[PATCH] UefiCpuPkg/PiSmmCpuDxeSmm: Remove dependence between APs.

["Dong, Eric" <eric.dong@intel.com>]

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2268

In current implementation, when check whether APs called by StartUpAllAPs
or StartUpThisAp, it checks the Tokens value used by other APs. Also the AP
will update the Token value for itself if its task finished. In this
case, the potential race condition  issues happens for the tokens.
Because of this, system may trig ASSERT during cycling test.

This change enhance the code logic, add new attributes for the token to
remove the reference for the tokens belongs to other APs.

Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Eric Dong <eric.dong@intel.com>
---
 UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c      | 107 +++++++--------------
 UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h |   4 +-
 2 files changed, 36 insertions(+), 75 deletions(-)

diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
index 757f1056f7..bd5fdfd728 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
@@ -402,38 +402,6 @@ IsPresentAp (
     *(mSmmMpSyncData->CpuData[CpuIndex].Present));
 }
 
-/**
-  Check whether execute in single AP or all APs.
-
-  Compare two Tokens used by different APs to know whether in StartAllAps call.
-
-  Whether is an valid AP base on AP's Present flag.
-
-  @retval  TRUE      IN StartAllAps call.
-  @retval  FALSE     Not in StartAllAps call.
-
-**/
-BOOLEAN
-InStartAllApsCall (
-  VOID
-  )
-{
-  UINTN      ApIndex;
-  UINTN      ApIndex2;
-
-  for (ApIndex = mMaxNumberOfCpus; ApIndex-- > 0;) {
-    if (IsPresentAp (ApIndex) && (mSmmMpSyncData->CpuData[ApIndex].Token != NULL)) {
-      for (ApIndex2 = ApIndex; ApIndex2-- > 0;) {
-        if (IsPresentAp (ApIndex2) && (mSmmMpSyncData->CpuData[ApIndex2].Token != NULL)) {
-          return mSmmMpSyncData->CpuData[ApIndex2].Token == mSmmMpSyncData->CpuData[ApIndex].Token;
-        }
-      }
-    }
-  }
-
-  return FALSE;
-}
-
 /**
   Clean up the status flags used during executing the procedure.
 
@@ -445,40 +413,20 @@ ReleaseToken (
   IN UINTN                  CpuIndex
   )
 {
-  UINTN                             Index;
-  BOOLEAN                           Released;
+  PROCEDURE_TOKEN                         *Token;
 
-  if (InStartAllApsCall ()) {
-    //
-    // In Start All APs mode, make sure all APs have finished task.
-    //
-    if (WaitForAllAPsNotBusy (FALSE)) {
-      //
-      // Clean the flags update in the function call.
-      //
-      Released = FALSE;
-      for (Index = mMaxNumberOfCpus; Index-- > 0;) {
-        //
-        // Only In SMM APs need to be clean up.
-        //
-        if (mSmmMpSyncData->CpuData[Index].Present && mSmmMpSyncData->CpuData[Index].Token != NULL) {
-          if (!Released) {
-            ReleaseSpinLock (mSmmMpSyncData->CpuData[Index].Token);
-            Released = TRUE;
-          }
-          mSmmMpSyncData->CpuData[Index].Token = NULL;
-        }
-      }
-    }
-  } else {
-    //
-    // In single AP mode.
-    //
-    if (mSmmMpSyncData->CpuData[CpuIndex].Token != NULL) {
-      ReleaseSpinLock (mSmmMpSyncData->CpuData[CpuIndex].Token);
-      mSmmMpSyncData->CpuData[CpuIndex].Token = NULL;
+  Token = mSmmMpSyncData->CpuData[CpuIndex].Token;
+  mSmmMpSyncData->CpuData[CpuIndex].Token = NULL;
+
+  if (!Token->SingleAp) {
+    ReleaseSemaphore (&Token->FinishedApCount);
+
+    if (Token->FinishedApCount < (UINT32)mMaxNumberOfCpus) {
+      return;
     }
   }
+
+  ReleaseSpinLock (Token->ProcedureToken);
 }
 
 /**
@@ -912,12 +860,14 @@ APHandler (
       *mSmmMpSyncData->CpuData[CpuIndex].Status = ProcedureStatus;
     }
 
+    if (mSmmMpSyncData->CpuData[CpuIndex].Token != NULL) {
+      ReleaseToken (CpuIndex);
+    }
+
     //
     // Release BUSY
     //
     ReleaseSpinLock (mSmmMpSyncData->CpuData[CpuIndex].Busy);
-
-    ReleaseToken (CpuIndex);
   }
 
   if (SmmCpuFeaturesNeedConfigureMtrrs()) {
@@ -1127,7 +1077,7 @@ IsTokenInUse (
   @retval    return the spin lock used as token.
 
