[Patch V3 0/5] Eliminate the second INIT-SIPI-SIPI sequence

[Patch V3 0/5] Eliminate the second INIT-SIPI-SIPI sequence

[Yuanhao Xie]

To speed up MP initialization, this set of patches replaces the 
time-consuming init-sipi-sipi process in the DXE phase. Instead, 
a start-up signal is used to wake up the APs and switch context
 from the PEI phase to the DXE phase. This optimization is 
 effective when both PEI and DXE operate in the same bit mode. 

The current HOB characterized by mCpuInitMpLibHobGuid has 
two purposes:
  Acting as a global variable for the PEI phase.
  Transferring information from the PEI phase to the DXE phase.
This series of patches creates a new HOB specifically designed 
to transfer only the minimal necessary information 
(MpHandoff structure) from the PEI phase to the DXE phase.

YuanhaoXie (5):
  UefiCpuPkg: Refactor the logic for placing APs in HltLoop.
  UefiCpuPkg: Refactor the logic for placing APs in Mwait/Runloop.
  UefiCpuPkg: Create MpHandOff.
  UefiCpuPkg: ApWakeupFunction directly use CpuMpData.
  UefiCpuPkg: Eliminate the second INIT-SIPI-SIPI sequence.

 UefiCpuPkg/Library/MpInitLib/Ia32/MpFuncs.nasm |   4 ++--
 UefiCpuPkg/Library/MpInitLib/MpLib.c           | 360 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----------------------------------------------------------------
 UefiCpuPkg/Library/MpInitLib/MpLib.h           |  75 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 UefiCpuPkg/Library/MpInitLib/PeiMpLib.c        |  32 +++++++++++++++++++++++++++++++-
 UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm  |   3 +--
 5 files changed, 404 insertions(+), 70 deletions(-)

-- 
2.36.1.windows.1

[Patch V3 1/5] UefiCpuPkg: Refactor the logic for placing APs in HltLoop.

[Yuanhao Xie]

Refactor the logic for placing APs in HltLoop into a separate function.

Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Yuanhao Xie <yuanhao.xie@intel.com>
---
 UefiCpuPkg/Library/MpInitLib/MpLib.c | 35 ++++++++++++++++++++++++-----------
 1 file changed, 24 insertions(+), 11 deletions(-)

diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index f1f2840714..9560b39220 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -636,6 +636,28 @@ InitializeApData (
   SetApState (&CpuMpData->CpuData[ProcessorNumber], CpuStateIdle);
 }
 
+/**
+  This function place APs in Halt loop.
+
+  @param[in] CpuMpData        Pointer to CPU MP Data
+**/
+VOID
+PlaceAPInHltLoop (
+  IN CPU_MP_DATA  *CpuMpData
+  )
+{
+  while (TRUE) {
+    DisableInterrupts ();
+    if (CpuMpData->UseSevEsAPMethod) {
+      SevEsPlaceApHlt (CpuMpData);
+    } else {
+      CpuSleep ();
+    }
+
+    CpuPause ();
+  }
+}
+
 /**
   This function will be called from AP reset code if BSP uses WakeUpAP.
 
@@ -812,19 +834,10 @@ ApWakeupFunction (
     // Place AP is specified loop mode
     //
     if (CpuMpData->ApLoopMode == ApInHltLoop) {
+      PlaceAPInHltLoop (CpuMpData);
       //
-      // Place AP in HLT-loop
+      // Never run here
       //
-      while (TRUE) {
-        DisableInterrupts ();
-        if (CpuMpData->UseSevEsAPMethod) {
-          SevEsPlaceApHlt (CpuMpData);
-        } else {
-          CpuSleep ();
-        }
-
-        CpuPause ();
-      }
     }
 
     while (TRUE) {
-- 
2.36.1.windows.1

[Patch V3 2/5] UefiCpuPkg: Refactor the logic for placing APs in Mwait/Runloop.

[Yuanhao Xie]

Refactor the logic for placing APs in
Mwait/Runloop into a separate function.

Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Yuanhao Xie <yuanhao.xie@intel.com>
---
 UefiCpuPkg/Library/MpInitLib/MpLib.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++++++---------------------------------
 1 file changed, 50 insertions(+), 33 deletions(-)

diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index 9560b39220..e8dd640f9b 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -658,6 +658,54 @@ PlaceAPInHltLoop (
   }
 }
 
+/**
+  This function place APs in Mwait or Run loop.
+
+  @param[in] ApLoopMode                   Ap Loop Mode
+  @param[in] ApStartupSignalBuffer        Pointer to Ap Startup Signal Buffer
+  @param[in] ApTargetCState               Ap Target CState
+**/
+VOID
+PlaceAPInMwaitLoopOrRunLoop (
+  IN UINT8            ApLoopMode,
+  IN volatile UINT32  *ApStartupSignalBuffer,
+  IN UINT8            ApTargetCState
+  )
+{
+  while (TRUE) {
+    DisableInterrupts ();
+    if (ApLoopMode == ApInMwaitLoop) {
+      //
+      // Place AP in MWAIT-loop
+      //
+      AsmMonitor ((UINTN)ApStartupSignalBuffer, 0, 0);
+      if (*ApStartupSignalBuffer != WAKEUP_AP_SIGNAL) {
+        //
+        // Check AP start-up signal again.
+        // If AP start-up signal is not set, place AP into
+        // the specified C-state
+        //
+        AsmMwait (ApTargetCState << 4, 0);
+      }
+    } else if (ApLoopMode == ApInRunLoop) {
+      //
+      // Place AP in Run-loop
+      //
+      CpuPause ();
+    } else {
+      ASSERT (FALSE);
+    }
+
+    //
+    // If AP start-up signal is written, AP is waken up
+    // otherwise place AP in loop again
+    //
+    if (*ApStartupSignalBuffer == WAKEUP_AP_SIGNAL) {
+      break;
+    }
+  }
+}
+
 /**
   This function will be called from AP reset code if BSP uses WakeUpAP.
 
@@ -838,39 +886,8 @@ ApWakeupFunction (
       //
       // Never run here
       //
-    }
-
-    while (TRUE) {
-      DisableInterrupts ();
-      if (CpuMpData->ApLoopMode == ApInMwaitLoop) {
-        //
-        // Place AP in MWAIT-loop
-        //
-        AsmMonitor ((UINTN)ApStartupSignalBuffer, 0, 0);
-        if (*ApStartupSignalBuffer != WAKEUP_AP_SIGNAL) {
-          //
-          // Check AP start-up signal again.
-          // If AP start-up signal is not set, place AP into
-          // the specified C-state
-          //
-          AsmMwait (CpuMpData->ApTargetCState << 4, 0);
-        }
-      } else if (CpuMpData->ApLoopMode == ApInRunLoop) {
-        //
-        // Place AP in Run-loop
-        //
-        CpuPause ();
-      } else {
-        ASSERT (FALSE);
-      }
-
-      //
-      // If AP start-up signal is written, AP is waken up
-      // otherwise place AP in loop again
-      //
-      if (*ApStartupSignalBuffer == WAKEUP_AP_SIGNAL) {
-        break;
-      }
+    } else {
+      PlaceAPInMwaitLoopOrRunLoop (CpuMpData->ApLoopMode, ApStartupSignalBuffer, CpuMpData->ApTargetCState);
     }
   }
 }
-- 
2.36.1.windows.1

[Patch V3 3/5] UefiCpuPkg: Create MpHandOff.

[Yuanhao Xie]

Initially, the purpose of the Hob was twofold: it served as a way to
transfer information from PEI to DXE. However, during the DXE phase,
only a few fields from the CPU_MP_DATA which collected in PEI phase were
 needed. A new Hob was specifically created to transfer information
 to the DXE phase. This new Hob contained only the essential fields
 required for reuse in DXE. For instance, instead of directly including
  the BspNumber in MpHandOff, the DXE phase introduced the use of
  GetBspNumber() to collect the BspNumber from ApicID and CpuCount.

The SaveCpuMpData() function was updated to construct the MP_HAND_OFF
Hob. Additionally, the function introduced the MP_HAND_OFF_SIGNAL,
which solely served the purpose of awakening the APs
and transitioning their context from PEI to DXE. The
WaitLoopExecutionMode field indicated whether the bit mode of PEI
matched that of DXE. Both of them were filled only if the ApLoopMode
was not ApInHltLoop. In the case of ApLoopMode, it remained necessary
to wake up the APs using the init-sipi-sipi sequence.

