MdeModulePkg PiSmmCore: Remove a hidden assumption of SMRAM reservation

that assumes the SMRAM reserved range is only at the end of the SMRAM descriptor.

          //
          // This range has reserved area, calculate the left free size
          //
          gSmmCorePrivate->SmramRanges[Index].PhysicalSize = SmramResRegion->SmramReservedStart - gSmmCorePrivate->SmramRanges[Index].CpuStart;

Imagine the following scenario where we just reserve the first page of the SMRAM range:

SMRAM Descriptor:
  Start: 0x80000000
  Size: 0x02000000

Reserved Range:
  Start: 0x80000000
  Size: 0x00001000

In this case the adjustment to the SMRAM range size yields zero: ReservedStart - SMRAM Start is 0x80000000 - 0x80000000 = 0.
So even though most of the range is still free the IPL code decides its unusable.

The problem comes from the email thread: [edk2] PiSmmIpl SMRAM Reservation Logic.
http://thread.gmane.org/gmane.comp.bios.tianocore.devel/15268

Also to follow the idea in the email thread, the patch is to
1. Keep only one copy of full SMRAM ranges in gSmmCorePrivate->SmramRanges,
split record for SmmConfiguration->SmramReservedRegions and SMM Core that
will be marked to be EFI_ALLOCATED in gSmmCorePrivate->SmramRanges.
2. Handle SmmConfiguration->SmramReservedRegions at beginning of, at end of,
in the middle of, or cross multiple SmramRanges.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18031 6f19259b-4bc3-4df7-8a09-765794883524

3 files changed, 442 insertions, 79 deletions

diff --git a/MdeModulePkg/Core/PiSmmCore/PiSmmCore.c b/MdeModulePkg/Core/PiSmmCore/PiSmmCore.c
index c91f14907a..55dcf31713 100644
--- a/MdeModulePkg/Core/PiSmmCore/PiSmmCore.c
+++ b/MdeModulePkg/Core/PiSmmCore/PiSmmCore.c
@@ -523,10 +523,10 @@ SmmMain (
   //

   // Copy FullSmramRanges to SMRAM

   //

-  mFullSmramRangeCount = gSmmCorePrivate->FullSmramRangeCount;

+  mFullSmramRangeCount = gSmmCorePrivate->SmramRangeCount;

   mFullSmramRanges = AllocatePool (mFullSmramRangeCount * sizeof (EFI_SMRAM_DESCRIPTOR));

   ASSERT (mFullSmramRanges != NULL);

-  CopyMem (mFullSmramRanges, gSmmCorePrivate->FullSmramRanges, mFullSmramRangeCount * sizeof (EFI_SMRAM_DESCRIPTOR));

+  CopyMem (mFullSmramRanges, gSmmCorePrivate->SmramRanges, mFullSmramRangeCount * sizeof (EFI_SMRAM_DESCRIPTOR));

 

   //

   // Register all SMI Handlers required by the SMM Core

diff --git a/MdeModulePkg/Core/PiSmmCore/PiSmmCorePrivateData.h b/MdeModulePkg/Core/PiSmmCore/PiSmmCorePrivateData.h
index 9915669c6e..8aec7a6568 100644
--- a/MdeModulePkg/Core/PiSmmCore/PiSmmCorePrivateData.h
+++ b/MdeModulePkg/Core/PiSmmCore/PiSmmCorePrivateData.h
@@ -120,9 +120,6 @@ typedef struct {
   EFI_PHYSICAL_ADDRESS            PiSmmCoreImageBase;

   UINT64                          PiSmmCoreImageSize;

   EFI_PHYSICAL_ADDRESS            PiSmmCoreEntryPoint;

-

-  UINTN                           FullSmramRangeCount;

-  EFI_SMRAM_DESCRIPTOR            *FullSmramRanges;

 } SMM_CORE_PRIVATE_DATA;

 

 #endif

diff --git a/MdeModulePkg/Core/PiSmmCore/PiSmmIpl.c b/MdeModulePkg/Core/PiSmmCore/PiSmmIpl.c
index ebef741876..9b269779ea 100644
--- a/MdeModulePkg/Core/PiSmmCore/PiSmmIpl.c
+++ b/MdeModulePkg/Core/PiSmmCore/PiSmmIpl.c
@@ -861,17 +861,21 @@ GetPeCoffImageFixLoadingAssignedAddress(
 /**

   Load the SMM Core image into SMRAM and executes the SMM Core from SMRAM.

