[mirror_edk2.git] / MdePkg / Library / BaseLib / X86Msr.c

/** @file\r
  IA-32/x64 MSR functions.\r
\r
  Copyright (c) 2006, Intel Corporation<BR>\r
  All rights reserved. This program and the accompanying materials\r
  are licensed and made available under the terms and conditions of the BSD License\r
  which accompanies this distribution.  The full text of the license may be found at\r
  http://opensource.org/licenses/bsd-license.php\r
\r
  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
\r
**/\r
\r
\r
#include "BaseLibInternals.h"\r
\r
\r
/**\r
  Returns the lower 32-bits of a Machine Specific Register(MSR).\r
\r
  Reads and returns the lower 32-bits of the MSR specified by Index.\r
  No parameter checking is performed on Index, and some Index values may cause\r
  CPU exceptions. The caller must either guarantee that Index is valid, or the\r
  caller must set up exception handlers to catch the exceptions. This function\r
  is only available on IA-32 and x64.\r
\r
  @param  Index The 32-bit MSR index to read.\r
\r
  @return The lower 32 bits of the MSR identified by Index.\r
\r
**/\r
UINT32\r
EFIAPI\r
AsmReadMsr32 (\r
  IN      UINT32                    Index\r
  )\r
{\r
  return (UINT32)AsmReadMsr64 (Index);\r
}\r
\r
/**\r
  Zero-extend a 32-bit value and writes it to a Machine Specific Register(MSR).\r
\r
  Writes the 32-bit value specified by Value to the MSR specified by Index. The\r
  upper 32-bits of the MSR write are set to zero. The 32-bit value written to\r
  the MSR is returned. No parameter checking is performed on Index or Value,\r
  and some of these may cause CPU exceptions. The caller must either guarantee\r
  that Index and Value are valid, or the caller must establish proper exception\r
  handlers. This function is only available on IA-32 and x64.\r
\r
  @param  Index The 32-bit MSR index to write.\r
  @param  Value The 32-bit value to write to the MSR.\r
\r
  @return Value\r
\r
**/\r
UINT32\r
EFIAPI\r
AsmWriteMsr32 (\r
  IN      UINT32                    Index,\r
  IN      UINT32                    Value\r
  )\r
{\r
  return (UINT32)AsmWriteMsr64 (Index, Value);\r
}\r
\r
/**\r
  Reads a 64-bit MSR, performs a bitwise OR on the lower 32-bits, and\r
  writes the result back to the 64-bit MSR.\r
\r
  Reads the 64-bit MSR specified by Index, performs a bitwise OR\r
  between the lower 32-bits of the read result and the value specified by\r
  OrData, and writes the result to the 64-bit MSR specified by Index. The lower\r
  32-bits of the value written to the MSR is returned. No parameter checking is\r
  performed on Index or OrData, and some of these may cause CPU exceptions. The\r
  caller must either guarantee that Index and OrData are valid, or the caller\r
  must establish proper exception handlers. This function is only available on\r
  IA-32 and x64.\r
\r
  @param  Index   The 32-bit MSR index to write.\r
  @param  OrData  The value to OR with the read value from the MSR.\r
\r
  @return The lower 32-bit value written to the MSR.\r
\r
**/\r
UINT32\r
EFIAPI\r
AsmMsrOr32 (\r
  IN      UINT32                    Index,\r
  IN      UINT32                    OrData\r
  )\r
{\r
  return (UINT32)AsmMsrOr64 (Index, OrData);\r
}\r
\r
/**\r
  Reads a 64-bit MSR, performs a bitwise AND on the lower 32-bits, and writes\r
  the result back to the 64-bit MSR.\r
\r
  Reads the 64-bit MSR specified by Index, performs a bitwise AND between the\r
  lower 32-bits of the read result and the value specified by AndData, and\r
  writes the result to the 64-bit MSR specified by Index. The lower 32-bits of\r
  the value written to the MSR is returned. No parameter checking is performed\r
  on Index or AndData, and some of these may cause CPU exceptions. The caller\r
  must either guarantee that Index and AndData are valid, or the caller must\r
  establish proper exception handlers. This function is only available on IA-32\r
  and x64.\r
\r
  @param  Index   The 32-bit MSR index to write.\r
  @param  AndData The value to AND with the read value from the MSR.\r
\r
  @return The lower 32-bit value written to the MSR.\r
