OvmfPkg/MemEncryptSevLib: find pages of initial SMRAM save state map

[mirror_edk2.git] / OvmfPkg / Library / BaseMemEncryptSevLib / MemEncryptSevLibInternal.c

/** @file\r
\r
  Secure Encrypted Virtualization (SEV) library helper function\r
\r
  Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>\r
\r
  This program and the accompanying materials are licensed and made available\r
  under the terms and conditions of the BSD License which accompanies this\r
  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
#include <Library/BaseLib.h>\r
#include <Library/DebugLib.h>\r
#include <Library/MemEncryptSevLib.h>\r
#include <Library/PcdLib.h>\r
#include <Register/Amd/Cpuid.h>\r
#include <Register/Amd/Msr.h>\r
#include <Register/Cpuid.h>\r
#include <Register/QemuSmramSaveStateMap.h>\r
#include <Register/SmramSaveStateMap.h>\r
#include <Uefi/UefiBaseType.h>\r
\r
STATIC BOOLEAN mSevStatus = FALSE;\r
STATIC BOOLEAN mSevStatusChecked = FALSE;\r
\r
/**\r
\r
  Returns a boolean to indicate whether SEV is enabled\r
\r
  @retval TRUE           SEV is enabled\r
  @retval FALSE          SEV is not enabled\r
  **/\r
STATIC\r
BOOLEAN\r
EFIAPI\r
InternalMemEncryptSevIsEnabled (\r
  VOID\r
  )\r
{\r
  UINT32                            RegEax;\r
  MSR_SEV_STATUS_REGISTER           Msr;\r
  CPUID_MEMORY_ENCRYPTION_INFO_EAX  Eax;\r
\r
  //\r
  // Check if memory encryption leaf exist\r
  //\r
  AsmCpuid (CPUID_EXTENDED_FUNCTION, &RegEax, NULL, NULL, NULL);\r
  if (RegEax >= CPUID_MEMORY_ENCRYPTION_INFO) {\r
    //\r
    // CPUID Fn8000_001F[EAX] Bit 1 (Sev supported)\r
    //\r
    AsmCpuid (CPUID_MEMORY_ENCRYPTION_INFO, &Eax.Uint32, NULL, NULL, NULL);\r
\r
    if (Eax.Bits.SevBit) {\r
      //\r
      // Check MSR_0xC0010131 Bit 0 (Sev Enabled)\r
      //\r
      Msr.Uint32 = AsmReadMsr32 (MSR_SEV_STATUS);\r
      if (Msr.Bits.SevBit) {\r
        return TRUE;\r
      }\r
    }\r
  }\r
\r
  return FALSE;\r
}\r
\r
/**\r
  Returns a boolean to indicate whether SEV is enabled\r
\r
  @retval TRUE           SEV is enabled\r
  @retval FALSE          SEV is not enabled\r
**/\r
BOOLEAN\r
EFIAPI\r
MemEncryptSevIsEnabled (\r
  VOID\r
  )\r
{\r
  if (mSevStatusChecked) {\r
    return mSevStatus;\r
  }\r
\r
  mSevStatus = InternalMemEncryptSevIsEnabled();\r
  mSevStatusChecked = TRUE;\r
\r
  return mSevStatus;\r
}\r
\r
\r
/**\r
  Locate the page range that covers the initial (pre-SMBASE-relocation) SMRAM\r
  Save State Map.\r
\r
  @param[out] BaseAddress     The base address of the lowest-address page that\r
                              covers the initial SMRAM Save State Map.\r
\r
  @param[out] NumberOfPages   The number of pages in the page range that covers\r
                              the initial SMRAM Save State Map.\r
\r
  @retval RETURN_SUCCESS      BaseAddress and NumberOfPages have been set on\r
                              output.\r
\r
  @retval RETURN_UNSUPPORTED  SMM is unavailable.\r
**/\r
RETURN_STATUS\r
EFIAPI\r
MemEncryptSevLocateInitialSmramSaveStateMapPages (\r
  OUT UINTN *BaseAddress,\r
  OUT UINTN *NumberOfPages\r
  )\r
{\r
  UINTN MapStart;\r
  UINTN MapEnd;\r
  UINTN MapPagesStart; // MapStart rounded down to page boundary\r
  UINTN MapPagesEnd;   // MapEnd rounded up to page boundary\r
  UINTN MapPagesSize;  // difference between MapPagesStart and MapPagesEnd\r
\r
  if (!FeaturePcdGet (PcdSmmSmramRequire)) {\r
    return RETURN_UNSUPPORTED;\r
  }\r
\r
  MapStart      = SMM_DEFAULT_SMBASE + SMRAM_SAVE_STATE_MAP_OFFSET;\r
  MapEnd        = MapStart + sizeof (QEMU_SMRAM_SAVE_STATE_MAP);\r
  MapPagesStart = MapStart & ~(UINTN)EFI_PAGE_MASK;\r
  MapPagesEnd   = ALIGN_VALUE (MapEnd, EFI_PAGE_SIZE);\r
  MapPagesSize  = MapPagesEnd - MapPagesStart;\r
\r
  ASSERT ((MapPagesSize & EFI_PAGE_MASK) == 0);\r
\r
  *BaseAddress   = MapPagesStart;\r
  *NumberOfPages = MapPagesSize >> EFI_PAGE_SHIFT;\r
\r
  return RETURN_SUCCESS;\r
}\r