VMM + OVS Error creating macvtap interface ~ Device or resource busy

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NoctisLucisCaelum
Posts: 1
Joined: 2018/01/24 08:12:22

VMM + OVS Error creating macvtap interface ~ Device or resource busy

Post by NoctisLucisCaelum » 2018/01/24 08:28:18

Hello, thanks for your attention.

I would like to request support for a simple implementation (I believe) that is giving me a nasty time (thanks to OVS esoteric documentation).

I have created 7 Virtual Machines using CentOS Virtual Machine Manager (v1.4.1) and want to connect them all to an OpenVSwitch (v2.5.2/DB Schema 7.12.1) for SDN purposes.

I installed OpenVSwitch following this very useful guide: https://gist.github.com/umardx/a31bf6a1 ... ca33133834

And later on I deployed and OVS bridge with 7 vports to each one of the Virtual Machines that I want to control its traffic. I followed this very clear guide on how to do it: https://www.youtube.com/watch?v=rYW7kQRyUvA . I must mention that I skipped the configuration of linking the eht0 interface to the "mybridge" since I do not want my VM to have access to the "outside".

I did not encounter any issue while following the previous two guides, but when I try to start any of the 7 virtual machines I get the following error (copy from a particular VM):

Error starting domain: error creating macvtap interface macvtap0@vport6 (52:54:00:38:63:68): Device or resource busy

Traceback (most recent call last):
File "/usr/share/virt-manager/virtManager/asyncjob.py", line 88, in cb_wrapper
callback(asyncjob, *args, **kwargs)
File "/usr/share/virt-manager/virtManager/asyncjob.py", line 124, in tmpcb
callback(*args, **kwargs)
File "/usr/share/virt-manager/virtManager/libvirtobject.py", line 83, in newfn
ret = fn(self, *args, **kwargs)
File "/usr/share/virt-manager/virtManager/domain.py", line 1489, in startup
self._backend.create()
File "/usr/lib64/python2.7/site-packages/libvirt.py", line 1039, in create
if ret == -1: raise libvirtError ('virDomainCreate() failed', dom=self)
libvirtError: error creating macvtap interface macvtap0@vport6 (52:54:00:38:63:68): Device or resource busy


So far I've tried cloning one of the VMs to see if the issue could have been because I added the interface after the VM was created, but wit no success.

I would like to kindly request advice/support for this error. I appreciate in advance your feedback, and apologize if I have posted this in the wrong category of the forum.

rbennell
Posts: 1
Joined: 2018/08/01 16:36:07

Re: VMM + OVS Error creating macvtap interface ~ Device or resource busy

Post by rbennell » 2018/08/01 16:41:03

I had the exact same issue. I'm not going to pretend to understand the cause, but creating the interfaces using network scripts instead of using tuntap on the command line seemed to resolve it for me. I found this link for help on creating the correct network scripts. http://prolinuxhub.com/configure-start- ... d-red-hat/

so my scripts for example were:

DEVICE=br0
BOOTPROTO=none
IPADDR=10.0.0.2
PREFIX=24
ONBOOT=yes
TYPE=OVSBridge
DEVICETYPE=ovs

TYPE=Ethernet
NAME=enp0s31f6
DEVICE=enp0s31f6
ONBOOT=yes
OVS_BRIDGE=br0
TYPE=OVSPort
DEVICETYPE=ovs

DEVICE=tap0
ONBOOT=yes
OVS_BRIDGE=br0
DEVICETYPE=ovs
TYPE=OVSIntPort

which resulted in

ovs-vsctl show
Bridge "br0"
Port "br0"
Interface "br0"
type: internal
Port "enp0s31f6"
Interface "enp0s31f6"
Port "tap0"
Interface "tap0"
type: internal

I hope this helps!

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