Criteria used to allow or not live migration

Hello, I would like to know what are the criteria that allow or not live migration when source and dest hosts have same CPU type (eg Intel) but different models (eg cascade lake vs ice lake). I imagine it is libvirtd to drive this decision, correct? Does libvirt has a sort of table or list of cpu flags that are mandatory / optional? Or how is it established to prevent or not live migration across different couodels systems? Thanks, Gianluca