Description of problem:

Live migration will not be triggered if the VM name exceeds 48 characters

Version-Release number of selected component (if applicable):

OCP virtualization 4.18

How reproducible:

1. Create the VM and set the name with 48 characters:

vm0123456789abcdefghijklmnopqrstuvwxyz0123456789

2. Let it running and Click "Migrate", nothing will happen. only can click "Cancel Migrate" to cancel.

3. if using the name with 47 characters, it will be fine

vm0123456789abcdefghijklmnopqrstuvwxyz012345678

Actual results:

vm0123456789abcdefghijklmnopqrstuvwxyz0123456789: not work
vm0123456789abcdefghijklmnopqrstuvwxyz012345678: work

Additional info:

• From the events

  # oc describe vmi vm0123456789abcdefghijklmnopqrstuvwxyz0123456789
  
  ...
  Events:
    Type     Reason            Age                   From                         Message
    ----     ------            ----                  ----                         -------
    Normal   SuccessfulCreate  61m                   disruptionbudget-controller  Created PodDisruptionBudget kubevirt-disruption-budget-jpqd5
    Normal   SuccessfulCreate  61m                   virtualmachine-controller    Created virtual machine pod virt-launcher-vm0123456789abcdefghijklmnopqrstuvwxyz0123454st78
    Normal   Created           61m                   virt-handler                 VirtualMachineInstance defined.
    Normal   Started           61m                   virt-handler                 VirtualMachineInstance started.
    Warning  FailedUpdate      59m (x15 over 60m)    virtualmachine-controller    Error expanding the PodDisruptionBudget kubevirt-disruption-budget-jpqd5: PodDisruptionBudget.policy "kubevirt-disruption-budget-jpqd5" is invalid: metadata.labels: Invalid value: "vm0123456789abcdefghijklmnopqrstuvwxyz0123456789-migration-rhiau": must be no more than 63 characters
    Warning  FailedUpdate      46m (x16 over 49m)    virtualmachine-controller    Error expanding the PodDisruptionBudget kubevirt-disruption-budget-jpqd5: PodDisruptionBudget.policy "kubevirt-disruption-budget-jpqd5" is invalid: metadata.labels: Invalid value: "vm0123456789abcdefghijklmnopqrstuvwxyz0123456789-migration-9xpju": must be no more than 63 characters
    Warning  FailedUpdate      6m16s (x20 over 44m)  virtualmachine-controller    Error expanding the PodDisruptionBudget kubevirt-disruption-budget-jpqd5: PodDisruptionBudget.policy "kubevirt-disruption-budget-jpqd5" is invalid: metadata.labels: Invalid value: "vm0123456789abcdefghijklmnopqrstuvwxyz0123456789-migration-4uf8z": must be no more than 63 characters

  the process will add the fixed 16 fixed characters, 16+48=64 extended 63:

  -migration-XXXXX

  not quite sure whether it is a bug, or something limit by the DNS name(RFC 1034) ?