[mirror_edk2.git] / OvmfPkg / PlatformPei / MemDetect.c

/**@file\r
  Memory Detection for Virtual Machines.\r
\r
  Copyright (c) 2006 - 2016, Intel Corporation. All rights reserved.<BR>\r
  SPDX-License-Identifier: BSD-2-Clause-Patent\r
\r
Module Name:\r
\r
  MemDetect.c\r
\r
**/\r
\r
//\r
// The package level header files this module uses\r
//\r
#include <IndustryStandard/E820.h>\r
#include <IndustryStandard/Q35MchIch9.h>\r
#include <PiPei.h>\r
\r
//\r
// The Library classes this module consumes\r
//\r
#include <Library/BaseLib.h>\r
#include <Library/BaseMemoryLib.h>\r
#include <Library/DebugLib.h>\r
#include <Library/HobLib.h>\r
#include <Library/IoLib.h>\r
#include <Library/PcdLib.h>\r
#include <Library/PciLib.h>\r
#include <Library/PeimEntryPoint.h>\r
#include <Library/ResourcePublicationLib.h>\r
#include <Library/MtrrLib.h>\r
#include <Library/QemuFwCfgLib.h>\r
\r
#include "Platform.h"\r
#include "Cmos.h"\r
\r
UINT8 mPhysMemAddressWidth;\r
\r
STATIC UINT32 mS3AcpiReservedMemoryBase;\r
STATIC UINT32 mS3AcpiReservedMemorySize;\r
\r
STATIC UINT16 mQ35TsegMbytes;\r
\r
UINT32 mQemuUc32Base;\r
\r
VOID\r
Q35TsegMbytesInitialization (\r
  VOID\r
  )\r
{\r
  UINT16        ExtendedTsegMbytes;\r
  RETURN_STATUS PcdStatus;\r
\r
  if (mHostBridgeDevId != INTEL_Q35_MCH_DEVICE_ID) {\r
    DEBUG ((\r
      DEBUG_ERROR,\r
      "%a: no TSEG (SMRAM) on host bridge DID=0x%04x; "\r
      "only DID=0x%04x (Q35) is supported\n",\r
      __FUNCTION__,\r
      mHostBridgeDevId,\r
      INTEL_Q35_MCH_DEVICE_ID\r
      ));\r
    ASSERT (FALSE);\r
    CpuDeadLoop ();\r
  }\r
\r
  //\r
  // Check if QEMU offers an extended TSEG.\r
  //\r
  // This can be seen from writing MCH_EXT_TSEG_MB_QUERY to the MCH_EXT_TSEG_MB\r
  // register, and reading back the register.\r
  //\r
  // On a QEMU machine type that does not offer an extended TSEG, the initial\r
  // write overwrites whatever value a malicious guest OS may have placed in\r
  // the (unimplemented) register, before entering S3 or rebooting.\r
  // Subsequently, the read returns MCH_EXT_TSEG_MB_QUERY unchanged.\r
  //\r
  // On a QEMU machine type that offers an extended TSEG, the initial write\r
  // triggers an update to the register. Subsequently, the value read back\r
  // (which is guaranteed to differ from MCH_EXT_TSEG_MB_QUERY) tells us the\r
  // number of megabytes.\r
  //\r
  PciWrite16 (DRAMC_REGISTER_Q35 (MCH_EXT_TSEG_MB), MCH_EXT_TSEG_MB_QUERY);\r
  ExtendedTsegMbytes = PciRead16 (DRAMC_REGISTER_Q35 (MCH_EXT_TSEG_MB));\r
  if (ExtendedTsegMbytes == MCH_EXT_TSEG_MB_QUERY) {\r
    mQ35TsegMbytes = PcdGet16 (PcdQ35TsegMbytes);\r
    return;\r
  }\r
\r
  DEBUG ((\r
    DEBUG_INFO,\r
    "%a: QEMU offers an extended TSEG (%d MB)\n",\r
    __FUNCTION__,\r
    ExtendedTsegMbytes\r
    ));\r
  PcdStatus = PcdSet16S (PcdQ35TsegMbytes, ExtendedTsegMbytes);\r
  ASSERT_RETURN_ERROR (PcdStatus);\r
  mQ35TsegMbytes = ExtendedTsegMbytes;\r
}\r
\r
\r
/**\r
  Iterate over the RAM entries in QEMU's fw_cfg E820 RAM map that start outside\r
  of the 32-bit address range.\r
\r
  Find the highest exclusive >=4GB RAM address, or produce memory resource\r
  descriptor HOBs for RAM entries that start at or above 4GB.\r
\r
  @param[out] MaxAddress  If MaxAddress is NULL, then ScanOrAdd64BitE820Ram()\r
