[vfio-users] sriov on network card and sharing interfaces with host

[Torbjorn Jansson]

Hello

on my box with the i350-t2v2 network card i tried something that didn't quite 
work the way i had hoped.

the i350 card have 2 physical interfaces and i have setup both with sriov and 
this works fine with my vms, i can assign a VF to each vm and it works.

since most of the time those two physical interfaces will be lightly loaded i 
figured i could make use of them on the host as well, currently the physical 
interfaces on the host got no ip assigned so they are completely unused by host 
and only used via VFs on the vms.

what i did was:
with one vm running for testing purposes i assigned created a lacp bond of the 
two physical interfaces.
this didn't work out at all, as i remember it it worked fine for the host but 
the running vm lost network connection.

then when i tried to remove everything and put things back the way it was all 
network interfaces including the other 2 built in to the main board stopped 
working (they were never part of the bond or even touched by me)
so i had to plugin screen and keyboard and logon localy to properly remove the 
bond and put things back again.


so my questions then are:

when you have sriov running on a network card, can you share this with the 
host? or am i just stupid for even considering it?

whats the best way to do it?
use the physical interfaces on host or fiddle around with the VFs via sysfs so 
i get 1 VF on each physical interface on the host loaded with proper module 
instead of vfio-pci and the use the 2 VFs on the host?

i guess i could also ignore the bonding completely and use either physical or 
VF on host directly.

another thing i'm a bit curious about is if i use VF on the host, will i then 
be able to communicate between vm and host that shares VFs on the same physical 
interface?
i know when you use things like macvtap (or was it macvlan or similar) you can 
communicate with everything except for the host which in my case is a bit 
problematic.