The function GetMpHandOffHob() was added to facilitate access to the
collected MpHandOff in the DXE phase. The CpuMpData in the DXE phase
was updated by gathering information from MpHandOff. Since MpHandOff
replaced the usage of OldCpuMpData and contained essential information
from the PEI phase to the DXE phase. AmdSevUpdateCpuMpData was included
to maintain the original implementation of AmdSev, ensuring that
OldCpuMpData->NewCpuMpData pointed to CpuMpData.

Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Yuanhao Xie <yuanhao.xie@intel.com>
---
 UefiCpuPkg/Library/MpInitLib/MpLib.c    | 100 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------------
 UefiCpuPkg/Library/MpInitLib/MpLib.h    |  66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 UefiCpuPkg/Library/MpInitLib/PeiMpLib.c |  32 +++++++++++++++++++++++++++++++-
 3 files changed, 184 insertions(+), 14 deletions(-)

diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index e8dd640f9b..1252ee9673 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -14,6 +14,7 @@
 #include <Register/Amd/Ghcb.h>
 
 EFI_GUID  mCpuInitMpLibHobGuid = CPU_INIT_MP_LIB_HOB_GUID;
+EFI_GUID  mMpHandOffGuid       = MP_HANDOFF_GUID;
 
 /**
   Save the volatile registers required to be restored following INIT IPI.
@@ -1814,6 +1815,54 @@ CheckAllAPs (
   return EFI_NOT_READY;
 }
 
+/**
+  This function Get BspNumber.
+
+  @param[in] MpHandOff        Pointer to MpHandOff
+  @return                     BspNumber
+**/
+UINT32
+GetBspNumber (
+  IN CONST MP_HAND_OFF  *MpHandOff
+  )
+{
+  UINT32  ApicId;
+  UINT32  BspNumber;
+  UINT32  Index;
+
+  //
+  // Get the processor number for the BSP
+  //
+  BspNumber = MAX_UINT32;
+  ApicId    = GetInitialApicId ();
+  for (Index = 0; Index < MpHandOff->CpuCount; Index++) {
+    if (MpHandOff->Info[Index].ApicId == ApicId) {
+      BspNumber = Index;
+    }
+  }
+
+  ASSERT (BspNumber != MAX_UINT32);
+
+  return BspNumber;
+}
+
+/**
+  Get pointer to CPU MP Data structure from GUIDed HOB.
+
+  @param[in] CpuMpData  The pointer to CPU MP Data structure.
+**/
+VOID
+AmdSevUpdateCpuMpData (
+  IN CPU_MP_DATA  *CpuMpData
+  )
+{
+  CPU_MP_DATA  *OldCpuMpData;
+
+  OldCpuMpData = GetCpuMpDataFromGuidedHob ();
+
+  OldCpuMpData->NewCpuMpData = CpuMpData;
+}
+
 /**
   MP Initialize Library initialization.
 
@@ -1833,7 +1882,7 @@ MpInitLibInitialize (
   VOID
   )
 {
-  CPU_MP_DATA              *OldCpuMpData;
+  MP_HAND_OFF              *MpHandOff;
   CPU_INFO_IN_HOB          *CpuInfoInHob;
   UINT32                   MaxLogicalProcessorNumber;
   UINT32                   ApStackSize;
@@ -1852,11 +1901,11 @@ MpInitLibInitialize (
   UINTN                    BackupBufferAddr;
   UINTN                    ApIdtBase;
 
-  OldCpuMpData = GetCpuMpDataFromGuidedHob ();
-  if (OldCpuMpData == NULL) {
+  MpHandOff = GetMpHandOffHob ();
+  if (MpHandOff == NULL) {
     MaxLogicalProcessorNumber = PcdGet32 (PcdCpuMaxLogicalProcessorNumber);
   } else {
-    MaxLogicalProcessorNumber = OldCpuMpData->CpuCount;
+    MaxLogicalProcessorNumber = MpHandOff->CpuCount;
   }
 
   ASSERT (MaxLogicalProcessorNumber != 0);
@@ -2000,7 +2049,7 @@ MpInitLibInitialize (
   //
   ProgramVirtualWireMode ();
 
-  if (OldCpuMpData == NULL) {
+  if (MpHandOff == NULL) {
     if (MaxLogicalProcessorNumber > 1) {
       //
       // Wakeup all APs and calculate the processor count in system
@@ -2012,15 +2061,18 @@ MpInitLibInitialize (
     // APs have been wakeup before, just get the CPU Information
     // from HOB
     //
-    OldCpuMpData->NewCpuMpData = CpuMpData;
-    CpuMpData->CpuCount        = OldCpuMpData->CpuCount;
-    CpuMpData->BspNumber       = OldCpuMpData->BspNumber;
-    CpuMpData->CpuInfoInHob    = OldCpuMpData->CpuInfoInHob;
-    CpuInfoInHob               = (CPU_INFO_IN_HOB *)(UINTN)CpuMpData->CpuInfoInHob;
+    AmdSevUpdateCpuMpData (CpuMpData);
+    CpuMpData->CpuCount  = MpHandOff->CpuCount;
+    CpuMpData->BspNumber = GetBspNumber (MpHandOff);
+    CpuInfoInHob         = (CPU_INFO_IN_HOB *)(UINTN)CpuMpData->CpuInfoInHob;
     for (Index = 0; Index < CpuMpData->CpuCount; Index++) {
       InitializeSpinLock (&CpuMpData->CpuData[Index].ApLock);
-      CpuMpData->CpuData[Index].CpuHealthy = (CpuInfoInHob[Index].Health == 0) ? TRUE : FALSE;
+      CpuMpData->CpuData[Index].CpuHealthy = (MpHandOff->Info[Index].Health == 0) ? TRUE : FALSE;
       CpuMpData->CpuData[Index].ApFunction = 0;
+      CpuInfoInHob[Index].InitialApicId    = MpHandOff->Info[Index].ApicId;
+      CpuInfoInHob[Index].ApTopOfStack     = CpuMpData->Buffer + (Index + 1) * CpuMpData->CpuApStackSize;
+      CpuInfoInHob[Index].ApicId           = MpHandOff->Info[Index].ApicId;
+      CpuInfoInHob[Index].Health           = MpHandOff->Info[Index].Health;
     }
   }
 
@@ -2049,7 +2101,7 @@ MpInitLibInitialize (
   // Wakeup APs to do some AP initialize sync (Microcode & MTRR)
   //
   if (CpuMpData->CpuCount > 1) {
-    if (OldCpuMpData != NULL) {
+    if (MpHandOff != NULL) {
       //
       // Only needs to use this flag for DXE phase to update the wake up
       // buffer. Wakeup buffer allocated in PEI phase is no longer valid
@@ -2066,7 +2118,7 @@ MpInitLibInitialize (
       CpuPause ();
     }
 
-    if (OldCpuMpData != NULL) {
+    if (MpHandOff != NULL) {
       CpuMpData->InitFlag = ApInitDone;
     }
 
@@ -2793,6 +2845,28 @@ StartupThisAPWorker (
   return Status;
 }
 
+/**
+  Get pointer to MP_HAND_OFF GUIDed HOB.
+
+  @return  The pointer to MP_HAND_OFF structure.
+**/
+MP_HAND_OFF *
+GetMpHandOffHob (
+  VOID
+  )
+{
+  EFI_HOB_GUID_TYPE  *GuidHob;
+  MP_HAND_OFF        *MpHandOff;
+
+  MpHandOff = NULL;
+  GuidHob   = GetFirstGuidHob (&mMpHandOffGuid);
+  if (GuidHob != NULL) {
+    MpHandOff = (MP_HAND_OFF *)GET_GUID_HOB_DATA (GuidHob);
+  }
+
+  return MpHandOff;
+}
+
 /**
   Get pointer to CPU MP Data structure from GUIDed HOB.
 
diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.h b/UefiCpuPkg/Library/MpInitLib/MpLib.h
index b694c7b40f..daf9e62012 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.h
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.h
@@ -41,12 +41,25 @@
 #include <Guid/MicrocodePatchHob.h>
 
 #define WAKEUP_AP_SIGNAL  SIGNATURE_32 ('S', 'T', 'A', 'P')
+//
+// To trigger the start-up signal, BSP writes the specified
+// StartupSignalValue to the StartupSignalAddress of each processor.
+// This address is monitored by the APs, and as soon as they receive
+// the value that matches the MP_HAND_OFF_SIGNAL, they will wake up
+// and switch the context from PEI to DXE phase.
+//
+#define MP_HAND_OFF_SIGNAL  SIGNATURE_32 ('M', 'P', 'H', 'O')
 
