[PATCH 1/2] UefiCpuPkg/MpInitLib: Restore IDT context for APs.

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

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2683

This patch used to fix a ASSERT because AP can't find the CpuMpData.

When AP been waked up through Init-Sipi-Sipi, the IDT should
been restore to preallcated buffer to make it can get the
CpuMpData through IDT base address.
Not when CpuMpData->InitFlag is ApInitReconfig or ApInitConfig,
AP will be wake up through Init-Sipi-Sipi. Current code already
has logic to handle ApInitConfig, but miss the handler for
ApInitReconfig. This patch fixes this gap.

Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Chandana Kumar <chandana.c.kumar@intel.com>
Signed-off-by: Eric Dong <eric.dong@intel.com>
---
 UefiCpuPkg/Library/MpInitLib/MpLib.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index 64a4c3546e..ac7f92fd48 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -664,8 +664,9 @@ ApWakeupFunction (
       BistData = *(UINT32 *) ((UINTN) ApTopOfStack - sizeof (UINTN));
       //
       // CpuMpData->CpuData[0].VolatileRegisters is initialized based on BSP environment,
-      //   to initialize AP in InitConfig path.
-      // NOTE: IDTR.BASE stored in CpuMpData->CpuData[0].VolatileRegisters points to a different IDT shared by all APs.
+      //   to initialize AP in InitConfig/ApInitReconfig path.
+      // NOTE: IDTR.BASE stored in CpuMpData->CpuData[0].VolatileRegisters points to a
+      //  different IDT shared by all APs.
       //
       RestoreVolatileRegisters (&CpuMpData->CpuData[0].VolatileRegisters, FALSE);
       InitializeApData (CpuMpData, ProcessorNumber, BistData, ApTopOfStack);
@@ -673,6 +674,16 @@ ApWakeupFunction (
 
       InterlockedDecrement ((UINT32 *) &CpuMpData->MpCpuExchangeInfo->NumApsExecuting);
     } else {
+      if ((CpuMpData->InitFlag == ApInitReconfig) && (CpuMpData->ApLoopMode != ApInHltLoop)) {
+        //
+        // CpuMpData->CpuData[0].VolatileRegisters is initialized based on BSP environment,
+        //   to initialize AP in InitConfig/ApInitReconfig path.
+        // NOTE: IDTR.BASE stored in CpuMpData->CpuData[0].VolatileRegisters points to a
+        //   different IDT shared by all APs.
+        //
+        RestoreVolatileRegisters (&CpuMpData->CpuData[0].VolatileRegisters, FALSE);
+      }
+
       //
       // Execute AP function if AP is ready
       //
-- 
2.23.0.windows.1