Virtual Machine Monitor: Construction and Functionality

This lecture covers the construction of a Virtual Machine Monitor (VMM) and its essential components. It begins with an overview of virtualization, explaining the need for multiplexing and emulation in building a VMM. The instructor discusses how each virtual machine (VM) operates with its own virtual CPU and memory, emphasizing the importance of hardware support like system-level limited direct execution and extended page tables for efficient virtualization. The lecture also delves into the emulation of I/O devices, highlighting the role of software in managing virtual disks, keyboards, and network interfaces. The concept of limited direct execution is revisited, illustrating how applications interact with the CPU and operating system. The instructor explains the architecture of VMMs, including the introduction of additional privilege levels to enhance performance and isolation. Finally, the lecture summarizes the virtualization of physical memory, detailing the management of two independent page table trees and the implications for performance, including the use of superpages to optimize memory references.