 #define CPU_INIT_MP_LIB_HOB_GUID \
   { \
     0x58eb6a19, 0x3699, 0x4c68, { 0xa8, 0x36, 0xda, 0xcd, 0x8e, 0xdc, 0xad, 0x4a } \
   }
 
+#define MP_HANDOFF_GUID \
+  { \
+    0x11e2bd88, 0xed38, 0x4abd, {0xa3, 0x99, 0x21, 0xf2, 0x5f, 0xd0, 0x7a, 0x60 } \
+  }
+
 //
 //  The MP data for switch BSP
 //
@@ -59,6 +72,37 @@
 //
 #define DEFAULT_MAX_MICROCODE_PATCH_NUM  8
 
+//
+// The information required to transfer from the PEI phase to the
+// DXE phase is contained within the MP_HAND_OFF and PROCESSOR_HAND_OFF.
+// If the SizeOfPointer (WaitLoopExecutionMode) of both phases are equal,
+// and the APs is not in halt mode,
+// then the APs can be awakened by triggering the start-up
+// signal, rather than using INIT-SIPI-SIPI.
+// To trigger the start-up signal, BSP writes the specified
+// StartupSignalValue to the StartupSignalAddress of each processor.
+// This address is monitored by the APs.
+//
+typedef struct {
+  UINT32    ApicId;
+  UINT32    Health;
+  UINT64    StartupSignalAddress;
+  UINT64    StartupProcedureAddress;
+} PROCESSOR_HAND_OFF;
+
+typedef struct {
+  //
+  // The ProcessorIndex indicates the range of processors. If it is set to 0, it signifies
+  // processors from 0 to CpuCount - 1. Multiple instances in the HOB list describe
+  // processors from ProcessorIndex to ProcessorIndex + CpuCount - 1.
+  //
+  UINT32                ProcessorIndex;
+  UINT32                CpuCount;
+  UINT32                WaitLoopExecutionMode;
+  UINT32                StartupSignalValue;
+  PROCESSOR_HAND_OFF    Info[];
+} MP_HAND_OFF;
+
 //
 // Data structure for microcode patch information
 //
@@ -347,6 +391,7 @@ typedef
   );
 
 extern EFI_GUID  mCpuInitMpLibHobGuid;
+extern EFI_GUID  mMpHandOffGuid;
 
 /**
   Assembly code to place AP into safe loop mode.
@@ -452,6 +497,17 @@ SaveCpuMpData (
   IN CPU_MP_DATA  *CpuMpData
   );
 
+/**
+  This function Get BspNumber.
+
+  @param[in] MpHandOff        Pointer to MpHandOff
+  @return                     BspNumber
+**/
+UINT32
+GetBspNumber (
+  IN CONST MP_HAND_OFF  *MpHandOff
+  );
+
 /**
   Get available system memory below 1MB by specified size.
 
@@ -652,6 +708,16 @@ EnableDisableApWorker (
   IN  UINT32   *HealthFlag OPTIONAL
   );
 
+/**
+  Get pointer to MP_HAND_OFF GUIDed HOB.
+
+  @return  The pointer to MP_HAND_OFF structure.
+**/
+MP_HAND_OFF *
+GetMpHandOffHob (
+  VOID
+  );
+
 /**
   Get pointer to CPU MP Data structure from GUIDed HOB.
 
diff --git a/UefiCpuPkg/Library/MpInitLib/PeiMpLib.c b/UefiCpuPkg/Library/MpInitLib/PeiMpLib.c
index 013f89b197..f80e00edcf 100644
--- a/UefiCpuPkg/Library/MpInitLib/PeiMpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/PeiMpLib.c
@@ -126,7 +126,37 @@ SaveCpuMpData (
   IN CPU_MP_DATA  *CpuMpData
   )
 {
-  UINT64  Data64;
+  UINT64           Data64;
+  UINTN            Index;
+  CPU_INFO_IN_HOB  *CpuInfoInHob;
+  MP_HAND_OFF      *MpHandOff;
+  UINTN            MpHandOffSize;
+
+  //
+  // When APs are in a state that can be waken up by a store operation to a memory address,
+  // report the MP_HAND_OFF data for DXE to use.
+  //
+  CpuInfoInHob  = (CPU_INFO_IN_HOB *)(UINTN)CpuMpData->CpuInfoInHob;
+  MpHandOffSize = sizeof (MP_HAND_OFF) + sizeof (PROCESSOR_HAND_OFF) * CpuMpData->CpuCount;
+  MpHandOff     = (MP_HAND_OFF *)BuildGuidHob (&mMpHandOffGuid, MpHandOffSize);
+  ASSERT (MpHandOff != NULL);
+  ZeroMem (MpHandOff, MpHandOffSize);
+  MpHandOff->ProcessorIndex = 0;
+
+  MpHandOff->CpuCount = CpuMpData->CpuCount;
+  if (CpuMpData->ApLoopMode != ApInHltLoop) {
+    MpHandOff->StartupSignalValue    = MP_HAND_OFF_SIGNAL;
+    MpHandOff->WaitLoopExecutionMode = sizeof (VOID *);
+  }
+
+  for (Index = 0; Index < MpHandOff->CpuCount; Index++) {
+    MpHandOff->Info[Index].ApicId = CpuInfoInHob[Index].ApicId;
+    MpHandOff->Info[Index].Health = CpuInfoInHob[Index].Health;
+    if (CpuMpData->ApLoopMode != ApInHltLoop) {
+      MpHandOff->Info[Index].StartupSignalAddress    = (UINT64)(UINTN)CpuMpData->CpuData[Index].StartupApSignal;
+      MpHandOff->Info[Index].StartupProcedureAddress = (UINT64)(UINTN)&CpuMpData->CpuData[Index].ApFunction;
+    }
+  }
 
   //
   // Build location of CPU MP DATA buffer in HOB
-- 
2.36.1.windows.1

[Patch V3 4/5] UefiCpuPkg: ApWakeupFunction directly use CpuMpData.

[Yuanhao Xie]

In the original design, once the APs finished executing their assembly
code and switched to executing C code, they would enter a continuous
loop within a function. In this function, they would collect CpuMpData
using the MP_CPU_EXCHANGE_INFO mechanism. However, in the updated
approach, CpuMpData can now be passed directly to the ApWakeUpFunction,
bypassing the need for MP_CPU_EXCHANGE_INFO. This modification is made
in preparation for eliminating the requirement of a second
INIT-SIPI-SIPI sequence in the DXE phase.

Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Yuanhao Xie <yuanhao.xie@intel.com>
---
 UefiCpuPkg/Library/MpInitLib/Ia32/MpFuncs.nasm |  4 ++--
 UefiCpuPkg/Library/MpInitLib/MpLib.c           | 12 +++---------
 UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm  |  3 +--
 3 files changed, 6 insertions(+), 13 deletions(-)

diff --git a/UefiCpuPkg/Library/MpInitLib/Ia32/MpFuncs.nasm b/UefiCpuPkg/Library/MpInitLib/Ia32/MpFuncs.nasm
index 59db4081d6..d117f09ef5 100644
--- a/UefiCpuPkg/Library/MpInitLib/Ia32/MpFuncs.nasm
+++ b/UefiCpuPkg/Library/MpInitLib/Ia32/MpFuncs.nasm
@@ -197,8 +197,8 @@ CProcedureInvoke:
 
     push       ebx               ; Push ApIndex
     mov        eax, esi
-    add        eax, MP_CPU_EXCHANGE_INFO_OFFSET
-    push       eax               ; push address of exchange info data buffer
+    add        eax, MP_CPU_EXCHANGE_INFO_FIELD (CpuMpData)
+    push       dword [eax]       ; push address of CpuMpData
 
     mov        edi, esi
     add        edi, MP_CPU_EXCHANGE_INFO_FIELD (CFunction)
diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index 1252ee9673..15b24b1805 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -710,17 +710,16 @@ PlaceAPInMwaitLoopOrRunLoop (
 /**
   This function will be called from AP reset code if BSP uses WakeUpAP.
 
