OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLibInternal.c

   1 /** @file
   2
   3   Secure Encrypted Virtualization (SEV) library helper function
   4
   5   Copyright (c) 2020, AMD Incorporated. All rights reserved.<BR>
   6
   7   SPDX-License-Identifier: BSD-2-Clause-Patent
   8
   9 **/
  10
  11 #include <Library/BaseLib.h>
  12 #include <Library/DebugLib.h>
  13 #include <Library/MemEncryptSevLib.h>
  14 #include <Library/PcdLib.h>
  15 #include <Register/Amd/Cpuid.h>
  16 #include <Register/Amd/Msr.h>
  17 #include <Register/Cpuid.h>
  18 #include <Uefi/UefiBaseType.h>
  19
  20 /**
  21    Read the workarea to determine whether SEV is enabled. If enabled,
  22    then return the SevEsWorkArea pointer.
  23
  24   **/
  25 STATIC
  26 SEC_SEV_ES_WORK_AREA *
  27 EFIAPI
  28 GetSevEsWorkArea (
  29   VOID
  30   )
  31 {
  32   OVMF_WORK_AREA  *WorkArea;
  33
  34   WorkArea = (OVMF_WORK_AREA *)FixedPcdGet32 (PcdOvmfWorkAreaBase);
  35
  36   //
  37   // If its not SEV guest then SevEsWorkArea is not valid.
  38   //
  39   if ((WorkArea == NULL) || (WorkArea->Header.GuestType != GUEST_TYPE_AMD_SEV)) {
  40     return NULL;
  41   }
  42
  43   return (SEC_SEV_ES_WORK_AREA *)FixedPcdGet32 (PcdSevEsWorkAreaBase);
  44 }
  45
  46 /**
  47   Read the SEV Status MSR value from the workarea
  48
  49   **/
  50 STATIC
  51 UINT32
  52 EFIAPI
  53 InternalMemEncryptSevStatus (
  54   VOID
  55   )
  56 {
  57   SEC_SEV_ES_WORK_AREA  *SevEsWorkArea;
  58
  59   SevEsWorkArea = GetSevEsWorkArea ();
  60   if (SevEsWorkArea == NULL) {
  61     return 0;
  62   }
  63
  64   return (UINT32)(UINTN)SevEsWorkArea->SevStatusMsrValue;
  65 }
  66
  67 /**
  68   Returns a boolean to indicate whether SEV-SNP is enabled.
  69
  70   @retval TRUE           SEV-SNP is enabled
  71   @retval FALSE          SEV-SNP is not enabled
  72 **/
  73 BOOLEAN
  74 EFIAPI
  75 MemEncryptSevSnpIsEnabled (
  76   VOID
  77   )
  78 {
  79   MSR_SEV_STATUS_REGISTER  Msr;
  80
  81   Msr.Uint32 = InternalMemEncryptSevStatus ();
  82
  83   return Msr.Bits.SevSnpBit ? TRUE : FALSE;
  84 }
  85
  86 /**
  87   Returns a boolean to indicate whether SEV-ES is enabled.
  88
  89   @retval TRUE           SEV-ES is enabled
  90   @retval FALSE          SEV-ES is not enabled
  91 **/
  92 BOOLEAN
  93 EFIAPI
  94 MemEncryptSevEsIsEnabled (
  95   VOID
  96   )
  97 {
  98   MSR_SEV_STATUS_REGISTER  Msr;
  99
 100   Msr.Uint32 = InternalMemEncryptSevStatus ();
 101
 102   return Msr.Bits.SevEsBit ? TRUE : FALSE;
 103 }
 104
 105 /**
 106   Returns a boolean to indicate whether SEV is enabled.
 107
 108   @retval TRUE           SEV is enabled
 109   @retval FALSE          SEV is not enabled
 110 **/
 111 BOOLEAN
 112 EFIAPI
 113 MemEncryptSevIsEnabled (
 114   VOID
 115   )
 116 {
 117   MSR_SEV_STATUS_REGISTER  Msr;
 118
 119   Msr.Uint32 = InternalMemEncryptSevStatus ();
 120
 121   return Msr.Bits.SevBit ? TRUE : FALSE;
 122 }
 123
 124 /**
 125   Returns the SEV encryption mask.
 126
 127   @return  The SEV pagtable encryption mask
 128 **/
 129 UINT64
 130 EFIAPI
 131 MemEncryptSevGetEncryptionMask (
 132   VOID
 133   )
 134 {
 135   SEC_SEV_ES_WORK_AREA  *SevEsWorkArea;
 136
 137   SevEsWorkArea = GetSevEsWorkArea ();
 138   if (SevEsWorkArea == NULL) {
 139     return 0;
 140   }
 141
 142   return SevEsWorkArea->EncryptionMask;
 143 }