microsoft · makubacki · Feb 23, 2026 · Feb 20, 2026
diff --git a/AdvLoggerPkg/Library/AdvLoggerMmAccessLib/AdvLoggerMmAccessLib.c b/AdvLoggerPkg/Library/AdvLoggerMmAccessLib/AdvLoggerMmAccessLib.c
@@ -13,20 +13,23 @@
 #include <AdvancedLoggerInternal.h>
 
 #include <Protocol/AdvancedLogger.h>
+#include <Protocol/MmReadyToLock.h>
 
 #include <Library/AdvLoggerAccessLib.h>
 #include <Library/BaseLib.h>
 #include <Library/BaseMemoryLib.h>
 #include <Library/DebugLib.h>
 #include <Library/HobLib.h>
 #include <Library/PcdLib.h>
+#include <Library/MmServicesTableLib.h>
 #include <Library/SafeIntLib.h>
 #include <Library/UefiBootServicesTableLib.h>
 
 STATIC ADVANCED_LOGGER_INFO  *mLoggerInfo        = NULL;
 STATIC UINT32                mBufferSize         = 0;
 STATIC EFI_PHYSICAL_ADDRESS  mMaxAddress         = 0;
 STATIC UINTN                 mLoggerTransferSize = 0;
+STATIC BOOLEAN               mReadyToLock        = FALSE;
 extern UINTN                 mVariableBufferPayloadSize;
 
 /**
@@ -139,6 +142,38 @@ ValidateInfoBlock (
   return TRUE;
 }
 
+/**
+  MM ReadyToLock notification handler.
+
+  Ensures any move needed to the new logger buffer is done before ReadyToLock completes.
+
+  @param[in] Protocol   Protocol GUID pointer.
+  @param[in] Interface  Protocol interface pointer.
+  @param[in] Handle     The handle on which the interface was installed.
+
+  @retval EFI_SUCCESS   The notification handler completed successfully.
+
+**/
+STATIC
+EFI_STATUS
+EFIAPI
+OnMmReadyToLock (
+  IN CONST EFI_GUID  *Protocol,
+  IN VOID            *Interface,
+  IN EFI_HANDLE      Handle
+  )
+{
+  if ((mLoggerInfo != NULL) && !FeaturePcdGet (PcdAdvancedLoggerFixedInRAM)) {
+    if (AdvancedLoggerCheckForNewerLogger (&mLoggerInfo, &mMaxAddress, &mBufferSize)) {
+      DEBUG ((DEBUG_INFO, "%a: Logger buffer migrated at ReadyToLock. LoggerInfo=%p\n", __FUNCTION__, mLoggerInfo));
+    }
+  }
+
+  mReadyToLock = TRUE;
+
+  return EFI_SUCCESS;
+}
+
 /**
     AdvLoggerInit - Obtain the address of the logger info block.
 
@@ -152,6 +187,7 @@ AdvLoggerAccessInit (
   )
 {
   EFI_HOB_GUID_TYPE    *GuidHob;
+  VOID                 *Registration;
   ADVANCED_LOGGER_PTR  *LogPtr;
   EFI_STATUS           Status;
   UINTN                TempSize;
@@ -173,11 +209,11 @@ AdvLoggerAccessInit (
 
   if (mLoggerInfo != NULL) {
     mMaxAddress = LOG_MAX_ADDRESS (mLoggerInfo);
-  }
 
-  if ((mLoggerInfo != NULL) && !FeaturePcdGet (PcdAdvancedLoggerFixedInRAM)) {
-    if (AdvancedLoggerCheckForNewerLogger (&mLoggerInfo, &mMaxAddress, &mBufferSize)) {
-      DEBUG ((DEBUG_INFO, "%a: Logger buffer migrated. LoggerInfo=%p\n", __FUNCTION__, mLoggerInfo));
+    if (!FeaturePcdGet (PcdAdvancedLoggerFixedInRAM)) {
+      if (AdvancedLoggerCheckForNewerLogger (&mLoggerInfo, &mMaxAddress, &mBufferSize)) {
+        DEBUG ((DEBUG_INFO, "%a: Logger buffer migrated. LoggerInfo=%p\n", __FUNCTION__, mLoggerInfo));
+      }
     }
   }
 
@@ -208,6 +244,15 @@ AdvLoggerAccessInit (
   //
 
   DEBUG ((DEBUG_INFO, "%a: LoggerInfo=%p, code=%r\n", __FUNCTION__, mLoggerInfo, Status));
+
+  Status = gMmst->MmRegisterProtocolNotify (
+                    &gEfiMmReadyToLockProtocolGuid,
+                    OnMmReadyToLock,
+                    &Registration
+                    );
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_ERROR, "%a: Failed to register ReadyToLock notify - %r\n", __func__, Status));
+  }
 }
 