-  @param[in] ExchangeInfo     Pointer to the MP exchange info buffer
+  @param[in] CpuMpData        Pointer to CPU MP Data
   @param[in] ApIndex          Number of current executing AP
 **/
 VOID
 EFIAPI
 ApWakeupFunction (
-  IN MP_CPU_EXCHANGE_INFO  *ExchangeInfo,
-  IN UINTN                 ApIndex
+  IN CPU_MP_DATA  *CpuMpData,
+  IN UINTN        ApIndex
   )
 {
-  CPU_MP_DATA       *CpuMpData;
   UINTN             ProcessorNumber;
   EFI_AP_PROCEDURE  Procedure;
   VOID              *Parameter;
@@ -731,11 +730,6 @@ ApWakeupFunction (
   UINTN             CurrentApicMode;
   AP_STACK_DATA     *ApStackData;
 
-  //
-  // AP finished assembly code and begin to execute C code
-  //
-  CpuMpData = ExchangeInfo->CpuMpData;
-
   //
   // AP's local APIC settings will be lost after received INIT IPI
   // We need to re-initialize them at here
diff --git a/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm b/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm
index 5bcdf7726b..40e80ffab4 100644
--- a/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm
+++ b/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm
@@ -259,8 +259,7 @@ CProcedureInvoke:
     add        rsp, 20h
 
     mov        edx, ebx          ; edx is ApIndex
-    mov        ecx, esi
-    add        ecx, MP_CPU_EXCHANGE_INFO_OFFSET ; rcx is address of exchange info data buffer
+    mov        rcx, qword [esi + MP_CPU_EXCHANGE_INFO_FIELD (CpuMpData)]
 
     mov        edi, esi
     add        edi, MP_CPU_EXCHANGE_INFO_FIELD (CFunction)
-- 
2.36.1.windows.1

[Patch V3 5/5] UefiCpuPkg: Eliminate the second INIT-SIPI-SIPI sequence.

[Yuanhao Xie]

When both the PEI and DXE phases operate in the same execution
mode(32-bit/64-bit), the BSP send a special start-up signal during
the DXE phase to awaken the Application APs.

To eliminate the need for the INIT-SIPI-SIPI sequence at the beginning
of the DXE phase, the BSP call the SwitchApContext function to trigger
the special  start-up signal. By writing the specified
StartupSignalValue to the designated StartupSignalAddress, the BSP
wakes up the APs from mwait mode. Once the APs receive the
MP_HAND_OFF_SIGNAL value, they are awakened and proceed to execute the
SwitchContextPerAp procedure. They enter another while loop,
transitioning their context from the PEI phase to the DXE phase.

The original state transitions for an AP during the procedure are as
follows:
Idle ----> Ready ----> Busy ----> Idle
      [BSP]      [AP]      [AP]

Instead of init-sipi-sipi sequence, we make use of a
start-up signal to awaken the APs and transfer their context from
PEI to DXE. Consequently, APs, rather than the BSP, to set their state
to CpuStateReady.

Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Yuanhao Xie <yuanhao.xie@intel.com>
---
 UefiCpuPkg/Library/MpInitLib/MpLib.c | 136 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 UefiCpuPkg/Library/MpInitLib/MpLib.h |   9 +++++++++
 2 files changed, 143 insertions(+), 2 deletions(-)

diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index 15b24b1805..391e6f19ef 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -680,7 +680,7 @@ PlaceAPInMwaitLoopOrRunLoop (
       // Place AP in MWAIT-loop
       //
       AsmMonitor ((UINTN)ApStartupSignalBuffer, 0, 0);
-      if (*ApStartupSignalBuffer != WAKEUP_AP_SIGNAL) {
+      if ((*ApStartupSignalBuffer != WAKEUP_AP_SIGNAL) && (*ApStartupSignalBuffer != MP_HAND_OFF_SIGNAL)) {
         //
         // Check AP start-up signal again.
         // If AP start-up signal is not set, place AP into
@@ -701,7 +701,7 @@ PlaceAPInMwaitLoopOrRunLoop (
     // If AP start-up signal is written, AP is waken up
     // otherwise place AP in loop again
     //
-    if (*ApStartupSignalBuffer == WAKEUP_AP_SIGNAL) {
+    if ((*ApStartupSignalBuffer == WAKEUP_AP_SIGNAL) || (*ApStartupSignalBuffer == MP_HAND_OFF_SIGNAL)) {
       break;
     }
   }
@@ -729,6 +729,7 @@ ApWakeupFunction (
   UINT64            ApTopOfStack;
   UINTN             CurrentApicMode;
   AP_STACK_DATA     *ApStackData;
+  UINT32            OriginalValue;
 
   //
   // AP's local APIC settings will be lost after received INIT IPI
@@ -769,6 +770,15 @@ ApWakeupFunction (
       // Clear AP start-up signal when AP waken up
       //
       ApStartupSignalBuffer = CpuMpData->CpuData[ProcessorNumber].StartupApSignal;
+      OriginalValue         = InterlockedCompareExchange32 (
+                                (UINT32 *)ApStartupSignalBuffer,
+                                MP_HAND_OFF_SIGNAL,
+                                0
+                                );
+      if (OriginalValue == MP_HAND_OFF_SIGNAL) {
+        SetApState (&CpuMpData->CpuData[ProcessorNumber], CpuStateReady);
+      }
+
       InterlockedCompareExchange32 (
         (UINT32 *)ApStartupSignalBuffer,
         WAKEUP_AP_SIGNAL,
@@ -887,6 +897,32 @@ ApWakeupFunction (
   }
 }
 
+/**
+  This function serves as the entry point for APs when
+  they are awakened by the stores in the memory address
+  indicated by the MP_HANDOFF_INFO structure.
+
+  @param[in] CpuMpData        Pointer to PEI CPU MP Data
+**/
+VOID
+EFIAPI
+DxeApEntryPoint (
+  CPU_MP_DATA  *CpuMpData
+  )
+{
+  UINTN  ProcessorNumber;
+
+  GetProcessorNumber (CpuMpData, &ProcessorNumber);
+  InterlockedIncrement ((UINT32 *)&CpuMpData->FinishedCount);
+  RestoreVolatileRegisters (&CpuMpData->CpuData[0].VolatileRegisters, FALSE);
+  PlaceAPInMwaitLoopOrRunLoop (
+    CpuMpData->ApLoopMode,
+    CpuMpData->CpuData[ProcessorNumber].StartupApSignal,
+    CpuMpData->ApTargetCState
+    );
+  ApWakeupFunction (CpuMpData, ProcessorNumber);
+}
+
 /**
   Wait for AP wakeup and write AP start-up signal till AP is waken up.
 
@@ -1457,6 +1493,70 @@ CalculateTimeout (
   }
 }
 
+/**
+  Switch Context for each AP.
+
+**/
+VOID
+EFIAPI
+SwitchContextPerAp (
+  VOID
+  )
+{
+  UINTN            ProcessorNumber;
+  CPU_MP_DATA      *CpuMpData;
+  CPU_INFO_IN_HOB  *CpuInfoInHob;
+
+  CpuMpData    = GetCpuMpData ();
+  CpuInfoInHob = (CPU_INFO_IN_HOB *)(UINTN)CpuMpData->CpuInfoInHob;
+  GetProcessorNumber (CpuMpData, &ProcessorNumber);
+
+  SwitchStack (
+    (SWITCH_STACK_ENTRY_POINT)(UINTN)DxeApEntryPoint,
+    (VOID *)(UINTN)CpuMpData,
+    NULL,
+    (VOID *)((UINTN)CpuInfoInHob[ProcessorNumber].ApTopOfStack)
+    );
+}
+
+/**
+  This function is intended to be invoked by the BSP in order
+  to wake up the AP. The BSP accomplishes this by triggering a
+  start-up signal, which in turn causes any APs that are
+  currently in a loop on the PEI-prepared memory to awaken and
+  begin running the procedure called SwitchContextPerAp.
+  This procedure allows the AP to switch to another section of
+  memory and continue its loop there.
+
+  @param[in] MpHandOff  Pointer to MP hand-off data structure.
+**/
+VOID
+SwitchApContext (
+  IN MP_HAND_OFF  *MpHandOff
+  )
+{
+  UINTN   Index;
+  UINT32  BspNumber;
+
+  BspNumber = GetBspNumber (MpHandOff);
+
+  for (Index = 0; Index < MpHandOff->CpuCount; Index++) {
+    if (Index != BspNumber) {
+      *(UINTN *)(UINTN)MpHandOff->Info[Index].StartupProcedureAddress = (UINTN)SwitchContextPerAp;
+      *(UINT32 *)(UINTN)MpHandOff->Info[Index].StartupSignalAddress   = MpHandOff->StartupSignalValue;
+    }
+  }
+
+  //
+  // Wait all APs waken up if this is not the 1st broadcast of SIPI
+  //
+  for (Index = 0; Index < MpHandOff->CpuCount; Index++) {
+    if (Index != BspNumber) {
+      WaitApWakeup ((UINT32 *)(UINTN)(MpHandOff->Info[Index].StartupSignalAddress));
+    }
+  }
+}
+
 /**
   Checks whether timeout expires.
 
