AdvLoggerPkg: Drop buffer migration (#868)

## Description

Effectively reverts commits af0f64c and 9fc8521 preserving structure
compatibility and general cleanup.

The advanced logger buffer starts accumulating messages in the first
phase advanced logger is active, and the buffer continues to be used
throughout remaining phases. Each phase has to account for either
allocating or using an existing logger buffer. Due to the persistent
nature of the buffer throughout boot, it is allocated as a runtime
memory type early in boot to support its preservation and access at OS
runtime.

However, S4 resume relies upon a stable memory map across suspend and
resume. Since the advanced logger buffer is allocated as a runtime
memory type prior to DXE, it is in a buffer outside the DXE memory bins.
This leads to an increased likelihood of the buffer being at a different
address across suspend and resume affecting hibernate resume. Advanced
logger buffer migration was a mechanism to address this but doing so
complicates MM treatment of the buffer.

Because a single advanced logger buffer is used across all phases,
including a shared buffer between PEI and MM and DXE and MM, the buffer
must be unlocked for MM access to accommodate a PEI MM IPL. This creates
a problem where both requirements cannot simultaneously be met without
additional complexity in MM access code. In addition, MM environments
are inconsistent in their support for memory unlocking.

In the end, hibernation has always been a best effort scenario with this
flow and other MM solutions already require runtime allocations outside
of DXE memory bins, so this change removes the functional logic for
migration.

The memory bin scenario will be addressed in the future when the bins
are allocated in a pre-DXE phase (e.g. PEI) and picked up by DXE.

- [x] Impacts functionality?
- [ ] Impacts security?
- [ ] Breaking change?
- [ ] Includes tests?
- [ ] Includes documentation?

## How This Was Tested

- AdvLoggerPkg CI
- Boot to OS on QEMU Q35 and SBSA
- Boot to EFI shell on OVMF X64 w/ edk2 Standalone MM

## Integration Instructions

- N/A

Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>

Author: makubacki

AdvLoggerPkg/Include/AdvancedLoggerInternal.h

@@ -45,11 +45,6 @@
 #define ADVANCED_LOGGER_PHASE_TFA          10
 #define ADVANCED_LOGGER_PHASE_CNT          11
 
-//
-// The maximum depth to follow when traversing chains of advanced logger info structures
-//
-#define ADVANCED_LOGGER_MAX_LOGGER_CHAIN_DEPTH  3
-
 //
 // These Pcds are used to carve out a PEI memory buffer from the temporary RAM.
 //
@@ -84,7 +79,9 @@ typedef volatile struct {
   EFI_TIME                Time;                   // Uefi Time Field
   UINT32                  HwPrintLevel;           // Logging level to be printed at hw port
   UINT32                  Reserved3;              //
-  EFI_PHYSICAL_ADDRESS    NewLoggerInfoAddress;   // If non-zero, this field holds the address of new logger info that should be used
+  EFI_PHYSICAL_ADDRESS    Deprecated;             // Deprecated field that should be preserved for binary compatibility
+                                                  // and not reused. Previous description: If non-zero, this field
+                                                  // holds the address of new logger info that should be used
 } ADVANCED_LOGGER_INFO;
 
 typedef struct {

AdvLoggerPkg/Library/AdvLoggerMmAccessLib/AdvLoggerMmAccessLib.c

@@ -13,88 +13,22 @@
 #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;
 