 **/
-SPIN_LOCK *
+PROCEDURE_TOKEN *
 CreateToken (
   VOID
   )
@@ -1170,10 +1120,12 @@ CreateToken (
   ASSERT (ProcToken != NULL);
   ProcToken->Signature = PROCEDURE_TOKEN_SIGNATURE;
   ProcToken->ProcedureToken = CpuToken;
+  ProcToken->FinishedApCount = 0;
+  ProcToken->SingleAp = TRUE;
 
   InsertTailList (&gSmmCpuPrivate->TokenList, &ProcToken->Link);
 
-  return CpuToken;
+  return ProcToken;
 }
 
 /**
@@ -1278,14 +1230,11 @@ InternalSmmStartupThisAp (
 
   AcquireSpinLock (mSmmMpSyncData->CpuData[CpuIndex].Busy);
 
-  if (Token != NULL) {
-    *Token = (MM_COMPLETION) CreateToken ();
-  }
-
   mSmmMpSyncData->CpuData[CpuIndex].Procedure = Procedure;
   mSmmMpSyncData->CpuData[CpuIndex].Parameter = ProcArguments;
   if (Token != NULL) {
-    mSmmMpSyncData->CpuData[CpuIndex].Token   = (SPIN_LOCK *)(*Token);
+    mSmmMpSyncData->CpuData[CpuIndex].Token = CreateToken ();
+    *Token = (MM_COMPLETION) mSmmMpSyncData->CpuData[CpuIndex].Token->ProcedureToken;
   }
   mSmmMpSyncData->CpuData[CpuIndex].Status    = CpuStatus;
   if (mSmmMpSyncData->CpuData[CpuIndex].Status != NULL) {
@@ -1343,6 +1292,7 @@ InternalSmmStartupAllAPs (
 {
   UINTN               Index;
   UINTN               CpuCount;
+  PROCEDURE_TOKEN     *ProcToken;
 
   if ((TimeoutInMicroseconds != 0) && ((mSmmMp.Attributes & EFI_MM_MP_TIMEOUT_SUPPORTED) == 0)) {
     return EFI_INVALID_PARAMETER;
@@ -1371,7 +1321,11 @@ InternalSmmStartupAllAPs (
   }
 
   if (Token != NULL) {
-    *Token = (MM_COMPLETION) CreateToken ();
+    ProcToken = CreateToken ();
+    *Token = (MM_COMPLETION)ProcToken->ProcedureToken;
+    ProcToken->SingleAp = FALSE;
+  } else {
+    ProcToken = NULL;
   }
 
   //
@@ -1392,7 +1346,7 @@ InternalSmmStartupAllAPs (
       mSmmMpSyncData->CpuData[Index].Procedure = (EFI_AP_PROCEDURE2) Procedure;
       mSmmMpSyncData->CpuData[Index].Parameter = ProcedureArguments;
       if (Token != NULL) {
-        mSmmMpSyncData->CpuData[Index].Token   = (SPIN_LOCK *)(*Token);
+        mSmmMpSyncData->CpuData[Index].Token   = ProcToken;
       }
       if (CPUStatus != NULL) {
         mSmmMpSyncData->CpuData[Index].Status    = &CPUStatus[Index];
@@ -1408,6 +1362,11 @@ InternalSmmStartupAllAPs (
       if (CPUStatus != NULL) {
         CPUStatus[Index] = EFI_NOT_STARTED;
       }
+
+      //
+      // Increate the count to mark this AP as finished.
+      //
+      ReleaseSemaphore (&ProcToken->FinishedApCount);
     }
   }
 
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
index 5c1a01e42b..0551539aee 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
@@ -213,6 +213,8 @@ typedef struct {
   LIST_ENTRY              Link;
 
   SPIN_LOCK               *ProcedureToken;
+  BOOLEAN                 SingleAp;
+  volatile UINT32         FinishedApCount;
 } PROCEDURE_TOKEN;
 
 #define PROCEDURE_TOKEN_FROM_LINK(a)  CR (a, PROCEDURE_TOKEN, Link, PROCEDURE_TOKEN_SIGNATURE)
@@ -407,7 +409,7 @@ typedef struct {
   volatile VOID                     *Parameter;
   volatile UINT32                   *Run;
   volatile BOOLEAN                  *Present;
-  SPIN_LOCK                         *Token;
+  PROCEDURE_TOKEN                   *Token;
   EFI_STATUS                        *Status;
 } SMM_CPU_DATA_BLOCK;
 
-- 
2.23.0.windows.1