[vfio-users] Lost link when pass through rtl8168 to guest

[Wei Xu]

Hi Guys,
I'm trying to pass through a rtl8168 nic to linux guest on my laptop 
recently, the link is directly connected to my notebook with a cable.

qemu: 2.7.0-rc4
host/guest kernel: 4.7.0-rc5
driver name: r8169

After binding the driver to vfio-pci and launching the VM for a few 
seconds, the connection led on the nic was turned off, and the guest
only see a link down nic with below messages.

[    6.173188] r8169 0000:00:04.0 ens4: rtl_phy_reset_cond == 1 (loop: 
100, delay: 1).
[    6.177234] r8169 0000:00:04.0 ens4: link down
[    6.177592] r8169 0000:00:04.0 ens4: link down
[    6.177889] IPv6: ADDRCONF(NETDEV_UP): ens4: link is not ready


It's quite similar as below bug except it's for windows driver while
i'm testing linux.

https://bugs.launchpad.net/qemu/+bug/1384892


More info:
My vm image is a pre-installed fedora 22 desktop, i also tried a fresh 
fedora live iso, looks it can load the driver correctly.

I tried to disable auto negotiation for the link but it didn't work for me.

I did the same test with my notebook with a Intel I218-LM ethernet 
controller, it works pretty well every time.

I googled around and looks it happened to bare metal too, so just wonder
if this is a bug of network-manager, or is being caused by the nic 
driver or an issue in qemu/kernel vfio, anybody can help?

Thanks,
Wei