 

-  @param[in] SmramRange  Descriptor for the range of SMRAM to reload the 

-                         currently executing image.

-  @param[in] Context     Context to pass into SMM Core

+  @param[in, out] SmramRange            Descriptor for the range of SMRAM to reload the 

+                                        currently executing image, the rang of SMRAM to

+                                        hold SMM Core will be excluded.

+  @param[in, out] SmramRangeSmmCore     Descriptor for the range of SMRAM to hold SMM Core.

+

+  @param[in]      Context               Context to pass into SMM Core

 

   @return  EFI_STATUS

 

 **/

 EFI_STATUS

 ExecuteSmmCoreFromSmram (

-  IN EFI_SMRAM_DESCRIPTOR  *SmramRange,

-  IN VOID                  *Context

+  IN OUT EFI_SMRAM_DESCRIPTOR   *SmramRange,

+  IN OUT EFI_SMRAM_DESCRIPTOR   *SmramRangeSmmCore,

+  IN     VOID                   *Context

   )

 {

   EFI_STATUS                    Status;

@@ -879,7 +883,6 @@ ExecuteSmmCoreFromSmram (
   UINTN                         SourceSize;

   PE_COFF_LOADER_IMAGE_CONTEXT  ImageContext;

   UINTN                         PageCount;

-  EFI_PHYSICAL_ADDRESS          DestinationBuffer;

   EFI_IMAGE_ENTRY_POINT         EntryPoint;

 

   //

@@ -924,7 +927,7 @@ ExecuteSmmCoreFromSmram (
       // Since the memory range to load SMM CORE will be cut out in SMM core, so no need to allocate and free this range

       //

       PageCount = 0;

-     } else {

+    } else {

       DEBUG ((EFI_D_INFO, "LOADING MODULE FIXED ERROR: Loading module at fixed address at address failed\n"));

       //

       // Allocate memory for the image being loaded from the EFI_SRAM_DESCRIPTOR 

@@ -936,12 +939,15 @@ ExecuteSmmCoreFromSmram (
       ASSERT (SmramRange->PhysicalSize > EFI_PAGES_TO_SIZE (PageCount));

 

       SmramRange->PhysicalSize -= EFI_PAGES_TO_SIZE (PageCount);

-      DestinationBuffer = SmramRange->CpuStart + SmramRange->PhysicalSize;

+      SmramRangeSmmCore->CpuStart = SmramRange->CpuStart + SmramRange->PhysicalSize;

+      SmramRangeSmmCore->PhysicalStart = SmramRange->PhysicalStart + SmramRange->PhysicalSize;

+      SmramRangeSmmCore->RegionState = SmramRange->RegionState | EFI_ALLOCATED;

+      SmramRangeSmmCore->PhysicalSize = EFI_PAGES_TO_SIZE (PageCount);

 

       //

-      // Align buffer on section boundry

+      // Align buffer on section boundary

       //

-      ImageContext.ImageAddress = DestinationBuffer;

+      ImageContext.ImageAddress = SmramRangeSmmCore->CpuStart;

     }

   } else {

     //

@@ -954,12 +960,15 @@ ExecuteSmmCoreFromSmram (
     ASSERT (SmramRange->PhysicalSize > EFI_PAGES_TO_SIZE (PageCount));

 

     SmramRange->PhysicalSize -= EFI_PAGES_TO_SIZE (PageCount);

-    DestinationBuffer = SmramRange->CpuStart + SmramRange->PhysicalSize;

+    SmramRangeSmmCore->CpuStart = SmramRange->CpuStart + SmramRange->PhysicalSize;

+    SmramRangeSmmCore->PhysicalStart = SmramRange->PhysicalStart + SmramRange->PhysicalSize;

+    SmramRangeSmmCore->RegionState = SmramRange->RegionState | EFI_ALLOCATED;

+    SmramRangeSmmCore->PhysicalSize = EFI_PAGES_TO_SIZE (PageCount);

 

     //

-    // Align buffer on section boundry

+    // Align buffer on section boundary

     //

-    ImageContext.ImageAddress = DestinationBuffer;

+    ImageContext.ImageAddress = SmramRangeSmmCore->CpuStart;

   }

   

   ImageContext.ImageAddress += ImageContext.SectionAlignment - 1;

@@ -1006,20 +1015,424 @@ ExecuteSmmCoreFromSmram (
   }

 

   //

-  // If the load operation, relocate operation, or the image execution return an

-  // error, then free memory allocated from the EFI_SRAM_DESCRIPTOR specified by 

-  // SmramRange

+  // Always free memory allocted by GetFileBufferByFilePath ()

   //

-  if (EFI_ERROR (Status)) {

-    SmramRange->PhysicalSize += EFI_PAGES_TO_SIZE (PageCount);

+  FreePool (SourceBuffer);

+

+  return Status;

+}

+

+/**

+  SMM split SMRAM entry.

