commit e78a2a49ee6b0c0d7c6997c87ace31d7761cf636
author Jeff Fan <jeff.fan@intel.com> Fri Jul 15 14:24:28 2016 +0800
committer Michael Kinney <michael.d.kinney@intel.com> Wed Jul 20 18:50:53 2016 -0700
tree 5c14fc5408ec4c29e40657cbd4a92d68cafe4d69
parent 8ff7187cfd998d2b6db43075a4a7908281b6da00

UefiCpuPkg/PiSmmCpuDxeSmm: SMM_CPU_DATA_BLOCK is not cleared

The commit 8b9311 changed the zeroing of mSmmMpSyncData of type
SMM_DISPATCHER_MP_SYNC_DATA by the following patch.
 -    ZeroMem (mSmmMpSyncData, mSmmMpSyncDataSize);
 +    mSmmMpSyncData->SwitchBsp = FALSE;

mSmmMpSyncDataSize not only includes SMM_DISPATCHER_MP_SYNC_DATA, but
also includes the SMM_CPU_DATA_BLOCK array and one BOOLEAN variable
array as shown here:

  mSmmMpSyncDataSize = sizeof (SMM_DISPATCHER_MP_SYNC_DATA) +
       (sizeof (SMM_CPU_DATA_BLOCK) + sizeof (BOOLEAN)) *
       gSmmCpuPrivate->SmmCoreEntryContext.NumberOfCpus;

This patch restores the original ZeroMem() to clear all CPU Sync data.
The commit 8b9311 may cause unexpected behavior.

v2:
  Mentioned CandidateBsp array in comments to make it more accurate.

Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Feng Tian <feng.tian@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jeff Fan <jeff.fan@intel.com>
Reviewed-by: Feng Tian <feng.tian@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>

UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c

diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
index 5ba0514..12466ef 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
@@ -1276,7 +1276,11 @@
   UINTN                      CpuIndex;

 

   if (mSmmMpSyncData != NULL) {

-    mSmmMpSyncData->SwitchBsp = FALSE;

+    //

+    // mSmmMpSyncDataSize includes one structure of SMM_DISPATCHER_MP_SYNC_DATA, one

+    // CpuData array of SMM_CPU_DATA_BLOCK and one CandidateBsp array of BOOLEAN.

+    //

+    ZeroMem (mSmmMpSyncData, mSmmMpSyncDataSize);

     mSmmMpSyncData->CpuData = (SMM_CPU_DATA_BLOCK *)((UINT8 *)mSmmMpSyncData + sizeof (SMM_DISPATCHER_MP_SYNC_DATA));

     mSmmMpSyncData->CandidateBsp = (BOOLEAN *)(mSmmMpSyncData->CpuData + gSmmCpuPrivate->SmmCoreEntryContext.NumberOfCpus);

     if (FeaturePcdGet (PcdCpuSmmEnableBspElection)) {