Administering registered virtual addresses in a hybrid computing environment including maintaining a watch list of currently registered virtual addresses by an operating system

Administering registered virtual addresses in a hybrid computing environment that includes a host computer and an accelerator, the accelerator architecture optimized, with respect to the host computer architecture, for speed of execution of a particular class of computing functions, the host computer and the accelerator adapted to one another for data communications by a system level message passing module, where administering registered virtual addresses includes maintaining, by an operating system, a watch list of ranges of currently registered virtual addresses; upon a change in physical to virtual address mappings of a particular range of virtual addresses falling within the ranges included in the watch list, notifying the system level message passing module by the operating system of the change; and updating, by the system level message passing module, a cache of ranges of currently registered virtual addresses to reflect the change in physical to virtual address mappings.