FatPkg/FatPei: Simplify the GPT Header Check

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4860

- The condition of GPT header checking is mismatched between PEI FatPei
  module in FatPkg and DXE PartitionDxe module in MdeModulePkg.

- This patch is intended to simplify the checking condition within
  FatPei module to align with PartitionDxe module to reduce code flow gap
  between both of them.

- Below of condition would be checked on GPT header,
    1. GPT header signature value
    2. GPT header CRC value
    3. GPT header LBA value
    4. GPT header size of partition entry

Signed-off-by: Jason1 Lin <[email protected]>

FatPkg/FatPei/Gpt.c

@@ -110,7 +110,6 @@ PartitionCheckGptHeader (
 {
   PEI_FAT_BLOCK_DEVICE  *ParentBlockDev;
   EFI_PEI_LBA           Lba;
-  EFI_PEI_LBA           AlternateLba;
   EFI_PEI_LBA           EntryArrayLastLba;
 
   UINT64  PartitionEntryArraySize;
@@ -120,46 +119,15 @@ PartitionCheckGptHeader (
   ParentBlockDev = &(PrivateData->BlockDevice[ParentBlockDevNo]);
 
   if (IsPrimaryHeader) {
-    Lba          = PRIMARY_PART_HEADER_LBA;
-    AlternateLba = ParentBlockDev->LastBlock;
+    Lba = PRIMARY_PART_HEADER_LBA;
   } else {
-    Lba          = ParentBlockDev->LastBlock;
-    AlternateLba = PRIMARY_PART_HEADER_LBA;
+    Lba = ParentBlockDev->LastBlock;
   }
 
   if ((PartHdr->Header.Signature != EFI_PTAB_HEADER_ID) ||
-      (PartHdr->Header.Revision != 0x00010000) ||
-      (PartHdr->Header.HeaderSize < 92) ||
-      (PartHdr->Header.HeaderSize > ParentBlockDev->BlockSize) ||
       (!PartitionCheckGptHeaderCRC (PartHdr)) ||
-      (PartHdr->Header.Reserved != 0)
-      )
-  {
-    DEBUG ((DEBUG_ERROR, "Invalid efi partition table header\n"));
-    return FALSE;
-  }
-
-  //
-  // |    Block0    |    Block1    |Block2 ~ FirstUsableLBA - 1|FirstUsableLBA, ... ,LastUsableLBA|LastUsableLBA+1 ~ LastBlock-1|  LastBlock  |
-  // |Protective MBR|Primary Header|Entry Array(At Least 16384)|             Partition            | Entry Array(At Least 16384) |BackUp Header|
-  //
-  // 1. Protective MBR is fixed at Block 0.
-  // 2. Primary Header is fixed at Block 1.
-  // 3. Backup Header is fixed at LastBlock.
-  // 4. Must be remain 128*128 bytes for primary entry array.
-  // 5. Must be remain 128*128 bytes for backup entry array.
-  // 6. SizeOfPartitionEntry must be equals to 128 * 2^n.
-  //
-  if ((PartHdr->MyLBA != Lba) ||
-      (PartHdr->AlternateLBA != AlternateLba) ||
-      (PartHdr->FirstUsableLBA < 2 + EFI_SIZE_TO_BLOCKS (EFI_GPT_PART_ENTRY_MIN_SIZE, ParentBlockDev->BlockSize)) ||
-      (PartHdr->LastUsableLBA  > ParentBlockDev->LastBlock - 1 - EFI_SIZE_TO_BLOCKS (EFI_GPT_PART_ENTRY_MIN_SIZE, ParentBlockDev->BlockSize)) ||
-      (PartHdr->FirstUsableLBA > PartHdr->LastUsableLBA) ||
-      (PartHdr->PartitionEntryLBA < 2) ||
-      (PartHdr->PartitionEntryLBA > ParentBlockDev->LastBlock - 1) ||
-      ((PartHdr->PartitionEntryLBA >= PartHdr->FirstUsableLBA) && (PartHdr->PartitionEntryLBA <= PartHdr->LastUsableLBA)) ||
-      (PartHdr->SizeOfPartitionEntry%128 != 0) ||
-      (PartHdr->SizeOfPartitionEntry != sizeof (EFI_PARTITION_ENTRY))
+      (PartHdr->MyLBA != Lba) ||
+      (PartHdr->SizeOfPartitionEntry < sizeof (EFI_PARTITION_ENTRY))
       )
   {
     DEBUG ((DEBUG_ERROR, "Invalid efi partition table header\n"));