From e50f951286d8dbc35404e01dd77b9eacfb16191f Mon Sep 17 00:00:00 2001
From: Jiewen Yao <jiewen.yao@intel.com>
Date: Mon, 28 Nov 2016 21:45:40 +0800
Subject: [PATCH] UefiCpuPkg/PiSmmCpu: relax superpage protection on page
 split.

PiSmmCpu driver may split page for page attribute request.
Current logic not only propagates the super page attribute to
the leaf page attribut, but also to the directory page attribute.

However, the later might be wrong because we cannot clear protection
without touching directory page attribute.
The effective protection is the strictest combination
across the levels.

We should always clear protection on directory page and set
protection on leaf page for easy clearing later.

Cc: Jeff Fan <jeff.fan@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jiewen Yao <jiewen.yao@intel.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jeff Fan <jeff.fan@intel.com>
---
 UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
index c85e025424..d841dd014c 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
@@ -299,7 +299,7 @@ SplitPage (
       for (Index = 0; Index < SIZE_4KB / sizeof(UINT64); Index++) {
         NewPageEntry[Index] = BaseAddress + SIZE_4KB * Index + ((*PageEntry) & PAGE_PROGATE_BITS);
       }
-      (*PageEntry) = (UINT64)(UINTN)NewPageEntry + ((*PageEntry) & PAGE_PROGATE_BITS);
+      (*PageEntry) = (UINT64)(UINTN)NewPageEntry + PAGE_ATTRIBUTE_BITS;
       return RETURN_SUCCESS;
     } else {
       return RETURN_UNSUPPORTED;
@@ -320,7 +320,7 @@ SplitPage (
       for (Index = 0; Index < SIZE_4KB / sizeof(UINT64); Index++) {
         NewPageEntry[Index] = BaseAddress + SIZE_2MB * Index + IA32_PG_PS + ((*PageEntry) & PAGE_PROGATE_BITS);
       }
-      (*PageEntry) = (UINT64)(UINTN)NewPageEntry + ((*PageEntry) & PAGE_PROGATE_BITS);
+      (*PageEntry) = (UINT64)(UINTN)NewPageEntry + PAGE_ATTRIBUTE_BITS;
       return RETURN_SUCCESS;
     } else {
       return RETURN_UNSUPPORTED;