audk/OvmfPkg/Library/BaseMemEncryptSevLib/Ia32/MemEncryptSevLib.c

/** @file

  Secure Encrypted Virtualization (SEV) library helper function

  Copyright (c) 2017, AMD Incorporated. 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.

**/

#include <Library/BaseLib.h>
#include <Library/DebugLib.h>
#include <Register/Cpuid.h>
#include <Register/Amd/Cpuid.h>
#include <Register/Amd/Msr.h>
#include <Library/MemEncryptSevLib.h>

/**
  This function clears memory encryption bit for the memory region specified
  by BaseAddress and Number of pages from the current page table context.

  @param[in]  Cr3BaseAddress        Cr3 Base Address (if zero then use current
                                    CR3)
  @param[in]  BaseAddress           The physical address that is the start
                                    address of a memory region.
  @param[in]  NumberOfPages         The number of pages from start memory
                                    region.
  @param[in]  Flush                 Flush the caches before clearing the bit
                                    (mostly TRUE except MMIO addresses)

  @retval RETURN_SUCCESS            The attributes were cleared for the memory
                                    region.
  @retval RETURN_INVALID_PARAMETER  Number of pages is zero.
  @retval RETURN_UNSUPPORTED        Clearing memory encryption attribute is not
                                    supported
  **/
RETURN_STATUS
EFIAPI
MemEncryptSevClearPageEncMask (
  IN PHYSICAL_ADDRESS         Cr3BaseAddress,
  IN PHYSICAL_ADDRESS         BaseAddress,
  IN UINTN                    NumberOfPages,
  IN BOOLEAN                  Flush
  )
{
  //
  // Memory encryption bit is not accessible in 32-bit mode
  //
  return RETURN_UNSUPPORTED;
}

/**
  This function sets memory encryption bit for the memory region specified by
  BaseAddress and Number of pages from the current page table context.

  @param[in]  Cr3BaseAddress        Cr3 Base Address (if zero then use current
                                    CR3)
  @param[in]  BaseAddress           The physical address that is the start
                                    address of a memory region.
  @param[in]  NumberOfPages         The number of pages from start memory
                                    region.
  @param[in]  Flush                 Flush the caches before clearing the bit
                                    (mostly TRUE except MMIO addresses)

  @retval RETURN_SUCCESS            The attributes were set for the memory
                                    region.
  @retval RETURN_INVALID_PARAMETER  Number of pages is zero.
  @retval RETURN_UNSUPPORTED        Clearing memory encryption attribute is not
                                    supported
  **/
RETURN_STATUS
EFIAPI
MemEncryptSevSetPageEncMask (
  IN PHYSICAL_ADDRESS         Cr3BaseAddress,
  IN PHYSICAL_ADDRESS         BaseAddress,
  IN UINTN                    NumberOfPages,
  IN BOOLEAN                  Flush
  )
{
  //
  // Memory encryption bit is not accessible in 32-bit mode
  //
  return RETURN_UNSUPPORTED;
}