OvmfPkg/BaseMemEncryptSevLib: skip the pre-validated system RAM

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

/** @file\r
\r
  Secure Encrypted Virtualization (SEV) library helper function\r
\r
  Copyright (c) 2020, AMD Incorporated. All rights reserved.<BR>\r
\r
  SPDX-License-Identifier: BSD-2-Clause-Patent\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 <Uefi/UefiBaseType.h>\r
\r
STATIC BOOLEAN  mSevStatus        = FALSE;\r
STATIC BOOLEAN  mSevEsStatus      = FALSE;\r
STATIC BOOLEAN  mSevSnpStatus     = FALSE;\r
STATIC BOOLEAN  mSevStatusChecked = FALSE;\r
\r
STATIC UINT64   mSevEncryptionMask      = 0;\r
STATIC BOOLEAN  mSevEncryptionMaskSaved = FALSE;\r
\r
/**\r
  Reads and sets the status of SEV features.\r
\r
  **/\r
STATIC\r
VOID\r
EFIAPI\r
InternalMemEncryptSevStatus (\r
  VOID\r
  )\r
{\r
  UINT32                            RegEax;\r
  MSR_SEV_STATUS_REGISTER           Msr;\r
  CPUID_MEMORY_ENCRYPTION_INFO_EAX  Eax;\r
  BOOLEAN                           ReadSevMsr;\r
  SEC_SEV_ES_WORK_AREA              *SevEsWorkArea;\r
\r
  ReadSevMsr = FALSE;\r
\r
  SevEsWorkArea = (SEC_SEV_ES_WORK_AREA *)FixedPcdGet32 (PcdSevEsWorkAreaBase);\r
  if ((SevEsWorkArea != NULL) && (SevEsWorkArea->EncryptionMask != 0)) {\r
    //\r
    // The MSR has been read before, so it is safe to read it again and avoid\r
    // having to validate the CPUID information.\r
    //\r
    ReadSevMsr = TRUE;\r
  } else {\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
        ReadSevMsr = TRUE;\r
      }\r
    }\r
  }\r
\r
  if (ReadSevMsr) {\r
    //\r
    // Check MSR_0xC0010131 Bit 0 (Sev Enabled)\r
    //\r
    Msr.Uint32 = AsmReadMsr32 (MSR_SEV_STATUS);\r
    if (Msr.Bits.SevBit) {\r
      mSevStatus = TRUE;\r
    }\r
\r
    //\r
    // Check MSR_0xC0010131 Bit 1 (Sev-Es Enabled)\r
    //\r
    if (Msr.Bits.SevEsBit) {\r
      mSevEsStatus = TRUE;\r
    }\r
\r
    //\r
    // Check MSR_0xC0010131 Bit 2 (Sev-Snp Enabled)\r
    //\r
    if (Msr.Bits.SevSnpBit) {\r
      mSevSnpStatus = TRUE;\r
    }\r
  }\r
\r
  mSevStatusChecked = TRUE;\r
}\r
\r
/**\r
  Returns a boolean to indicate whether SEV-SNP is enabled.\r
\r
  @retval TRUE           SEV-SNP is enabled\r
  @retval FALSE          SEV-SNP is not enabled\r
**/\r
BOOLEAN\r
EFIAPI\r
MemEncryptSevSnpIsEnabled (\r
  VOID\r
  )\r
{\r
  if (!mSevStatusChecked) {\r
    InternalMemEncryptSevStatus ();\r
  }\r
\r
  return mSevSnpStatus;\r
}\r
\r
/**\r
  Returns a boolean to indicate whether SEV-ES is enabled.\r
\r
  @retval TRUE           SEV-ES is enabled\r
  @retval FALSE          SEV-ES is not enabled\r
**/\r
BOOLEAN\r
EFIAPI\r
MemEncryptSevEsIsEnabled (\r
  VOID\r
  )\r
{\r
  if (!mSevStatusChecked) {\r
    InternalMemEncryptSevStatus ();\r
  }\r
\r
  return mSevEsStatus;\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
    InternalMemEncryptSevStatus ();\r
  }\r
\r
  return mSevStatus;\r
}\r
\r
/**\r
  Returns the SEV encryption mask.\r
\r
  @return  The SEV pagtable encryption mask\r
**/\r
UINT64\r
EFIAPI\r
MemEncryptSevGetEncryptionMask (\r
  VOID\r
  )\r
{\r
  if (!mSevEncryptionMaskSaved) {\r
    SEC_SEV_ES_WORK_AREA  *SevEsWorkArea;\r
\r
    SevEsWorkArea = (SEC_SEV_ES_WORK_AREA *)FixedPcdGet32 (PcdSevEsWorkAreaBase);\r
    if (SevEsWorkArea != NULL) {\r
      mSevEncryptionMask = SevEsWorkArea->EncryptionMask;\r
    } else {\r
      CPUID_MEMORY_ENCRYPTION_INFO_EBX  Ebx;\r
\r
      //\r
      // CPUID Fn8000_001F[EBX] Bit 0:5 (memory encryption bit position)\r
      //\r
      AsmCpuid (CPUID_MEMORY_ENCRYPTION_INFO, NULL, &Ebx.Uint32, NULL, NULL);\r
      mSevEncryptionMask = LShiftU64 (1, Ebx.Bits.PtePosBits);\r
    }\r
\r
    mSevEncryptionMaskSaved = TRUE;\r
  }\r
\r
  return mSevEncryptionMask;\r
}\r