                          produces memory resource descriptor HOBs for RAM\r
                          entries that start at or above 4GB.\r
\r
                          Otherwise, MaxAddress holds the highest exclusive\r
                          >=4GB RAM address on output. If QEMU's fw_cfg E820\r
                          RAM map contains no RAM entry that starts outside of\r
                          the 32-bit address range, then MaxAddress is exactly\r
                          4GB on output.\r
\r
  @retval EFI_SUCCESS         The fw_cfg E820 RAM map was found and processed.\r
\r
  @retval EFI_PROTOCOL_ERROR  The RAM map was found, but its size wasn't a\r
                              whole multiple of sizeof(EFI_E820_ENTRY64). No\r
                              RAM entry was processed.\r
\r
  @return                     Error codes from QemuFwCfgFindFile(). No RAM\r
                              entry was processed.\r
**/\r
STATIC\r
EFI_STATUS\r
ScanOrAdd64BitE820Ram (\r
  OUT UINT64 *MaxAddress OPTIONAL\r
  )\r
{\r
  EFI_STATUS           Status;\r
  FIRMWARE_CONFIG_ITEM FwCfgItem;\r
  UINTN                FwCfgSize;\r
  EFI_E820_ENTRY64     E820Entry;\r
  UINTN                Processed;\r
\r
  Status = QemuFwCfgFindFile ("etc/e820", &FwCfgItem, &FwCfgSize);\r
  if (EFI_ERROR (Status)) {\r
    return Status;\r
  }\r
  if (FwCfgSize % sizeof E820Entry != 0) {\r
    return EFI_PROTOCOL_ERROR;\r
  }\r
\r
  if (MaxAddress != NULL) {\r
    *MaxAddress = BASE_4GB;\r
  }\r
\r
  QemuFwCfgSelectItem (FwCfgItem);\r
  for (Processed = 0; Processed < FwCfgSize; Processed += sizeof E820Entry) {\r
    QemuFwCfgReadBytes (sizeof E820Entry, &E820Entry);\r
    DEBUG ((\r
      DEBUG_VERBOSE,\r
      "%a: Base=0x%Lx Length=0x%Lx Type=%u\n",\r
      __FUNCTION__,\r
      E820Entry.BaseAddr,\r
      E820Entry.Length,\r
      E820Entry.Type\r
      ));\r
    if (E820Entry.Type == EfiAcpiAddressRangeMemory &&\r
        E820Entry.BaseAddr >= BASE_4GB) {\r
      if (MaxAddress == NULL) {\r
        UINT64 Base;\r
        UINT64 End;\r
\r
        //\r
        // Round up the start address, and round down the end address.\r
        //\r
        Base = ALIGN_VALUE (E820Entry.BaseAddr, (UINT64)EFI_PAGE_SIZE);\r
        End = (E820Entry.BaseAddr + E820Entry.Length) &\r
              ~(UINT64)EFI_PAGE_MASK;\r
        if (Base < End) {\r
          AddMemoryRangeHob (Base, End);\r
          DEBUG ((\r
            DEBUG_VERBOSE,\r
            "%a: AddMemoryRangeHob [0x%Lx, 0x%Lx)\n",\r
            __FUNCTION__,\r
            Base,\r
            End\r
            ));\r
        }\r
      } else {\r
        UINT64 Candidate;\r
\r
        Candidate = E820Entry.BaseAddr + E820Entry.Length;\r
        if (Candidate > *MaxAddress) {\r
          *MaxAddress = Candidate;\r
          DEBUG ((\r
            DEBUG_VERBOSE,\r
            "%a: MaxAddress=0x%Lx\n",\r
            __FUNCTION__,\r
            *MaxAddress\r
            ));\r
        }\r
      }\r
    }\r
  }\r
  return EFI_SUCCESS;\r
}\r
\r
\r
UINT32\r
GetSystemMemorySizeBelow4gb (\r
  VOID\r
  )\r
{\r
  UINT8 Cmos0x34;\r
  UINT8 Cmos0x35;\r
\r
  //\r
  // CMOS 0x34/0x35 specifies the system memory above 16 MB.\r
  // * CMOS(0x35) is the high byte\r
