According to PI specification PEI Services table pointer is stored
right before ITD base. Starting from commit c563077a380437c1
BSP and AP have different IDT instances.
PEI Services table pointer was not initialized in the AP IDT instance.
As a result, any attempt to use functions from
PeiServicesTablePointerLib or PeiServicesLib on AP caused CPU exception.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Felix Polyudov <[email protected]>
---
 UefiCpuPkg/Library/MpInitLib/MpLib.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c 
b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index 7f4d6e6..0e3e362 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -1567,6 +1567,7 @@ MpInitLibInitialize (
   BufferSize  = ApStackSize * MaxLogicalProcessorNumber;
   BufferSize += MonitorFilterSize * MaxLogicalProcessorNumber;
   BufferSize += ApResetVectorSize;
+  BufferSize += sizeof(UINTN);
   BufferSize  = ALIGN_VALUE (BufferSize, 8);
   BufferSize += VolatileRegisters.Idtr.Limit + 1;
   BufferSize += sizeof (CPU_MP_DATA);
@@ -1587,6 +1588,8 @@ MpInitLibInitialize (
   //         Backup Buffer
   //    +--------------------+
   //           Padding
+  //    +--------------------+
+  //    PEI Services Table Pointer
   //    +--------------------+ <-- ApIdtBase (8-byte boundary)
   //           AP IDT          All APs share one separate IDT. So AP can get 
address of CPU_MP_DATA from IDT Base.
   //    +--------------------+ <-- CpuMpData
@@ -1599,7 +1602,7 @@ MpInitLibInitialize (
   //
   MonitorBuffer    = (UINT8 *) (Buffer + ApStackSize * 
MaxLogicalProcessorNumber);
   BackupBufferAddr = (UINTN) MonitorBuffer + MonitorFilterSize * 
MaxLogicalProcessorNumber;
-  ApIdtBase        = ALIGN_VALUE (BackupBufferAddr + ApResetVectorSize, 8);
+  ApIdtBase        = ALIGN_VALUE (BackupBufferAddr + ApResetVectorSize + 
sizeof(UINTN), 8);
   CpuMpData        = (CPU_MP_DATA *) (ApIdtBase + VolatileRegisters.Idtr.Limit 
+ 1);
   CpuMpData->Buffer           = Buffer;
   CpuMpData->CpuApStackSize   = ApStackSize;
@@ -1653,6 +1656,11 @@ MpInitLibInitialize (
           Buffer + BufferSize);
 
   //
+  // Initialize PEI Services table pointer. Copy the address from BSP.
+  //
+  *(UINTN*)(ApIdtBase - sizeof(UINTN)) = *(UINTN*)(VolatileRegisters.Idtr.Base 
- sizeof (UINTN));
+
+  //
   // Duplicate BSP's IDT to APs.
   // All APs share one separate IDT. So AP can get the address of CpuMpData by 
using IDTR.BASE + IDTR.LIMIT + 1
   //
-- 
2.10.0.windows.1



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