Hardware-Assisted Virtualization Technology

Hardware-based visualization technology (specifically Intel VT or AMD-V) improves the fundamental flexibility and robustness of traditional software-based virtualization solutions by accelerating key functions of the virtualized platform. This efficiency offers benefits to the IT, embedded developer, and intelligent systems communities.
With hardware-based visualization technology instead of software based virtualizing platforms,have  some new instructions to control virtualization. With them, controlling software (VMM, Virtual Machine Monitor) can be simpler, thus improving performance compared to software-based solutions including,

  • Speeding up the transfer of platform control between the guest operating systems (OSs) and the virtual machine manager (VMM)/hypervisor
  • Enabling the VMM to uniquely assign I/O devices to guest OSs
  • Optimizing the network for virtualization with adapter-based acceleration


An extra instruction set known as Virtual Machine Extensions or VMX has in processors with Virtualization Technology . VMX brings 10 new virtualization-specific instructions to the CPU: VMPTRLD, VMPTRST, VMCLEAR, VMREAD, VMWRITE, VMCALL, VMLAUNCH, VMRESUME, VMXOFF, and VMXON.

There are two modes to run under virtualization:
1. VMX root operation
2. VMX non-root operation.

Usually, only the virtualization controlling software (VMM), runs under root operation, while operating systems running on top of the virtual machines run under non-root operation.

To enter virtualization mode, the software should execute the VMXON instruction and then call the VMM software. The VMM software can enter each virtual machine using the VMLAUNCH instruction, and exit it by using the VMRESUME instruction. If the VMM wants to shutdown and exit the virtualization mode, it executes the VMXOFF instruction.

More recent processors have an extension called EPT (Extended Page Tables), which allows each guest to have its own page table to keep track of memory addresses. Without this extension, the VMM has to exit the virtual machine to perform address translations. This exiting-and-returning task reduces performance.

Intel VT
Intel VT performs above virtualization tasks in hardware, like memory address translation, which reduces the overhead and footprint of virtualization software and improves its performance. In fact, Intel developed a complete set of hardware based virtualization features designed to improve performance and security for virtualized applications.

Server virtualization with Intel VT
Get enhanced server virtualization performance in the data center using platforms based on Intel® Xeon® processors with Intel VT, and achieve faster VM boot times with Intel® Virtualization Technology FlexPriority and more flexible live migrations with Intel® Virtualization Technology FlexMigration (Intel® VT FlexMigration).

The Intel® Xeon® processor E5 family enables superior virtualization performance and a flexible, efficient, and secure data center that is fully equipped for the cloud.

The Intel® Xeon® processor 6500 series delivers intelligent and scalable performance optimized for efficient data center virtualization.

The Intel® Xeon® processor E7 family features flexible virtualization that automatically adapts to the diverse needs of a virtualized environment with built-in hardware assists.

With revolutionary architecture featuring up to 16 cores, AMD Opteron processors are built to support more VMs per server for greater consolidation—which can translate into lower server acquisition costs, operational expense, power consumption and data center floor space.
AMD Virtualization (AMD-V) technology is a set of on-chip features that help to make better use of and improve the performance in virtualization resources.

Virtualization Extensions to the x86 Instruction Set Enables software to more efficiently create VMs so that multiple operating systems and their applications can run simultaneously on the same computer
Tagged TLB Hardware features that facilitate efficient switching between VMs for better application responsiveness
Rapid Virtualization Indexing (RVI) Helps accelerate the performance of many virtualized applications by enabling hardware-based VM memory management
AMD-V Extended Migration Helps virtualization software with live migrations of VMs between all available AMD Opteron processor generations
I/O Virtualization Enables direct device access by aVM, bypassing the hypervisor for improved application performance and improved isolation of VMs for increased integrity and security



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