  // * CMOS(0x34) is the low byte\r
  // * The size is specified in 64kb chunks\r
  // * Since this is memory above 16MB, the 16MB must be added\r
  //   into the calculation to get the total memory size.\r
  //\r
\r
  Cmos0x34 = (UINT8) CmosRead8 (0x34);\r
  Cmos0x35 = (UINT8) CmosRead8 (0x35);\r
\r
  return (UINT32) (((UINTN)((Cmos0x35 << 8) + Cmos0x34) << 16) + SIZE_16MB);\r
}\r
\r
\r
STATIC\r
UINT64\r
GetSystemMemorySizeAbove4gb (\r
  )\r
{\r
  UINT32 Size;\r
  UINTN  CmosIndex;\r
\r
  //\r
  // CMOS 0x5b-0x5d specifies the system memory above 4GB MB.\r
  // * CMOS(0x5d) is the most significant size byte\r
  // * CMOS(0x5c) is the middle size byte\r
  // * CMOS(0x5b) is the least significant size byte\r
  // * The size is specified in 64kb chunks\r
  //\r
\r
  Size = 0;\r
  for (CmosIndex = 0x5d; CmosIndex >= 0x5b; CmosIndex--) {\r
    Size = (UINT32) (Size << 8) + (UINT32) CmosRead8 (CmosIndex);\r
  }\r
\r
  return LShiftU64 (Size, 16);\r
}\r
\r
\r
/**\r
  Return the highest address that DXE could possibly use, plus one.\r
**/\r
STATIC\r
UINT64\r
GetFirstNonAddress (\r
  VOID\r
  )\r
{\r
  UINT64               FirstNonAddress;\r
  UINT64               Pci64Base, Pci64Size;\r
  CHAR8                MbString[7 + 1];\r
  EFI_STATUS           Status;\r
  FIRMWARE_CONFIG_ITEM FwCfgItem;\r
  UINTN                FwCfgSize;\r
  UINT64               HotPlugMemoryEnd;\r
  RETURN_STATUS        PcdStatus;\r
\r
  //\r
  // set FirstNonAddress to suppress incorrect compiler/analyzer warnings\r
  //\r
  FirstNonAddress = 0;\r
\r
  //\r
  // If QEMU presents an E820 map, then get the highest exclusive >=4GB RAM\r
  // address from it. This can express an address >= 4GB+1TB.\r
  //\r
  // Otherwise, get the flat size of the memory above 4GB from the CMOS (which\r
  // can only express a size smaller than 1TB), and add it to 4GB.\r
  //\r
  Status = ScanOrAdd64BitE820Ram (&FirstNonAddress);\r
  if (EFI_ERROR (Status)) {\r
    FirstNonAddress = BASE_4GB + GetSystemMemorySizeAbove4gb ();\r
  }\r
\r
  //\r
  // If DXE is 32-bit, then we're done; PciBusDxe will degrade 64-bit MMIO\r
  // resources to 32-bit anyway. See DegradeResource() in\r
  // "PciResourceSupport.c".\r
  //\r
#ifdef MDE_CPU_IA32\r
  if (!FeaturePcdGet (PcdDxeIplSwitchToLongMode)) {\r
    return FirstNonAddress;\r
  }\r
#endif\r
\r
  //\r
  // Otherwise, in order to calculate the highest address plus one, we must\r
  // consider the 64-bit PCI host aperture too. Fetch the default size.\r
  //\r
  Pci64Size = PcdGet64 (PcdPciMmio64Size);\r
\r
  //\r
  // See if the user specified the number of megabytes for the 64-bit PCI host\r
  // aperture. The number of non-NUL characters in MbString allows for\r
  // 9,999,999 MB, which is approximately 10 TB.\r
  //\r
  // As signaled by the "X-" prefix, this knob is experimental, and might go\r
  // away at any time.\r
  //\r
  Status = QemuFwCfgFindFile ("opt/ovmf/X-PciMmio64Mb", &FwCfgItem,\r
             &FwCfgSize);\r
  if (!EFI_ERROR (Status)) {\r
    if (FwCfgSize >= sizeof MbString) {\r
      DEBUG ((EFI_D_WARN,\r
        "%a: ignoring malformed 64-bit PCI host aperture size from fw_cfg\n",\r
        __FUNCTION__));\r
    } else {\r
      QemuFwCfgSelectItem (FwCfgItem);\r
      QemuFwCfgReadBytes (FwCfgSize, MbString);\r