@@ -2068,6 +2168,38 @@ MpInitLibInitialize (
       CpuInfoInHob[Index].ApicId           = MpHandOff->Info[Index].ApicId;
       CpuInfoInHob[Index].Health           = MpHandOff->Info[Index].Health;
     }
+
+    DEBUG ((DEBUG_INFO, "MpHandOff->WaitLoopExecutionMode: %04d, sizeof (VOID *): %04d\n", MpHandOff->WaitLoopExecutionMode, sizeof (VOID *)));
+    if (MpHandOff->WaitLoopExecutionMode == sizeof (VOID *)) {
+      //
+      // In scenarios where both the PEI and DXE phases run in the same
+      // execution mode (32bit or 64bit), the BSP triggers
+      // a start-up signal during the DXE phase to wake up the APs. This causes any
+      // APs that are currently in a loop on the memory prepared during the PEI
+      // phase to awaken and run the SwitchContextPerAp procedure. This procedure
+      // enables the APs to switch to a different memory section and continue their
+      // looping process there.
+      //
+      CpuMpData->FinishedCount = 0;
+      CpuMpData->InitFlag      = ApInitDone;
+      SaveCpuMpData (CpuMpData);
+      SwitchApContext (MpHandOff);
+      ASSERT (CpuMpData->FinishedCount == (CpuMpData->CpuCount - 1));
+
+      //
+      // Set Apstate as Idle, otherwise Aps cannot be waken-up again.
+      // If any enabled AP is not idle, return EFI_NOT_READY during waken-up.
+      //
+      for (Index = 0; Index < CpuMpData->CpuCount; Index++) {
+        SetApState (&CpuMpData->CpuData[Index], CpuStateIdle);
+      }
+
+      //
+      // Initialize global data for MP support
+      //
+      InitMpGlobalData (CpuMpData);
+      return EFI_SUCCESS;
+    }
   }
 
   if (!GetMicrocodePatchInfoFromHob (
diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.h b/UefiCpuPkg/Library/MpInitLib/MpLib.h
index daf9e62012..468d3a5925 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.h
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.h
@@ -521,6 +521,15 @@ GetWakeupBuffer (
   IN UINTN  WakeupBufferSize
   );
 
+/**
+  Switch Context for each AP.
+
+**/
+VOID
+SwitchApContext (
+  IN MP_HAND_OFF  *MpHandOff
+  );
+
 /**
   Get available EfiBootServicesCode memory below 4GB by specified size.
 
-- 
2.36.1.windows.1

Re: [Patch V3 1/5] UefiCpuPkg: Refactor the logic for placing APs in HltLoop.

[Ni, Ray]

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

> -----Original Message-----
> From: Xie, Yuanhao <yuanhao.xie@intel.com>
> Sent: Monday, June 26, 2023 1:57 PM
> To: devel@edk2.groups.io
> Cc: Gerd Hoffmann <kraxel@redhat.com>; Dong, Eric <eric.dong@intel.com>; Ni,
> Ray <ray.ni@intel.com>; Kumar, Rahul R <rahul.r.kumar@intel.com>; Tom
> Lendacky <thomas.lendacky@amd.com>; Xie, Yuanhao
> <yuanhao.xie@intel.com>
> Subject: [Patch V3 1/5] UefiCpuPkg: Refactor the logic for placing APs in HltLoop.
> 
> Refactor the logic for placing APs in HltLoop into a separate function.
> 
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Rahul Kumar <rahul1.kumar@intel.com>
> Cc: Tom Lendacky <thomas.lendacky@amd.com>
> Signed-off-by: Yuanhao Xie <yuanhao.xie@intel.com>
> ---
>  UefiCpuPkg/Library/MpInitLib/MpLib.c | 35 ++++++++++++++++++++++++-------
> ----
>  1 file changed, 24 insertions(+), 11 deletions(-)
> 
> diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c
> b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> index f1f2840714..9560b39220 100644
> --- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
> +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> @@ -636,6 +636,28 @@ InitializeApData (
>    SetApState (&CpuMpData->CpuData[ProcessorNumber], CpuStateIdle);
>  }
> 
> +/**
> +  This function place APs in Halt loop.
> +
> +  @param[in] CpuMpData        Pointer to CPU MP Data
> +**/
> +VOID
> +PlaceAPInHltLoop (
> +  IN CPU_MP_DATA  *CpuMpData
> +  )
> +{
> +  while (TRUE) {
> +    DisableInterrupts ();
> +    if (CpuMpData->UseSevEsAPMethod) {
> +      SevEsPlaceApHlt (CpuMpData);
> +    } else {
> +      CpuSleep ();
> +    }
> +
> +    CpuPause ();
> +  }
> +}
> +
>  /**
>    This function will be called from AP reset code if BSP uses WakeUpAP.
> 
> @@ -812,19 +834,10 @@ ApWakeupFunction (
>      // Place AP is specified loop mode
>      //
>      if (CpuMpData->ApLoopMode == ApInHltLoop) {
> +      PlaceAPInHltLoop (CpuMpData);
>        //
> -      // Place AP in HLT-loop
> +      // Never run here
>        //
> -      while (TRUE) {
> -        DisableInterrupts ();
> -        if (CpuMpData->UseSevEsAPMethod) {
> -          SevEsPlaceApHlt (CpuMpData);
> -        } else {
> -          CpuSleep ();
> -        }
> -
> -        CpuPause ();
> -      }
>      }
> 
>      while (TRUE) {
> --
> 2.36.1.windows.1

Re: [Patch V3 2/5] UefiCpuPkg: Refactor the logic for placing APs in Mwait/Runloop.

[Ni, Ray]

