Comment 0 for bug 1903822

When the vm does not specify a host for live migration, it will call libvirt's compareCPU() to compare cpu features, which is not very useful. For example, when the kernel version of the host is different, compareCPU() passes the check, but in fact the cpu features of the host may be different, When the vm is live migrated to this host, a startup error will occur.

Steps to reproduce:
1. Prepare two compute nodes with the same cpu features, the system is centos7.6 and the kernel is 3.10.
2. It is normal not to specify host live migration between two nodes.
3. Upgrade the kernel of one of the nodes to 4.19.
4. Do not specify the host live migration, the vm migrates from one node to another node, but an error is reported during startup, and the error log is as follows:
    Live Migration failure: operation failed: guest CPU doesn't match specification: missing features: xsaves: libvirtError: operation failed: guest CPU doesn't match specification: missing features: xsaves