+

+  @param[in, out] RangeToCompare             Pointer to EFI_SMRAM_DESCRIPTOR to compare.

+  @param[in, out] ReservedRangeToCompare     Pointer to EFI_SMM_RESERVED_SMRAM_REGION to compare.

+  @param[out]     Ranges                     Output pointer to hold split EFI_SMRAM_DESCRIPTOR entry.

+  @param[in, out] RangeCount                 Pointer to range count.

+  @param[out]     ReservedRanges             Output pointer to hold split EFI_SMM_RESERVED_SMRAM_REGION entry.

+  @param[in, out] ReservedRangeCount         Pointer to reserved range count.

+  @param[out]     FinalRanges                Output pointer to hold split final EFI_SMRAM_DESCRIPTOR entry

+                                             that no need to be split anymore.

+  @param[in, out] FinalRangeCount            Pointer to final range count.

+

+**/

+VOID

+SmmSplitSmramEntry (

+  IN OUT EFI_SMRAM_DESCRIPTOR           *RangeToCompare,

+  IN OUT EFI_SMM_RESERVED_SMRAM_REGION  *ReservedRangeToCompare,

+  OUT    EFI_SMRAM_DESCRIPTOR           *Ranges,

+  IN OUT UINTN                          *RangeCount,

+  OUT    EFI_SMM_RESERVED_SMRAM_REGION  *ReservedRanges,

+  IN OUT UINTN                          *ReservedRangeCount,

+  OUT    EFI_SMRAM_DESCRIPTOR           *FinalRanges,

+  IN OUT UINTN                          *FinalRangeCount

+  )

+{

+  UINT64    RangeToCompareEnd;

+  UINT64    ReservedRangeToCompareEnd;

+

+  RangeToCompareEnd         = RangeToCompare->CpuStart + RangeToCompare->PhysicalSize;

+  ReservedRangeToCompareEnd = ReservedRangeToCompare->SmramReservedStart + ReservedRangeToCompare->SmramReservedSize;

+

+  if ((RangeToCompare->CpuStart >= ReservedRangeToCompare->SmramReservedStart) &&

+      (RangeToCompare->CpuStart < ReservedRangeToCompareEnd)) {

+    if (RangeToCompareEnd < ReservedRangeToCompareEnd) {

+      //

+      // RangeToCompare  ReservedRangeToCompare

+      //                 ----                    ----    --------------------------------------

+      //                 |  |                    |  | -> 1. ReservedRangeToCompare

+      // ----            |  |                    |--|    --------------------------------------

+      // |  |            |  |                    |  |

+      // |  |            |  |                    |  | -> 2. FinalRanges[*FinalRangeCount] and increment *FinalRangeCount

+      // |  |            |  |                    |  |       RangeToCompare->PhysicalSize = 0

+      // ----            |  |                    |--|    --------------------------------------

+      //                 |  |                    |  | -> 3. ReservedRanges[*ReservedRangeCount] and increment *ReservedRangeCount

+      //                 ----                    ----    --------------------------------------

+      //

+

+      //

+      // 1. Update ReservedRangeToCompare.

+      //

+      ReservedRangeToCompare->SmramReservedSize = RangeToCompare->CpuStart - ReservedRangeToCompare->SmramReservedStart;

+      //

+      // 2. Update FinalRanges[FinalRangeCount] and increment *FinalRangeCount.

+      //    Zero RangeToCompare->PhysicalSize.

+      //

+      FinalRanges[*FinalRangeCount].CpuStart      = RangeToCompare->CpuStart;

+      FinalRanges[*FinalRangeCount].PhysicalStart = RangeToCompare->PhysicalStart;

+      FinalRanges[*FinalRangeCount].RegionState   = RangeToCompare->RegionState | EFI_ALLOCATED;

+      FinalRanges[*FinalRangeCount].PhysicalSize  = RangeToCompare->PhysicalSize;

+      *FinalRangeCount += 1;

+      RangeToCompare->PhysicalSize = 0;

+      //

+      // 3. Update ReservedRanges[*ReservedRangeCount] and increment *ReservedRangeCount.

