[PATCH v2] UefiCpuPkg: Fix potential spinLock issue in SmmStartupThisAp

[damian.nikodem@intel.com]

Due to needs a tackling the deficiency of the AP API, is necessary to ensure that in non-blocking mode
previous AP executed command is finished before start new one. 

To remedy above: 
  1) execute AcquireSpinLock instead AcquireSpinLockOrFail - this will ensure time "window" to eliminate potential
     race condition beetwen BSP and AP spinLock release in non-blocking mode.
     This also will eliminate possibility to start executing new AP function before last is finished.
  2) remove returns EFI_STATUS - EFI_INVALID_PARAMETER - in new scenario returned status is not necessary to caller.

Signed-off-by: Damian Nikodem <damian.nikodem@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Benjamin You <benjamin.you@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Krzysztof Rusocki <krzysztof.rusocki@intel.com>

diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
index d8d2b6f444..0685637c2b 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
@@ -1235,14 +1235,9 @@ InternalSmmStartupThisAp (
     return EFI_INVALID_PARAMETER;
   }
 
-  if (Token == NULL) {
-    AcquireSpinLock (mSmmMpSyncData->CpuData[CpuIndex].Busy);
-  } else {
-    if (!AcquireSpinLockOrFail (mSmmMpSyncData->CpuData[CpuIndex].Busy)) {
-      DEBUG((DEBUG_ERROR, "Can't acquire mSmmMpSyncData->CpuData[%d].Busy\n", CpuIndex));
-      return EFI_NOT_READY;
-    }
+  AcquireSpinLock (mSmmMpSyncData->CpuData[CpuIndex].Busy);
 
+  if (Token != NULL) {
     *Token = (MM_COMPLETION) CreateToken ();
   }
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