[edk2-devel] [PATCH v1 6/6] UefiCpuPkg/PiSmmCpuDxeSmm: Reduce one round BSP & AP sync

["Wu, Jiaxin" <jiaxin.wu@intel.com>]

One round BSP & AP sync for exit SMI is shown as below:
BSP: SmmCpuSyncWaitForAPs  <--  AP: SmmCpuSyncReleaseBsp
BSP: ReleaseAllAPs         -->  AP: SmmCpuSyncWaitForBsp

Above is only required if need configure MTRR and support
SMM source level debug, So, reduce one round BSP & AP sync
if both are unsupported.

Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Zeng Star <star.zeng@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Signed-off-by: Jiaxin Wu <jiaxin.wu@intel.com>
---
 UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c | 36 +++++++++++++++++++----------------
 1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
index 04622c66a2..d0139228bb 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
@@ -643,19 +643,21 @@ BSPHandler (
     //
     SmmCpuFeaturesReenableSmrr ();
     MtrrSetAllMtrrs (&Mtrrs);
   }
 
-  //
-  // Wait for all APs to complete their pending tasks including MTRR programming if needed.
-  //
-  SmmCpuSyncWaitForAPs (mSmmMpSyncData->SyncContext, ApCount, CpuIndex);
+  if (SmmCpuFeaturesNeedConfigureMtrrs () || *mSmmDebugAgentSupport) {
+    //
+    // Wait for all APs to complete their pending tasks including MTRR programming if needed.
+    //
+    SmmCpuSyncWaitForAPs (mSmmMpSyncData->SyncContext, ApCount, CpuIndex);
 
-  //
-  // Signal APs to Reset states/semaphore for this processor
-  //
-  ReleaseAllAPs ();
+    //
+    // Signal APs to Reset states/semaphore for this processor
+    //
+    ReleaseAllAPs ();
+  }
 
   if (*mSmmDebugAgentSupport) {
     //
     // Stop source level debug in BSP handler, the code below will not be
     // debugged.
@@ -894,19 +896,21 @@ APHandler (
     //
     SmmCpuFeaturesReenableSmrr ();
     MtrrSetAllMtrrs (&Mtrrs);
   }
 
-  //
-  // Notify BSP the readiness of this AP to Reset states/semaphore for this processor
-  //
-  SmmCpuSyncReleaseBsp (mSmmMpSyncData->SyncContext, CpuIndex, BspIndex);
+  if (SmmCpuFeaturesNeedConfigureMtrrs () || *mSmmDebugAgentSupport) {
+    //
+    // Notify BSP the readiness of this AP to Reset states/semaphore for this processor
+    //
+    SmmCpuSyncReleaseBsp (mSmmMpSyncData->SyncContext, CpuIndex, BspIndex);
 
-  //
-  // Wait for the signal from BSP to Reset states/semaphore for this processor
-  //
-  SmmCpuSyncWaitForBsp (mSmmMpSyncData->SyncContext, CpuIndex, BspIndex);
+    //
+    // Wait for the signal from BSP to Reset states/semaphore for this processor
+    //
+    SmmCpuSyncWaitForBsp (mSmmMpSyncData->SyncContext, CpuIndex, BspIndex);
+  }
 
   //
   // Reset states/semaphore for this processor
   //
   *(mSmmMpSyncData->CpuData[CpuIndex].Present) = FALSE;
-- 
2.16.2.windows.1



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