OvmfPkg/Library/BaseMemEncryptSevLib/Ia32/MemEncryptSevLib.c

/** @file

  Secure Encrypted Virtualization (SEV) library helper function

  Copyright (c) 2017 - 2020, AMD Incorporated. All rights reserved.<BR>

  SPDX-License-Identifier: BSD-2-Clause-Patent

**/

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

/**
  This function clears memory encryption bit for the memory region specified by
  BaseAddress and NumPages 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]  NumPages                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 the memory encryption attribute
                                      is not supported
**/
RETURN_STATUS
EFIAPI
MemEncryptSevClearPageEncMask (
  IN PHYSICAL_ADDRESS         Cr3BaseAddress,
  IN PHYSICAL_ADDRESS         BaseAddress,
  IN UINTN                    NumPages,
  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 NumPages 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]  NumPages                The number of pages from start memory
                                      region.
  @param[in]  Flush                   Flush the caches before setting 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          Setting the memory encryption attribute
                                      is not supported
**/
RETURN_STATUS
EFIAPI
MemEncryptSevSetPageEncMask (
  IN PHYSICAL_ADDRESS         Cr3BaseAddress,
  IN PHYSICAL_ADDRESS         BaseAddress,
  IN UINTN                    NumPages,
  IN BOOLEAN                  Flush
  )
{
  //
  // Memory encryption bit is not accessible in 32-bit mode
  //
  return RETURN_UNSUPPORTED;
}

/**
  Returns the encryption state of the specified virtual address range.

  @param[in]  Cr3BaseAddress          Cr3 Base Address (if zero then use
                                      current CR3)
  @param[in]  BaseAddress             Base address to check
  @param[in]  Length                  Length of virtual address range

  @retval MemEncryptSevAddressRangeUnencrypted  Address range is mapped
                                                unencrypted
  @retval MemEncryptSevAddressRangeEncrypted    Address range is mapped
                                                encrypted
  @retval MemEncryptSevAddressRangeMixed        Address range is mapped mixed
  @retval MemEncryptSevAddressRangeError        Address range is not mapped
**/
MEM_ENCRYPT_SEV_ADDRESS_RANGE_STATE
EFIAPI
MemEncryptSevGetAddressRangeState (
  IN PHYSICAL_ADDRESS         Cr3BaseAddress,
  IN PHYSICAL_ADDRESS         BaseAddress,
  IN UINTN                    Length
  )
{
  //
  // Memory is always encrypted in 32-bit mode
  //
  return MemEncryptSevAddressRangeEncrypted;
}