MdePkg/Library/BaseLib/Ia32/ReadMsr64.c

/** @file
  AsmReadMsr64 function

  Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
  This program and the accompanying materials
  are licensed and made available under the terms and conditions of the BSD License
  which accompanies this distribution.  The full text of the license may be found at
  http://opensource.org/licenses/bsd-license.php.

  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

**/




/**
  Returns a 64-bit Machine Specific Register(MSR).

  Reads and returns the 64-bit MSR specified by Index. No parameter checking is
  performed on Index, and some Index values may cause CPU exceptions. The
  caller must either guarantee that Index is valid, or the caller must set up
  exception handlers to catch the exceptions. This function is only available
  on IA-32 and x64.

  @param  Index The 32-bit MSR index to read.

  @return The value of the MSR identified by Index.

**/
UINT64
EFIAPI
AsmReadMsr64 (
  IN UINT32  Index
  )
{
  _asm {
    mov     ecx, Index
    rdmsr
  }
}