[edk2-devel] [PATCH v1 3/4] MdeModulePkg: PeiMain: Introduce implementation of delayed dispatch

["Kun Qin" <kuqin12@gmail.com>]

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4496

This change adds the implementation that fits the needs and description
of PI spec defined Delayed Dispatch PPI in Pei Core.

The PPI would allow minimal delay for registered callbacks. As well as
allowing other functions to wait for GUIDed delayed dispatch callbacks.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Dandan Bi <dandan.bi@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Debkumar De <debkumar.de@intel.com>
Cc: Catharine West <catharine.west@intel.com>

Co-authored-by: Mike Turner <mikeyt@pobox.com>
Signed-off-by: Kun Qin <kuqin12@gmail.com>
---
 MdeModulePkg/Core/Pei/Dispatcher/Dispatcher.c | 353 ++++++++++++++++++++
 MdeModulePkg/Core/Pei/PeiMain/PeiMain.c       |   3 +
 MdeModulePkg/Core/Pei/PeiMain.h               |  76 +++++
 MdeModulePkg/Core/Pei/PeiMain.inf             |   7 +
 MdeModulePkg/MdeModulePkg.dec                 |  15 +
 5 files changed, 454 insertions(+)

diff --git a/MdeModulePkg/Core/Pei/Dispatcher/Dispatcher.c b/MdeModulePkg/Core/Pei/Dispatcher/Dispatcher.c
index 5f32ebb560ae..50e59bdbe732 100644
--- a/MdeModulePkg/Core/Pei/Dispatcher/Dispatcher.c
+++ b/MdeModulePkg/Core/Pei/Dispatcher/Dispatcher.c
@@ -3,12 +3,339 @@
 
 Copyright (c) 2006 - 2019, Intel Corporation. All rights reserved.<BR>
 (C) Copyright 2016 Hewlett Packard Enterprise Development LP<BR>
+Copyright (c) Microsoft Corporation.
 SPDX-License-Identifier: BSD-2-Clause-Patent
 
 **/
 
 #include "PeiMain.h"
 