      MbString[FwCfgSize] = '\0';\r
      Pci64Size = LShiftU64 (AsciiStrDecimalToUint64 (MbString), 20);\r
    }\r
  }\r
\r
  if (Pci64Size == 0) {\r
    if (mBootMode != BOOT_ON_S3_RESUME) {\r
      DEBUG ((EFI_D_INFO, "%a: disabling 64-bit PCI host aperture\n",\r
        __FUNCTION__));\r
      PcdStatus = PcdSet64S (PcdPciMmio64Size, 0);\r
      ASSERT_RETURN_ERROR (PcdStatus);\r
    }\r
\r
    //\r
    // There's nothing more to do; the amount of memory above 4GB fully\r
    // determines the highest address plus one. The memory hotplug area (see\r
    // below) plays no role for the firmware in this case.\r
    //\r
    return FirstNonAddress;\r
  }\r
\r
  //\r
  // The "etc/reserved-memory-end" fw_cfg file, when present, contains an\r
  // absolute, exclusive end address for the memory hotplug area. This area\r
  // starts right at the end of the memory above 4GB. The 64-bit PCI host\r
  // aperture must be placed above it.\r
  //\r
  Status = QemuFwCfgFindFile ("etc/reserved-memory-end", &FwCfgItem,\r
             &FwCfgSize);\r
  if (!EFI_ERROR (Status) && FwCfgSize == sizeof HotPlugMemoryEnd) {\r
    QemuFwCfgSelectItem (FwCfgItem);\r
    QemuFwCfgReadBytes (FwCfgSize, &HotPlugMemoryEnd);\r
    DEBUG ((DEBUG_VERBOSE, "%a: HotPlugMemoryEnd=0x%Lx\n", __FUNCTION__,\r
      HotPlugMemoryEnd));\r
\r
    ASSERT (HotPlugMemoryEnd >= FirstNonAddress);\r
    FirstNonAddress = HotPlugMemoryEnd;\r
  }\r
\r
  //\r
  // SeaBIOS aligns both boundaries of the 64-bit PCI host aperture to 1GB, so\r
  // that the host can map it with 1GB hugepages. Follow suit.\r
  //\r
  Pci64Base = ALIGN_VALUE (FirstNonAddress, (UINT64)SIZE_1GB);\r
  Pci64Size = ALIGN_VALUE (Pci64Size, (UINT64)SIZE_1GB);\r
\r
  //\r
  // The 64-bit PCI host aperture should also be "naturally" aligned. The\r
  // alignment is determined by rounding the size of the aperture down to the\r
  // next smaller or equal power of two. That is, align the aperture by the\r
  // largest BAR size that can fit into it.\r
  //\r
  Pci64Base = ALIGN_VALUE (Pci64Base, GetPowerOfTwo64 (Pci64Size));\r
\r
  if (mBootMode != BOOT_ON_S3_RESUME) {\r
    //\r
    // The core PciHostBridgeDxe driver will automatically add this range to\r
    // the GCD memory space map through our PciHostBridgeLib instance; here we\r
    // only need to set the PCDs.\r
    //\r
    PcdStatus = PcdSet64S (PcdPciMmio64Base, Pci64Base);\r
    ASSERT_RETURN_ERROR (PcdStatus);\r
    PcdStatus = PcdSet64S (PcdPciMmio64Size, Pci64Size);\r
    ASSERT_RETURN_ERROR (PcdStatus);\r
\r
    DEBUG ((EFI_D_INFO, "%a: Pci64Base=0x%Lx Pci64Size=0x%Lx\n",\r
      __FUNCTION__, Pci64Base, Pci64Size));\r
  }\r
\r
  //\r
  // The useful address space ends with the 64-bit PCI host aperture.\r
  //\r
  FirstNonAddress = Pci64Base + Pci64Size;\r
  return FirstNonAddress;\r
}\r
\r
\r
/**\r
  Initialize the mPhysMemAddressWidth variable, based on guest RAM size.\r
**/\r
VOID\r
AddressWidthInitialization (\r
  VOID\r
  )\r
{\r
  UINT64 FirstNonAddress;\r
\r
  //\r
  // As guest-physical memory size grows, the permanent PEI RAM requirements\r
  // are dominated by the identity-mapping page tables built by the DXE IPL.\r
  // The DXL IPL keys off of the physical address bits advertized in the CPU\r
