The Bareflank Virtual Machine Monitor (VMM) is the part of the hypervisor that monitors each virtual machine. The term "hypervisor" can mean a lot of things. Generally speaking, it should refer to the piece of code that maintains control of the supervisor, but instead generally refers to everything within a hypervisor's project including the drivers and userspace code (e.g. the Xen hypervisor is made up of everything from the actual hypervisor itself, but also its hypercall libraries, libXL, etc...). Thus, the Bareflank hypervisor describes the entire project, while the VMM is the piece of code that oversees the management of each virtual machine, and the "exit handler", which is contained in the VMM, is the actual piece of code that maintains control over the supervisor with so called "ring -1" privileges.