+/**
+  DelayedDispatchDispatcher
+
+  ayed Dispach cycle (ie one pass) through each entry, calling functions when their
+  e has expired.  When UniqueId is specified, if there are any of the specified entries
+  the dispatch queue during dispatch, repeat the DelayedDispatch cycle.
+
+  @param DelayedDispatchTable  Pointer to dispatch table
+  @param OPTIONAL              UniqueId used to insure particular time is met.
+
+  @return BOOLEAN
+**/
+BOOLEAN
+DelayedDispatchDispatcher (
+  IN DELAYED_DISPATCH_TABLE  *DelayedDispatchTable,
+  IN EFI_GUID                *UniqueId           OPTIONAL
+  );
+
+/**
+  DelayedDispatch End of PEI callback function. Insure that all of the delayed dispatch
+  entries are complete before exiting PEI.
+
+  @param[in] PeiServices   - Pointer to PEI Services Table.
+  @param[in] NotifyDesc    - Pointer to the descriptor for the Notification event that
+                             caused this function to execute.
+  @param[in] Ppi           - Pointer to the PPI data associated with this function.
+
+  @retval EFI_STATUS       - Always return EFI_SUCCESS
+**/
+EFI_STATUS
+EFIAPI
+PeiDelayedDispatchOnEndOfPei (
+  IN EFI_PEI_SERVICES           **PeiServices,
+  IN EFI_PEI_NOTIFY_DESCRIPTOR  *NotifyDesc,
+  IN VOID                       *Ppi
+  );
+
+EFI_DELAYED_DISPATCH_PPI  mDelayedDispatchPpi  = { PeiDelayedDispatchRegister, PeiDelayedDispatchWaitOnUniqueId };
+EFI_PEI_PPI_DESCRIPTOR    mDelayedDispatchDesc = {
+  (EFI_PEI_PPI_DESCRIPTOR_PPI | EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST),
+  &gEfiPeiDelayedDispatchPpiGuid,
+  &mDelayedDispatchPpi
+};
+
+EFI_PEI_NOTIFY_DESCRIPTOR  mDelayedDispatchNotifyDesc = {
+  EFI_PEI_PPI_DESCRIPTOR_NOTIFY_CALLBACK | EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST,
+  &gEfiEndOfPeiSignalPpiGuid,
+  PeiDelayedDispatchOnEndOfPei
+};
+
+/**
+  Helper function to look up DELAYED_DISPATCH_TABLE published in HOB.
+
+  @return Pointer to DELAYED_DISPATCH_TABLE from HOB
+**/
+DELAYED_DISPATCH_TABLE *
+GetDelayedDispatchTable (
+  VOID
+  )
+{
+  EFI_HOB_GUID_TYPE  *GuidHob;
+
+  GuidHob = GetFirstGuidHob (&gEfiDelayedDispatchTableGuid);
+  if (NULL == GuidHob) {
+    DEBUG ((DEBUG_ERROR, "Delayed Dispatch PPI ERROR - Delayed Dispatch Hob not available.\n"));
+    ASSERT (FALSE);
+    return NULL;
+  }
+
+  return (DELAYED_DISPATCH_TABLE *)GET_GUID_HOB_DATA (GuidHob);
+}
+
+/**
+Register a callback to be called after a minimum delay has occurred.
+
+This service is the single member function of the EFI_DELAYED_DISPATCH_PPI
+
+  @param[in] This           Pointer to the EFI_DELAYED_DISPATCH_PPI instance
+  @param[in] Function       Function to call back
+  @param[in] Context        Context data
+  @param[in] UniqueId       GUID for this Delayed Dispatch request.
+  @param[in] Delay          Delay interval
+
+  @retval EFI_SUCCESS               Function successfully loaded
+  @retval EFI_INVALID_PARAMETER     One of the Arguments is not supported
+  @retval EFI_OUT_OF_RESOURCES      No more entries
+
+**/
+EFI_STATUS
+EFIAPI
+PeiDelayedDispatchRegister (
+  IN  EFI_DELAYED_DISPATCH_PPI       *This,
+  IN  EFI_DELAYED_DISPATCH_FUNCTION  Function,
+  IN  UINT64                         Context,
+  IN  EFI_GUID                       *UniqueId   OPTIONAL,
+  IN  UINT32                         Delay
+  )
+{
+  DELAYED_DISPATCH_TABLE  *DelayedDispatchTable;
+  DELAYED_DISPATCH_ENTRY  *Entry;
+
+  // Check input parameters
+  if ((NULL == Function) || (Delay > FixedPcdGet32 (PcdDelayedDispatchMaxDelayUs)) || (NULL == This)) {
+    DEBUG ((DEBUG_ERROR, "%a Invalid parameter\n", __func__));
+    return EFI_INVALID_PARAMETER;
+  }
+
+  // Get delayed dispatch table
+  DelayedDispatchTable = GetDelayedDispatchTable ();
+  if (NULL == DelayedDispatchTable) {
+    DEBUG ((DEBUG_ERROR, "%a Unable to locate dispatch table\n", __func__));
+    return EFI_UNSUPPORTED;
+  }
+
+  // Check for available entry slots
+  if (DelayedDispatchTable->Count >= FixedPcdGet32 (PcdDelayedDispatchMaxEntries)) {
+    ASSERT (DelayedDispatchTable->Count < FixedPcdGet32 (PcdDelayedDispatchMaxEntries));
+    DEBUG ((DEBUG_ERROR, "%a Too many entries requested\n", __func__));
+    return EFI_OUT_OF_RESOURCES;
+  }
+
+  Entry               = &(DelayedDispatchTable->Entry[DelayedDispatchTable->Count]);
+  Entry->Function     = Function;
+  Entry->Context      = Context;
+  Entry->DispatchTime = GET_TIME_IN_US () + Delay;
+  if (NULL != UniqueId) {
+    CopyGuid (&Entry->UniqueId, UniqueId);
+  } else {
+    ZeroMem (&Entry->UniqueId, sizeof (EFI_GUID));
+  }
+
+  Entry->MicrosecondDelay = Delay;
+  DelayedDispatchTable->Count++;
+
+  DEBUG ((DEBUG_INFO, "%a  Adding dispatch Entry\n", __func__));
+  DEBUG ((DEBUG_INFO, "    Requested Delay = %d\n", Delay));
+  DEBUG ((DEBUG_INFO, "    Trigger Time = %d\n", Entry->DispatchTime));
+  DEBUG ((DEBUG_INFO, "    Context = 0x%08lx\n", Entry->Context));
+  DEBUG ((DEBUG_INFO, "    Function = %p\n", Entry->Function));
+  DEBUG ((DEBUG_INFO, "    GuidHandle = %g\n", &(Entry->UniqueId)));
+
+  if (0 == Delay) {
+    // Force early dispatch point
+    DelayedDispatchDispatcher (DelayedDispatchTable, NULL);
+  }
+
+  return EFI_SUCCESS;
+}
+
+/**
+  DelayedDispatchDispatcher
+
+  ayed Dispach cycle (ie one pass) through each entry, calling functions when their
+  e has expired.  When UniqueId is specified, if there are any of the specified entries
+  the dispatch queue during dispatch, repeat the DelayedDispatch cycle.
+
+  @param DelayedDispatchTable  Pointer to dispatch table
+  @param OPTIONAL              UniqueId used to insure particular time is met.
+
+  @return BOOLEAN
+**/
+BOOLEAN
+DelayedDispatchDispatcher (