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

> -----Original Message-----
> From: Xie, Yuanhao <yuanhao.xie@intel.com>
> Sent: Monday, June 26, 2023 1:57 PM
> To: devel@edk2.groups.io
> Cc: Gerd Hoffmann <kraxel@redhat.com>; Dong, Eric <eric.dong@intel.com>; Ni,
> Ray <ray.ni@intel.com>; Kumar, Rahul R <rahul.r.kumar@intel.com>; Tom
> Lendacky <thomas.lendacky@amd.com>; Xie, Yuanhao
> <yuanhao.xie@intel.com>
> Subject: [Patch V3 2/5] UefiCpuPkg: Refactor the logic for placing APs in
> Mwait/Runloop.
> 
> Refactor the logic for placing APs in
> Mwait/Runloop into a separate function.
> 
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Rahul Kumar <rahul1.kumar@intel.com>
> Cc: Tom Lendacky <thomas.lendacky@amd.com>
> Signed-off-by: Yuanhao Xie <yuanhao.xie@intel.com>
> ---
>  UefiCpuPkg/Library/MpInitLib/MpLib.c | 83
> ++++++++++++++++++++++++++++++++++++++++++++++++++-----------------------
> ----------
>  1 file changed, 50 insertions(+), 33 deletions(-)
> 
> diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c
> b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> index 9560b39220..e8dd640f9b 100644
> --- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
> +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> @@ -658,6 +658,54 @@ PlaceAPInHltLoop (
>    }
>  }
> 
> +/**
> +  This function place APs in Mwait or Run loop.
> +
> +  @param[in] ApLoopMode                   Ap Loop Mode
> +  @param[in] ApStartupSignalBuffer        Pointer to Ap Startup Signal Buffer
> +  @param[in] ApTargetCState               Ap Target CState
> +**/
> +VOID
> +PlaceAPInMwaitLoopOrRunLoop (
> +  IN UINT8            ApLoopMode,
> +  IN volatile UINT32  *ApStartupSignalBuffer,
> +  IN UINT8            ApTargetCState
> +  )
> +{
> +  while (TRUE) {
> +    DisableInterrupts ();
> +    if (ApLoopMode == ApInMwaitLoop) {
> +      //
> +      // Place AP in MWAIT-loop
> +      //
> +      AsmMonitor ((UINTN)ApStartupSignalBuffer, 0, 0);
> +      if (*ApStartupSignalBuffer != WAKEUP_AP_SIGNAL) {
> +        //
> +        // Check AP start-up signal again.
> +        // If AP start-up signal is not set, place AP into
> +        // the specified C-state
> +        //
> +        AsmMwait (ApTargetCState << 4, 0);
> +      }
> +    } else if (ApLoopMode == ApInRunLoop) {
> +      //
> +      // Place AP in Run-loop
> +      //
> +      CpuPause ();
> +    } else {
> +      ASSERT (FALSE);
> +    }
> +
> +    //
> +    // If AP start-up signal is written, AP is waken up
> +    // otherwise place AP in loop again
> +    //
> +    if (*ApStartupSignalBuffer == WAKEUP_AP_SIGNAL) {
> +      break;
> +    }
> +  }
> +}
> +
>  /**
>    This function will be called from AP reset code if BSP uses WakeUpAP.
> 
> @@ -838,39 +886,8 @@ ApWakeupFunction (
>        //
>        // Never run here
>        //
> -    }
> -
> -    while (TRUE) {
> -      DisableInterrupts ();
> -      if (CpuMpData->ApLoopMode == ApInMwaitLoop) {
> -        //
> -        // Place AP in MWAIT-loop
> -        //
> -        AsmMonitor ((UINTN)ApStartupSignalBuffer, 0, 0);
> -        if (*ApStartupSignalBuffer != WAKEUP_AP_SIGNAL) {
> -          //
> -          // Check AP start-up signal again.
> -          // If AP start-up signal is not set, place AP into
> -          // the specified C-state
> -          //
> -          AsmMwait (CpuMpData->ApTargetCState << 4, 0);
> -        }
> -      } else if (CpuMpData->ApLoopMode == ApInRunLoop) {
> -        //
> -        // Place AP in Run-loop
> -        //
> -        CpuPause ();
> -      } else {
> -        ASSERT (FALSE);
> -      }
> -
> -      //
> -      // If AP start-up signal is written, AP is waken up
> -      // otherwise place AP in loop again
> -      //
> -      if (*ApStartupSignalBuffer == WAKEUP_AP_SIGNAL) {
> -        break;
> -      }
> +    } else {
> +      PlaceAPInMwaitLoopOrRunLoop (CpuMpData->ApLoopMode,
> ApStartupSignalBuffer, CpuMpData->ApTargetCState);
>      }
>    }
>  }
> --
> 2.36.1.windows.1

Re: [Patch V3 3/5] UefiCpuPkg: Create MpHandOff.

[Ni, Ray]

Several comments below:

> 
> The SaveCpuMpData() function was updated to construct the MP_HAND_OFF
> Hob. Additionally, the function introduced the MP_HAND_OFF_SIGNAL,
> which solely served the purpose of awakening the APs
> and transitioning their context from PEI to DXE. The
> WaitLoopExecutionMode field indicated whether the bit mode of PEI
> matched that of DXE. Both of them were filled only if the ApLoopMode
> was not ApInHltLoop. In the case of ApLoopMode, it remained necessary

1. "ApLoopMode" -> "ApInHltMode"?

2. can you update commit message to highlight that this patch still sends
INIT-SIPI-SIPI even AP is wait in run-loop or mwait loop?

> +
> +/**
> +  Get pointer to CPU MP Data structure from GUIDed HOB.
> +
> +  @param[in] CpuMpData  The pointer to CPU MP Data structure.
> +**/
> +VOID
> +AmdSevUpdateCpuMpData (
> +  IN CPU_MP_DATA  *CpuMpData
> +  )
> +{
> +  CPU_MP_DATA  *OldCpuMpData;
> +
> +  OldCpuMpData = GetCpuMpDataFromGuidedHob ();
> +
> +  OldCpuMpData->NewCpuMpData = CpuMpData;
> +}

3. Can you please move this function implementation into MpInitLib/AmdSev.c?

> +//
> +// To trigger the start-up signal, BSP writes the specified
> +// StartupSignalValue to the StartupSignalAddress of each processor.
> +// This address is monitored by the APs, and as soon as they receive
> +// the value that matches the MP_HAND_OFF_SIGNAL, they will wake up
> +// and switch the context from PEI to DXE phase.
> +//
> +#define MP_HAND_OFF_SIGNAL  SIGNATURE_32 ('M', 'P', 'H', 'O')
4. It's ok to define the signal signature here.


> +#define MP_HANDOFF_GUID \
> +  { \
> +    0x11e2bd88, 0xed38, 0x4abd, {0xa3, 0x99, 0x21, 0xf2, 0x5f, 0xd0, 0x7a, 0x60 }
> \
> +  }

5. can you please move this GUID definition to MpInitLib/MpHandOff.h?

> +//
> +// The information required to transfer from the PEI phase to the
> +// DXE phase is contained within the MP_HAND_OFF and
> PROCESSOR_HAND_OFF.
> +// If the SizeOfPointer (WaitLoopExecutionMode) of both phases are equal,
> +// and the APs is not in halt mode,
> +// then the APs can be awakened by triggering the start-up
> +// signal, rather than using INIT-SIPI-SIPI.
> +// To trigger the start-up signal, BSP writes the specified
> +// StartupSignalValue to the StartupSignalAddress of each processor.
> +// This address is monitored by the APs.
> +//
> +typedef struct {
> +  UINT32    ApicId;
> +  UINT32    Health;
> +  UINT64    StartupSignalAddress;
> +  UINT64    StartupProcedureAddress;
> +} PROCESSOR_HAND_OFF;
> +
> +typedef struct {
> +  //
> +  // The ProcessorIndex indicates the range of processors. If it is set to 0, it
> signifies
> +  // processors from 0 to CpuCount - 1. Multiple instances in the HOB list
> describe
> +  // processors from ProcessorIndex to ProcessorIndex + CpuCount - 1.
> +  //
> +  UINT32                ProcessorIndex;
> +  UINT32                CpuCount;
> +  UINT32                WaitLoopExecutionMode;
> +  UINT32                StartupSignalValue;
> +  PROCESSOR_HAND_OFF    Info[];
> +} MP_HAND_OFF;

6. can you please move the above 2 structure definitions to MpInitLib/MpHandOff.h?

> +
>  //
>  // Data structure for microcode patch information
>  //
> @@ -347,6 +391,7 @@ typedef
>    );
> 
>  extern EFI_GUID  mCpuInitMpLibHobGuid;
> +extern EFI_GUID  mMpHandOffGuid;
> 
>  /**
>    Assembly code to place AP into safe loop mode.
> @@ -452,6 +497,17 @@ SaveCpuMpData (
>    IN CPU_MP_DATA  *CpuMpData
>    );
> 
> +/**
> +  This function Get BspNumber.
> +
> +  @param[in] MpHandOff        Pointer to MpHandOff
> +  @return                     BspNumber
> +**/
> +UINT32
> +GetBspNumber (
> +  IN CONST MP_HAND_OFF  *MpHandOff
> +  );

7. It seems above "GetBspNumber" prototype declaration can be removed. Can you confirm?

> +
>  /**
>    Get available system memory below 1MB by specified size.
> 
> @@ -652,6 +708,16 @@ EnableDisableApWorker (
>    IN  UINT32   *HealthFlag OPTIONAL
>    );
> 
> +/**
> +  Get pointer to MP_HAND_OFF GUIDed HOB.
> +
> +  @return  The pointer to MP_HAND_OFF structure.
> +**/
> +MP_HAND_OFF *
> +GetMpHandOffHob (
> +  VOID
> +  );
> +

8. It seems above "GetMpHandOffHob" prototype declaration can be removed if you implement it in front of
    MpInitLibInitialize() in MpLib.c. can you confirm?

Re: [Patch V3 4/5] UefiCpuPkg: ApWakeupFunction directly use CpuMpData.