\r
**/\r
UINT32\r
EFIAPI\r
AsmMsrAnd32 (\r
  IN      UINT32                    Index,\r
  IN      UINT32                    AndData\r
  )\r
{\r
  return (UINT32)AsmMsrAnd64 (Index, AndData);\r
}\r
\r
/**\r
  Reads a 64-bit MSR, performs a bitwise AND followed by a bitwise OR\r
  on the lower 32-bits, and writes the result back to the 64-bit MSR.\r
\r
  Reads the 64-bit MSR specified by Index, performs a bitwise AND between the\r
  lower 32-bits of the read result and the value specified by AndData\r
  preserving the upper 32-bits, performs a bitwise OR between the\r
  result of the AND operation and the value specified by OrData, and writes the\r
  result to the 64-bit MSR specified by Address. The lower 32-bits of the value\r
  written to the MSR is returned. No parameter checking is performed on Index,\r
  AndData, or OrData, and some of these may cause CPU exceptions. The caller\r
  must either guarantee that Index, AndData, and OrData are valid, or the\r
  caller must establish proper exception handlers. This function is only\r
  available on IA-32 and x64.\r
\r
  @param  Index   The 32-bit MSR index to write.\r
  @param  AndData The value to AND with the read value from the MSR.\r
  @param  OrData  The value to OR with the result of the AND operation.\r
\r
  @return The lower 32-bit value written to the MSR.\r
\r
**/\r
UINT32\r
EFIAPI\r
AsmMsrAndThenOr32 (\r
  IN      UINT32                    Index,\r
  IN      UINT32                    AndData,\r
  IN      UINT32                    OrData\r
  )\r
{\r
  return (UINT32)AsmMsrAndThenOr64 (Index, AndData, OrData);\r
}\r
\r
/**\r
  Reads a bit field of an MSR.\r
\r
  Reads the bit field in the lower 32-bits of a 64-bit MSR. The bit field is\r
  specified by the StartBit and the EndBit. The value of the bit field is\r
  returned. The caller must either guarantee that Index is valid, or the caller\r
  must set up exception handlers to catch the exceptions. This function is only\r
  available on IA-32 and x64.\r
\r
  If StartBit is greater than 31, then ASSERT().\r
  If EndBit is greater than 31, then ASSERT().\r
  If EndBit is less than StartBit, then ASSERT().\r
\r
  @param  Index     The 32-bit MSR index to read.\r
  @param  StartBit  The ordinal of the least significant bit in the bit field.\r
                    Range 0..31.\r
  @param  EndBit    The ordinal of the most significant bit in the bit field.\r
                    Range 0..31.\r
\r
  @return The bit field read from the MSR.\r
\r
**/\r
UINT32\r
EFIAPI\r
AsmMsrBitFieldRead32 (\r
  IN      UINT32                    Index,\r
  IN      UINTN                     StartBit,\r
  IN      UINTN                     EndBit\r
  )\r
{\r
  return BitFieldRead32 (AsmReadMsr32 (Index), StartBit, EndBit);\r
}\r
\r
/**\r
  Writes a bit field to an MSR.\r
\r
  Writes Value to a bit field in the lower 32-bits of a  64-bit MSR. The bit\r
  field is specified by the StartBit and the EndBit. All other bits in the\r
  destination MSR are preserved. The lower 32-bits of the MSR written is\r
  returned. The caller must either guarantee that Index and the data written \r
  is valid, or the caller must set up exception handlers to catch the exceptions. \r
  This function is only available on IA-32 and x64.\r
\r
  If StartBit is greater than 31, then ASSERT().\r
  If EndBit is greater than 31, then ASSERT().\r
  If EndBit is less than StartBit, then ASSERT().\r
\r
  @param  Index     The 32-bit MSR index to write.\r
  @param  StartBit  The ordinal of the least significant bit in the bit field.\r
                    Range 0..31.\r
  @param  EndBit    The ordinal of the most significant bit in the bit field.\r
                    Range 0..31.\r
  @param  Value     New value of the bit field.\r
\r
  @return The lower 32-bit of the value written to the MSR.\r
\r
**/\r
UINT32\r
EFIAPI\r
AsmMsrBitFieldWrite32 (\r
  IN      UINT32                    Index,\r
  IN      UINTN                     StartBit,\r
  IN      UINTN                     EndBit,\r
  IN      UINT32                    Value\r
  )\r
{\r
