any help would be welcome :)


the guest config:

<domain type='kvm' id='7'>
  <name>bar</name>
  <uuid>8055f2fc-df9d-0ec2-9707-283ca503eb95</uuid>
  <memory>4194304</memory>
  <currentMemory>4194304</currentMemory>
  <vcpu>2</vcpu>
  <os>
    <type>hvm</type>
    <boot dev='hd'/>
  </os>
  <features>
    <acpi/>
  </features>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>destroy</on_crash>
  <devices>
    <emulator>/usr/bin/kvm</emulator>
    <disk type='block' device='disk'>
      <source dev='/dev/vg_foo/vm_bar'/>
      <target dev='hda' bus='ide'/>
    </disk>
    <disk type='file' device='cdrom'>
      <source file='/var/lib/kvm/isos/debian-31r0-i386-netinst.iso'/>
      <target dev='hdc' bus='ide'/>
      <readonly/>
    </disk>
    <interface type='bridge'>
      <mac address='00:16:3e:02:00:15'/>
      <source bridge='br0'/>
      <target dev='tap5'/>
      <model type='virtio'/>
    </interface>
    <input type='mouse' bus='ps2'/>
    <graphics type='vnc' port='5905' listen='127.0.0.1' keymap='fr'/>
  </devices>
</domain>