 /**
@@ -263,7 +308,7 @@ AdvLoggerAccessGetVariable (
   UINT8       *LogBufferEnd;
   UINTN       LogBufferSize;
 
-  if ((mLoggerInfo != NULL) && !mLoggerInfo->AtRuntime && !FeaturePcdGet (PcdAdvancedLoggerFixedInRAM)) {
+  if ((mLoggerInfo != NULL) && !mReadyToLock && !FeaturePcdGet (PcdAdvancedLoggerFixedInRAM)) {
     if (AdvancedLoggerCheckForNewerLogger (&mLoggerInfo, &mMaxAddress, &mBufferSize)) {
       DEBUG ((DEBUG_INFO, "%a: Logger buffer migrated during access. LoggerInfo=%p\n", __FUNCTION__, mLoggerInfo));
     }
@@ -335,12 +380,6 @@ AdvLoggerAccessAtRuntime (
   VOID
   )
 {
-  if ((mLoggerInfo != NULL) && !FeaturePcdGet (PcdAdvancedLoggerFixedInRAM)) {
-    if (AdvancedLoggerCheckForNewerLogger (&mLoggerInfo, &mMaxAddress, &mBufferSize)) {
-      DEBUG ((DEBUG_INFO, "%a: Logger buffer migrated at ExitBootServices. LoggerInfo=%p\n", __FUNCTION__, mLoggerInfo));
-    }
-  }
-
   if (mLoggerInfo != NULL) {
     mLoggerInfo->AtRuntime = TRUE;
   }

diff --git a/AdvLoggerPkg/Library/AdvLoggerMmAccessLib/AdvLoggerMmAccessLib.inf b/AdvLoggerPkg/Library/AdvLoggerMmAccessLib/AdvLoggerMmAccessLib.inf
@@ -34,13 +34,17 @@
   BaseMemoryLib
   DebugLib
   HobLib
+  MmServicesTableLib
   PcdLib
   SafeIntLib
 
 [Guids]
   gAdvancedLoggerHobGuid
   gAdvLoggerAccessGuid                      ## CONSUMES
 
+[Protocols]
+  gEfiMmReadyToLockProtocolGuid             ## NOTIFY
+
 [Pcd]
   gEfiMdeModulePkgTokenSpaceGuid.PcdMaxVariableSize
   gAdvLoggerPkgTokenSpaceGuid.PcdAdvancedLoggerBase

diff --git a/AdvLoggerPkg/Library/AdvLoggerSmmAccessLib/AdvLoggerSmmAccessLib.c b/AdvLoggerPkg/Library/AdvLoggerSmmAccessLib/AdvLoggerSmmAccessLib.c
@@ -13,6 +13,7 @@
 #include <Guid/SmmVariableCommon.h>
 
 #include <Protocol/AdvancedLogger.h>
+#include <Protocol/SmmReadyToLock.h>
 #include <AdvancedLoggerInternalProtocol.h>
 
 #include <Library/AdvLoggerAccessLib.h>
@@ -21,12 +22,14 @@
 #include <Library/DebugLib.h>
 #include <Library/PcdLib.h>
 #include <Library/SafeIntLib.h>
+#include <Library/SmmServicesTableLib.h>
 #include <Library/UefiBootServicesTableLib.h>
 
 STATIC ADVANCED_LOGGER_INFO  *mLoggerInfo        = NULL;
 STATIC UINT32                mBufferSize         = 0;
 STATIC EFI_PHYSICAL_ADDRESS  mMaxAddress         = 0;
 STATIC UINTN                 mLoggerTransferSize = 0;
+STATIC BOOLEAN               mReadyToLock        = FALSE;
 extern UINTN                 mVariableBufferPayloadSize;
 
 /**
@@ -141,6 +144,38 @@ ValidateInfoBlock (
   return TRUE;
 }
 
+/**
+  SMM ReadyToLock notification handler.
+
+  Ensures any move needed to the new logger buffer is done before ReadyToLock completes.
+
+  @param[in] Protocol   Protocol GUID pointer.
+  @param[in] Interface  Protocol interface pointer.
+  @param[in] Handle     The handle on which the interface was installed.
+
+  @retval EFI_SUCCESS   The notification handler completed successfully.
+
+**/
+STATIC
+EFI_STATUS
+EFIAPI
+OnSmmReadyToLock (
+  IN CONST EFI_GUID  *Protocol,
+  IN VOID            *Interface,
+  IN EFI_HANDLE      Handle
+  )
+{
+  if (mLoggerInfo != NULL) {
+    if (AdvancedLoggerCheckForNewerLogger (&mLoggerInfo, &mMaxAddress, &mBufferSize)) {
+      DEBUG ((DEBUG_INFO, "%a: Logger buffer migrated at ReadyToLock. LoggerInfo=%p\n", __func__, mLoggerInfo));
+    }
+  }
+
+  mReadyToLock = TRUE;
+
+  return EFI_SUCCESS;
+}
+
 /**
     AdvLoggerInit - Obtain the address of the logger info block.
 