  ASSERT (EndBit < sizeof (Value) * 8);\r
  ASSERT (StartBit <= EndBit);\r
  return (UINT32)AsmMsrBitFieldWrite64 (Index, StartBit, EndBit, Value);\r
}\r
\r
/**\r
  Reads a bit field in a 64-bit MSR, performs a bitwise OR, and writes the\r
  result back to the bit field in the 64-bit MSR.\r
\r
  Reads the 64-bit MSR specified by Index, performs a bitwise OR\r
  between the read result and the value specified by OrData, and writes the\r
  result to the 64-bit MSR specified by Index. The lower 32-bits of the value\r
  written to the MSR are returned. Extra left bits in OrData are stripped. The\r
  caller must either guarantee that Index and the data written is valid, or\r
  the caller must set up exception handlers to catch the exceptions. This\r
  function is only available on IA-32 and x64.\r
\r
  If StartBit is greater than 31, then ASSERT().\r
  If EndBit is greater than 31, then ASSERT().\r
  If EndBit is less than StartBit, then ASSERT().\r
\r
  @param  Index     The 32-bit MSR index to write.\r
  @param  StartBit  The ordinal of the least significant bit in the bit field.\r
                    Range 0..31.\r
  @param  EndBit    The ordinal of the most significant bit in the bit field.\r
                    Range 0..31.\r
  @param  OrData    The value to OR with the read value from the MSR.\r
\r
  @return The lower 32-bit of the value written to the MSR.\r
\r
**/\r
UINT32\r
EFIAPI\r
AsmMsrBitFieldOr32 (\r
  IN      UINT32                    Index,\r
  IN      UINTN                     StartBit,\r
  IN      UINTN                     EndBit,\r
  IN      UINT32                    OrData\r
  )\r
{\r
  ASSERT (EndBit < sizeof (OrData) * 8);\r
  ASSERT (StartBit <= EndBit);\r
  return (UINT32)AsmMsrBitFieldOr64 (Index, StartBit, EndBit, OrData);\r
}\r
\r
/**\r
  Reads a bit field in a 64-bit MSR, performs a bitwise AND, and writes the\r
  result back to the bit field in the 64-bit MSR.\r
\r
  Reads the 64-bit MSR specified by Index, performs a bitwise AND between the\r
  read result and the value specified by AndData, and writes the result to the\r
  64-bit MSR specified by Index. The lower 32-bits of the value written to the\r
  MSR are returned. Extra left bits in AndData are stripped. The caller must\r
  either guarantee that Index and the data written is valid, or the caller must\r
  set up exception handlers to catch the exceptions. This function is only\r
  available on IA-32 and x64.\r
\r
  If StartBit is greater than 31, then ASSERT().\r
  If EndBit is greater than 31, then ASSERT().\r
  If EndBit is less than StartBit, then ASSERT().\r
\r
  @param  Index     The 32-bit MSR index to write.\r
  @param  StartBit  The ordinal of the least significant bit in the bit field.\r
                    Range 0..31.\r
  @param  EndBit    The ordinal of the most significant bit in the bit field.\r
                    Range 0..31.\r
  @param  AndData   The value to AND with the read value from the MSR.\r
\r
  @return The lower 32-bit of the value written to the MSR.\r
\r
**/\r
UINT32\r
EFIAPI\r
AsmMsrBitFieldAnd32 (\r
  IN      UINT32                    Index,\r
  IN      UINTN                     StartBit,\r
  IN      UINTN                     EndBit,\r
  IN      UINT32                    AndData\r
  )\r
{\r
  ASSERT (EndBit < sizeof (AndData) * 8);\r
  ASSERT (StartBit <= EndBit);\r
  return (UINT32)AsmMsrBitFieldAnd64 (Index, StartBit, EndBit, AndData);\r
}\r
\r
/**\r
  Reads a bit field in a 64-bit MSR, performs a bitwise AND followed by a\r
  bitwise OR, and writes the result back to the bit field in the\r
  64-bit MSR.\r
\r
  Reads the 64-bit MSR specified by Index, performs a bitwise AND followed by a\r
  bitwise OR between the read result and the value specified by\r
  AndData, and writes the result to the 64-bit MSR specified by Index. The\r
  lower 32-bits of the value written to the MSR are returned. Extra left bits\r
  in both AndData and OrData are stripped. The caller must either guarantee\r
  that Index and the data written is valid, or the caller must set up exception\r
  handlers to catch the exceptions. This function is only available on IA-32\r
