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Instruction set extensions that have been added to the x86 instruction set in order to support hardware virtualization.These extensions provide instructions for entering and leaving a virtualized execution context and for loading virtual-machine control structures (VMCSs), which hold the state of the guest and host, along with fields which control processor behavior within the virtual machine.
x86 virtualization is the use of hardware-assisted virtualization capabilities on an x86/x86-64 CPU.. In the late 1990s x86 virtualization was achieved by complex software techniques, necessary to compensate for the processor's lack of hardware-assisted virtualization capabilities while attaining reasonable performance.
The x86 instruction set refers to the set of instructions that x86-compatible microprocessors support. The instructions are usually part of an executable program, often stored as a computer file and executed on the processor. The x86 instruction set has been extended several times, introducing wider registers and datatypes as well as new ...
Pages in category "x86 instructions" ... List of x86 virtualization instructions; Load task register; LOADALL; M. MMX (instruction set) Model-specific register; ModR/M;
The x86 instruction set has several times been extended with SIMD (Single instruction, multiple data) instruction set extensions.These extensions, starting from the MMX instruction set extension introduced with Pentium MMX in 1997, typically define sets of wide registers and instructions that subdivide these registers into fixed-size lanes and perform a computation for each lane in parallel.
The virtualization of such architectures requires correct handling of critical instructions, i.e., sensitive but unprivileged instructions. One approach, known as patching , adopts techniques commonly used in dynamic recompilation : critical instructions are discovered at run-time and replaced with a trap into the VMM.
A hypervisor, also known as a virtual machine monitor (VMM) or virtualizer, is a type of computer software, firmware or hardware that creates and runs virtual machines. A computer on which a hypervisor runs one or more virtual machines is called a host machine , and each virtual machine is called a guest machine .
Recent CPUs from Intel and AMD offer x86 virtualization instructions for a hypervisor to control Ring 0 hardware access. Although they are mutually incompatible, both Intel VT-x (codenamed "Vanderpool") and AMD-V (codenamed "Pacifica") allow a guest operating system to run Ring 0 operations natively without affecting other guests or the host OS.