Overview of the Intel VT Virtualization Features

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This article will explain the various components of Intel Virtualization Technology (Intel VT).

Intel VT-x (Intel Virtualization Technology for IA-32 and Intel 64 Processors)

Intel VT-x (previously known as Intel VT) is the implementation of an Intel Secure Virtual Machine for the x86 IA-32 and Intel 64 architectures. The older designation, “Intel VT” (without the “x”), continues to be used by many BIOS menus.

VT-x is necessary for Intel systems in order to:

  • run domUs under Xen Hardware Virtual Machine (HVM) (as well as run a guest system under Windows).
  • run 64-bit guest systems under VMware.[1]
  • to run virtualization with KVM.[2]

Information regarding the activation of Intel VT-x at the BIOS level (if supported by the Intel processor) can be found in the article, Activating the Intel VT Virtualization Feature.

As of the Nehalem architecture (Intel Xeon 55xx CPUs), VT-x includes the Intel Extended Page Tables (EPT).[3][4]

Intel VT-i (Intel Virtualization Technology for Itanium Processors)

Intel VT-i is the implementation of an Intel Secure Virtual Machine for the IA-64 architecture (Itanium).

Intel VT-d (Intel Virtualization Technology for Directed I/O)

Intel VT-d makes direct access to a PCI device possible for guest systems with the help of the Input/Output Memory Management Unit (IOMMU) provided. This allows a LAN card to be dedicated to a guest system, which makes attainment of increased network performance beyond that of an emulated LAN card possible. Of course, once such a direct access system has been implemented, live migration of the guest system is no longer possible. VMware can be configured for use with an activated Intel VT-d system using VMware VMDirectPath for direct access to PCI cards.

Pre-requisites for Intel VT-d

  • The chip set as well as the BIOS used must support Intel VT-d.
    • Requires the Intel Nehalem or later micro-architecture, such as that found in Xeon 34xx, 55xx and more recent, as well as other, desktop CPUs (see A List of Intel CPUs).
    • There are no special requirements placed on the CPUs themselves, since VT-d is a function of the chip set. The CPU need merely support VT in general (see [5]).

Information regarding the activation of Intel VT-d at the BIOS level (if supported by the Intel processor) can be found in the article, Activating the Intel VT-d Virtualization Feature.

For additional information regarding VT-d, see:

Intel VT-c (Intel Virtualization Technology for Connectivity)

Intel VT-c is a collection of input/output (I/O) virtualization technologies. These technologies include:[6]

The article, Activating the SR-IOV Virtualization Feature contains additional information about activating SR-IOV.

For additional information regarding VT-c, see:

The following, as well as other, platforms support VT-c:

  • Intel 75xx systems (Intel 7500 Chipset Boxboro-EX)[7]

Table of References

  1. VMware Knowledge Base: Hardware and Firmware Requirements for 64-Bit Guest Operating Systems
  2. KVM FAQs:What do I need to use kvm?
  3. Technology Brief: Intel Nehalem Virtualization Technology Micro-architecture
  4. First the Tick, Now the Tock: Next Generation Intel Microarchitecture (Nehalem)
  5. VT-d Support on the Intel® Xeon® processor 5500/5600 Series (intel.com)
  6. Technology Brief: Intel Virtualization Technology for Connectivity
  7. Features Enabled by the Intel® 7500 Chipset Include: Supports Intel® VT for Connectivity: (Intel® VT-c) which reduces I/O latency. Intel Xeon Processor 7500 Series Product Brief (page 6)

Additional Information


Foto Werner Fischer.jpg

Author: Werner Fischer

Werner Fischer, working in the Web Operations & Knowledge Transfer team at Thomas-Krenn, completed his studies of Computer and Media Security at FH Hagenberg in Austria. He is a regular speaker at many conferences like LinuxTag, OSMC, OSDC, LinuxCon, and author for various IT magazines. In his spare time he enjoys playing the piano and training for a good result at the annual Linz marathon relay.


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