libvirt users - Mar 2020 - Ovs error when starting vm: ovs-vsctl: 'del-port' command requires at least 1 arguments

Hi,

my system got updated to libvirt 6.0.0 (from 5.6.0) this morning, and
now I'm having problems starting VMs that make use of openvswitch
portgroups.

When I start a VM, I get this error message on virsh:
> virsh # start testvm
> error: Failed to start domain testvm
> error: An error occurred, but the cause is unknown
The system log contains:
> Mar 30 09:45:39 tplinux ovs-vsctl[2763]:
ovs|00001|db_ctl_base|ERR|'del-port' command requires at least 1
arguments
> Mar 30 09:45:39 tplinux libvirtd[735]: internal error: Child process
(ovs-vsctl --timeout=5 -- --if-exists del-port) unexpected exit status 1:
ovs-vsctl: 'del-port' command requires at least 1 arguments
> Mar 30 09:45:39 tplinux libvirtd[735]: internal error: Unable to delete
port (null) from OVS
My network "test-net" looks like:
> <network>
>   <name>test-net</name>
>   <forward mode='bridge'/>
>   <bridge name='test-net'/>
>   <virtualport type='openvswitch'/>
>   <portgroup name='fabric' default='yes'>
>     <vlan trunk='yes'>
>       <tag id='10' nativeMode='untagged'/>
>       <tag id='20'/>
>       <tag id='30'/>
>       <tag id='40'/>
>       <tag id='50'/>
>       <tag id='60'/>
>       <tag id='70'/>
>     </vlan>
>   </portgroup>
> </network>
And the network in the domain xml file is:
>     <interface type='network'>
>       <mac address='01:23:45:67:89:ab'/>
>       <source network='test-net' portgroup='fabric'/>
>       <model type='e1000'/>
>       <address type='pci' domain='0x0000'
bus='0x00' slot='0x04' function='0x0'/>
>     </interface>
I didn't see any change in the changelog related to ovs or portgroups.
Is there something I need to change in my VM definition?

Thanks,
Thomas

On 30. 3. 2020 11:10, Thomas Pircher wrote:
> Hi,
> 
> my system got updated to libvirt 6.0.0 (from 5.6.0) this morning, and
> now I'm having problems starting VMs that make use of openvswitch
> portgroups.
I don't see any changes between 5.6.0 and now done to openvswitch in
libvirt (apart from harmless code reworks towards glib).
> 
> When I start a VM, I get this error message on virsh:
>> virsh # start testvm
>> error: Failed to start domain testvm
>> error: An error occurred, but the cause is unknown
I suspect this is the problem. Something fails during startup (I think
it's creating the TAP device which fails) and later, when clearing up
then NULL is passed as "generated" TAP device name. But this is just
my
guess, because I'm unable to reproduce.

But in order to confirm, we need to trace the domain command line
generation process. Can you attach debugger to libvirtd, set a break
point on virNetDevTapCreateInBridgePort() and step through it to find
which function fails, please?

Can you please turn on debug logs and share them?

https://wiki.libvirt.org/page/DebugLogs

Michal

Michal Prívozník wrote:
> Can you please turn on debug logs and share them?
>
> https://wiki.libvirt.org/page/DebugLogs
Thanks for replying, I have downgraded libvirt back to version 5.6.0
(and VMs were again able to start), but I will try to reproduce the
problem on another machine in the next few days and post the logs here.

Thanks,
Thomas