  // HOB. To conserve memory, we calculate the minimum address width here.\r
  //\r
  FirstNonAddress      = GetFirstNonAddress ();\r
  mPhysMemAddressWidth = (UINT8)HighBitSet64 (FirstNonAddress);\r
\r
  //\r
  // If FirstNonAddress is not an integral power of two, then we need an\r
  // additional bit.\r
  //\r
  if ((FirstNonAddress & (FirstNonAddress - 1)) != 0) {\r
    ++mPhysMemAddressWidth;\r
  }\r
\r
  //\r
  // The minimum address width is 36 (covers up to and excluding 64 GB, which\r
  // is the maximum for Ia32 + PAE). The theoretical architecture maximum for\r
  // X64 long mode is 52 bits, but the DXE IPL clamps that down to 48 bits. We\r
  // can simply assert that here, since 48 bits are good enough for 256 TB.\r
  //\r
  if (mPhysMemAddressWidth <= 36) {\r
    mPhysMemAddressWidth = 36;\r
  }\r
  ASSERT (mPhysMemAddressWidth <= 48);\r
}\r
\r
\r
/**\r
  Calculate the cap for the permanent PEI memory.\r
**/\r
STATIC\r
UINT32\r
GetPeiMemoryCap (\r
  VOID\r
  )\r
{\r
  BOOLEAN Page1GSupport;\r
  UINT32  RegEax;\r
  UINT32  RegEdx;\r
  UINT32  Pml4Entries;\r
  UINT32  PdpEntries;\r
  UINTN   TotalPages;\r
\r
  //\r
  // If DXE is 32-bit, then just return the traditional 64 MB cap.\r
  //\r
#ifdef MDE_CPU_IA32\r
  if (!FeaturePcdGet (PcdDxeIplSwitchToLongMode)) {\r
    return SIZE_64MB;\r
  }\r
#endif\r
\r
  //\r
  // Dependent on physical address width, PEI memory allocations can be\r
  // dominated by the page tables built for 64-bit DXE. So we key the cap off\r
  // of those. The code below is based on CreateIdentityMappingPageTables() in\r
  // "MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c".\r
  //\r
  Page1GSupport = FALSE;\r
  if (PcdGetBool (PcdUse1GPageTable)) {\r
    AsmCpuid (0x80000000, &RegEax, NULL, NULL, NULL);\r
    if (RegEax >= 0x80000001) {\r
      AsmCpuid (0x80000001, NULL, NULL, NULL, &RegEdx);\r
      if ((RegEdx & BIT26) != 0) {\r
        Page1GSupport = TRUE;\r
      }\r
    }\r
  }\r
\r
  if (mPhysMemAddressWidth <= 39) {\r
    Pml4Entries = 1;\r
    PdpEntries = 1 << (mPhysMemAddressWidth - 30);\r
    ASSERT (PdpEntries <= 0x200);\r
  } else {\r
    Pml4Entries = 1 << (mPhysMemAddressWidth - 39);\r
    ASSERT (Pml4Entries <= 0x200);\r
    PdpEntries = 512;\r
  }\r
\r
  TotalPages = Page1GSupport ? Pml4Entries + 1 :\r
                               (PdpEntries + 1) * Pml4Entries + 1;\r
  ASSERT (TotalPages <= 0x40201);\r
\r
  //\r
  // Add 64 MB for miscellaneous allocations. Note that for\r
  // mPhysMemAddressWidth values close to 36, the cap will actually be\r
  // dominated by this increment.\r
  //\r
  return (UINT32)(EFI_PAGES_TO_SIZE (TotalPages) + SIZE_64MB);\r
}\r
\r
\r
/**\r
  Publish PEI core memory\r
\r
  @return EFI_SUCCESS     The PEIM initialized successfully.\r
\r
**/\r
EFI_STATUS\r
PublishPeiMemory (\r
  VOID\r
  )\r
{\r
  EFI_STATUS                  Status;\r
  EFI_PHYSICAL_ADDRESS        MemoryBase;\r
  UINT64                      MemorySize;\r
  UINT32                      LowerMemorySize;\r
  UINT32                      PeiMemoryCap;\r
\r
  LowerMemorySize = GetSystemMemorySizeBelow4gb ();\r
  if (FeaturePcdGet (PcdSmmSmramRequire)) {\r
    //\r
    // TSEG is chipped from the end of low RAM\r
    //\r
    LowerMemorySize -= mQ35TsegMbytes * SIZE_1MB;\r
