[virt-tools-list] possible bug in passing host cpu configuration

[Cole Robinson]

On 11/08/2015 10:37 AM, LK wrote:
> Hi,
> 
> I have banged my head for a few days on a problem with a virtual machine
> configuration.
> 
> I want to use Nested Virtualization, but virt-manager did not let me to pass
> the host cpu configuration (I checked the "Copy host CPU configuration").
> 
> After countless tests I was giving up (I also tried to modify manually the xml
> file in /etc/libvirt/qemu/vm.xml), but as last attempt I discarded
> virt-manager and used virsh instead.
> 
> I modified the configuration of the VM (virsh edit vm) and added this cpu
> configuration:
> 
> ###########
> <cpu mode='host-passthrough'>
> </cpu>
> ###########
> 
> I saved the configuration and launched the VM and finally the guest operating
> system (proxmox4) shows me that it can use the nested virtualization.
> 
> I'm using as host Fedora 23 x86_64 and virt-manager  1.2.1.
> 
> The funny thing is that after configuring the VM using virsh edit, now
> virt-manager retain the correct configuration.
> 

Yes, for some reason mode=host-model isn't sufficient for virt passthrough on
some machines. We don't expose host-passthrough in the UI because it's not
generally recommended for libvirt usage since we can't insulate the VM from
qemu logic changes. But you can specify it in the UI by manually entering
host-passthrough in the CPU model field

- Cole