Hardware Support for Virtualization & Memory Utilization

Explain hardware support for virtualization?. Discuss the role of hardware support for Intel processor virtualization and memory virtualization.                                                                     

Hardware-assisted virtualization is a platform virtualization approach that enables efficient full virtualization using help from hardware capabilities, i.e., from the host processors. Hardware-assisted virtualization is supported on Intel processors,i.e., VT-x (X86 processors). It provides support for executing instructions and to keep track of state of the virtual machine with the help of Virtual Machine Control Structure (VMCS).

Support for processor virtulization:

-       It provides hardware assists  for processor execution in two modes: VMX root operation and VMX non-root operation.

-       Sensitive instructions are executed in Root operation mode and non-sensitive instructions are executed in non-root mode.

Support for memory virtulization:

The hardware assists for memory virtulization:

-       Extended page table (EPT): The virtual machine stores the mapping from the guest virtual page to guest physical phage in the page tables. The hypervisor stores the mapping from the guest physical page to the actual physical page. Here, the hypervisor may trap the vitural machine only the first time it tries to access guest physical page x in order to map x in the EPT.

-       Virtual Processor ID also assists in eliminating the need for the hypervisor to flush the TLB upon the exit of a VM.