+      //

+      ReservedRanges[*ReservedRangeCount].SmramReservedStart = FinalRanges[*FinalRangeCount - 1].CpuStart + FinalRanges[*FinalRangeCount - 1].PhysicalSize;

+      ReservedRanges[*ReservedRangeCount].SmramReservedSize  = ReservedRangeToCompareEnd - RangeToCompareEnd;

+      *ReservedRangeCount += 1;

+    } else {

+      //

+      // RangeToCompare  ReservedRangeToCompare

+      //                 ----                    ----    --------------------------------------

+      //                 |  |                    |  | -> 1. ReservedRangeToCompare

+      // ----            |  |                    |--|    --------------------------------------

+      // |  |            |  |                    |  |

+      // |  |            |  |                    |  | -> 2. FinalRanges[*FinalRangeCount] and increment *FinalRangeCount

+      // |  |            |  |                    |  |

+      // |  |            ----                    |--|    --------------------------------------

+      // |  |                                    |  | -> 3. RangeToCompare

+      // ----                                    ----    --------------------------------------

+      //

+

+      //

+      // 1. Update ReservedRangeToCompare.

+      //

+      ReservedRangeToCompare->SmramReservedSize = RangeToCompare->CpuStart - ReservedRangeToCompare->SmramReservedStart;

+      //

+      // 2. Update FinalRanges[FinalRangeCount] and increment *FinalRangeCount.

+      //

+      FinalRanges[*FinalRangeCount].CpuStart      = RangeToCompare->CpuStart;

+      FinalRanges[*FinalRangeCount].PhysicalStart = RangeToCompare->PhysicalStart;

+      FinalRanges[*FinalRangeCount].RegionState   = RangeToCompare->RegionState | EFI_ALLOCATED;

+      FinalRanges[*FinalRangeCount].PhysicalSize  = ReservedRangeToCompareEnd - RangeToCompare->CpuStart;

+      *FinalRangeCount += 1;

+      //

+      // 3. Update RangeToCompare.

+      //

+      RangeToCompare->CpuStart      += FinalRanges[*FinalRangeCount - 1].PhysicalSize;

+      RangeToCompare->PhysicalStart += FinalRanges[*FinalRangeCount - 1].PhysicalSize;

+      RangeToCompare->PhysicalSize  -= FinalRanges[*FinalRangeCount - 1].PhysicalSize;

+    }

+  } else if ((ReservedRangeToCompare->SmramReservedStart >= RangeToCompare->CpuStart) &&

+             (ReservedRangeToCompare->SmramReservedStart < RangeToCompareEnd)) {

+    if (ReservedRangeToCompareEnd < RangeToCompareEnd) {

+      //

+      // RangeToCompare  ReservedRangeToCompare

+      // ----                                    ----    --------------------------------------

+      // |  |                                    |  | -> 1. RangeToCompare

+      // |  |            ----                    |--|    --------------------------------------

+      // |  |            |  |                    |  |

+      // |  |            |  |                    |  | -> 2. FinalRanges[*FinalRangeCount] and increment *FinalRangeCount

+      // |  |            |  |                    |  |       ReservedRangeToCompare->SmramReservedSize = 0

+      // |  |            ----                    |--|    --------------------------------------

+      // |  |                                    |  | -> 3. Ranges[*RangeCount] and increment *RangeCount

+      // ----                                    ----    --------------------------------------

+      //

+

+      //

+      // 1. Update RangeToCompare.

+      //

+      RangeToCompare->PhysicalSize = ReservedRangeToCompare->SmramReservedStart - RangeToCompare->CpuStart;

+      //

+      // 2. Update FinalRanges[FinalRangeCount] and increment *FinalRangeCount.

+      //    ReservedRangeToCompare->SmramReservedSize = 0

+      //

+      FinalRanges[*FinalRangeCount].CpuStart      = ReservedRangeToCompare->SmramReservedStart;

+      FinalRanges[*FinalRangeCount].PhysicalStart = RangeToCompare->PhysicalStart + RangeToCompare->PhysicalSize;

+      FinalRanges[*FinalRangeCount].RegionState   = RangeToCompare->RegionState | EFI_ALLOCATED;

+      FinalRanges[*FinalRangeCount].PhysicalSize  = ReservedRangeToCompare->SmramReservedSize;

+      *FinalRangeCount += 1;

+      ReservedRangeToCompare->SmramReservedSize = 0;

+      //

+      // 3. Update Ranges[*RangeCount] and increment *RangeCount.

