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Microsoft Specific

This topic is new for Visual Studio 2005 SP1.

Initializes the specified virtual machine control structure (VMCS) and sets its launch state to Clear.

unsigned char __vmx_vmclear(
      unsigned __int64 *VmcsPhysicalAddress


Parameter Description

[in] VmcsPhysicalAddress

A pointer to a 64-bit memory location that contains the physical address of the VMCS to clear.

Value Meaning


The operation succeeded.


The operation failed with extended status available in the VM-instruction error field of the current VMCS.


The operation failed without status available.

An application can perform a VM-enter operation by using either the __vmx_vmlaunch or __vmx_vmresume function. The __vmx_vmlaunch function can be used only with a VMCS whose launch state is Clear, and the __vmx_vmresume function can be used only with a VMCS whose launch state is Launched. Consequently, use the __vmx_vmclear function to set the launch state of a VMCS to Clear. Use the __vmx_vmlaunch function for your first VM-enter operation and the __vmx_vmresume function for subsequent VM-enter operations.

The __vmx_vmclear function is equivalent to the VMCLEAR machine instruction. This function supports the interaction of a host's virtual machine monitor with a guest operating system and its applications. For more information, search for the document, "Intel Virtualization Technical Specification for the IA-32 Intel Architecture," document number C97063-002, at the Intel Corporation site.

Intrinsic Architecture



Header file <intrin.h>

END Microsoft Specific

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