[PATCH 5/6] UefiCpuPkg/MpInitLib: Disable and restore system timer interrupt

[Jeff Fan <jeff.fan@intel.com>]

We need to disable system timer interrup to avoid generating the pending
interrupt on the old BSP.

Cc: Feng Tian <feng.tian@intel.com>
Cc: Kinney, Michael D <michael.d.kinney@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jeff Fan <jeff.fan@intel.com>
---
 UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf |  3 +++
 UefiCpuPkg/Library/MpInitLib/DxeMpLib.c       | 31 ++++++++++++++++++++++++++-
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf b/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
index cc4f2e9..9751ba1 100644
--- a/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
+++ b/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
@@ -57,6 +57,9 @@
   UefiBootServicesTableLib
   DebugAgentLib
 
+[Protocols]
+  gEfiTimerArchProtocolGuid                     ## SOMETIMES_CONSUMES
+
 [Guids]
   gEfiEventExitBootServicesGuid                 ## CONSUMES  ## Event
   gEfiEventLegacyBootGuid                       ## CONSUMES  ## Event
diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
index 733a9fb..5e50b4c 100644
--- a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
@@ -18,6 +18,8 @@
 #include <Library/UefiBootServicesTableLib.h>
 #include <Library/DebugAgentLib.h>
 
+#include <Protocol/Timer.h>
+
 #define  AP_CHECK_INTERVAL     (EFI_TIMER_PERIOD_MILLISECONDS (100))
 #define  AP_SAFE_STACK_SIZE    128
 
@@ -645,11 +647,38 @@ MpInitLibSwitchBSP (
   IN BOOLEAN                   EnableOldBSP
   )
 {
-  EFI_STATUS            Status;
+  EFI_STATUS                   Status;
+  EFI_TIMER_ARCH_PROTOCOL      *Timer;
+  UINT64                       TimerPeriod;
 
+  //
+  // Locate Timer Arch Protocol
+  //
+  Status = gBS->LocateProtocol (&gEfiTimerArchProtocolGuid, NULL, (VOID **) &Timer);
+  if (EFI_ERROR (Status)) {
+    Timer = NULL;
+  }
+
+  if (Timer != NULL) {
+    //
+    // Save current rate of DXE Timer
+    //
+    Timer->GetTimerPeriod (Timer, &TimerPeriod);
+    //
+    // Disable DXE Timer and drain pending interrupts
+    //
+    Timer->SetTimerPeriod (Timer, 0);
+  }
 
   Status = SwitchBSPWorker (ProcessorNumber, EnableOldBSP);
 
+  if (Timer != NULL) {
+    //
+    // Enable and restore rate of DXE Timer
+    //
+    Timer->SetTimerPeriod (Timer, TimerPeriod);
+  }
+
   return Status;
 }
 
-- 
2.9.3.windows.2