I pointed out about device access in my earlier post, differentiating between emulated device and non-emulated device in Hyper-V. Ever wondered how non-emulating devices work internally in Hyper-V? If not, then read on...

Device access virtualization is a method for sharing hardware efficiently without any emulation. All physical devices are controlled by existing device drivers without creating new ones.

VSP's or Virtualization Service Providers runs within parent partition. It talks to the respective device driver and acts as a multiplexer and offers hardware services to guests by establishing a communication with VSC's or Virtualization Server Clients over VMBUS (A communication channel for VSP's and VSC's).

VSC's runs within the child partition and acts as a service. For every VSC, there will a corresponding VSP in parent partition. It's the VSP/VSC pair which makes a device type within a guest. Microsoft provides VSP/VSC pairs for storage, networking, video, input, USB.