  }\r
\r
  //\r
  // If S3 is supported, then the S3 permanent PEI memory is placed next,\r
  // downwards. Its size is primarily dictated by CpuMpPei. The formula below\r
  // is an approximation.\r
  //\r
  if (mS3Supported) {\r
    mS3AcpiReservedMemorySize = SIZE_512KB +\r
      mMaxCpuCount *\r
      PcdGet32 (PcdCpuApStackSize);\r
    mS3AcpiReservedMemoryBase = LowerMemorySize - mS3AcpiReservedMemorySize;\r
    LowerMemorySize = mS3AcpiReservedMemoryBase;\r
  }\r
\r
  if (mBootMode == BOOT_ON_S3_RESUME) {\r
    MemoryBase = mS3AcpiReservedMemoryBase;\r
    MemorySize = mS3AcpiReservedMemorySize;\r
  } else {\r
    PeiMemoryCap = GetPeiMemoryCap ();\r
    DEBUG ((EFI_D_INFO, "%a: mPhysMemAddressWidth=%d PeiMemoryCap=%u KB\n",\r
      __FUNCTION__, mPhysMemAddressWidth, PeiMemoryCap >> 10));\r
\r
    //\r
    // Determine the range of memory to use during PEI\r
    //\r
    // Technically we could lay the permanent PEI RAM over SEC's temporary\r
    // decompression and scratch buffer even if "secure S3" is needed, since\r
    // their lifetimes don't overlap. However, PeiFvInitialization() will cover\r
    // RAM up to PcdOvmfDecompressionScratchEnd with an EfiACPIMemoryNVS memory\r
    // allocation HOB, and other allocations served from the permanent PEI RAM\r
    // shouldn't overlap with that HOB.\r
    //\r
    MemoryBase = mS3Supported && FeaturePcdGet (PcdSmmSmramRequire) ?\r
      PcdGet32 (PcdOvmfDecompressionScratchEnd) :\r
      PcdGet32 (PcdOvmfDxeMemFvBase) + PcdGet32 (PcdOvmfDxeMemFvSize);\r
    MemorySize = LowerMemorySize - MemoryBase;\r
    if (MemorySize > PeiMemoryCap) {\r
      MemoryBase = LowerMemorySize - PeiMemoryCap;\r
      MemorySize = PeiMemoryCap;\r
    }\r
  }\r
\r
  //\r
  // Publish this memory to the PEI Core\r
  //\r
  Status = PublishSystemMemory(MemoryBase, MemorySize);\r
  ASSERT_EFI_ERROR (Status);\r
\r
  return Status;\r
}\r
\r
\r
/**\r
  Peform Memory Detection for QEMU / KVM\r
\r
**/\r
STATIC\r
VOID\r
QemuInitializeRam (\r
  VOID\r
  )\r
{\r
  UINT64                      LowerMemorySize;\r
  UINT64                      UpperMemorySize;\r
  MTRR_SETTINGS               MtrrSettings;\r
  EFI_STATUS                  Status;\r
\r
  DEBUG ((EFI_D_INFO, "%a called\n", __FUNCTION__));\r
\r
  //\r
  // Determine total memory size available\r
  //\r
  LowerMemorySize = GetSystemMemorySizeBelow4gb ();\r
  UpperMemorySize = GetSystemMemorySizeAbove4gb ();\r
\r
  if (mBootMode == BOOT_ON_S3_RESUME) {\r
    //\r
    // Create the following memory HOB as an exception on the S3 boot path.\r
    //\r
    // Normally we'd create memory HOBs only on the normal boot path. However,\r
    // CpuMpPei specifically needs such a low-memory HOB on the S3 path as\r
    // well, for "borrowing" a subset of it temporarily, for the AP startup\r
    // vector.\r
    //\r
    // CpuMpPei saves the original contents of the borrowed area in permanent\r
    // PEI RAM, in a backup buffer allocated with the normal PEI services.\r
    // CpuMpPei restores the original contents ("returns" the borrowed area) at\r
    // End-of-PEI. End-of-PEI in turn is emitted by S3Resume2Pei before\r
    // transferring control to the OS's wakeup vector in the FACS.\r
    //\r
