[PATCH] UefiCpuPkg/MpInitLib: fix issue in wakeup buffer initialization

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

To fix an issue in which enabling NX feature will mark the AP wakeup
buffer as non-executable and fail the AP init, the buffer was split
into two part: the lower part in memory within 1MB and the higher part
within allocated executable memory (EfiBootServicesCode). But the
address of higher part memory was stored in lower part memory, which
is actually shared with legacy components and will be overwritten by
LegacyBiosDxe driver if CSM is enabled.

This patch fixes this issue by storing the address of higher part
memory in CpuMpData instead of ExchangeInfo.

Cc: Ruiyu Ni <ruiyu.ni@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/MpLib.c | 20 ++++++++++----------
 UefiCpuPkg/Library/MpInitLib/MpLib.h |  1 +
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index 6231968c74..42011d6231 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -823,19 +823,20 @@ FillExchangeInfoData (
   // Copy all 32-bit code and 64-bit code into memory with type of
   // EfiBootServicesCode to avoid page fault if NX memory protection is enabled.
   //
-  if (ExchangeInfo->ModeTransitionMemory != 0) {
+  if (CpuMpData->WakeupBufferHigh != 0) {
     Size = CpuMpData->AddressMap.RendezvousFunnelSize -
            CpuMpData->AddressMap.ModeTransitionOffset;
     CopyMem (
-      (VOID *)(UINTN)ExchangeInfo->ModeTransitionMemory,
+      (VOID *)CpuMpData->WakeupBufferHigh,
       CpuMpData->AddressMap.RendezvousFunnelAddress +
       CpuMpData->AddressMap.ModeTransitionOffset,
       Size
       );
 
-    ExchangeInfo->ModeHighMemory = ExchangeInfo->ModeTransitionMemory;
-    ExchangeInfo->ModeHighMemory += (UINT32)ExchangeInfo->ModeOffset -
-               (UINT32)CpuMpData->AddressMap.ModeTransitionOffset;
+    ExchangeInfo->ModeTransitionMemory = (UINT32)CpuMpData->WakeupBufferHigh;
+    ExchangeInfo->ModeHighMemory = (UINT32)CpuMpData->WakeupBufferHigh +
+                                   (UINT32)ExchangeInfo->ModeOffset -
+                                   (UINT32)CpuMpData->AddressMap.ModeTransitionOffset;
     ExchangeInfo->ModeHighSegment = (UINT16)ExchangeInfo->CodeSegment;
   } else {
     ExchangeInfo->ModeTransitionMemory = (UINT32)
@@ -916,11 +917,10 @@ AllocateResetVector (
     CpuMpData->WakeupBuffer      = GetWakeupBuffer (ApResetVectorSize);
     CpuMpData->MpCpuExchangeInfo = (MP_CPU_EXCHANGE_INFO *) (UINTN)
                     (CpuMpData->WakeupBuffer + CpuMpData->AddressMap.RendezvousFunnelSize);
-    CpuMpData->MpCpuExchangeInfo->ModeTransitionMemory = (UINT32)
-                    GetModeTransitionBuffer (
-                      CpuMpData->AddressMap.RendezvousFunnelSize -
-                      CpuMpData->AddressMap.ModeTransitionOffset
-                      );
+    CpuMpData->WakeupBufferHigh  = GetModeTransitionBuffer (
+                                    CpuMpData->AddressMap.RendezvousFunnelSize -
+                                    CpuMpData->AddressMap.ModeTransitionOffset
+                                    );
   }
   BackupAndPrepareWakeupBuffer (CpuMpData);
 }
diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.h b/UefiCpuPkg/Library/MpInitLib/MpLib.h
index 0232fe896a..e7f9a4de0a 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.h
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.h
@@ -208,6 +208,7 @@ struct _CPU_MP_DATA {
   UINTN                          CpuApStackSize;
   MP_ASSEMBLY_ADDRESS_MAP        AddressMap;
   UINTN                          WakeupBuffer;
+  UINTN                          WakeupBufferHigh;
   UINTN                          BackupBuffer;
   UINTN                          BackupBufferSize;
 
-- 
2.15.1.windows.2