+  IN DELAYED_DISPATCH_TABLE  *DelayedDispatchTable,
+  IN EFI_GUID                *UniqueId           OPTIONAL
+  )
+{
+  BOOLEAN                 Dispatched;
+  UINT32                  TimeCurrent;
+  UINT32                  MaxDispatchTime;
+  UINTN                   Index1;
+  BOOLEAN                 UniqueIdPresent;
+  DELAYED_DISPATCH_ENTRY  *Entry;
+
+  Dispatched      = FALSE;
+  UniqueIdPresent = TRUE;
+  MaxDispatchTime = GET_TIME_IN_US () + FixedPcdGet32 (PcdDelayedDispatchCompletionTimeoutUs);
+  while ((DelayedDispatchTable->Count > 0) && (UniqueIdPresent)) {
+    UniqueIdPresent = FALSE;
+    DelayedDispatchTable->DispCount++;
+
+    // If dispatching is messed up, clear DelayedDispatchTable and exit.
+    TimeCurrent =  GET_TIME_IN_US ();
+    if (TimeCurrent > MaxDispatchTime) {
+      DEBUG ((DEBUG_ERROR, "%a - DelayedDispatch Completion timeout!\n", __func__));
+      ReportStatusCode ((EFI_ERROR_MAJOR | EFI_ERROR_CODE), (EFI_SOFTWARE_PEI_CORE | EFI_SW_EC_ABORTED));
+      ASSERT (FALSE);
+      DelayedDispatchTable->Count = 0;
+      break;
+    }
+
+    // Check each entry in the table for possible dispatch
+    for (Index1 = 0; Index1 < DelayedDispatchTable->Count;) {
+      Entry = &(DelayedDispatchTable->Entry[Index1]);
+      // If UniqueId is present, insure there is an additional check of the table.
+      if (NULL != UniqueId) {
+        if (CompareGuid (UniqueId, &Entry->UniqueId)) {
+          UniqueIdPresent = TRUE;
+        }
+      }
+
+      TimeCurrent =  GET_TIME_IN_US ();
+      if (TimeCurrent >= Entry->DispatchTime) {
+        // Time expired, invoked the function
+        DEBUG ((
+          DEBUG_ERROR,
+          "Delayed dispatch entry %d @ %p, Target=%d, Act=%d Disp=%d\n",
+          Index1,
+          Entry->Function,
+          Entry->DispatchTime,
+          TimeCurrent,
+          DelayedDispatchTable->DispCount
+          ));
+        Dispatched              = TRUE;
+        Entry->MicrosecondDelay = 0;
+        Entry->Function (
+                 &Entry->Context,
+                 &Entry->MicrosecondDelay
+                 );
+        DEBUG ((DEBUG_ERROR, "Delayed dispatch Function returned delay=%d\n", Entry->MicrosecondDelay));
+        if (0 == Entry->MicrosecondDelay) {
+          // NewTime = 0 = delete this entry from the table
+          DelayedDispatchTable->Count--;
+          CopyMem (Entry, Entry+1, sizeof (DELAYED_DISPATCH_ENTRY) * (DelayedDispatchTable->Count - Index1));
+        } else {
+          if (Entry->MicrosecondDelay > FixedPcdGet32 (PcdDelayedDispatchMaxDelayUs)) {
+            DEBUG ((DEBUG_ERROR, "%a Illegal new delay %d requested\n", __func__, Entry->MicrosecondDelay));
+            ASSERT (FALSE);
+            Entry->MicrosecondDelay = FixedPcdGet32 (PcdDelayedDispatchMaxDelayUs);
+          }
+
+          // NewTime != 0 - update the time from us to Dispatch time
+          Entry->DispatchTime =  GET_TIME_IN_US () + Entry->MicrosecondDelay;
+          Index1++;
+        }
+      } else {
+        Index1++;
+      }
+    }
+  }
+
+  return Dispatched;
+}
+
+/**
+  Wait on a registered Delayed Dispatch unit that has a UniqueId.  Continue
+  to dispatch all registered delayed dispatch entries until *ALL* entries with
+  UniqueId have completed.
+
+  @param[in]     This            The Delayed Dispatch PPI pointer.
+  @param[in]     UniqueId        UniqueId of delayed dispatch entry.
+
+  @retval EFI_SUCCESS            The operation succeeds.
+  @retval EFI_INVALID_PARAMETER  The parameters are invalid.
+
+**/
+EFI_STATUS
+EFIAPI
+PeiDelayedDispatchWaitOnUniqueId (
+  IN EFI_DELAYED_DISPATCH_PPI  *This,
+  IN EFI_GUID                  *UniqueId
+  )
+{
+  PERF_FUNCTION_BEGIN ();
+  DELAYED_DISPATCH_TABLE  *DelayedDispatchTable;
+
+  // Get delayed dispatch table
+  DelayedDispatchTable = GetDelayedDispatchTable ();
+  if (NULL == DelayedDispatchTable) {
+    PERF_FUNCTION_END ();
+    return EFI_UNSUPPORTED;
+  }
+
+  if ((NULL == UniqueId) || (IsZeroGuid (UniqueId))) {
+    ASSERT (FALSE);
+    PERF_FUNCTION_END ();
+    return EFI_UNSUPPORTED;
+  }
+
+  DEBUG ((DEBUG_INFO, "Delayed dispatch on %g. Count=%d, DispatchCount=%d\n", UniqueId, DelayedDispatchTable->Count, DelayedDispatchTable->DispCount));
+  PERF_EVENT_SIGNAL_BEGIN (UniqueId);
+  DelayedDispatchDispatcher (DelayedDispatchTable, UniqueId);
+  PERF_EVENT_SIGNAL_END (UniqueId);
+
+  PERF_FUNCTION_END ();
+  return EFI_SUCCESS;
+}
+
+/**
+  DelayedDispatch End of PEI callback function. Insure that all of the delayed dispatch
+  entries are complete before exiting PEI.
+
+  @param[in] PeiServices   - Pointer to PEI Services Table.
+  @param[in] NotifyDesc    - Pointer to the descriptor for the Notification event that
+                             caused this function to execute.
+  @param[in] Ppi           - Pointer to the PPI data associated with this function.
+
+  @retval EFI_STATUS       - Always return EFI_SUCCESS
+**/
+EFI_STATUS
+EFIAPI
+PeiDelayedDispatchOnEndOfPei (
+  IN EFI_PEI_SERVICES           **PeiServices,
+  IN EFI_PEI_NOTIFY_DESCRIPTOR  *NotifyDesc,
+  IN VOID                       *Ppi
+  )
+{
+  DELAYED_DISPATCH_TABLE  *DelayedDispatchTable;
+
+  // Get delayed dispatch table
+  DelayedDispatchTable = GetDelayedDispatchTable ();
+  if (NULL == DelayedDispatchTable) {
+    return EFI_UNSUPPORTED;
+  }
+
+  PERF_INMODULE_BEGIN ("PerfDelayedDispatchEndOfPei");
+  while (DelayedDispatchTable->Count > 0) {
+    DelayedDispatchDispatcher (DelayedDispatchTable, NULL);
+  }
+
+  DEBUG ((DEBUG_ERROR, "%a Count of dispatch cycles is %d\n", __func__, DelayedDispatchTable->DispCount));
+  PERF_INMODULE_END ("PerfDelayedDispatchEndOfPei");
+
+  return EFI_SUCCESS;
+}
+
 /**
 