    // We expect any other PEIMs that "borrow" memory similarly to CpuMpPei to\r
    // restore the original contents. Furthermore, we expect all such PEIMs\r
    // (CpuMpPei included) to claim the borrowed areas by producing memory\r
    // allocation HOBs, and to honor preexistent memory allocation HOBs when\r
    // looking for an area to borrow.\r
    //\r
    AddMemoryRangeHob (0, BASE_512KB + BASE_128KB);\r
  } else {\r
    //\r
    // Create memory HOBs\r
    //\r
    AddMemoryRangeHob (0, BASE_512KB + BASE_128KB);\r
\r
    if (FeaturePcdGet (PcdSmmSmramRequire)) {\r
      UINT32 TsegSize;\r
\r
      TsegSize = mQ35TsegMbytes * SIZE_1MB;\r
      AddMemoryRangeHob (BASE_1MB, LowerMemorySize - TsegSize);\r
      AddReservedMemoryBaseSizeHob (LowerMemorySize - TsegSize, TsegSize,\r
        TRUE);\r
    } else {\r
      AddMemoryRangeHob (BASE_1MB, LowerMemorySize);\r
    }\r
\r
    //\r
    // If QEMU presents an E820 map, then create memory HOBs for the >=4GB RAM\r
    // entries. Otherwise, create a single memory HOB with the flat >=4GB\r
    // memory size read from the CMOS.\r
    //\r
    Status = ScanOrAdd64BitE820Ram (NULL);\r
    if (EFI_ERROR (Status) && UpperMemorySize != 0) {\r
      AddMemoryBaseSizeHob (BASE_4GB, UpperMemorySize);\r
    }\r
  }\r
\r
  //\r
  // We'd like to keep the following ranges uncached:\r
  // - [640 KB, 1 MB)\r
  // - [LowerMemorySize, 4 GB)\r
  //\r
  // Everything else should be WB. Unfortunately, programming the inverse (ie.\r
  // keeping the default UC, and configuring the complement set of the above as\r
  // WB) is not reliable in general, because the end of the upper RAM can have\r
  // practically any alignment, and we may not have enough variable MTRRs to\r
  // cover it exactly.\r
  //\r
  if (IsMtrrSupported ()) {\r
    UINT32 Uc32Size;\r
\r
    MtrrGetAllMtrrs (&MtrrSettings);\r
\r
    //\r
    // MTRRs disabled, fixed MTRRs disabled, default type is uncached\r
    //\r
    ASSERT ((MtrrSettings.MtrrDefType & BIT11) == 0);\r
    ASSERT ((MtrrSettings.MtrrDefType & BIT10) == 0);\r
    ASSERT ((MtrrSettings.MtrrDefType & 0xFF) == 0);\r
\r
    //\r
    // flip default type to writeback\r
    //\r
    SetMem (&MtrrSettings.Fixed, sizeof MtrrSettings.Fixed, 0x06);\r
    ZeroMem (&MtrrSettings.Variables, sizeof MtrrSettings.Variables);\r
    MtrrSettings.MtrrDefType |= BIT11 | BIT10 | 6;\r
    MtrrSetAllMtrrs (&MtrrSettings);\r
\r
    //\r
    // Set memory range from 640KB to 1MB to uncacheable\r
    //\r
    Status = MtrrSetMemoryAttribute (BASE_512KB + BASE_128KB,\r
               BASE_1MB - (BASE_512KB + BASE_128KB), CacheUncacheable);\r
    ASSERT_EFI_ERROR (Status);\r
\r
    //\r
    // Set memory range from the "top of lower RAM" (RAM below 4GB) to 4GB as\r
    // uncacheable. Make sure one variable MTRR suffices by truncating the size\r
    // to a whole power of two. This will round the base *up*, and a gap (not\r
    // used for either RAM or MMIO) may stay in the middle, marked as\r
    // cacheable-by-default.\r
    //\r
    Uc32Size = GetPowerOfTwo32 ((UINT32)(SIZE_4GB - LowerMemorySize));\r
    mQemuUc32Base = (UINT32)(SIZE_4GB - Uc32Size);\r
    if (mQemuUc32Base != LowerMemorySize) {\r
      DEBUG ((DEBUG_VERBOSE, "%a: rounded UC32 base from 0x%x up to 0x%x, for "\r
