What were you trying to do that didn't work?

iperf transfer guest to host or guest to external with extremely short packet length (2 bytes, for example)

under various conditions can be reproduced also with larger packets even with 32 bytes

Please provide the package NVR for which bug is seen:

virtio-win build 239

How reproducible:

close to 100%

Steps to reproduce

1. start qemu with q35 and virtio-net with 1 queue (I used 8G and 4 CPU)
2.  run iperf server on the host or on the external host 
3. run "iperf -c <host> -l 2 -t 60"
4. on both sides the connection drops, the server prints "recv error: ...", the client "write error: ..."
5. If the problem does not happen, increase number of streams

Expected results, Actual results

Obvious

Note

This happens due to overfragmentation (in terms of memory fragments) of the transmitted packet (we can handle max of 256 fragments, but can receive more). The driver should be stable even in such scenario