[Ni, Ray]

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

> -----Original Message-----
> From: Xie, Yuanhao <yuanhao.xie@intel.com>
> Sent: Monday, June 26, 2023 1:57 PM
> To: devel@edk2.groups.io
> Cc: Gerd Hoffmann <kraxel@redhat.com>; Dong, Eric <eric.dong@intel.com>; Ni,
> Ray <ray.ni@intel.com>; Kumar, Rahul R <rahul.r.kumar@intel.com>; Tom
> Lendacky <thomas.lendacky@amd.com>; Xie, Yuanhao
> <yuanhao.xie@intel.com>
> Subject: [Patch V3 4/5] UefiCpuPkg: ApWakeupFunction directly use CpuMpData.
> 
> In the original design, once the APs finished executing their assembly
> code and switched to executing C code, they would enter a continuous
> loop within a function. In this function, they would collect CpuMpData
> using the MP_CPU_EXCHANGE_INFO mechanism. However, in the updated
> approach, CpuMpData can now be passed directly to the ApWakeUpFunction,
> bypassing the need for MP_CPU_EXCHANGE_INFO. This modification is made
> in preparation for eliminating the requirement of a second
> INIT-SIPI-SIPI sequence in the DXE phase.
> 
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Rahul Kumar <rahul1.kumar@intel.com>
> Cc: Tom Lendacky <thomas.lendacky@amd.com>
> Signed-off-by: Yuanhao Xie <yuanhao.xie@intel.com>
> ---
>  UefiCpuPkg/Library/MpInitLib/Ia32/MpFuncs.nasm |  4 ++--
>  UefiCpuPkg/Library/MpInitLib/MpLib.c           | 12 +++---------
>  UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm  |  3 +--
>  3 files changed, 6 insertions(+), 13 deletions(-)
> 
> diff --git a/UefiCpuPkg/Library/MpInitLib/Ia32/MpFuncs.nasm
> b/UefiCpuPkg/Library/MpInitLib/Ia32/MpFuncs.nasm
> index 59db4081d6..d117f09ef5 100644
> --- a/UefiCpuPkg/Library/MpInitLib/Ia32/MpFuncs.nasm
> +++ b/UefiCpuPkg/Library/MpInitLib/Ia32/MpFuncs.nasm
> @@ -197,8 +197,8 @@ CProcedureInvoke:
> 
>      push       ebx               ; Push ApIndex
>      mov        eax, esi
> -    add        eax, MP_CPU_EXCHANGE_INFO_OFFSET
> -    push       eax               ; push address of exchange info data buffer
> +    add        eax, MP_CPU_EXCHANGE_INFO_FIELD (CpuMpData)
> +    push       dword [eax]       ; push address of CpuMpData
> 
>      mov        edi, esi
>      add        edi, MP_CPU_EXCHANGE_INFO_FIELD (CFunction)
> diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c
> b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> index 1252ee9673..15b24b1805 100644
> --- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
> +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> @@ -710,17 +710,16 @@ PlaceAPInMwaitLoopOrRunLoop (
>  /**
>    This function will be called from AP reset code if BSP uses WakeUpAP.
> 
> -  @param[in] ExchangeInfo     Pointer to the MP exchange info buffer
> +  @param[in] CpuMpData        Pointer to CPU MP Data
>    @param[in] ApIndex          Number of current executing AP
>  **/
>  VOID
>  EFIAPI
>  ApWakeupFunction (
> -  IN MP_CPU_EXCHANGE_INFO  *ExchangeInfo,
> -  IN UINTN                 ApIndex
> +  IN CPU_MP_DATA  *CpuMpData,
> +  IN UINTN        ApIndex
>    )
>  {
> -  CPU_MP_DATA       *CpuMpData;
>    UINTN             ProcessorNumber;
>    EFI_AP_PROCEDURE  Procedure;
>    VOID              *Parameter;
> @@ -731,11 +730,6 @@ ApWakeupFunction (
>    UINTN             CurrentApicMode;
>    AP_STACK_DATA     *ApStackData;
> 
> -  //
> -  // AP finished assembly code and begin to execute C code
> -  //
> -  CpuMpData = ExchangeInfo->CpuMpData;
> -
>    //
>    // AP's local APIC settings will be lost after received INIT IPI
>    // We need to re-initialize them at here
> diff --git a/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm
> b/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm
> index 5bcdf7726b..40e80ffab4 100644
> --- a/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm
> +++ b/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm
> @@ -259,8 +259,7 @@ CProcedureInvoke:
>      add        rsp, 20h
> 
>      mov        edx, ebx          ; edx is ApIndex
> -    mov        ecx, esi
> -    add        ecx, MP_CPU_EXCHANGE_INFO_OFFSET ; rcx is address of exchange
> info data buffer
> +    mov        rcx, qword [esi + MP_CPU_EXCHANGE_INFO_FIELD (CpuMpData)]
> 
>      mov        edi, esi
>      add        edi, MP_CPU_EXCHANGE_INFO_FIELD (CFunction)
> --
> 2.36.1.windows.1

Re: [Patch V3 5/5] UefiCpuPkg: Eliminate the second INIT-SIPI-SIPI sequence.

[Ni, Ray]

> +      OriginalValue         = InterlockedCompareExchange32 (
> +                                (UINT32 *)ApStartupSignalBuffer,
> +                                MP_HAND_OFF_SIGNAL,
> +                                0
> +                                );
> +      if (OriginalValue == MP_HAND_OFF_SIGNAL) {
> +        SetApState (&CpuMpData->CpuData[ProcessorNumber], CpuStateReady);
> +      }

1. I don't think InterlockedCompareExchange32() is needed. But it's consistent with the following code. Ok to me.

> +
>        InterlockedCompareExchange32 (
>          (UINT32 *)ApStartupSignalBuffer,
>          WAKEUP_AP_SIGNAL,
> @@ -887,6 +897,32 @@ ApWakeupFunction (
>    }
>  }
> 

> +DxeApEntryPoint (
> +  CPU_MP_DATA  *CpuMpData
> +  )
> +{
> +  UINTN  ProcessorNumber;
> +
> +  GetProcessorNumber (CpuMpData, &ProcessorNumber);
> +  InterlockedIncrement ((UINT32 *)&CpuMpData->FinishedCount);
> +  RestoreVolatileRegisters (&CpuMpData->CpuData[0].VolatileRegisters, FALSE);
> +  PlaceAPInMwaitLoopOrRunLoop (
> +    CpuMpData->ApLoopMode,
> +    CpuMpData->CpuData[ProcessorNumber].StartupApSignal,
> +    CpuMpData->ApTargetCState
> +    );

2. CpuMpData->ApLoopMode is set to PcdGet8 (PcdCpuApLoopMode) in DXE phase.
     It's possible that when building the Dxe instance of the library, PcdCpuApLoopMode is ApInHltLoop.
     Then above code should not expect the CpuMpData->ApLoopMode is either MwaitLoop or RunLoop.
     But, if the CPU runs here, PcdCpuApLoopMode in PEI phase should not be APInHltLoop.
     So the question becomes: Shall MpInitLib support different PcdCpuApLoopMode values?
     I prefer no for keeping the configuration simple.
     Then, can you please add an assertion before calling SwitchApContext()? (see comments below)


> +    if (MpHandOff->WaitLoopExecutionMode == sizeof (VOID *)) {

3. can you add "ASSERT (CpuMpData->ApLoopMode != APInHltLoop)" here?

> +      //
> +      // In scenarios where both the PEI and DXE phases run in the same
> +      // execution mode (32bit or 64bit), the BSP triggers
> +      // a start-up signal during the DXE phase to wake up the APs. This causes any
> +      // APs that are currently in a loop on the memory prepared during the PEI
> +      // phase to awaken and run the SwitchContextPerAp procedure. This
> procedure
> +      // enables the APs to switch to a different memory section and continue their
> +      // looping process there.
> +      //
> +      CpuMpData->FinishedCount = 0;
> +      CpuMpData->InitFlag      = ApInitDone;
> +      SaveCpuMpData (CpuMpData);
> +      SwitchApContext (MpHandOff);
> +      ASSERT (CpuMpData->FinishedCount == (CpuMpData->CpuCount - 1));

Re: [Patch V3 5/5] UefiCpuPkg: Eliminate the second INIT-SIPI-SIPI sequence.

[Yuanhao Xie]

Hi Ray,

Please check V4 patch series.
Thanks for the feedbacks.

Yuanhao


> +      OriginalValue         = InterlockedCompareExchange32 (
> +                                (UINT32 *)ApStartupSignalBuffer,
> +                                MP_HAND_OFF_SIGNAL,
> +                                0
> +                                );
> +      if (OriginalValue == MP_HAND_OFF_SIGNAL) {
> +        SetApState (&CpuMpData->CpuData[ProcessorNumber], CpuStateReady);
> +      }

1. I don't think InterlockedCompareExchange32() is needed. But it's consistent with the following code. Ok to me.
A: I keep this in V4 patch series.