  and x64.\r
\r
  If StartBit is greater than 31, then ASSERT().\r
  If EndBit is greater than 31, then ASSERT().\r
  If EndBit is less than StartBit, then ASSERT().\r
\r
  @param  Index     The 32-bit MSR index to write.\r
  @param  StartBit  The ordinal of the least significant bit in the bit field.\r
                    Range 0..31.\r
  @param  EndBit    The ordinal of the most significant bit in the bit field.\r
                    Range 0..31.\r
  @param  AndData   The value to AND with the read value from the MSR.\r
  @param  OrData    The value to OR with the result of the AND operation.\r
\r
  @return The lower 32-bit of the value written to the MSR.\r
\r
**/\r
UINT32\r
EFIAPI\r
AsmMsrBitFieldAndThenOr32 (\r
  IN      UINT32                    Index,\r
  IN      UINTN                     StartBit,\r
  IN      UINTN                     EndBit,\r
  IN      UINT32                    AndData,\r
  IN      UINT32                    OrData\r
  )\r
{\r
  ASSERT (EndBit < sizeof (AndData) * 8);\r
  ASSERT (StartBit <= EndBit);\r
  return (UINT32)AsmMsrBitFieldAndThenOr64 (\r
                   Index,\r
                   StartBit,\r
                   EndBit,\r
                   AndData,\r
                   OrData\r
                   );\r
}\r
\r
/**\r
  Reads a 64-bit MSR, performs a bitwise OR, and writes the result\r
  back to the 64-bit MSR.\r
\r
  Reads the 64-bit MSR specified by Index, performs a bitwise OR\r
  between the read result and the value specified by OrData, and writes the\r
  result to the 64-bit MSR specified by Index. The value written to the MSR is\r
  returned. No parameter checking is performed on Index or OrData, and some of\r
  these may cause CPU exceptions. The caller must either guarantee that Index\r
  and OrData are valid, or the caller must establish proper exception handlers.\r
  This function is only available on IA-32 and x64.\r
\r
  @param  Index   The 32-bit MSR index to write.\r
  @param  OrData  The value to OR with the read value from the MSR.\r
\r
  @return The value written back to the MSR.\r
\r
**/\r
UINT64\r
EFIAPI\r
AsmMsrOr64 (\r
  IN      UINT32                    Index,\r
  IN      UINT64                    OrData\r
  )\r
{\r
  return AsmWriteMsr64 (Index, AsmReadMsr64 (Index) | OrData);\r
}\r
\r
/**\r
  Reads a 64-bit MSR, performs a bitwise AND, and writes the result back to the\r
  64-bit MSR.\r
\r
  Reads the 64-bit MSR specified by Index, performs a bitwise AND between the\r
  read result and the value specified by OrData, and writes the result to the\r
  64-bit MSR specified by Index. The value written to the MSR is returned. No\r
  parameter checking is performed on Index or OrData, and some of these may\r
  cause CPU exceptions. The caller must either guarantee that Index and OrData\r
  are valid, or the caller must establish proper exception handlers. This\r
  function is only available on IA-32 and x64.\r
\r
  @param  Index   The 32-bit MSR index to write.\r
  @param  AndData The value to AND with the read value from the MSR.\r
\r
  @return The value written back to the MSR.\r
\r
**/\r
UINT64\r
EFIAPI\r
AsmMsrAnd64 (\r
  IN      UINT32                    Index,\r
  IN      UINT64                    AndData\r
  )\r
{\r
  return AsmWriteMsr64 (Index, AsmReadMsr64 (Index) & AndData);\r
}\r
\r
/**\r
  Reads a 64-bit MSR, performs a bitwise AND followed by a bitwise \r
  OR, and writes the result back to the 64-bit MSR.\r
\r
  Reads the 64-bit MSR specified by Index, performs a bitwise AND between read\r
  result and the value specified by AndData, performs a bitwise OR\r
  between the result of the AND operation and the value specified by OrData,\r
  and writes the result to the 64-bit MSR specified by Index. The value written\r
  to the MSR is returned. No parameter checking is performed on Index, AndData,\r
  or OrData, and some of these may cause CPU exceptions. The caller must either\r
  guarantee that Index, AndData, and OrData are valid, or the caller must\r
  establish proper exception handlers. This function is only available on IA-32\r
