OvmfPkg/PlatformPei/MemTypeInfo.c

   1 /** @file
   2   Produce the memory type information HOB.
   3
   4   Copyright (C) 2017-2020, Red Hat, Inc.
   5
   6   SPDX-License-Identifier: BSD-2-Clause-Patent
   7 **/
   8
   9 #include <Guid/MemoryTypeInformation.h>
  10 #include <Library/BaseLib.h>
  11 #include <Library/DebugLib.h>
  12 #include <Library/HobLib.h>
  13 #include <Library/PcdLib.h>
  14 #include <Library/PeiServicesLib.h>
  15 #include <Ppi/ReadOnlyVariable2.h>
  16 #include <Uefi/UefiMultiPhase.h>
  17
  18 #include "Platform.h"
  19
  20 //
  21 // The NumberOfPages values below are ad-hoc. They are updated sporadically at
  22 // best (please refer to git-blame for past updates). The values capture a set
  23 // of BIN hints that made sense at a particular time, for some (now likely
  24 // unknown) workloads / boot paths.
  25 //
  26 STATIC EFI_MEMORY_TYPE_INFORMATION mMemoryTypeInformation[] = {
  27   { EfiACPIMemoryNVS,       0x004 },
  28   { EfiACPIReclaimMemory,   0x008 },
  29   { EfiReservedMemoryType,  0x004 },
  30   { EfiRuntimeServicesData, 0x024 },
  31   { EfiRuntimeServicesCode, 0x030 },
  32   { EfiMaxMemoryType,       0x000 }
  33 };
  34
  35 STATIC
  36 VOID
  37 BuildMemTypeInfoHob (
  38   VOID
  39   )
  40 {
  41   BuildGuidDataHob (
  42     &gEfiMemoryTypeInformationGuid,
  43     mMemoryTypeInformation,
  44     sizeof mMemoryTypeInformation
  45     );
  46 }
  47
  48 /**
  49   Refresh the mMemoryTypeInformation array (which we'll turn into the
  50   MemoryTypeInformation HOB) from the MemoryTypeInformation UEFI variable.
  51
  52   Normally, the DXE IPL PEIM builds the HOB from the UEFI variable. But it does
  53   so *transparently*. Instead, we consider the UEFI variable as a list of
  54   hints, for updating our HOB defaults:
  55
  56   - Record types not covered in mMemoryTypeInformation are ignored. In
  57     particular, this hides record types from the UEFI variable that may lead to
  58     reboots without benefiting SMM security, such as EfiBootServicesData.
  59
  60   - Records that would lower the defaults in mMemoryTypeInformation are also
  61     ignored.
  62
  63   @param[in] ReadOnlyVariable2  The EFI_PEI_READ_ONLY_VARIABLE2_PPI used for
  64                                 retrieving the MemoryTypeInformation UEFI
  65                                 variable.
  66 **/
  67 STATIC
  68 VOID
  69 RefreshMemTypeInfo (
  70   IN EFI_PEI_READ_ONLY_VARIABLE2_PPI *ReadOnlyVariable2
  71   )
  72 {
  73   UINTN                       DataSize;
  74   EFI_MEMORY_TYPE_INFORMATION Entries[EfiMaxMemoryType + 1];
  75   EFI_STATUS                  Status;
  76   UINTN                       NumEntries;
  77   UINTN                       HobRecordIdx;
  78
  79   //
  80   // Read the MemoryTypeInformation UEFI variable from the
  81   // gEfiMemoryTypeInformationGuid namespace.
  82   //
  83   DataSize = sizeof Entries;
  84   Status = ReadOnlyVariable2->GetVariable (
  85                                 ReadOnlyVariable2,
  86                                 EFI_MEMORY_TYPE_INFORMATION_VARIABLE_NAME,
  87                                 &gEfiMemoryTypeInformationGuid,
  88                                 NULL,
  89                                 &DataSize,
  90                                 Entries
  91                                 );
  92   if (EFI_ERROR (Status)) {
  93     //
  94     // If the UEFI variable does not exist (EFI_NOT_FOUND), we can't use it for
  95     // udpating mMemoryTypeInformation.
  96     //
  97     // If the UEFI variable exists but Entries is too small to hold it
  98     // (EFI_BUFFER_TOO_SMALL), then the variable contents are arguably invalid.
  99     // That's because Entries has room for every distinct EFI_MEMORY_TYPE,
 100     // including the terminator record with EfiMaxMemoryType. Thus, we can't
 101     // use the UEFI variable for updating mMemoryTypeInformation.
 102     //
 103     // If the UEFI variable couldn't be read for some other reason, we
 104     // similarly can't use it for udpating mMemoryTypeInformation.
