Re: [edk2-devel] [PATCH] UefiCpuPkg/MpLib:Do not assume BSP is #0.

["Ni, Ray" <ray.ni@intel.com>]

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Reviewed-by: Ray Ni <ray.ni@intel.com>

Thanks,
Ray
________________________________
From: Feng, Ning <ning.feng@intel.com>
Sent: Saturday, May 25, 2024 15:42
To: devel@edk2.groups.io <devel@edk2.groups.io>
Cc: Feng, Ning <ning.feng@intel.com>; Ni, Ray <ray.ni@intel.com>
Subject: [PATCH] UefiCpuPkg/MpLib:Do not assume BSP is #0.

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=4778
MPInitlib have wrong expectation that BSP index should always be 0 in
MpInitLibInitialize(), SwitchBsp(),ApWakeupFunction().
That will cause the data mismatch, if the initial BSP is not 0.
Cc: Ray Ni <ray.ni@intel.com>
Signed-off-by: Ning Feng <ning.feng@intel.com>
---
 UefiCpuPkg/Library/MpInitLib/MpLib.c | 47 ++++++++++++++++++----------
 1 file changed, 30 insertions(+), 17 deletions(-)

diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index d724456502..ba497cbfd9 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -114,6 +114,10 @@ FutureBSPProc (
   SaveVolatileRegisters (&DataInHob->APInfo.VolatileRegisters);

   AsmExchangeRole (&DataInHob->APInfo, &DataInHob->BSPInfo);

   RestoreVolatileRegisters (&DataInHob->APInfo.VolatileRegisters, FALSE);

+  //

+  // Restore VolatileReg saved in CpuMpData->CpuData

+  //

+  CopyMem (&DataInHob->CpuData[DataInHob->BspNumber].VolatileRegisters, &DataInHob->APInfo.VolatileRegisters, sizeof (CPU_VOLATILE_REGISTERS));

 }



 /**

@@ -761,11 +765,11 @@ ApWakeupFunction (
       BistData     = (UINT32)ApStackData->Bist;



       //

-      // CpuMpData->CpuData[0].VolatileRegisters is initialized based on BSP environment,

+      // CpuMpData->CpuData[BspNumber].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.

+      // NOTE: IDTR.BASE stored in CpuMpData->CpuData[BspNumber].VolatileRegisters points to a different IDT shared by all APs.

       //

-      RestoreVolatileRegisters (&CpuMpData->CpuData[0].VolatileRegisters, FALSE);

+      RestoreVolatileRegisters (&CpuMpData->CpuData[CpuMpData->BspNumber].VolatileRegisters, FALSE);

       InitializeApData (CpuMpData, ProcessorNumber, BistData, ApTopOfStack);

       ApStartupSignalBuffer = CpuMpData->CpuData[ProcessorNumber].StartupApSignal;

     } else {

@@ -798,10 +802,10 @@ ApWakeupFunction (
         // 1. AP is re-enabled after it's disabled, in either PEI or DXE phase.

         // 2. AP is initialized in DXE phase.

         // In either case, use the volatile registers value derived from BSP.

-        // NOTE: IDTR.BASE stored in CpuMpData->CpuData[0].VolatileRegisters points to a

+        // NOTE: IDTR.BASE stored in CpuMpData->CpuData[BspNumber].VolatileRegisters points to a

         //   different IDT shared by all APs.

         //

-        RestoreVolatileRegisters (&CpuMpData->CpuData[0].VolatileRegisters, FALSE);

+        RestoreVolatileRegisters (&CpuMpData->CpuData[CpuMpData->BspNumber].VolatileRegisters, FALSE);

       } else {

         if (CpuMpData->ApLoopMode == ApInHltLoop) {

           //

@@ -927,7 +931,7 @@ DxeApEntryPoint (
     AsmWriteMsr64 (MSR_IA32_EFER, EferMsr.Uint64);

   }



-  RestoreVolatileRegisters (&CpuMpData->CpuData[0].VolatileRegisters, FALSE);

+  RestoreVolatileRegisters (&CpuMpData->CpuData[CpuMpData->BspNumber].VolatileRegisters, FALSE);

   InterlockedIncrement ((UINT32 *)&CpuMpData->FinishedCount);