  and x64.\r
\r
  @param  Index   The 32-bit MSR index to write.\r
  @param  AndData The value to AND with the read value from the MSR.\r
  @param  OrData  The value to OR with the result of the AND operation.\r
\r
  @return The value written back to the MSR.\r
\r
**/\r
UINT64\r
EFIAPI\r
AsmMsrAndThenOr64 (\r
  IN      UINT32                    Index,\r
  IN      UINT64                    AndData,\r
  IN      UINT64                    OrData\r
  )\r
{\r
  return AsmWriteMsr64 (Index, (AsmReadMsr64 (Index) & AndData) | OrData);\r
}\r
\r
/**\r
  Reads a bit field of an MSR.\r
\r
  Reads the bit field in the 64-bit MSR. The bit field is specified by the\r
  StartBit and the EndBit. The value of the bit field is returned. The caller\r
  must either guarantee that Index is valid, or the caller must set up\r
  exception handlers to catch the exceptions. This function is only available\r
  on IA-32 and x64.\r
\r
  If StartBit is greater than 63, then ASSERT().\r
  If EndBit is greater than 63, then ASSERT().\r
  If EndBit is less than StartBit, then ASSERT().\r
\r
  @param  Index     The 32-bit MSR index to read.\r
  @param  StartBit  The ordinal of the least significant bit in the bit field.\r
                    Range 0..63.\r
  @param  EndBit    The ordinal of the most significant bit in the bit field.\r
                    Range 0..63.\r
\r
  @return The value written back to the MSR.\r
\r
**/\r
UINT64\r
EFIAPI\r
AsmMsrBitFieldRead64 (\r
  IN      UINT32                    Index,\r
  IN      UINTN                     StartBit,\r
  IN      UINTN                     EndBit\r
  )\r
{\r
  return BitFieldRead64 (AsmReadMsr64 (Index), StartBit, EndBit);\r
}\r
\r
/**\r
  Writes a bit field to an MSR.\r
\r
  Writes Value to a bit field in a 64-bit MSR. The bit field is specified by\r
  the StartBit and the EndBit. All other bits in the destination MSR are\r
  preserved. The MSR written is returned. The caller must either guarantee \r
  that Index and the data written is valid, or the caller must set up exception \r
  handlers to catch the exceptions. This function is only available on IA-32 and x64.\r
\r
  If StartBit is greater than 63, then ASSERT().\r
  If EndBit is greater than 63, then ASSERT().\r
  If EndBit is less than StartBit, then ASSERT().\r
\r
  @param  Index     The 32-bit MSR index to write.\r
  @param  StartBit  The ordinal of the least significant bit in the bit field.\r
                    Range 0..63.\r
  @param  EndBit    The ordinal of the most significant bit in the bit field.\r
                    Range 0..63.\r
  @param  Value     New value of the bit field.\r
\r
  @return The value written back to the MSR.\r
\r
**/\r
UINT64\r
EFIAPI\r
AsmMsrBitFieldWrite64 (\r
  IN      UINT32                    Index,\r
  IN      UINTN                     StartBit,\r
  IN      UINTN                     EndBit,\r
  IN      UINT64                    Value\r
  )\r
{\r
  return AsmWriteMsr64 (\r
           Index,\r
           BitFieldWrite64 (AsmReadMsr64 (Index), StartBit, EndBit, Value)\r
           );\r
}\r
\r
/**\r
  Reads a bit field in a 64-bit MSR, performs a bitwise OR, and\r
  writes the result back to the bit field in the 64-bit MSR.\r
\r
  Reads the 64-bit MSR specified by Index, performs a bitwise OR\r
  between the read result and the value specified by OrData, and writes the\r
  result to the 64-bit MSR specified by Index. The value written to the MSR is\r
  returned. Extra left bits in OrData are stripped. The caller must either\r
  guarantee that Index and the data written is valid, or the caller must set up\r
  exception handlers to catch the exceptions. This function is only available\r
  on IA-32 and x64.\r
\r
  If StartBit is greater than 63, then ASSERT().\r
  If EndBit is greater than 63, then ASSERT().\r
  If EndBit is less than StartBit, then ASSERT().\r
\r
  @param  Index     The 32-bit MSR index to write.\r
  @param  StartBit  The ordinal of the least significant bit in the bit field.\r
                    Range 0..63.\r
