OvmfPkg/Library/BaseMemEncryptSevLib/MemEncryptSevLibInternal.c

   1 /** @file
   2
   3   Secure Encrypted Virtualization (SEV) library helper function
   4
   5   Copyright (c) 2017, 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 <Register/QemuSmramSaveStateMap.h>
  19 #include <Register/SmramSaveStateMap.h>
  20 #include <Uefi/UefiBaseType.h>
  21
  22 STATIC BOOLEAN mSevStatus = FALSE;
  23 STATIC BOOLEAN mSevStatusChecked = FALSE;
  24
  25 /**
  26
  27   Returns a boolean to indicate whether SEV is enabled
  28
  29   @retval TRUE           SEV is enabled
  30   @retval FALSE          SEV is not enabled
  31   **/
  32 STATIC
  33 BOOLEAN
  34 EFIAPI
  35 InternalMemEncryptSevIsEnabled (
  36   VOID
  37   )
  38 {
  39   UINT32                            RegEax;
  40   MSR_SEV_STATUS_REGISTER           Msr;
  41   CPUID_MEMORY_ENCRYPTION_INFO_EAX  Eax;
  42
  43   //
  44   // Check if memory encryption leaf exist
  45   //
  46   AsmCpuid (CPUID_EXTENDED_FUNCTION, &RegEax, NULL, NULL, NULL);
  47   if (RegEax >= CPUID_MEMORY_ENCRYPTION_INFO) {
  48     //
  49     // CPUID Fn8000_001F[EAX] Bit 1 (Sev supported)
  50     //
  51     AsmCpuid (CPUID_MEMORY_ENCRYPTION_INFO, &Eax.Uint32, NULL, NULL, NULL);
  52
  53     if (Eax.Bits.SevBit) {
  54       //
  55       // Check MSR_0xC0010131 Bit 0 (Sev Enabled)
  56       //
  57       Msr.Uint32 = AsmReadMsr32 (MSR_SEV_STATUS);
  58       if (Msr.Bits.SevBit) {
  59         return TRUE;
  60       }
  61     }
  62   }
  63
  64   return FALSE;
  65 }
  66
  67 /**
  68   Returns a boolean to indicate whether SEV is enabled
  69
  70   @retval TRUE           SEV is enabled
  71   @retval FALSE          SEV is not enabled
  72 **/
  73 BOOLEAN
  74 EFIAPI
  75 MemEncryptSevIsEnabled (
  76   VOID
  77   )
  78 {
  79   if (mSevStatusChecked) {
  80     return mSevStatus;
  81   }
  82
  83   mSevStatus = InternalMemEncryptSevIsEnabled();
  84   mSevStatusChecked = TRUE;
  85
  86   return mSevStatus;
  87 }
  88
  89
  90 /**
  91   Locate the page range that covers the initial (pre-SMBASE-relocation) SMRAM
  92   Save State Map.
  93
  94   @param[out] BaseAddress     The base address of the lowest-address page that
  95                               covers the initial SMRAM Save State Map.
  96
  97   @param[out] NumberOfPages   The number of pages in the page range that covers
  98                               the initial SMRAM Save State Map.
  99
 100   @retval RETURN_SUCCESS      BaseAddress and NumberOfPages have been set on
 101                               output.
 102
 103   @retval RETURN_UNSUPPORTED  SMM is unavailable.
 104 **/
 105 RETURN_STATUS
 106 EFIAPI
 107 MemEncryptSevLocateInitialSmramSaveStateMapPages (
 108   OUT UINTN *BaseAddress,
 109   OUT UINTN *NumberOfPages
 110   )
 111 {
 112   UINTN MapStart;
 113   UINTN MapEnd;
 114   UINTN MapPagesStart; // MapStart rounded down to page boundary
 115   UINTN MapPagesEnd;   // MapEnd rounded up to page boundary
 116   UINTN MapPagesSize;  // difference between MapPagesStart and MapPagesEnd
 117
 118   if (!FeaturePcdGet (PcdSmmSmramRequire)) {
 119     return RETURN_UNSUPPORTED;
 120   }
 121
 122   MapStart      = SMM_DEFAULT_SMBASE + SMRAM_SAVE_STATE_MAP_OFFSET;
 123   MapEnd        = MapStart + sizeof (QEMU_SMRAM_SAVE_STATE_MAP);
 124   MapPagesStart = MapStart & ~(UINTN)EFI_PAGE_MASK;
 125   MapPagesEnd   = ALIGN_VALUE (MapEnd, EFI_PAGE_SIZE);
 126   MapPagesSize  = MapPagesEnd - MapPagesStart;
 127
 128   ASSERT ((MapPagesSize & EFI_PAGE_MASK) == 0);
 129
 130   *BaseAddress   = MapPagesStart;
 131   *NumberOfPages = MapPagesSize >> EFI_PAGE_SHIFT;
 132
 133   return RETURN_SUCCESS;
 134 }