[edk2-devel] [PATCH v2 3/5] MdeModulePkg/DxeIpl: Align Page table Level setting with previous level.

[Wu, Jiaxin]

System paging 5 level enabled or not can be checked via CR4.LA57, system
preferred Page table Level (PcdUse5LevelPageTable) must align with previous
level for 64bit long mode.

This patch is to do the wise check:
If cpu has already runned in 64bit long mode PEI, Page table Level in DXE
must align with previous level.
If cpu runs in 32bit protected mode PEI, Page table Level in DXE is decided
by PCD and feature capability.

Cc: Dandan Bi <dandan.bi at intel.com>
Cc: Liming Gao <gaoliming at byosoft.com.cn>
Cc: Eric Dong <eric.dong at intel.com>
Cc: Ray Ni <ray.ni at intel.com>
Cc: Zeng Star <star.zeng at intel.com>
Cc: Gerd Hoffmann <kraxel at redhat.com>
Cc: Rahul Kumar <rahul1.kumar at intel.com>
Signed-off-by: Jiaxin Wu <jiaxin.wu at intel.com>
---
 MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c | 39 ++++++++++++++++--------
 1 file changed, 27 insertions(+), 12 deletions(-)

diff --git a/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c b/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c
index 18b121d768..a8e46eacc3 100644
--- a/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c
+++ b/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c
@@ -737,22 +737,37 @@ CreateIdentityMappingPageTables (
     } else {
       PhysicalAddressBits = 36;
     }
   }
 
-  Page5LevelSupport = FALSE;
-  if (PcdGetBool (PcdUse5LevelPageTable)) {
-    AsmCpuidEx (
-      CPUID_STRUCTURED_EXTENDED_FEATURE_FLAGS,
-      CPUID_STRUCTURED_EXTENDED_FEATURE_FLAGS_SUB_LEAF_INFO,
-      NULL,
-      NULL,
-      &EcxFlags.Uint32,
-      NULL
-      );
-    if (EcxFlags.Bits.FiveLevelPage != 0) {
-      Page5LevelSupport = TRUE;
+  //
+  // Check cpu runs in 64bit long mode or 32bit protected mode.
+  //
+  if (sizeof (UINTN) == sizeof (UINT64)) {
+    //
+    // If cpu has already runned in 64bit long mode PEI, Page table Level in DXE must align with previous level.
+    //
+    Cr4.UintN         = AsmReadCr4 ();
+    Page5LevelSupport = Cr4.Bits.LA57 ? TRUE : FALSE;
+    ASSERT (PcdGetBool (PcdUse5LevelPageTable) == Page5LevelSupport);
+  } else {
+    //
+    // If cpu runs in 32bit protected mode PEI, Page table Level in DXE is decided by PCD and feature capability.
+    //
+    Page5LevelSupport = FALSE;
+    if (PcdGetBool (PcdUse5LevelPageTable)) {
+      AsmCpuidEx (
+        CPUID_STRUCTURED_EXTENDED_FEATURE_FLAGS,
+        CPUID_STRUCTURED_EXTENDED_FEATURE_FLAGS_SUB_LEAF_INFO,
+        NULL,
+        NULL,
+        &EcxFlags.Uint32,
+        NULL
+        );
+      if (EcxFlags.Bits.FiveLevelPage != 0) {
+        Page5LevelSupport = TRUE;
+      }
     }
   }
 
   DEBUG ((DEBUG_INFO, "AddressBits=%u 5LevelPaging=%u 1GPage=%u\n", PhysicalAddressBits, Page5LevelSupport, Page1GSupport));
 
-- 
2.16.2.windows.1



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