UefiCpuPkg/MtrrLib: Fix a MTRR calculation bug

80                   A8   B0   B8   C0
+----------WB--------+-UC-+-WT-+-WB-+

For above memory settings, current code caused the final MTRR
settings miss [A8, B0, UC] when default memory type is UC.

The root cause is the code only checks the mandatory weight
between A8 to B0, but skips to check the optional weight.
The patch fixes this issue.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>

diff --git a/UefiCpuPkg/Library/MtrrLib/MtrrLib.c b/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
index fafa15fd63f38561a4e864f3b6e49512b41b908a..768d4d5cff0671b6e6476cb83416254798fb696c 100644 (file)
--- a/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
+++ b/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
@@ -47,7 +47,7 @@ typedef struct {
   UINT64                 Address;\r
   UINT64                 Alignment;\r
   UINT64                 Length;\r
-  UINT8                  Type : 7;\r
+  MTRR_MEMORY_CACHE_TYPE Type : 7;\r
 \r
   //\r
   // Temprary use for calculating the best MTRR settings.\r
@@ -1429,7 +1429,7 @@ MtrrLibCalculateSubtractivePath (
           while (SubStart != SubStop) {\r
             Status = MtrrLibAppendVariableMtrr (\r
               Mtrrs, MtrrCapacity, MtrrCount,\r
-              Vertices[SubStart].Address, Vertices[SubStart].Length, (MTRR_MEMORY_CACHE_TYPE) Vertices[SubStart].Type\r
+              Vertices[SubStart].Address, Vertices[SubStart].Length, Vertices[SubStart].Type\r
             );\r
             if (RETURN_ERROR (Status)) {\r
               return Status;\r
@@ -1450,10 +1450,11 @@ MtrrLibCalculateSubtractivePath (
             Pre = Vertices[Cur].Previous;\r
             SubStop = Pre;\r
 \r
-            if (Weight[M (Pre, Cur)] != 0) {\r
+            if (Weight[M (Pre, Cur)] + Weight[O (Pre, Cur)] != 0) {\r
               Status = MtrrLibAppendVariableMtrr (\r
                 Mtrrs, MtrrCapacity, MtrrCount,\r
-                Vertices[Pre].Address, Vertices[Cur].Address - Vertices[Pre].Address, LowestPrecedentType\r
+                Vertices[Pre].Address, Vertices[Cur].Address - Vertices[Pre].Address,\r
+                (Pre != Cur - 1) ? LowestPrecedentType : Vertices[Pre].Type\r
               );\r
               if (RETURN_ERROR (Status)) {\r
                 return Status;\r