@@ -154,9 +189,12 @@ AdvLoggerAccessInit (
   )
 {
   ADVANCED_LOGGER_PROTOCOL  *LoggerProtocol;
+  VOID                      *Registration;
   UINTN                     TempSize;
   EFI_STATUS                Status;
 
+  Registration = NULL;
+
   if (gBS == NULL) {
     return;
   }
@@ -191,7 +229,7 @@ AdvLoggerAccessInit (
     if (mLoggerInfo != NULL) {
       mMaxAddress = LOG_MAX_ADDRESS (mLoggerInfo);
 
-      if (AdvancedLoggerCheckForNewerLogger (&mLoggerInfo, &mMaxAddress, &mBufferSize)) {
+      if (!FeaturePcdGet (PcdAdvancedLoggerFixedInRAM) && AdvancedLoggerCheckForNewerLogger (&mLoggerInfo, &mMaxAddress, &mBufferSize)) {
         DEBUG ((DEBUG_INFO, "%a: Logger buffer migrated. LoggerInfo=%p\n", __FUNCTION__, mLoggerInfo));
       }
     }
@@ -206,6 +244,17 @@ AdvLoggerAccessInit (
   //
 
   DEBUG ((DEBUG_INFO, "%a: LoggerInfo=%p, code=%r\n", __FUNCTION__, mLoggerInfo, Status));
+
+  if (!FeaturePcdGet (PcdAdvancedLoggerFixedInRAM)) {
+    Status = gSmst->SmmRegisterProtocolNotify (
+                      &gEfiSmmReadyToLockProtocolGuid,
+                      OnSmmReadyToLock,
+                      &Registration
+                      );
+    if (EFI_ERROR (Status)) {
+      DEBUG ((DEBUG_ERROR, "%a: Failed to register ReadyToLock notify - %r\n", __func__, Status));
+    }
+  }
 }
 
 /**
@@ -261,7 +310,7 @@ AdvLoggerAccessGetVariable (
   UINT8       *LogBufferEnd;
   UINTN       LogBufferSize;
 
-  if ((mLoggerInfo != NULL) && !mLoggerInfo->AtRuntime) {
+  if ((mLoggerInfo != NULL) && !mReadyToLock && !FeaturePcdGet (PcdAdvancedLoggerFixedInRAM)) {
     if (AdvancedLoggerCheckForNewerLogger (&mLoggerInfo, &mMaxAddress, &mBufferSize)) {
       DEBUG ((DEBUG_INFO, "%a: Logger buffer migrated during access. LoggerInfo=%p\n", __FUNCTION__, mLoggerInfo));
     }
@@ -333,12 +382,6 @@ AdvLoggerAccessAtRuntime (
   VOID
   )
 {
-  if (mLoggerInfo != NULL) {
-    if (AdvancedLoggerCheckForNewerLogger (&mLoggerInfo, &mMaxAddress, &mBufferSize)) {
-      DEBUG ((DEBUG_INFO, "%a: Logger buffer migrated at ExitBootServices. LoggerInfo=%p\n", __FUNCTION__, mLoggerInfo));
-    }
-  }
-
   if (mLoggerInfo != NULL) {
     mLoggerInfo->AtRuntime = TRUE;
   }

diff --git a/AdvLoggerPkg/Library/AdvLoggerSmmAccessLib/AdvLoggerSmmAccessLib.inf b/AdvLoggerPkg/Library/AdvLoggerSmmAccessLib/AdvLoggerSmmAccessLib.inf
@@ -34,13 +34,15 @@
   DebugLib
   PcdLib
   SafeIntLib
+  SmmServicesTableLib
   UefiBootServicesTableLib
 
 [Guids]
   gAdvLoggerAccessGuid                      ## CONSUMES
 
 [Protocols]
   gAdvancedLoggerProtocolGuid               ## CONSUMES
+  gEfiSmmReadyToLockProtocolGuid            ## NOTIFY
 
 [Pcd]
   gEfiMdeModulePkgTokenSpaceGuid.PcdMaxVariableSize

diff --git a/AdvLoggerPkg/Library/AdvancedLoggerLib/SmmCore/AdvancedLoggerLib.c b/AdvLoggerPkg/Library/AdvancedLoggerLib/SmmCore/AdvancedLoggerLib.c
@@ -11,6 +11,7 @@
 #include <AdvancedLoggerInternal.h>
 
