1. A system of reassigning physical processors of a processing environment, said system comprising: a logical processor backed by a physical processor; and another physical processor reassigned to the logical processor replacing the physical processor as the backing of the logical processor, wherein the another physical processor is reassigned concurrent to operation of the physical processor, wherein to reassign: the physical processor currently assigned to the logical processor is adapted to employ a new configuration of the processing environment to determine that it is to be replaced, and to store its operating state; and the another physical processor is adapted to check the new configuration of the processing environment to determine that the another physical processor is to be assigned to the logical processor, and to load the stored operating state.