+      //

+      Ranges[*RangeCount].CpuStart      = FinalRanges[*FinalRangeCount - 1].CpuStart + FinalRanges[*FinalRangeCount - 1].PhysicalSize;

+      Ranges[*RangeCount].PhysicalStart = FinalRanges[*FinalRangeCount - 1].PhysicalStart + FinalRanges[*FinalRangeCount - 1].PhysicalSize;

+      Ranges[*RangeCount].RegionState   = RangeToCompare->RegionState;

+      Ranges[*RangeCount].PhysicalSize  = RangeToCompareEnd - ReservedRangeToCompareEnd;

+      *RangeCount += 1;

+    } else {

+      //

+      // RangeToCompare  ReservedRangeToCompare

+      // ----                                    ----    --------------------------------------

+      // |  |                                    |  | -> 1. RangeToCompare

+      // |  |            ----                    |--|    --------------------------------------

+      // |  |            |  |                    |  |

+      // |  |            |  |                    |  | -> 2. FinalRanges[*FinalRangeCount] and increment *FinalRangeCount

+      // |  |            |  |                    |  |

+      // ----            |  |                    |--|    --------------------------------------

+      //                 |  |                    |  | -> 3. ReservedRangeToCompare

+      //                 ----                    ----    --------------------------------------

+      //

+

+      //

+      // 1. Update RangeToCompare.

+      //

+      RangeToCompare->PhysicalSize = ReservedRangeToCompare->SmramReservedStart - RangeToCompare->CpuStart;

+      //

+      // 2. Update FinalRanges[FinalRangeCount] and increment *FinalRangeCount.

+      //    ReservedRangeToCompare->SmramReservedSize = 0

+      //

+      FinalRanges[*FinalRangeCount].CpuStart      = ReservedRangeToCompare->SmramReservedStart;

+      FinalRanges[*FinalRangeCount].PhysicalStart = RangeToCompare->PhysicalStart + RangeToCompare->PhysicalSize;

+      FinalRanges[*FinalRangeCount].RegionState   = RangeToCompare->RegionState | EFI_ALLOCATED;

+      FinalRanges[*FinalRangeCount].PhysicalSize  = RangeToCompareEnd - ReservedRangeToCompare->SmramReservedStart;

+      *FinalRangeCount += 1;

+      //

+      // 3. Update ReservedRangeToCompare.

+      //

+      ReservedRangeToCompare->SmramReservedStart += FinalRanges[*FinalRangeCount - 1].PhysicalSize;

+      ReservedRangeToCompare->SmramReservedSize  -= FinalRanges[*FinalRangeCount - 1].PhysicalSize;

+    }

+  }

+}

+

+/**

+  Returns if SMRAM range and SMRAM reserved range are overlapped.

+

+  @param[in] RangeToCompare             Pointer to EFI_SMRAM_DESCRIPTOR to compare.

+  @param[in] ReservedRangeToCompare     Pointer to EFI_SMM_RESERVED_SMRAM_REGION to compare.

+

+  @retval TRUE  There is overlap.

+  @retval FALSE There is no overlap.

+

+**/

+BOOLEAN

+SmmIsSmramOverlap (

+  IN EFI_SMRAM_DESCRIPTOR           *RangeToCompare,

+  IN EFI_SMM_RESERVED_SMRAM_REGION  *ReservedRangeToCompare

+  )

+{

+  UINT64    RangeToCompareEnd;

+  UINT64    ReservedRangeToCompareEnd;

+

+  RangeToCompareEnd         = RangeToCompare->CpuStart + RangeToCompare->PhysicalSize;

+  ReservedRangeToCompareEnd = ReservedRangeToCompare->SmramReservedStart + ReservedRangeToCompare->SmramReservedSize;

+

+  if ((RangeToCompare->CpuStart >= ReservedRangeToCompare->SmramReservedStart) &&

+      (RangeToCompare->CpuStart < ReservedRangeToCompareEnd)) {

+    return TRUE;

+  } else if ((ReservedRangeToCompare->SmramReservedStart >= RangeToCompare->CpuStart) &&

+             (ReservedRangeToCompare->SmramReservedStart < RangeToCompareEnd)) {

+    return TRUE;

   }

+  return FALSE;

+}

 

+/**

+  Get full SMRAM ranges.

+

+  It will get SMRAM ranges from SmmAccess protocol and SMRAM reserved ranges from

+  SmmConfiguration protocol, split the entries if there is overlap between them.

+  It will also reserve one entry for SMM core.

+

+  @param[out] FullSmramRangeCount   Output pointer to full SMRAM range count.

+

+  @return Pointer to full SMRAM ranges.