   PlaceAPInMwaitLoopOrRunLoop (

     CpuMpData->ApLoopMode,

@@ -2151,11 +2155,16 @@ MpInitLibInitialize (
   CpuMpData->BackupBufferSize = ApResetVectorSizeBelow1Mb;

   CpuMpData->WakeupBuffer     = (UINTN)-1;

   CpuMpData->CpuCount         = 1;

-  CpuMpData->BspNumber        = 0;

-  CpuMpData->WaitEvent        = NULL;

-  CpuMpData->SwitchBspFlag    = FALSE;

-  CpuMpData->CpuData          = (CPU_AP_DATA *)(CpuMpData + 1);

-  CpuMpData->CpuInfoInHob     = (UINT64)(UINTN)(CpuMpData->CpuData + MaxLogicalProcessorNumber);

+  if (FirstMpHandOff == NULL) {

+    CpuMpData->BspNumber = 0;

+  } else {

+    CpuMpData->BspNumber = GetBspNumber (FirstMpHandOff);

+  }

+

+  CpuMpData->WaitEvent     = NULL;

+  CpuMpData->SwitchBspFlag = FALSE;

+  CpuMpData->CpuData       = (CPU_AP_DATA *)(CpuMpData + 1);

+  CpuMpData->CpuInfoInHob  = (UINT64)(UINTN)(CpuMpData->CpuData + MaxLogicalProcessorNumber);

   InitializeSpinLock (&CpuMpData->MpLock);

   CpuMpData->SevEsIsEnabled   = ConfidentialComputingGuestHas (CCAttrAmdSevEs);

   CpuMpData->SevSnpIsEnabled  = ConfidentialComputingGuestHas (CCAttrAmdSevSnp);

@@ -2186,11 +2195,11 @@ MpInitLibInitialize (
   // Don't pass BSP's TR to APs to avoid AP init failure.

   //

   VolatileRegisters.Tr = 0;

-  CopyMem (&CpuMpData->CpuData[0].VolatileRegisters, &VolatileRegisters, sizeof (VolatileRegisters));

+  CopyMem (&CpuMpData->CpuData[CpuMpData->BspNumber].VolatileRegisters, &VolatileRegisters, sizeof (VolatileRegisters));

   //

   // Set BSP basic information

   //

-  InitializeApData (CpuMpData, 0, 0, CpuMpData->Buffer + ApStackSize);

+  InitializeApData (CpuMpData, CpuMpData->BspNumber, 0, CpuMpData->Buffer + ApStackSize * (CpuMpData->BspNumber + 1));

   //

   // Save assembly code information

   //

@@ -2245,9 +2254,8 @@ MpInitLibInitialize (
       AmdSevUpdateCpuMpData (CpuMpData);

     }



-    CpuMpData->CpuCount  = MaxLogicalProcessorNumber;

-    CpuMpData->BspNumber = GetBspNumber (FirstMpHandOff);

-    CpuInfoInHob         = (CPU_INFO_IN_HOB *)(UINTN)CpuMpData->CpuInfoInHob;

+    CpuMpData->CpuCount = MaxLogicalProcessorNumber;

+    CpuInfoInHob        = (CPU_INFO_IN_HOB *)(UINTN)CpuMpData->CpuInfoInHob;

     for (MpHandOff = FirstMpHandOff;

          MpHandOff != NULL;

          MpHandOff = GetNextMpHandOffHob (MpHandOff))

@@ -2615,7 +2623,12 @@ SwitchBSPWorker (
   SaveVolatileRegisters (&CpuMpData->BSPInfo.VolatileRegisters);

   AsmExchangeRole (&CpuMpData->BSPInfo, &CpuMpData->APInfo);

   RestoreVolatileRegisters (&CpuMpData->BSPInfo.VolatileRegisters, FALSE);

-

+  //

+  // Restore VolatileRegs saved in CpuMpData->CpuData

+  // Don't pass BSP's TR to APs to avoid AP init failure.

+  //

+  CopyMem (&CpuMpData->CpuData[CpuMpData->NewBspNumber].VolatileRegisters, &CpuMpData->BSPInfo.VolatileRegisters, sizeof (CPU_VOLATILE_REGISTERS));

+  CpuMpData->CpuData[CpuMpData->NewBspNumber].VolatileRegisters.Tr = 0;

   //

   // Set the BSP bit of MSR_IA32_APIC_BASE on new BSP

   //

--
2.25.1



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