[PATCH v2 5/6] UefiCpuPkg/PiSmmCpuDxeSmm: Disable page table protection

[Jian J Wang <jian.j.wang@intel.com>]

> According to Eric's feedback:
> a. Enclose bit-or with parentheses
> b. Add code in 32-bit code to bypass setting page table to read-only

Heap guard feature will update page attributes frequently. The page table
should not set to be read-only if heap guard feature is enabled for SMM
mode. Otherwise this feature cannot work.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
---
 UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c     | 7 +++++++
 UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf | 1 +
 UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c      | 3 ++-
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c
index f295c2ebf2..27c11f1b8d 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c
@@ -184,6 +184,13 @@ SetPageTableAttributes (
   BOOLEAN               IsSplitted;
   BOOLEAN               PageTableSplitted;
 
+  //
+  // Don't mark page table as read-only if heap guard is enabled.
+  //
+  if ((PcdGet8 (PcdHeapGuardPropertyMask) & (BIT3 | BIT2)) != 0) {
+    return ;
+  }
+
   DEBUG ((DEBUG_INFO, "SetPageTableAttributes\n"));
 
   //
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf
index 099792e6ce..644709650c 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf
@@ -159,6 +159,7 @@
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmStaticPageTable               ## CONSUMES
   gEfiMdeModulePkgTokenSpaceGuid.PcdAcpiS3Enable                   ## CONSUMES
   gEfiMdeModulePkgTokenSpaceGuid.PcdPteMemoryEncryptionAddressOrMask    ## CONSUMES
+  gEfiMdeModulePkgTokenSpaceGuid.PcdHeapGuardPropertyMask               ## CONSUMES
 
 [Depex]
   gEfiMpServiceProtocolGuid
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
index 3dde80f9ba..4d4668a0c6 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
@@ -902,7 +902,8 @@ SetPageTableAttributes (
   BOOLEAN               IsSplitted;
   BOOLEAN               PageTableSplitted;
 
-  if (!mCpuSmmStaticPageTable) {
+  if (!mCpuSmmStaticPageTable
+      || (PcdGet8 (PcdHeapGuardPropertyMask) & (BIT3 | BIT2)) != 0) {
     return ;
   }
 
-- 
2.14.1.windows.1