Revision: 18715
          http://sourceforge.net/p/edk2/code/18715
Author:   vanjeff
Date:     2015-11-02 03:04:19 +0000 (Mon, 02 Nov 2015)
Log Message:
-----------
UefiCpuPkg/PiSmmCpuDxeSmm: Shouldn't use gSmst->CurrentlyExecutingCpu

In ConfigSmmCodeAccessCheck(), we used gSmst->CurrentlyExecutingCpu to get the
current SMM BSP. But ConfigSmmCodeAccessCheck() maybe invoked before executing
SmmCoreEntry() and gSmst->CurrentlyExecutingCpu hasn't been updated to the
latest value. The code flow is as below:

  BSPHandler()
    gSmmCpuPrivate->SmmCoreEntryContext.CurrentlyExecutingCpu = CpuIndex;
    //
    // when mRestoreSmmConfigurationInS3 is set:
    //
    ConfigSmmCodeAccessCheck()
      //
      // reads gSmst->CurrentlyExecutingCpu to early
      //
    gSmmCpuPrivate->SmmCoreEntry (&gSmmCpuPrivate->SmmCoreEntryContext)
      //
      // sets gSmst->CurrentlyExecutingCpu with CopyMem() too late
      //
      CopyMem (&gSmmCoreSmst.SmmStartupThisAp,
        SmmEntryContext, sizeof (EFI_SMM_ENTRY_CONTEXT));

Instead, we should use
gSmmCpuPrivate->SmmCoreEntryContext.CurrentlyExecutingCpu directly.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jeff Fan <[email protected]>
Reviewed-by: Laszlo Ersek <[email protected]>

Modified Paths:
--------------
    trunk/edk2/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c

Modified: trunk/edk2/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c
===================================================================
--- trunk/edk2/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c       2015-11-02 
02:38:24 UTC (rev 18714)
+++ trunk/edk2/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c       2015-11-02 
03:04:19 UTC (rev 18715)
@@ -1386,7 +1386,7 @@
   //
   // Check to see if the Feature Control MSR is supported on this CPU
   //
-  Index = gSmst->CurrentlyExecutingCpu;
+  Index = gSmmCpuPrivate->SmmCoreEntryContext.CurrentlyExecutingCpu;
   if (!SmmCpuFeaturesIsSmmRegisterSupported (Index, SmmRegFeatureControl)) {
     mSmmCodeAccessCheckEnable = FALSE;
     return;
@@ -1428,7 +1428,7 @@
   // Enable SMM Code Access Check feature for the APs.
   //
   for (Index = 0; Index < gSmst->NumberOfCpus; Index++) {
-    if (Index != gSmst->CurrentlyExecutingCpu) {
+    if (Index != gSmmCpuPrivate->SmmCoreEntryContext.CurrentlyExecutingCpu) {
 
       //
       // Acquire Config SMM Code Access Check spin lock.  The AP will release 
the


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