Patent ID: 8024730

Claim:
An apparatus comprising: a processor having a normal execution mode and a host execution mode operable in a computer system, wherein the normal execution mode executes without any virtual machine functionalities; a virtual machine monitor (VMM) implemented on the host execution mode creates original and target protected mode environments in two separate virtual machines to operate guest software, wherein responsive to a command to switch between the protected modes, the VMM causes the processor to atomically switch between the original protected mode environment and the target protected mode environment; and a virtual machine control structure (VMCS) to store state information for use in switching between the original protected mode environment and the target protected mode environment, the VMCS to store state information related to the original protected mode environment, wherein after the VMM receives a command from the original protected mode environment to enter a virtual machine extension (VMX) mode, the VMM causes the processor to enter the VMX mode to switch between the original and target protected mode environments; wherein the switch between the environments includes the VMM storing the original and target protected mode states in the VMCS, exiting out of the original protected mode environment, entering into the target protected mode environment, and then the VMM causing the target protected mode environment to exit out of the VMX mode such that the same processor of the computer system resumes operation in the target protected mode environment.