+

+**/

+EFI_SMRAM_DESCRIPTOR *

+GetFullSmramRanges (

+  OUT UINTN     *FullSmramRangeCount

+  )

+{

+  EFI_STATUS                        Status;

+  EFI_SMM_CONFIGURATION_PROTOCOL    *SmmConfiguration;

+  UINTN                             Size;

+  UINTN                             Index;

+  UINTN                             Index2;

+  EFI_SMRAM_DESCRIPTOR              *FullSmramRanges;

+  UINTN                             TempSmramRangeCount;

+  EFI_SMRAM_DESCRIPTOR              *TempSmramRanges;

+  UINTN                             SmramRangeCount;

+  EFI_SMRAM_DESCRIPTOR              *SmramRanges;

+  UINTN                             SmramReservedCount;

+  EFI_SMM_RESERVED_SMRAM_REGION     *SmramReservedRanges;

+  UINTN                             MaxCount;

+  BOOLEAN                           Rescan;

+

+  //

+  // Get SMM Configuration Protocol if it is present.

   //

-  // Always free memory allocted by GetFileBufferByFilePath ()

+  SmmConfiguration = NULL;

+  Status = gBS->LocateProtocol (&gEfiSmmConfigurationProtocolGuid, NULL, (VOID **) &SmmConfiguration);

+

   //

-  FreePool (SourceBuffer);

+  // Get SMRAM information.

+  //

+  Size = 0;

+  Status = mSmmAccess->GetCapabilities (mSmmAccess, &Size, NULL);

+  ASSERT (Status == EFI_BUFFER_TOO_SMALL);

 

-  return Status;

+  SmramRangeCount = Size / sizeof (EFI_SMRAM_DESCRIPTOR);

+

+  //

+  // Get SMRAM reserved region count.

+  //

+  SmramReservedCount = 0;

+  if (SmmConfiguration != NULL) {

+    while (SmmConfiguration->SmramReservedRegions[SmramReservedCount].SmramReservedSize != 0) {

+      SmramReservedCount++;

+    }

+  }

+

+  if (SmramReservedCount == 0) {

+    //

+    // No reserved SMRAM entry from SMM Configuration Protocol.

+    // Reserve one entry for SMM Core in the full SMRAM ranges.

+    //

+    *FullSmramRangeCount = SmramRangeCount + 1;

+    Size = (*FullSmramRangeCount) * sizeof (EFI_SMRAM_DESCRIPTOR);

+    FullSmramRanges = (EFI_SMRAM_DESCRIPTOR *) AllocatePool (Size);

+    ASSERT (FullSmramRanges != NULL);

+

+    Status = mSmmAccess->GetCapabilities (mSmmAccess, &Size, FullSmramRanges);

+    ASSERT_EFI_ERROR (Status);

+

+    return FullSmramRanges;

+  }

+

+  //

+  // Why MaxCount = X + 2 * Y?

+  // Take Y = 1 as example below, Y > 1 case is just the iteration of Y = 1.

+  //

+  //   X = 1 Y = 1     MaxCount = 3 = 1 + 2 * 1

+  //   ----            ----

+  //   |  |  ----      |--|

+  //   |  |  |  |  ->  |  |

+  //   |  |  ----      |--|

+  //   ----            ----

+  //

+  //   X = 2 Y = 1     MaxCount = 4 = 2 + 2 * 1

+  //   ----            ----

+  //   |  |            |  |

+  //   |  |  ----      |--|

+  //   |  |  |  |      |  |

+  //   |--|  |  |  ->  |--|

+  //   |  |  |  |      |  |

+  //   |  |  ----      |--|

+  //   |  |            |  |

+  //   ----            ----

+  //

+  //   X = 3 Y = 1     MaxCount = 5 = 3 + 2 * 1

+  //   ----            ----

+  //   |  |            |  |

+  //   |  |  ----      |--|

+  //   |--|  |  |      |--|

+  //   |  |  |  |  ->  |  |

+  //   |--|  |  |      |--|

+  //   |  |  ----      |--|

+  //   |  |            |  |

+  //   ----            ----

+  //

+  //   ......

