Virtual Machine Extension (VMX) operation

Virtual Machine Extension (VMX) operation is a form of processor operation that supports virtualization. TVMX operation belong to the following types:

• VMX root operation - executed by the Virtual machine monitor (VMM).

  Processor behavior in the VMX root operation differs from the usual one by the following:

  • Set of new instructions (VMX instructions) is available

  • Values that can be loaded into control registers are limited.

• VMX non-root operation - executed by the guest software (virtual machine)

  Processor behavior in the VMX non-root operation is modified to facilitate virtualization and the software functionality is limited due to ordinary operations replaced with VM exits (see below). This limitation allows the VMM to retain control of processor resources.

Transitions between VMX root and non-root operations - VMX transitions - are of two types either:

• VM entry - transition into the VMX non-root operation.

• VM exit - transition from the VMX non-root operation to the VMX root one.