MdeModulePkg: Optimize PEI Core Migration Algorithm

REF : https://bugzilla.tianocore.org/show_bug.cgi?id=4750 Migrate the FV that doesn't contain the currently executing PEI Core when permanent memory is initialized but PEI Core is still potentially running from faster memory (Tepmorary RAM). This may reduce the time required to migrate FVs to permanent memory. The FV containing PEI Core is migrated after the PEI Core reentry when it is executed from permanent memory. This may or may not improve performance depending on the behavior of temporary RAM and the actual performance changes must be measured with the feature enabled and disabled. This migration algorithm is only used for FVs specified in the gEdkiiMigrationInfoGuid HOB and built with flag FLAGS_FV_MIGRATE_BEFORE_PEI_CORE_REENTRY. Signed-off-by: Awiral Shrivastava <[email protected]>
igorkulchytskyy · Jul 30, 2024 · 5b08df0 · 5b08df0
1 parent 91a8227
commit 5b08df0
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Showing 3 changed files with 47 additions and 9 deletions.
diff --git a/MdeModulePkg/Core/Pei/Dispatcher/Dispatcher.c b/MdeModulePkg/Core/Pei/Dispatcher/Dispatcher.c
@@ -1205,16 +1205,21 @@ EvacuateTempRam (
     PeiCoreFvHandle.FvHandle = (EFI_PEI_FV_HANDLE)SecCoreData->BootFirmwareVolumeBase;
   }
 
-  for (FvIndex = 0; FvIndex < Private->FvCount; FvIndex++) {
-    if (Private->Fv[FvIndex].FvHandle == PeiCoreFvHandle.FvHandle) {
-      CopyMem (&PeiCoreFvHandle, &Private->Fv[FvIndex], sizeof (PEI_CORE_FV_HANDLE));
-      break;
+  if (Private->PeimDispatcherReenter) {
+    //
+    // PEI_CORE should be migrated after dispatcher re-enters from main memory.
+    //
+    for (FvIndex = 0; FvIndex < Private->FvCount; FvIndex++) {
+      if (Private->Fv[FvIndex].FvHandle == PeiCoreFvHandle.FvHandle) {
+        CopyMem (&PeiCoreFvHandle, &Private->Fv[FvIndex], sizeof (PEI_CORE_FV_HANDLE));
+        break;
+      }
     }
-  }
 
-  Status = EFI_SUCCESS;
+    Status = EFI_SUCCESS;
 
-  ConvertPeiCorePpiPointers (Private, &PeiCoreFvHandle);
+    ConvertPeiCorePpiPointers (Private, &PeiCoreFvHandle);
+  }
 
   Hob.Raw = GetFirstGuidHob (&gEdkiiMigrationInfoGuid);
   if (Hob.Raw != NULL) {
@@ -1237,6 +1242,14 @@ EvacuateTempRam (
         )
     {
       if ((MigrationInfo == NULL) || (MigrationInfo->MigrateAll == TRUE)) {
+        if (!Private->PeimDispatcherReenter) {
+          //
+          // Migration before dispatcher reentery is supported only when gEdkiiMigrationInfoGuid
+          // HOB is built for selective FV migration.
+          //
+          return EFI_SUCCESS;
+        }
+
         //
         // Migrate all FVs and copy raw data
         //
@@ -1253,10 +1266,18 @@ EvacuateTempRam (
           }
         }
 
-        if (Index == MigrationInfo->ToMigrateFvCount) {
+        if ((Index == MigrationInfo->ToMigrateFvCount) ||
+            ((!Private->PeimDispatcherReenter) &&
+             (((FvMigrationFlags & FLAGS_FV_MIGRATE_BEFORE_PEI_CORE_REENTRY) == 0) ||
+              (FvHeader == PeiCoreFvHandle.FvHandle))))
+        {
           //
           // This FV is not expected to migrate
           //
+          // FV should not be migrated before dispatcher reentry if any of the below condition is true:
+          // a. MigrationInfo HOB is not built with flag FLAGS_FV_MIGRATE_BEFORE_PEI_CORE_REENTRY.
+          // b. FV contains currently executing PEI Core.
+          //
           continue;
         }
       }

diff --git a/MdeModulePkg/Core/Pei/PeiMain/PeiMain.c b/MdeModulePkg/Core/Pei/PeiMain/PeiMain.c
@@ -323,6 +323,21 @@ PeiCore (
       //
       OldCoreData->PeiMemoryInstalled = TRUE;
 
+      if (PcdGetBool (PcdMigrateTemporaryRamFirmwareVolumes)) {
+        DEBUG ((DEBUG_VERBOSE, "Early Migration - PPI lists before temporary RAM evacuation:\n"));
+        DumpPpiList (OldCoreData);
+
+        //
+        // Migrate installed content from Temporary RAM to Permanent RAM at this
+        // stage when PEI core still runs from a cached location.
+        // FVs that doesn't contain PEI_CORE should be migrated here.
+        //
+        EvacuateTempRam (OldCoreData, SecCoreData);
+
+        DEBUG ((DEBUG_VERBOSE, "Early Migration - PPI lists after temporary RAM evacuation:\n"));
+        DumpPpiList (OldCoreData);
+      }
+
       //
       // Indicate that PeiCore reenter
       //
@@ -451,6 +466,7 @@ PeiCore (
 
       //
       // Migrate installed content from Temporary RAM to Permanent RAM
+      // FVs containing PEI_CORE should be migrated here.
       //
       EvacuateTempRam (&PrivateData, SecCoreData);
 

diff --git a/MdeModulePkg/Include/Guid/MigratedFvInfo.h b/MdeModulePkg/Include/Guid/MigratedFvInfo.h
@@ -18,7 +18,8 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 // 1: FV raw data will be copied to permanent memory for later phase use (such as
 //    FV measurement).
 //
-#define FLAGS_FV_RAW_DATA_COPY  BIT0
+#define FLAGS_FV_RAW_DATA_COPY                    BIT0
+#define FLAGS_FV_MIGRATE_BEFORE_PEI_CORE_REENTRY  BIT1
 
 ///
 /// In real use cases, not all FVs need migrate to permanent memory before TempRam tears