 105     //
 106     DEBUG ((DEBUG_ERROR, "%a: GetVariable(): %r\n", __FUNCTION__, Status));
 107     return;
 108   }
 109
 110   //
 111   // Sanity-check the UEFI variable size against the record size.
 112   //
 113   if (DataSize % sizeof Entries[0] != 0) {
 114     DEBUG ((DEBUG_ERROR, "%a: invalid UEFI variable size %Lu\n", __FUNCTION__,
 115       (UINT64)DataSize));
 116     return;
 117   }
 118   NumEntries = DataSize / sizeof Entries[0];
 119
 120   //
 121   // For each record in mMemoryTypeInformation, except the terminator record,
 122   // look up the first match (if any) in the UEFI variable, based on the memory
 123   // type.
 124   //
 125   for (HobRecordIdx = 0;
 126        HobRecordIdx < ARRAY_SIZE (mMemoryTypeInformation) - 1;
 127        HobRecordIdx++) {
 128     EFI_MEMORY_TYPE_INFORMATION *HobRecord;
 129     UINTN                       Idx;
 130     EFI_MEMORY_TYPE_INFORMATION *VariableRecord;
 131
 132     HobRecord = &mMemoryTypeInformation[HobRecordIdx];
 133
 134     for (Idx = 0; Idx < NumEntries; Idx++) {
 135       VariableRecord = &Entries[Idx];
 136
 137       if (VariableRecord->Type == HobRecord->Type) {
 138         break;
 139       }
 140     }
 141
 142     //
 143     // If there is a match, allow the UEFI variable to increase NumberOfPages.
 144     //
 145     if (Idx < NumEntries &&
 146         HobRecord->NumberOfPages < VariableRecord->NumberOfPages) {
 147       DEBUG ((DEBUG_VERBOSE, "%a: Type 0x%x: NumberOfPages 0x%x -> 0x%x\n",
 148         __FUNCTION__, HobRecord->Type, HobRecord->NumberOfPages,
 149         VariableRecord->NumberOfPages));
 150
 151       HobRecord->NumberOfPages = VariableRecord->NumberOfPages;
 152     }
 153   }
 154 }
 155
 156 /**
 157   Notification function called when EFI_PEI_READ_ONLY_VARIABLE2_PPI becomes
 158   available.
 159
 160   @param[in] PeiServices      Indirect reference to the PEI Services Table.
 161   @param[in] NotifyDescriptor Address of the notification descriptor data
 162                               structure.
 163   @param[in] Ppi              Address of the PPI that was installed.
 164
 165   @return  Status of the notification. The status code returned from this
 166            function is ignored.
 167 **/
 168 STATIC
 169 EFI_STATUS
 170 EFIAPI
 171 OnReadOnlyVariable2Available (
 172   IN EFI_PEI_SERVICES           **PeiServices,
 173   IN EFI_PEI_NOTIFY_DESCRIPTOR  *NotifyDescriptor,
 174   IN VOID                       *Ppi
 175   )
 176 {
 177   DEBUG ((DEBUG_VERBOSE, "%a\n", __FUNCTION__));
 178
 179   RefreshMemTypeInfo (Ppi);
 180   BuildMemTypeInfoHob ();
 181   return EFI_SUCCESS;
 182 }
 183
 184 //
 185 // Notification object for registering the callback, for when
 186 // EFI_PEI_READ_ONLY_VARIABLE2_PPI becomes available.
 187 //
 188 STATIC CONST EFI_PEI_NOTIFY_DESCRIPTOR mReadOnlyVariable2Notify = {
 189   (EFI_PEI_PPI_DESCRIPTOR_NOTIFY_DISPATCH |
 190    EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST),  // Flags
 191   &gEfiPeiReadOnlyVariable2PpiGuid,         // Guid
 192   OnReadOnlyVariable2Available              // Notify
 193 };
 194
 195 VOID
 196 MemTypeInfoInitialization (
 197   VOID
 198   )
 199 {
 200   EFI_STATUS Status;
 201
 202   if (!FeaturePcdGet (PcdSmmSmramRequire)) {
 203     //
 204     // EFI_PEI_READ_ONLY_VARIABLE2_PPI will never be available; install
 205     // the default memory type information HOB right away.
 206     //
 207     BuildMemTypeInfoHob ();
 208     return;
 209   }
 210
 211   Status = PeiServicesNotifyPpi (&mReadOnlyVariable2Notify);
 212   if (EFI_ERROR (Status)) {
 213     DEBUG ((DEBUG_ERROR, "%a: failed to set up R/O Variable 2 callback: %r\n",
 214       __FUNCTION__, Status));
 215     ASSERT (FALSE);
 216     CpuDeadLoop ();
 217   }
 218 }