Mastering Windows Server 2016 Hyper-V

VMMS and VMWP that run in the user mode. The VID talks to the Windows
Hypervisor Interface Library (WinHv) that communicates directly with the hypervisor
via the hypercall interface, which communicates with the WinHv that runs in each VM
(winhv.sys). There are a lot of moving parts, but generally you don’t need to know
about them. Things just work. It is, however, important to understand the VMBus and
the role it plays in enabling very fast access to nonprocessor and nonmemory
resources via the parent partition.