[PATCH v1] UefiCpuPkg/MpInitLib: Fix possible uninitialized 'InitFlag' field

["Wu, Hao A" <hao.a.wu@intel.com>]

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=2474

Previous commit d786a17232:
UefiCpuPkg/MpInitLib: Reduce the size when loading microcode patches

Removed the below assignments for the 'InitFlag' field of CPU_MP_DATA
structure in function MpInitLibInitialize() when APs are waken up to do
some initialize sync:

CpuMpData->InitFlag  = ApInitReconfig;
...
CpuMpData->InitFlag = ApInitDone;

Under some cases (e.g. when variable OldCpuMpData is not NULL, which means
function CollectProcessorCount() will not be called), this will left the
'InitFlag' field being uninitialized with a value of 0, which is a invalid
value for the type of 'InitFlag' (AP_INIT_STATE).

It may potentially cause the WakeUpAP() function to run some unnecessary
codes when the APs have been successfully waken up before:

  if (CpuMpData->WakeUpByInitSipiSipi ||
      CpuMpData->InitFlag   != ApInitDone) {
    ResetVectorRequired = TRUE;
    AllocateResetVector (CpuMpData);
    FillExchangeInfoData (CpuMpData);
    SaveLocalApicTimerSetting (CpuMpData);
  }

This commit will address the above-mentioned issue.

Test done:
* OS boot on a real platform with multi processors

Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Signed-off-by: Hao A Wu <hao.a.wu@intel.com>
---
 UefiCpuPkg/Library/MpInitLib/MpLib.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index 6ec9b172b8..17e19395f2 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -1775,11 +1775,12 @@ MpInitLibInitialize (
   // Wakeup APs to do some AP initialize sync (Microcode & MTRR)
   //
   if (CpuMpData->CpuCount > 1) {
+    CpuMpData->InitFlag = ApInitReconfig;
     WakeUpAP (CpuMpData, TRUE, 0, ApInitializeSync, CpuMpData, TRUE);
     while (CpuMpData->FinishedCount < (CpuMpData->CpuCount - 1)) {
       CpuPause ();
     }
-
+    CpuMpData->InitFlag = ApInitDone;
     for (Index = 0; Index < CpuMpData->CpuCount; Index++) {
       SetApState (&CpuMpData->CpuData[Index], CpuStateIdle);
     }
-- 
2.12.0.windows.1