+  //

+  MaxCount = SmramRangeCount + 2 * SmramReservedCount;

+

+  Size = MaxCount * sizeof (EFI_SMM_RESERVED_SMRAM_REGION);

+  SmramReservedRanges = (EFI_SMM_RESERVED_SMRAM_REGION *) AllocatePool (Size);

+  ASSERT (SmramReservedRanges != NULL);

+  for (Index = 0; Index < SmramReservedCount; Index++) {

+    CopyMem (&SmramReservedRanges[Index], &SmmConfiguration->SmramReservedRegions[Index], sizeof (EFI_SMM_RESERVED_SMRAM_REGION));

+  }

+

+  Size = MaxCount * sizeof (EFI_SMRAM_DESCRIPTOR);

+  TempSmramRanges = (EFI_SMRAM_DESCRIPTOR *) AllocatePool (Size);

+  ASSERT (TempSmramRanges != NULL);

+  TempSmramRangeCount = 0;

+

+  SmramRanges = (EFI_SMRAM_DESCRIPTOR *) AllocatePool (Size);

+  ASSERT (SmramRanges != NULL);

+  Status = mSmmAccess->GetCapabilities (mSmmAccess, &Size, SmramRanges);

+  ASSERT_EFI_ERROR (Status);

+

+  do {

+    Rescan = FALSE;

+    for (Index = 0; (Index < SmramRangeCount) && !Rescan; Index++) {

+      //

+      // Skip zero size entry.

+      //

+      if (SmramRanges[Index].PhysicalSize != 0) {

+        for (Index2 = 0; (Index2 < SmramReservedCount) && !Rescan; Index2++) {

+          //

+          // Skip zero size entry.

+          //

+          if (SmramReservedRanges[Index2].SmramReservedSize != 0) {

+            if (SmmIsSmramOverlap (

+                  &SmramRanges[Index],

+                  &SmramReservedRanges[Index2]

+                  )) {

+              //

+              // There is overlap, need to split entry and then rescan.

+              //

+              SmmSplitSmramEntry (

+                &SmramRanges[Index],

+                &SmramReservedRanges[Index2],

+                SmramRanges,

+                &SmramRangeCount,

+                SmramReservedRanges,

+                &SmramReservedCount,

+                TempSmramRanges,

+                &TempSmramRangeCount

+                );

+              Rescan = TRUE;

+            }

+          }

+        }

+        if (!Rescan) {

+          //

+          // No any overlap, copy the entry to the temp SMRAM ranges.

+          // Zero SmramRanges[Index].PhysicalSize = 0;

+          //

+          CopyMem (&TempSmramRanges[TempSmramRangeCount++], &SmramRanges[Index], sizeof (EFI_SMRAM_DESCRIPTOR));

+          SmramRanges[Index].PhysicalSize = 0;

+        }

+      }

+    }

+  } while (Rescan);

+  ASSERT (TempSmramRangeCount <= MaxCount);

+

+  //

+  // Sort the entries,

+  // and reserve one entry for SMM Core in the full SMRAM ranges.

+  //

+  FullSmramRanges = AllocatePool ((TempSmramRangeCount + 1) * sizeof (EFI_SMRAM_DESCRIPTOR));

+  ASSERT (FullSmramRanges != NULL);

+  *FullSmramRangeCount = 0;

+  do {

+    for (Index = 0; Index < TempSmramRangeCount; Index++) {

+      if (TempSmramRanges[Index].PhysicalSize != 0) {

+        break;

+      }

+    }

+    ASSERT (Index < TempSmramRangeCount);

+    for (Index2 = 0; Index2 < TempSmramRangeCount; Index2++) {

+      if ((Index2 != Index) && (TempSmramRanges[Index2].PhysicalSize != 0) && (TempSmramRanges[Index2].CpuStart < TempSmramRanges[Index].CpuStart)) {

+        Index = Index2;

+      }

+    }

+    CopyMem (&FullSmramRanges[*FullSmramRangeCount], &TempSmramRanges[Index], sizeof (EFI_SMRAM_DESCRIPTOR));

+    *FullSmramRangeCount += 1;

+    TempSmramRanges[Index].PhysicalSize = 0;

+  } while (*FullSmramRangeCount < TempSmramRangeCount);

+  ASSERT (*FullSmramRangeCount == TempSmramRangeCount);

+  *FullSmramRangeCount += 1;

+

+  FreePool (SmramRanges);

+  FreePool (SmramReservedRanges);

+  FreePool (TempSmramRanges);

+

+  return FullSmramRanges;

 }

 

 /**

@@ -1044,10 +1457,7 @@ SmmIplEntry (
   )

 {

   EFI_STATUS                      Status;

-  EFI_SMM_CONFIGURATION_PROTOCOL  *SmmConfiguration;

-  UINTN                           Size;

   UINTN                           Index;

-  EFI_SMM_RESERVED_SMRAM_REGION   *SmramResRegion;