> +
>        InterlockedCompareExchange32 (
>          (UINT32 *)ApStartupSignalBuffer,
>          WAKEUP_AP_SIGNAL,
> @@ -887,6 +897,32 @@ ApWakeupFunction (
>    }
>  }
> 

> +DxeApEntryPoint (
> +  CPU_MP_DATA  *CpuMpData
> +  )
> +{
> +  UINTN  ProcessorNumber;
> +
> +  GetProcessorNumber (CpuMpData, &ProcessorNumber);  
> + InterlockedIncrement ((UINT32 *)&CpuMpData->FinishedCount);  
> + RestoreVolatileRegisters (&CpuMpData->CpuData[0].VolatileRegisters, 
> + FALSE);  PlaceAPInMwaitLoopOrRunLoop (
> +    CpuMpData->ApLoopMode,
> +    CpuMpData->CpuData[ProcessorNumber].StartupApSignal,
> +    CpuMpData->ApTargetCState
> +    );

2. CpuMpData->ApLoopMode is set to PcdGet8 (PcdCpuApLoopMode) in DXE phase.
     It's possible that when building the Dxe instance of the library, PcdCpuApLoopMode is ApInHltLoop.
     Then above code should not expect the CpuMpData->ApLoopMode is either MwaitLoop or RunLoop.
     But, if the CPU runs here, PcdCpuApLoopMode in PEI phase should not be APInHltLoop.
     So the question becomes: Shall MpInitLib support different PcdCpuApLoopMode values?
     I prefer no for keeping the configuration simple.
     Then, can you please add an assertion before calling SwitchApContext()? (see comments below)

A: I added assertion in V4 patch series.

> +    if (MpHandOff->WaitLoopExecutionMode == sizeof (VOID *)) {

3. can you add "ASSERT (CpuMpData->ApLoopMode != APInHltLoop)" here?

> +      //
> +      // In scenarios where both the PEI and DXE phases run in the same
> +      // execution mode (32bit or 64bit), the BSP triggers
> +      // a start-up signal during the DXE phase to wake up the APs. This causes any
> +      // APs that are currently in a loop on the memory prepared during the PEI
> +      // phase to awaken and run the SwitchContextPerAp procedure. 
> + This
> procedure
> +      // enables the APs to switch to a different memory section and continue their
> +      // looping process there.
> +      //
> +      CpuMpData->FinishedCount = 0;
> +      CpuMpData->InitFlag      = ApInitDone;
> +      SaveCpuMpData (CpuMpData);
> +      SwitchApContext (MpHandOff);
> +      ASSERT (CpuMpData->FinishedCount == (CpuMpData->CpuCount - 1));

Re: [Patch V3 3/5] UefiCpuPkg: Create MpHandOff.

[Yuanhao Xie]

Hi Ray,

Please check V4 patch series.

Thanks for the feedbacks.
Yuanhao


> 
> The SaveCpuMpData() function was updated to construct the MP_HAND_OFF 
> Hob. Additionally, the function introduced the MP_HAND_OFF_SIGNAL, 
> which solely served the purpose of awakening the APs and transitioning 
> their context from PEI to DXE. The WaitLoopExecutionMode field 
> indicated whether the bit mode of PEI matched that of DXE. Both of 
> them were filled only if the ApLoopMode was not ApInHltLoop. In the 
> case of ApLoopMode, it remained necessary

1. "ApLoopMode" -> "ApInHltMode"?
2. can you update commit message to highlight that this patch still sends INIT-SIPI-SIPI even AP is wait in run-loop or mwait loop?
A: I updated commit message in patch V4.
> +
> +/**
> +  Get pointer to CPU MP Data structure from GUIDed HOB.
> +
> +  @param[in] CpuMpData  The pointer to CPU MP Data structure.
> +**/
> +VOID
> +AmdSevUpdateCpuMpData (
> +  IN CPU_MP_DATA  *CpuMpData
> +  )
> +{
> +  CPU_MP_DATA  *OldCpuMpData;
> +
> +  OldCpuMpData = GetCpuMpDataFromGuidedHob ();
> +
> +  OldCpuMpData->NewCpuMpData = CpuMpData; }

3. Can you please move this function implementation into MpInitLib/AmdSev.c?
A: This function is added in AmdSev.c


> +//
> +// To trigger the start-up signal, BSP writes the specified // 
> +StartupSignalValue to the StartupSignalAddress of each processor.
> +// This address is monitored by the APs, and as soon as they receive 
> +// the value that matches the MP_HAND_OFF_SIGNAL, they will wake up 
> +// and switch the context from PEI to DXE phase.
> +//
> +#define MP_HAND_OFF_SIGNAL  SIGNATURE_32 ('M', 'P', 'H', 'O')
4. It's ok to define the signal signature here.

> +#define MP_HANDOFF_GUID \
> +  { \
> +    0x11e2bd88, 0xed38, 0x4abd, {0xa3, 0x99, 0x21, 0xf2, 0x5f, 0xd0, 
> +0x7a, 0x60 }
> \
> +  }

5. can you please move this GUID definition to MpInitLib/MpHandOff.h?
A: MP_HANDOFF_GUID  and 2 structure definitions in below are put in MpInitLib/MpHandOff in patch V4.


> +//
> +// The information required to transfer from the PEI phase to the // 
> +DXE phase is contained within the MP_HAND_OFF and
> PROCESSOR_HAND_OFF.
> +// If the SizeOfPointer (WaitLoopExecutionMode) of both phases are 
> +equal, // and the APs is not in halt mode, // then the APs can be 
> +awakened by triggering the start-up // signal, rather than using 
> +INIT-SIPI-SIPI.
> +// To trigger the start-up signal, BSP writes the specified // 
> +StartupSignalValue to the StartupSignalAddress of each processor.
> +// This address is monitored by the APs.
> +//
> +typedef struct {
> +  UINT32    ApicId;
> +  UINT32    Health;
> +  UINT64    StartupSignalAddress;
> +  UINT64    StartupProcedureAddress;
> +} PROCESSOR_HAND_OFF;
> +
> +typedef struct {
> +  //
> +  // The ProcessorIndex indicates the range of processors. If it is 
> +set to 0, it
> signifies
> +  // processors from 0 to CpuCount - 1. Multiple instances in the HOB 
> + list
> describe
> +  // processors from ProcessorIndex to ProcessorIndex + CpuCount - 1.
> +  //
> +  UINT32                ProcessorIndex;
> +  UINT32                CpuCount;
> +  UINT32                WaitLoopExecutionMode;
> +  UINT32                StartupSignalValue;
> +  PROCESSOR_HAND_OFF    Info[];
> +} MP_HAND_OFF;

6. can you please move the above 2 structure definitions to MpInitLib/MpHandOff.h?

> +
>  //
>  // Data structure for microcode patch information  // @@ -347,6 
> +391,7 @@ typedef
>    );
> 
>  extern EFI_GUID  mCpuInitMpLibHobGuid;
> +extern EFI_GUID  mMpHandOffGuid;
> 
>  /**
>    Assembly code to place AP into safe loop mode.
> @@ -452,6 +497,17 @@ SaveCpuMpData (
>    IN CPU_MP_DATA  *CpuMpData
>    );
> 
> +/**
> +  This function Get BspNumber.
> +
> +  @param[in] MpHandOff        Pointer to MpHandOff
> +  @return                     BspNumber
> +**/
> +UINT32
> +GetBspNumber (
> +  IN CONST MP_HAND_OFF  *MpHandOff
> +  );

7. It seems above "GetBspNumber" prototype declaration can be removed. Can you confirm?
A: I agree. GetBspNumber is removed in patch V4.


> +
>  /**
>    Get available system memory below 1MB by specified size.
> 
> @@ -652,6 +708,16 @@ EnableDisableApWorker (
>    IN  UINT32   *HealthFlag OPTIONAL
>    );
> 
> +/**
> +  Get pointer to MP_HAND_OFF GUIDed HOB.
> +
> +  @return  The pointer to MP_HAND_OFF structure.
> +**/
> +MP_HAND_OFF *
> +GetMpHandOffHob (
> +  VOID
> +  );
> +

8. It seems above "GetMpHandOffHob" prototype declaration can be removed if you implement it in front of
    MpInitLibInitialize() in MpLib.c. can you confirm?
A: I agree. GetMpHandOffHob is removed in patch V4.