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> Reviewed-by: Feng Tian <feng.tian@intel.com>