Betreff: Cluster CPU Model setting - EVC like setting

[jayst136]

i noticed my cluster is defaulting to CPU model "host passthrough". 

On my nodes,  "virsh capabilities | grep -i model" shows:
<model>Skylake-Server-IBRS</model>

I don't know what this configuration means for the CPU features presented. What does "host-passthrough" actually do?

[u34666]

This is correct, the default cluster setting is "host passthrough".

My understanding is: host-passthrough, allows virtual machines to utilize the native capabilities of the underlying host CPU at power-on, without applying any CPU feature masking.

In your case the VM would see Skylake-Server-IBRS CPU features. 

[jayst136]

that would make sense but i read a few other posts here that contradict that in my opinion. What would this setting do when i have 2 types of CPU's in my cluster for example?

[u34666]

The lowest value (oldest generation). Otherwise you can't "Live Migrate" a VM that has been started on a host with a newer generation to a host that has an older generation.