UefiCpuPkg/PiSmmCpuDxeSmm: Check ProcessorId == INVALID_APIC_ID

If PcdCpuHotPlugSupport is TRUE, gSmst->NumberOfCpus will be the
PcdCpuMaxLogicalProcessorNumber. If gSmst->SmmStartupThisAp() is invoked for
those un-existed processors, ASSERT() happened in ConfigSmmCodeAccessCheck().

This fix is to check if ProcessorId is valid before invoke
gSmst->SmmStartupThisAp() in ConfigSmmCodeAccessCheck() and to check if
ProcessorId is valid in InternalSmmStartupThisAp() to avoid unexpected DEBUG
error message displayed.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jeff Fan <jeff.fan@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
(cherry picked from commit b7025df8f9)

UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c

@@ -1117,7 +1117,12 @@ ConfigSmmCodeAccessCheck (
   //
   for (Index = 0; Index < gSmst->NumberOfCpus; Index++) {
     if (Index != gSmmCpuPrivate->SmmCoreEntryContext.CurrentlyExecutingCpu) {
-
+      if (gSmmCpuPrivate->ProcessorInfo[Index].ProcessorId == INVALID_APIC_ID) {
+        //
+        // If this processor does not exist
+        //
+        continue;
+      }
       //
       // Acquire Config SMM Code Access Check spin lock.  The AP will release the
       // spin lock when it is done executing ConfigSmmCodeAccessCheckOnCurrentProcessor().