[Qemu-devel] Network traffic stuck in QEMU IO path?

[Fischer, Anna]

Hi,

I'm running qemu-kvm-0.12.1.2. I know it is an old version, but I hope people 
can still help me with this.

I run a VIF for my virtual machine with the following settings in the qemu 
command:

-netdev tap,ifname=vif-0-3, ,id=hostnet0 -device 
e1000,netdev=hostnet0,id=net0,mac=52:54:99:ff:15:14,bus=pci.0,addr=0x3

In parallel I do the same with using virtio-net instead of e1000 and it doesn't 
make a difference to my problem.

The problem is the following:
For a few hours my VM runs just fine and networking and everything else works. 
Then suddenly the VIF seems to hang. I transmit packets from inside the VM, and 
on the VM's networking interface (eth0) I can see the packet TX counter 
increasing. However, on the host side where vif-0-3 resides, I don't see the 
packet RX counter increasing at all anymore. Now I wonder, where do my packets 
get lost, when they definitely are transmitted on the guest interface, but 
don't show up at all on the host VIF? This only ever happens in this direction 
(packets transmitted from the guest), but never the other way round (packets 
are still being received on the guest).

Has anyone ever seen this? Is this a known bug of my QEMU version?

Thanks for your help.

Anna