   UINT64                          MaxSize;

   VOID                            *Registration;

   UINT64                          SmmCodeSize;

@@ -1074,34 +1484,7 @@ SmmIplEntry (
   Status = gBS->LocateProtocol (&gEfiSmmControl2ProtocolGuid, NULL, (VOID **)&mSmmControl2);

   ASSERT_EFI_ERROR (Status);

 

-  //

-  // Get SMM Configuration Protocol if it is present

-  //

-  SmmConfiguration = NULL;

-  Status = gBS->LocateProtocol (&gEfiSmmConfigurationProtocolGuid, NULL, (VOID **) &SmmConfiguration);

-

-  //

-  // Get SMRAM information

-  //

-  Size = 0;

-  Status = mSmmAccess->GetCapabilities (mSmmAccess, &Size, NULL);

-  ASSERT (Status == EFI_BUFFER_TOO_SMALL);

-

-  gSmmCorePrivate->SmramRanges = (EFI_SMRAM_DESCRIPTOR *)AllocatePool (Size);

-  ASSERT (gSmmCorePrivate->SmramRanges != NULL);

-

-  Status = mSmmAccess->GetCapabilities (mSmmAccess, &Size, gSmmCorePrivate->SmramRanges);

-  ASSERT_EFI_ERROR (Status);

-

-  gSmmCorePrivate->SmramRangeCount = Size / sizeof (EFI_SMRAM_DESCRIPTOR);

-

-  //

-  // Save a full copy

-  //

-  gSmmCorePrivate->FullSmramRangeCount = gSmmCorePrivate->SmramRangeCount;

-  gSmmCorePrivate->FullSmramRanges = (EFI_SMRAM_DESCRIPTOR *) AllocatePool (Size);

-  ASSERT (gSmmCorePrivate->FullSmramRanges != NULL);

-  CopyMem (gSmmCorePrivate->FullSmramRanges, gSmmCorePrivate->SmramRanges, Size);

+  gSmmCorePrivate->SmramRanges = GetFullSmramRanges (&gSmmCorePrivate->SmramRangeCount);

 

   //

   // Open all SMRAM ranges

@@ -1113,26 +1496,6 @@ SmmIplEntry (
   // Print debug message that the SMRAM window is now open.

   //

   DEBUG ((DEBUG_INFO, "SMM IPL opened SMRAM window\n"));

-

-  //

-  // Subtract SMRAM any reserved SMRAM regions.

-  //

-  if (SmmConfiguration != NULL) {

-    SmramResRegion = SmmConfiguration->SmramReservedRegions;

-    while (SmramResRegion->SmramReservedSize != 0) {

-      for (Index = 0; Index < gSmmCorePrivate->SmramRangeCount; Index ++) {

-        if ((SmramResRegion->SmramReservedStart >= gSmmCorePrivate->SmramRanges[Index].CpuStart)  &&      \

-           ((SmramResRegion->SmramReservedStart + SmramResRegion->SmramReservedSize) <=   \

-           (gSmmCorePrivate->SmramRanges[Index].CpuStart + gSmmCorePrivate->SmramRanges[Index].PhysicalSize))) {

-          //

-          // This range has reserved area, calculate the left free size

-          //

-          gSmmCorePrivate->SmramRanges[Index].PhysicalSize = SmramResRegion->SmramReservedStart - gSmmCorePrivate->SmramRanges[Index].CpuStart;

-        }

-      }

-      SmramResRegion++;

-    }

-  }

   

   //

   // Find the largest SMRAM range between 1MB and 4GB that is at least 256KB - 4K in size

@@ -1214,7 +1577,11 @@ SmmIplEntry (
     //

     // Load SMM Core into SMRAM and execute it from SMRAM

     //

-    Status = ExecuteSmmCoreFromSmram (mCurrentSmramRange, gSmmCorePrivate);

+    Status = ExecuteSmmCoreFromSmram (

+               mCurrentSmramRange,

+               &gSmmCorePrivate->SmramRanges[gSmmCorePrivate->SmramRangeCount - 1],

+               gSmmCorePrivate

+               );

     if (EFI_ERROR (Status)) {

       //

       // Print error message that the SMM Core failed to be loaded and executed.

@@ -1262,7 +1629,6 @@ SmmIplEntry (
     // Free all allocated resources

     //

     FreePool (gSmmCorePrivate->SmramRanges);

-    FreePool (gSmmCorePrivate->FullSmramRanges);

 

     return EFI_UNSUPPORTED;

   }