VM migration fails with 'guest CPU doesn't match specification: missing features: md-clear' error.

Problem

• VM migration fails with 'guest CPU doesn't match specification: missing features: md-clear' error.

• It looks like migration is failing because destination host is missing one of the CPU flag md-clear:

Javascript

2022-08-29 13:26:31.610 ERROR nova.virt.libvirt.driver [-] [instance: fff634fgh-b284-2048-a284-545c7a5b7876] Live Migration failure: operation failed: guest CPU doesn't match sp
ecification: missing features: md-clear: libvirt.libvirtError: operation failed: guest CPU doesn't match specification: missing features: md-clear
2022-08-29 13:26:32.241 INFO nova.virt.libvirt.driver [-] [instance: fff634fgh-b284-2048-a284-545c7a5b7876] Migration running for 0 secs, memory 100% remaining (bytes processed=0, remaining=0, total=0); disk 100% remaining (bytes processed=0, remaining=0, total=0).

Environment

• Platform9 Managed OpenStack - v5.4.0 and higher

Cause

• The instance is being migrated to a destination host that does not have the required CPU flag.

Resolution

• Update the destination host's kernel to have the required CPU flag.