What is the need for a shadow page table One or two brief se

What is the need for a shadow page table? (One or two brief sentences please)

Solution

Virtualization allows multiple operating system instances to run concurrently on a single computer. Virtualization is the creation of a virtual rather than actual version of something, such as an operating system, a server, a storage device or network resources.

Virtualization is where the framework divides the resource into one or more execution environments Even something as simple as partitioning a hard drive is considered virtualization because you take one drive and partition it to create two separate hard drives.

Types of virtualization:

Storage virtualization: is the pooling of physical storage from multiple network storage devices into what appears to be a single storage device

Data virtualization: is abstracting the traditional technical details of data and data management, such as location, performance or format..

Network virtualization: is a method of combining the available resources in a network by splitting up the available bandwidth into channels, each of which is independent from the others.

Server virtualization: the partitioning a physical server into smaller virtual servers.

Shadow Tables are objects used to improve the way machines, networks and programs handle information.

Shadow page tables are used by the hypervisor to keep track of the state in which the guest thinks its page tables should be.

The guest can\'t be allowed access to the hardware page tables because then it would essentially have control of the machine. So, the hypervisor keeps the \"real\" mappings guest virtual -> host physical in the hardware when the relevant guest is executing, and keeps a representation of the page table.