[PATCH] UefiCpuPkg/MpInitLib: Fix incorrect Guard page setup for APs

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

AP has its own stack for code execution. If PcdCpuStackGuard is enabled,
the page at the bottom of stack of AP will be disabled (NOT PRESENT) to
monitor the stack overflow issue. This requires PcdCpuApStackSize to be
set with value more than one page of memory.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
---
 UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf |  1 +
 UefiCpuPkg/Library/MpInitLib/DxeMpLib.c       | 34 ++++++++++++++++++++++++---
 2 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf b/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
index 805641b516..e7b9eb4462 100644
--- a/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
+++ b/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
@@ -73,4 +73,5 @@
   gUefiCpuPkgTokenSpaceGuid.PcdCpuMicrocodePatchRegionSize         ## CONSUMES
   gUefiCpuPkgTokenSpaceGuid.PcdCpuApLoopMode                       ## CONSUMES
   gUefiCpuPkgTokenSpaceGuid.PcdCpuApTargetCstate                   ## SOMETIMES_CONSUMES
+  gEfiMdeModulePkgTokenSpaceGuid.PcdCpuStackGuard                  ## CONSUMES
 
diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
index 479f8189f6..40c1bf407a 100644
--- a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
@@ -17,6 +17,7 @@
 #include <Library/UefiLib.h>
 #include <Library/UefiBootServicesTableLib.h>
 #include <Library/DebugAgentLib.h>
+#include <Library/DxeServicesTableLib.h>
 
 #include <Protocol/Timer.h>
 
@@ -288,9 +289,12 @@ InitMpGlobalData (
   IN CPU_MP_DATA               *CpuMpData
   )
 {
-  EFI_STATUS                 Status;
-  EFI_PHYSICAL_ADDRESS       Address;
-  UINTN                      ApSafeBufferSize;
+  EFI_STATUS                          Status;
+  EFI_PHYSICAL_ADDRESS                Address;
+  UINTN                               ApSafeBufferSize;
+  UINTN                               Index;
+  EFI_GCD_MEMORY_SPACE_DESCRIPTOR     MemDesc;
+  UINTN                               StackBase;
 
   SaveCpuMpData (CpuMpData);
 
@@ -301,6 +305,30 @@ InitMpGlobalData (
     return;
   }
 
+  if (PcdGetBool (PcdCpuStackGuard)) {
+    //
+    // One extra page at the bottom of the stack is needed for Guard page.
+    //
+    if (CpuMpData->CpuApStackSize <= EFI_PAGE_SIZE) {
+      DEBUG ((DEBUG_ERROR, "PcdCpuApStackSize is not big enough for Stack Guard!\n"));
+      ASSERT (FALSE);
+    }
+
+    for (Index = 0; Index < CpuMpData->CpuCount; ++Index) {
+      StackBase = CpuMpData->Buffer + Index * CpuMpData->CpuApStackSize;
+
+      Status = gDS->GetMemorySpaceDescriptor (StackBase, &MemDesc);
+      ASSERT_EFI_ERROR (Status);
+
+      Status = gDS->SetMemorySpaceAttributes (
+                      StackBase,
+                      EFI_PAGES_TO_SIZE (1),
+                      MemDesc.Attributes | EFI_MEMORY_RP
+                      );
+      ASSERT_EFI_ERROR (Status);
+    }
+  }
+
   //
   // Avoid APs access invalid buffer data which allocated by BootServices,
   // so we will allocate reserved data for AP loop code. We also need to
-- 
2.15.1.windows.2