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   This program and the accompanying materials are licensed and made available
   8   under the terms and conditions of the BSD License which accompanies this
   9   distribution.  The full text of the license may be found at
  10   http://opensource.org/licenses/bsd-license.php
  11
  12   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  13   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  14
  15 **/
  16
  17 #include <Library/BaseLib.h>
  18 #include <Library/DebugLib.h>
  19 #include <Library/MemEncryptSevLib.h>
  20 #include <Library/PcdLib.h>
  21 #include <Register/Amd/Cpuid.h>
  22 #include <Register/Amd/Msr.h>
  23 #include <Register/Cpuid.h>
  24 #include <Register/QemuSmramSaveStateMap.h>
  25 #include <Register/SmramSaveStateMap.h>
  26 #include <Uefi/UefiBaseType.h>
  27
  28 STATIC BOOLEAN mSevStatus = FALSE;
  29 STATIC BOOLEAN mSevStatusChecked = FALSE;
  30
  31 /**
  32
  33   Returns a boolean to indicate whether SEV is enabled
  34
  35   @retval TRUE           SEV is enabled
  36   @retval FALSE          SEV is not enabled
  37   **/
  38 STATIC
  39 BOOLEAN
  40 EFIAPI
  41 InternalMemEncryptSevIsEnabled (
  42   VOID
  43   )
  44 {
  45   UINT32                            RegEax;
  46   MSR_SEV_STATUS_REGISTER           Msr;
  47   CPUID_MEMORY_ENCRYPTION_INFO_EAX  Eax;
  48
  49   //
  50   // Check if memory encryption leaf exist
  51   //
  52   AsmCpuid (CPUID_EXTENDED_FUNCTION, &RegEax, NULL, NULL, NULL);
  53   if (RegEax >= CPUID_MEMORY_ENCRYPTION_INFO) {
  54     //
  55     // CPUID Fn8000_001F[EAX] Bit 1 (Sev supported)
  56     //
  57     AsmCpuid (CPUID_MEMORY_ENCRYPTION_INFO, &Eax.Uint32, NULL, NULL, NULL);
  58
  59     if (Eax.Bits.SevBit) {
  60       //
  61       // Check MSR_0xC0010131 Bit 0 (Sev Enabled)
  62       //
  63       Msr.Uint32 = AsmReadMsr32 (MSR_SEV_STATUS);
  64       if (Msr.Bits.SevBit) {
  65         return TRUE;
  66       }
  67     }
  68   }
  69
  70   return FALSE;
  71 }
  72
  73 /**
  74   Returns a boolean to indicate whether SEV is enabled
  75
  76   @retval TRUE           SEV is enabled
  77   @retval FALSE          SEV is not enabled
  78 **/
  79 BOOLEAN
  80 EFIAPI
  81 MemEncryptSevIsEnabled (
  82   VOID
  83   )
  84 {
  85   if (mSevStatusChecked) {
  86     return mSevStatus;
  87   }
  88
  89   mSevStatus = InternalMemEncryptSevIsEnabled();
  90   mSevStatusChecked = TRUE;
  91
  92   return mSevStatus;
  93 }
  94
  95
  96 /**
  97   Locate the page range that covers the initial (pre-SMBASE-relocation) SMRAM
  98   Save State Map.
  99
 100   @param[out] BaseAddress     The base address of the lowest-address page that
 101                               covers the initial SMRAM Save State Map.
 102
 103   @param[out] NumberOfPages   The number of pages in the page range that covers
 104                               the initial SMRAM Save State Map.
 105
 106   @retval RETURN_SUCCESS      BaseAddress and NumberOfPages have been set on
 107                               output.
 108
 109   @retval RETURN_UNSUPPORTED  SMM is unavailable.
 110 **/
 111 RETURN_STATUS
 112 EFIAPI
 113 MemEncryptSevLocateInitialSmramSaveStateMapPages (
 114   OUT UINTN *BaseAddress,
 115   OUT UINTN *NumberOfPages
 116   )
 117 {
 118   UINTN MapStart;
 119   UINTN MapEnd;
 120   UINTN MapPagesStart; // MapStart rounded down to page boundary
 121   UINTN MapPagesEnd;   // MapEnd rounded up to page boundary
 122   UINTN MapPagesSize;  // difference between MapPagesStart and MapPagesEnd
 123
 124   if (!FeaturePcdGet (PcdSmmSmramRequire)) {
 125     return RETURN_UNSUPPORTED;
 126   }
 127
 128   MapStart      = SMM_DEFAULT_SMBASE + SMRAM_SAVE_STATE_MAP_OFFSET;
 129   MapEnd        = MapStart + sizeof (QEMU_SMRAM_SAVE_STATE_MAP);
 130   MapPagesStart = MapStart & ~(UINTN)EFI_PAGE_MASK;
 131   MapPagesEnd   = ALIGN_VALUE (MapEnd, EFI_PAGE_SIZE);
 132   MapPagesSize  = MapPagesEnd - MapPagesStart;
 133
 134   ASSERT ((MapPagesSize & EFI_PAGE_MASK) == 0);
 135
 136   *BaseAddress   = MapPagesStart;
 137   *NumberOfPages = MapPagesSize >> EFI_PAGE_SHIFT;
 138
 139   return RETURN_SUCCESS;
 140 }