Question about migrate the vm with host-passthrough cpu

Hi there, Sorry to bother you, but could I ask you a question about the live migration of virtual machine configured with host-passthough cpu, it confuse me a lot. Here i have two hosts with different cpu, and the cpu feature set of old host is subset of the new one (by virsh cpu-compare). If the vm was first started on the old host,is it safe to migrate the vm between the two hosts back and forth with the vm always keep running? I've test the case in my environment, and the migration succeeds, the cpu family/model/stepping and features of lscpu in Guest OS is the same. -- Best Regards, Guoyi Tu