Hardware Virtualization

Hardware Virtualization

1. Defination

   • It is the abstraction of computing resources from the software that uses cloud resources. It involves embedding virtual machine software into the server's hardware components. That software is called the hypervisor. The hypervisor manages the shared physical hardware resources between the guest OS & the host OS.

2. Types

   • Full Virtualization
     • Define
       • Full virtualization is a common and cost-effective type of virtualization, which is basically a method by which computer service requests are separated from the physical hardware that facilitates them. With full virtualization, operating systems and their hosted software are run on top of virtual hardware.
     • Ring Structure
       • Virtual Machine Monitor (VMM) runs in the privileged Ring 0 .VMM decouples guest operating system (OS) from the underlying physical hardware
     • Properties
       • Each VM is assigned a VMM and Provides virtual components to each VM, Performs Binary Translation (BT) of non-virtualizable OS instructions. Guest OS is not aware of being virtualized
   • Para Virtualization
     • Define
       • paravirtualization or para-virtualization is a virtualization technique that presents a software interface to the virtual machines which is similar, yet not identical to the underlying hardware–software interface.
     • Ring Structure
       • Guest operating system (OS) knows that it is virtualized .Guest OS runs in Ring 0
     • Properties
       • Modified guest OS kernel is used, such as Linux and OpenBSD. Unmodified guest OS is not supported, such as Microsoft Windows
   • Hardware Assisted Virtualization
     • Define
       • Hardware virtualization is the virtualization of computers as complete hardware platforms, certain logical abstractions of their componentry, or only the functionality required to run various operating systems. Virtualization hides the physical characteristics of a computing platform from the users, presenting instead an abstract computing platform.[1][2] At its origins, the software that controlled virtualization was called a "control program", but the terms "hypervisor" or "virtual machine monitor" became preferred over time.
     • Ring Structure
       • User Apps run in RIng 3 ,Guest Os in ring 0 .Vmm is underlying the ring 0
     • Properties
       • Achieved by using hypervisor-aware CPU to handle privileged instructions Reduces virtualization overhead caused due to full and paravirtualization CPU and Memory virtualization support is provided in hardware