 #include <Protocol/AdvancedLogger.h>
+#include <Protocol/SmmReadyToLock.h>
 #include <AdvancedLoggerInternalProtocol.h>
 
 #include <Pi/PiSmmCis.h>
@@ -27,6 +28,7 @@ STATIC ADVANCED_LOGGER_INFO  *mLoggerInfo;
 STATIC UINT32                mBufferSize  = 0;
 STATIC EFI_PHYSICAL_ADDRESS  mMaxAddress  = 0;
 STATIC BOOLEAN               mInitialized = FALSE;
+STATIC BOOLEAN               mReadyToLock = FALSE;
 
 VOID
 EFIAPI
@@ -116,6 +118,38 @@ ValidateInfoBlock (
   return TRUE;
 }
 
+/**
+  SMM ReadyToLock notification handler.
+
+  Ensures any move needed to the new logger buffer is done before ReadyToLock completes.
+
+  @param[in] Protocol   Protocol GUID pointer.
+  @param[in] Interface  Protocol interface pointer.
+  @param[in] Handle     The handle on which the interface was installed.
+
+  @retval EFI_SUCCESS   The notification handler completed successfully.
+
+**/
+STATIC
+EFI_STATUS
+EFIAPI
+OnSmmReadyToLock (
+  IN CONST EFI_GUID  *Protocol,
+  IN VOID            *Interface,
+  IN EFI_HANDLE      Handle
+  )
+{
+  if (mLoggerInfo != NULL) {
+    if (AdvancedLoggerCheckForNewerLogger (&mLoggerInfo, &mMaxAddress, &mBufferSize)) {
+      mAdvLoggerProtocol.LoggerInfo = mLoggerInfo;
+    }
+  }
+
+  mReadyToLock = TRUE;
+
+  return EFI_SUCCESS;
+}
+
 /**
     Get the Logger Information Block published by DxeCore.
  **/
@@ -176,7 +210,9 @@ AdvancedLoggerGetLoggerInfo (
 {
   SmmInitializeLoggerInfo ();
 
-  if ((mLoggerInfo != NULL) && AdvancedLoggerCheckForNewerLogger (&mLoggerInfo, &mMaxAddress, &mBufferSize)) {
+  if ((mLoggerInfo != NULL) && !mReadyToLock && !FeaturePcdGet (PcdAdvancedLoggerFixedInRAM) &&
+      AdvancedLoggerCheckForNewerLogger (&mLoggerInfo, &mMaxAddress, &mBufferSize))
+  {
     DEBUG ((DEBUG_INFO, "MmCore %a: Logger Update. LoggerInfo=%p\n", __func__, mLoggerInfo));
   }
 
@@ -220,6 +256,9 @@ SmmCoreAdvancedLoggerLibConstructor (
 {
   EFI_HANDLE  Handle;
   EFI_STATUS  Status;
+  VOID        *Registration;
+
+  Registration = NULL;
 
   ASSERT ((gBS != NULL) && (gSmst != NULL));
 
@@ -242,5 +281,16 @@ SmmCoreAdvancedLoggerLibConstructor (
   DEBUG ((DEBUG_INFO, "%a: LoggerInfo=%p, Code=%r\n", __func__, mLoggerInfo, Status));
   ASSERT_EFI_ERROR (Status);
 
+  if (!FeaturePcdGet (PcdAdvancedLoggerFixedInRAM)) {
+    Status = gSmst->SmmRegisterProtocolNotify (
+                      &gEfiSmmReadyToLockProtocolGuid,
+                      OnSmmReadyToLock,
+                      &Registration
+                      );
+    if (EFI_ERROR (Status)) {
+      DEBUG ((DEBUG_ERROR, "%a: Failed to register ReadyToLock notify - %r\n", __func__, Status));
+    }
+  }
+
   return EFI_SUCCESS;
 }
diff --git a/AdvLoggerPkg/Library/AdvancedLoggerLib/SmmCore/AdvancedLoggerLib.inf b/AdvLoggerPkg/Library/AdvancedLoggerLib/SmmCore/AdvancedLoggerLib.inf
@@ -43,9 +43,11 @@
 
 [Protocols]
   gAdvancedLoggerProtocolGuid                                               ## CONSUMES
+  gEfiSmmReadyToLockProtocolGuid                                            ## NOTIFY
 
 [Pcd]
   gAdvLoggerPkgTokenSpaceGuid.PcdAdvancedLoggerHdwPortDebugPrintErrorLevel  ## SOMETIMES_CONSUMES
 
 [FeaturePcd]
   gAdvLoggerPkgTokenSpaceGuid.PcdAdvancedLoggerAutoWrapEnable
+  gAdvLoggerPkgTokenSpaceGuid.PcdAdvancedLoggerFixedInRAM