[libvirt-users] Usable and non-usable CPU models in nested virtualization
Hi, some custom CPU models are reported from
virConnectGetDomainCapabilities as usable='yes' on a physical machine
while as usable='no' inside a VM running on the same machine. That's
not completely surprising.
But what surprises me is that those models are still reported from
virConnectCompareCPU as supported (VIR_CPU_COMPARE_SUPERSET) in the
nested environment and VMs can be started happily with them.
For instance, virConnectGetDomainCapabilities reports
<model usable='no'>Skylake-Client</model>
but when I try to use that model anyway, the VM starts fine with it:
<cpu mode='custom' match='exact' check='full'>
<model fallback='forbid'>Skylake-Client</model>
<topology sockets='16' cores='1' threads='1'/>
<feature policy='require' name='hypervisor'/>
<feature policy='disable' name='invpcid'/>
<numa>
<cell id='0' cpus='0' memory='524288'
unit='KiB'/>
</numa>
</cpu>
That's actually good news, but unexpected. Do I miss something?
Thanks,
Milan