[Patch V2 03/14] UefiCpuPkg/CpuPageTableLib: Fix the non-1:1 mapping issue

["duntan" <dun.tan@intel.com>]

In previous code logic, when splitting a leaf parent entry to
smaller granularity child page table, if the parent entry
Attribute&Mask(without PageTableBaseAddress field) is equal to the
input attribute&mask(without PageTableBaseAddress field), the split
process won't happen. This may lead to failure in non-1:1 mapping.

For example, there is a page table in which [0, 1G] is mapped(Lv4[0]
,Lv3[0,0], a non-leaf level4 entry and a leaf level3 entry). And we
want to remap [0, 2M] linear address range to [1G, 1G + 2M] with the
same attibute. The expected behaviour should be: split Lv3[0,0]
entry into 512 level2 entries and remap the first level2 entry to
cover [0, 2M]. But the split won't happen in previous code since
PageTableBaseAddress of input Attribute is not checked.

So, when checking if a leaf parent entry needs to be splitted, we
should also check if PageTableBaseAddress calculated by parent entry
is equal to the value caculated by input attribute.

Signed-off-by: Dun Tan <dun.tan@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
---
 UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c b/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
index 4c9d70fa0a..ee27238edb 100644
--- a/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
+++ b/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
@@ -258,6 +258,7 @@ PageTableLibMapInLevel (
   UINTN               BitStart;
   UINTN               Index;
   IA32_PAGING_ENTRY   *PagingEntry;
+  UINTN               PagingEntryIndex;
   IA32_PAGING_ENTRY   *CurrentPagingEntry;
   UINT64              RegionLength;
   UINT64              SubLength;
@@ -288,6 +289,13 @@ PageTableLibMapInLevel (
   LocalParentAttribute.Uint64 = ParentAttribute->Uint64;
   ParentAttribute             = &LocalParentAttribute;
 
+  //
+  // RegionLength: 256T (1 << 48) 512G (1 << 39), 1G (1 << 30), 2M (1 << 21) or 4K (1 << 12).
+  //
+  BitStart         = 12 + (Level - 1) * 9;
+  PagingEntryIndex = (UINTN)BitFieldRead64 (LinearAddress + Offset, BitStart, BitStart + 9 - 1);
+  RegionLength     = REGION_LENGTH (Level);
+
   //
   // ParentPagingEntry ONLY is deferenced for checking Present and MustBeOne bits
   // when Modify is FALSE.
@@ -325,8 +333,11 @@ PageTableLibMapInLevel (
     // the actual attributes of grand-parents when determing the memory type.
     //
     PleBAttribute.Uint64 = PageTableLibGetPleBMapAttribute (&ParentPagingEntry->PleB, ParentAttribute);
-    if ((IA32_MAP_ATTRIBUTE_ATTRIBUTES (&PleBAttribute) & IA32_MAP_ATTRIBUTE_ATTRIBUTES (Mask))
-        == (IA32_MAP_ATTRIBUTE_ATTRIBUTES (Attribute) & IA32_MAP_ATTRIBUTE_ATTRIBUTES (Mask)))
+    if ((((IA32_MAP_ATTRIBUTE_ATTRIBUTES (&PleBAttribute) & IA32_MAP_ATTRIBUTE_ATTRIBUTES (Mask))
+          == (IA32_MAP_ATTRIBUTE_ATTRIBUTES (Attribute) & IA32_MAP_ATTRIBUTE_ATTRIBUTES (Mask)))) &&
+        (  (Mask->Bits.PageTableBaseAddress == 0)
+        || ((IA32_MAP_ATTRIBUTE_PAGE_TABLE_BASE_ADDRESS (&PleBAttribute) + PagingEntryIndex * RegionLength)
+            == (IA32_MAP_ATTRIBUTE_PAGE_TABLE_BASE_ADDRESS (Attribute) + Offset))))
     {
       //
       // This function is called when the memory length is less than the region length of the parent level.
@@ -353,8 +364,7 @@ PageTableLibMapInLevel (
       //
       PageTableLibSetPnle (&ParentPagingEntry->Pnle, &NopAttribute, &AllOneMask);
 
-      RegionLength = REGION_LENGTH (Level);
-      PagingEntry  = (IA32_PAGING_ENTRY *)(UINTN)IA32_PNLE_PAGE_TABLE_BASE_ADDRESS (&ParentPagingEntry->Pnle);
+      PagingEntry = (IA32_PAGING_ENTRY *)(UINTN)IA32_PNLE_PAGE_TABLE_BASE_ADDRESS (&ParentPagingEntry->Pnle);
       for (SubOffset = 0, Index = 0; Index < 512; Index++) {
         PagingEntry[Index].Uint64 = OneOfPagingEntry.Uint64 + SubOffset;
         SubOffset                += RegionLength;
@@ -425,14 +435,11 @@ PageTableLibMapInLevel (
   }
 
   //
-  // RegionLength: 256T (1 << 48) 512G (1 << 39), 1G (1 << 30), 2M (1 << 21) or 4K (1 << 12).
   // RegionStart:  points to the linear address that's aligned on RegionLength and lower than (LinearAddress + Offset).
   //
-  BitStart     = 12 + (Level - 1) * 9;
-  Index        = (UINTN)BitFieldRead64 (LinearAddress + Offset, BitStart, BitStart + 9 - 1);
-  RegionLength = LShiftU64 (1, BitStart);
-  RegionMask   = RegionLength - 1;
-  RegionStart  = (LinearAddress + Offset) & ~RegionMask;
+  Index       = PagingEntryIndex;
+  RegionMask  = RegionLength - 1;
+  RegionStart = (LinearAddress + Offset) & ~RegionMask;
 
   ParentAttribute->Uint64 = PageTableLibGetPnleMapAttribute (&ParentPagingEntry->Pnle, ParentAttribute);
 
-- 
2.31.1.windows.1