KVM: 0.130
other: 0.090
network: 0.085
device: 0.084
semantic: 0.076
boot: 0.073
PID: 0.067
socket: 0.064
permissions: 0.062
files: 0.057
graphic: 0.056
vnc: 0.055
debug: 0.054
performance: 0.049
KVM: 0.827
debug: 0.044
other: 0.031
PID: 0.016
semantic: 0.012
device: 0.012
network: 0.011
files: 0.011
socket: 0.009
vnc: 0.008
performance: 0.005
boot: 0.005
permissions: 0.005
graphic: 0.004

attach-interface - unexpected action

Hello,

Not sure where to report this, or if it is a bug. However, I feel like the behaviour is not what would/should be expected.

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Environment:
KVM Version:		root@hostname:~# virsh version
      			Compiled against library: libvirt 1.2.9
			Using library: libvirt 1.2.9
			Using API: QEMU 1.2.9
			Running hypervisor: QEMU 2.1.2
uname -a:		Linux hostname 3.16.0-4-amd64 #1 SMP Debian 3.16.39-1+deb8u2 (2017-03-07) x86_64 GNU/Linux
CPU:			Intel(R) Xeon(R) CPU E3-1240 V2 @ 3.40GHz
Host Debian Version:	8.7 (Jessie)
Guest Debian Version:	8.7 (Jessie)

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Issue:
When adding an interface to a live VM, the position of interfaces within the VM may change post reboot.
It appears a new interface takes up the first available “pci slot”. If you have removed an interface in the past, this will be the one that is taken up.

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Example:

If the VM Has the following interfaces layout:

eth0  HWaddr 00:00:00:00:00:00
eth1  HWaddr 11:11:11:11:11:11
eth2  HWaddr 22:22:22:22:22:22
eth3  HWaddr 33:33:33:33:33:33

Now I delete the interface with MAC address 11:11:11:11:11:11, you now have this:

eth0  HWaddr 00:00:00:00:00:00
eth1  HWaddr 22:22:22:22:22:22
eth2  HWaddr 33:33:33:33:33:33

And then you add a new interface with MAC address 44:44:44:44:44:44, using virsh:

virsh attach-interface --domain guest --type bridge --source br3 --mac 44:44:44:44:44:44 --model e1000 --target vmeth3 --live --persistent

It will now look like this:

eth0  HWaddr 00:00:00:00:00:00
eth1  HWaddr 22:22:22:22:22:22
eth2  HWaddr 33:33:33:33:33:33
eth3  HWaddr 44:44:44:44:44:44

However, after a reboot, it will look like this:

eth0  HWaddr 00:00:00:00:00:00
eth1  HWaddr 44:44:44:44:44:44
eth2  HWaddr 22:22:22:22:22:22
eth3  HWaddr 33:33:33:33:33:33 

This can be a problem, as /etc/network/interfaces file, etc., will be pointing to the wrong interfaces. I.E. originally eth1 was connected to br1 (for example), after reboot eth1 is now connected to br3.

To resolve this issue, I need to edit the .xml file in the KVM machine, and edit the following lines:

      <address type='pci' domain='0x0000' bus='0x00' slot='0x0c' function='0x0'/>

Changing these into the order I want them to be loaded in, i.e. eth0, eth1, eth2…. (I know 4 are taken already and not usable by ethernet interfaces.)

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Thanks in advance.

Kind regards,

Aaron Doyle

Looking through old bug tickets ... Have you tried to discuss this issue with the libvirt people? They might need to have a look at your virsh commands first before one could decide whether this is a libvirt or a qemu problem...

[Expired for QEMU because there has been no activity for 60 days.]