-/**
-  Follow the logger info redirection chain and update the provided logger info pointer.
-
-  @param[in,out]  LoggerInfo    Pointer to a logger info pointer to update.
-  @param[out]     MaxAddress    Optional pointer to update with the max address of the current logger.
-  @param[out]     BufferSize    Optional pointer to update with the buffer size of the current logger.
-
-  @retval         TRUE          A new logger was found and LoggerInfo was updated to the new address.
-  @retval         FALSE         A new logger was not found and no modification was made to LoggerInfo.
-**/
-STATIC
-BOOLEAN
-AdvancedLoggerCheckForNewerLogger (
-  IN OUT ADVANCED_LOGGER_INFO  **LoggerInfo,
-  OUT    EFI_PHYSICAL_ADDRESS  *MaxAddress  OPTIONAL,
-  OUT    UINT32                *BufferSize  OPTIONAL
-  )
-{
-  ADVANCED_LOGGER_INFO  *CurrentLoggerInfo;
-  ADVANCED_LOGGER_INFO  *NextLoggerInfo;
-  UINTN                 Depth;
-
-  if ((LoggerInfo == NULL) || (*LoggerInfo == NULL)) {
-    return FALSE;
-  }
-
-  CurrentLoggerInfo = *LoggerInfo;
-  Depth             = 0;
-
-  // Follow the chain to find the current logger
-  while ((CurrentLoggerInfo->NewLoggerInfoAddress != 0) && (Depth < ADVANCED_LOGGER_MAX_LOGGER_CHAIN_DEPTH)) {
-    NextLoggerInfo = ALI_FROM_PA (CurrentLoggerInfo->NewLoggerInfoAddress);
-
-    if (NextLoggerInfo->Signature != ADVANCED_LOGGER_SIGNATURE) {
-      return FALSE;
-    }
-
-    CurrentLoggerInfo = NextLoggerInfo;
-    Depth++;
-  }
-
-  if (Depth >= ADVANCED_LOGGER_MAX_LOGGER_CHAIN_DEPTH) {
-    return FALSE;
-  }
-
-  // Update if we found a newer logger
-  if (CurrentLoggerInfo != *LoggerInfo) {
-    *LoggerInfo = CurrentLoggerInfo;
-
-    if (MaxAddress != NULL) {
-      *MaxAddress = LOG_MAX_ADDRESS (CurrentLoggerInfo);
-    }
-
-    if (BufferSize != NULL) {
-      *BufferSize = CurrentLoggerInfo->LogBufferSize;
-    }
-
-    return TRUE;
-  }
-
-  return FALSE;
-}
-
 /**
     CheckAddress
 
@@ -142,38 +76,6 @@ 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.
 
@@ -187,7 +89,6 @@ AdvLoggerAccessInit (
   )
 {
   EFI_HOB_GUID_TYPE    *GuidHob;
-  VOID                 *Registration;
   ADVANCED_LOGGER_PTR  *LogPtr;
   EFI_STATUS           Status;
   UINTN                TempSize;
@@ -209,12 +110,6 @@ AdvLoggerAccessInit (
 
   if (mLoggerInfo != NULL) {
     mMaxAddress = LOG_MAX_ADDRESS (mLoggerInfo);
-
-    if (!FeaturePcdGet (PcdAdvancedLoggerFixedInRAM)) {
-      if (AdvancedLoggerCheckForNewerLogger (&mLoggerInfo, &mMaxAddress, &mBufferSize)) {
-        DEBUG ((DEBUG_INFO, "%a: Logger buffer migrated. LoggerInfo=%p\n", __FUNCTION__, mLoggerInfo));
-      }
-    }
   }
 
   //
@@ -244,15 +139,6 @@ 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));
-  }
 }
 
 /**
@@ -308,12 +194,6 @@ AdvLoggerAccessGetVariable (
   UINT8       *LogBufferEnd;
   UINTN       LogBufferSize;
 
-  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));
-    }
-  }
-
   if ((!ValidateInfoBlock ()) || (mLoggerTransferSize == 0)) {
     return EFI_UNSUPPORTED;
   }

AdvLoggerPkg/Library/AdvLoggerMmAccessLib/AdvLoggerMmAccessLib.inf

@@ -34,17 +34,13 @@
   BaseMemoryLib
   DebugLib
   HobLib
-  MmServicesTableLib
   PcdLib
   SafeIntLib
 
 [Guids]
   gAdvancedLoggerHobGuid
   gAdvLoggerAccessGuid                      ## CONSUMES
 
-[Protocols]
-  gEfiMmReadyToLockProtocolGuid             ## NOTIFY
-
 [Pcd]
   gEfiMdeModulePkgTokenSpaceGuid.PcdMaxVariableSize
   gAdvLoggerPkgTokenSpaceGuid.PcdAdvancedLoggerBase