Unable to establish TCP sessions between guests using virtio-net on Linux 3.12 and above

[Peter Kieser <peter@kieser.ca>]

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Hello,

Kernel versions tested: 3.13, 3.14, 3.15
Related debian bug report: 
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=738863

I'm not sure if this is a problem specific to openvswitch or KVM. I have 
a network setup where I have one openvswitch bridge setup, with various 
ports with VLAN tags and a firewall running as a guest. After upgrading 
to Linux 3.13, all guests with virtio interfaces with TSO enabled (the 
default) are unable to establish TCP connections via the guest firewall. 
ICMP ping works fine. If I disable TSO on the vnet interfaces (as 
outlined in the bug report above) guests are then able to communicate 
with each other.

Is there a patch for this issue that hasn't made it into mainline that I 
should test out? Is this an issue specific to KVM, or is it an 
openvswitch issue?

Than kyou,

-Peter


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