[SOLVED] Qemu 2.8.0-1 breaks virtio-net-pci networking

losko · 2017-01-02 20:21:54

Hello everyone,
I have a remote Archlinux host (I have a few actually), running Windows Server 2003 inside a Qemu/Kvm guest.
After latest qemu 2.8.0-1 update the guest became isolated, I can't ping from host to guest or even from guest to host...
Fortunately the guest is still administrable with spice.
For your information I'm using a tun/tap networking between host and guest, with the tap added to a bridge on the host side.

Here are the command line options I use for networking:

-device virtio-net-pci,netdev=net0,mac=52:54:12:34:56:00
-netdev type=tap,id=net0,ifname=tap0,script=no,downscript=no,vhost=on

If I replace "virtio-net-pci" with "rtl8139" everything works as expected, that's why I suspect virtio-net-pci is the problem.
However, downgrading to qemu 2.7.0-3 from archive.archlinux.org solved my problem.

Qemu's 2.8 changelog didn't mention substantial changes.
Is this a bug or I missed something?

Last edited by losko (2017-04-22 18:18:28)

qft · 2017-01-03 09:25:40

I run Windows Server 2016 as guest on qemu/kvm 2.8. I use similar command line options for network as you do, and I didn't notice any problem with network. Do you get IP address in your guest?

R00KIE · 2017-01-03 10:25:54

I use virtio-net-pci but use it to with a bridge and I'm not specifying a mac address and I see no breakage. Do you get any warnings on the console when your start qemu? For debugging you could try to simplify as much as possible to try to find out which option is causing problems, there isn't much to simplify there but I would try removing the mac address part and see if it improves anything.

losko · 2017-01-03 10:25:56

@qft
Static IP.
Only pinging with nmap shows the guest "up".

Last edited by losko (2017-01-03 10:26:39)

losko · 2017-01-03 13:29:10

R00KIE wrote:

I use virtio-net-pci but use it to with a bridge and I'm not specifying a mac address and I see no breakage. Do you get any warnings on the console when your start qemu? For debugging you could try to simplify as much as possible to try to find out which option is causing problems, there isn't much to simplify there but I would try removing the mac address part and see if it improves anything.

Yes, I can confirm, Windows 7 and Windows 10 guests are OK, I tested myself.
AFAIK only Windows Server 2003 guests are affected... two different VMs running this old crap in two different locations showed the same behavior.
Skipping package update with "IgnorePkg=qemu qemu-arch-exra" in /etc/pacman.conf is my temporary solution.
No warnings on start however...

Last edited by losko (2017-01-03 13:32:24)

lightdot · 2017-01-09 05:43:29

I just noticed what might as well be a same problem, only in this case the guest is Windows 7.

So, loss of guest network connectivity, no ping from host to guest or the other way around.

The VM is using a bridge (added with a qemu hook script when starting the VM, removed when stopping) and a TAP device. Custom routing and a static IP is used, the virtio device has a MAC. This same configuration has worked flawlessly for years.

For anyone else needing a quick fix, I can confirm downgrading qemu from 2.8.0-1 back to 2.7.0-3 solves the issue.

I'll do some more tests when I can.

losko · 2017-04-22 18:17:16

Fixed with qemu 2.9.0 now in [testing].

Arch Linux

#1 2017-01-02 20:21:54

[SOLVED] Qemu 2.8.0-1 breaks virtio-net-pci networking

#2 2017-01-03 09:25:40

Re: [SOLVED] Qemu 2.8.0-1 breaks virtio-net-pci networking

#3 2017-01-03 10:25:54

Re: [SOLVED] Qemu 2.8.0-1 breaks virtio-net-pci networking

#4 2017-01-03 10:25:56

Re: [SOLVED] Qemu 2.8.0-1 breaks virtio-net-pci networking

#5 2017-01-03 13:29:10

Re: [SOLVED] Qemu 2.8.0-1 breaks virtio-net-pci networking

#6 2017-01-09 05:43:29

Re: [SOLVED] Qemu 2.8.0-1 breaks virtio-net-pci networking

#7 2017-04-22 18:17:16

Re: [SOLVED] Qemu 2.8.0-1 breaks virtio-net-pci networking

Board footer