        "an UC32 size of 0x%x\n", __FUNCTION__, (UINT32)LowerMemorySize,\r
        mQemuUc32Base, Uc32Size));\r
    }\r
\r
    Status = MtrrSetMemoryAttribute (mQemuUc32Base, Uc32Size,\r
               CacheUncacheable);\r
    ASSERT_EFI_ERROR (Status);\r
  } else {\r
    mQemuUc32Base = (UINT32)LowerMemorySize;\r
  }\r
}\r
\r
/**\r
  Publish system RAM and reserve memory regions\r
\r
**/\r
VOID\r
InitializeRamRegions (\r
  VOID\r
  )\r
{\r
  if (!mXen) {\r
    QemuInitializeRam ();\r
  } else {\r
    XenPublishRamRegions ();\r
  }\r
\r
  if (mS3Supported && mBootMode != BOOT_ON_S3_RESUME) {\r
    //\r
    // This is the memory range that will be used for PEI on S3 resume\r
    //\r
    BuildMemoryAllocationHob (\r
      mS3AcpiReservedMemoryBase,\r
      mS3AcpiReservedMemorySize,\r
      EfiACPIMemoryNVS\r
      );\r
\r
    //\r
    // Cover the initial RAM area used as stack and temporary PEI heap.\r
    //\r
    // This is reserved as ACPI NVS so it can be used on S3 resume.\r
    //\r
    BuildMemoryAllocationHob (\r
      PcdGet32 (PcdOvmfSecPeiTempRamBase),\r
      PcdGet32 (PcdOvmfSecPeiTempRamSize),\r
      EfiACPIMemoryNVS\r
      );\r
\r
    //\r
    // SEC stores its table of GUIDed section handlers here.\r
    //\r
    BuildMemoryAllocationHob (\r
      PcdGet64 (PcdGuidedExtractHandlerTableAddress),\r
      PcdGet32 (PcdGuidedExtractHandlerTableSize),\r
      EfiACPIMemoryNVS\r
      );\r
\r
#ifdef MDE_CPU_X64\r
    //\r
    // Reserve the initial page tables built by the reset vector code.\r
    //\r
    // Since this memory range will be used by the Reset Vector on S3\r
    // resume, it must be reserved as ACPI NVS.\r
    //\r
    BuildMemoryAllocationHob (\r
      (EFI_PHYSICAL_ADDRESS)(UINTN) PcdGet32 (PcdOvmfSecPageTablesBase),\r
      (UINT64)(UINTN) PcdGet32 (PcdOvmfSecPageTablesSize),\r
      EfiACPIMemoryNVS\r
      );\r
#endif\r
  }\r
\r
  if (mBootMode != BOOT_ON_S3_RESUME) {\r
    if (!FeaturePcdGet (PcdSmmSmramRequire)) {\r
      //\r
      // Reserve the lock box storage area\r
      //\r
      // Since this memory range will be used on S3 resume, it must be\r
      // reserved as ACPI NVS.\r
      //\r
      // If S3 is unsupported, then various drivers might still write to the\r
      // LockBox area. We ought to prevent DXE from serving allocation requests\r
      // such that they would overlap the LockBox storage.\r
      //\r
      ZeroMem (\r
        (VOID*)(UINTN) PcdGet32 (PcdOvmfLockBoxStorageBase),\r
        (UINTN) PcdGet32 (PcdOvmfLockBoxStorageSize)\r
        );\r
      BuildMemoryAllocationHob (\r
        (EFI_PHYSICAL_ADDRESS)(UINTN) PcdGet32 (PcdOvmfLockBoxStorageBase),\r
        (UINT64)(UINTN) PcdGet32 (PcdOvmfLockBoxStorageSize),\r
        mS3Supported ? EfiACPIMemoryNVS : EfiBootServicesData\r
        );\r
    }\r
\r
    if (FeaturePcdGet (PcdSmmSmramRequire)) {\r
      UINT32 TsegSize;\r
\r
      //\r
      // Make sure the TSEG area that we reported as a reserved memory resource\r
      // cannot be used for reserved memory allocations.\r
      //\r
      TsegSize = mQ35TsegMbytes * SIZE_1MB;\r
      BuildMemoryAllocationHob (\r
        GetSystemMemorySizeBelow4gb() - TsegSize,\r
        TsegSize,\r
        EfiReservedMemoryType\r
        );\r
    }\r
  }\r
}\r