  @param  EndBit    The ordinal of the most significant bit in the bit field.\r
                    Range 0..63.\r
  @param  OrData    The value to OR with the read value from the bit field.\r
\r
  @return The value written back to the MSR.\r
\r
**/\r
UINT64\r
EFIAPI\r
AsmMsrBitFieldOr64 (\r
  IN      UINT32                    Index,\r
  IN      UINTN                     StartBit,\r
  IN      UINTN                     EndBit,\r
  IN      UINT64                    OrData\r
  )\r
{\r
  return AsmWriteMsr64 (\r
           Index,\r
           BitFieldOr64 (AsmReadMsr64 (Index), StartBit, EndBit, OrData)\r
           );\r
}\r
\r
/**\r
  Reads a bit field in a 64-bit MSR, performs a bitwise AND, and writes the\r
  result back to the bit field in the 64-bit MSR.\r
\r
  Reads the 64-bit MSR specified by Index, performs a bitwise AND between the\r
  read result and the value specified by AndData, and writes the result to the\r
  64-bit MSR specified by Index. The value written to the MSR is returned.\r
  Extra left bits in AndData are stripped. The caller must either guarantee\r
  that Index and the data written is valid, or the caller must set up exception\r
  handlers to catch the exceptions. This function is only available on IA-32\r
  and x64.\r
\r
  If StartBit is greater than 63, then ASSERT().\r
  If EndBit is greater than 63, then ASSERT().\r
  If EndBit is less than StartBit, then ASSERT().\r
\r
  @param  Index     The 32-bit MSR index to write.\r
  @param  StartBit  The ordinal of the least significant bit in the bit field.\r
                    Range 0..63.\r
  @param  EndBit    The ordinal of the most significant bit in the bit field.\r
                    Range 0..63.\r
  @param  AndData   The value to AND with the read value from the bit field.\r
\r
  @return The value written back to the MSR.\r
\r
**/\r
UINT64\r
EFIAPI\r
AsmMsrBitFieldAnd64 (\r
  IN      UINT32                    Index,\r
  IN      UINTN                     StartBit,\r
  IN      UINTN                     EndBit,\r
  IN      UINT64                    AndData\r
  )\r
{\r
  return AsmWriteMsr64 (\r
           Index,\r
           BitFieldAnd64 (AsmReadMsr64 (Index), StartBit, EndBit, AndData)\r
           );\r
}\r
\r
/**\r
  Reads a bit field in a 64-bit MSR, performs a bitwise AND followed by a\r
  bitwise OR, and writes the result back to the bit field in the\r
  64-bit MSR.\r
\r
  Reads the 64-bit MSR specified by Index, performs a bitwise AND followed by\r
  a bitwise OR between the read result and the value specified by\r
  AndData, and writes the result to the 64-bit MSR specified by Index. The\r
  value written to the MSR is returned. Extra left bits in both AndData and\r
  OrData are stripped. The caller must either guarantee that Index and the data\r
  written is valid, or the caller must set up exception handlers to catch the\r
  exceptions. This function is only available on IA-32 and x64.\r
\r
  If StartBit is greater than 63, then ASSERT().\r
  If EndBit is greater than 63, then ASSERT().\r
  If EndBit is less than StartBit, then ASSERT().\r
\r
  @param  Index     The 32-bit MSR index to write.\r
  @param  StartBit  The ordinal of the least significant bit in the bit field.\r
                    Range 0..63.\r
  @param  EndBit    The ordinal of the most significant bit in the bit field.\r
                    Range 0..63.\r
  @param  AndData   The value to AND with the read value from the bit field.\r
  @param  OrData    The value to OR with the result of the AND operation.\r
\r
  @return The value written back to the MSR.\r
\r
**/\r
UINT64\r
EFIAPI\r
AsmMsrBitFieldAndThenOr64 (\r
  IN      UINT32                    Index,\r
  IN      UINTN                     StartBit,\r
  IN      UINTN                     EndBit,\r
  IN      UINT64                    AndData,\r
  IN      UINT64                    OrData\r
  )\r
{\r
  return AsmWriteMsr64 (\r
           Index,\r
           BitFieldAndThenOr64 (\r
             AsmReadMsr64 (Index),\r
             StartBit,\r
             EndBit,\r
             AndData,\r
             OrData\r
             )\r
           );\r
}\r