Methods for migrating a virtual machine instance between devices include scoring a received migration request against one or more rules in a rule database to generate one or more scores for the migration request. Each rule relates to one or more respective validation sets. Each score is compared to a respective threshold. The migration request is validated by only those validation sets that correspond to the scores that exceed the respective threshold. A virtual machine is migrated to a target device in accordance with the migration request responsive to successful validation by the validation sets used.