IntelSiliconPkg IntelVTdDxe: Fix DMA does not work issue

Fix DMA does not work issue when system memory is not
greater than 4G.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>

diff --git a/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/TranslationTable.c b/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/TranslationTable.c
index cecb5d23efbf36aa4d3c578db276cb9bcf8e3e1d..7bdc4a5146bd88f56fda72106fdcedcbf09b5a99 100644 (file)
--- a/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/TranslationTable.c
+++ b/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/TranslationTable.c
@@ -286,9 +286,13 @@ CreateSecondLevelPagingEntry (
   if (SecondLevelPagingEntry == NULL) {\r
     return NULL;\r
   }\r
-  SecondLevelPagingEntry = CreateSecondLevelPagingEntryTable (VtdIndex, SecondLevelPagingEntry, SIZE_4GB, mAbove4GMemoryLimit, IoMmuAccess);\r
-  if (SecondLevelPagingEntry == NULL) {\r
-    return NULL;\r
+\r
+  if (mAbove4GMemoryLimit != 0) {\r
+    ASSERT (mAbove4GMemoryLimit > BASE_4GB);\r
+    SecondLevelPagingEntry = CreateSecondLevelPagingEntryTable (VtdIndex, SecondLevelPagingEntry, SIZE_4GB, mAbove4GMemoryLimit, IoMmuAccess);\r
+    if (SecondLevelPagingEntry == NULL) {\r
+      return NULL;\r
+    }\r
   }\r
 \r
   return SecondLevelPagingEntry;\r