   Discover all PEIMs and optional Apriori file in one FV. There is at most one
@@ -1365,12 +1692,31 @@ PeiDispatcher (
   EFI_PEI_FILE_HANDLE     SaveCurrentFileHandle;
   EFI_FV_FILE_INFO        FvFileInfo;
   PEI_CORE_FV_HANDLE      *CoreFvHandle;
+  EFI_HOB_GUID_TYPE       *GuidHob;
+  UINT32                  TableSize;
 
   PeiServices    = (CONST EFI_PEI_SERVICES **)&Private->Ps;
   PeimEntryPoint = NULL;
   PeimFileHandle = NULL;
   EntryPoint     = 0;
 
+  if (NULL == Private->DelayedDispatchTable) {
+    GuidHob = GetFirstGuidHob (&gEfiDelayedDispatchTableGuid);
+    if (NULL != GuidHob) {
+      Private->DelayedDispatchTable = (DELAYED_DISPATCH_TABLE *)(GET_GUID_HOB_DATA (GuidHob));
+    } else {
+      TableSize                     = sizeof (DELAYED_DISPATCH_TABLE) + ((FixedPcdGet32 (PcdDelayedDispatchMaxEntries) - 1) * sizeof (DELAYED_DISPATCH_ENTRY));
+      Private->DelayedDispatchTable = BuildGuidHob (&gEfiDelayedDispatchTableGuid, TableSize);
+      if (NULL != Private->DelayedDispatchTable) {
+        ZeroMem (Private->DelayedDispatchTable, TableSize);
+        Status = PeiServicesInstallPpi (&mDelayedDispatchDesc);
+        ASSERT_EFI_ERROR (Status);
+        Status = PeiServicesNotifyPpi (&mDelayedDispatchNotifyDesc);
+        ASSERT_EFI_ERROR (Status);
+      }
+    }
+  }
+
   if ((Private->PeiMemoryInstalled) &&
       (PcdGetBool (PcdMigrateTemporaryRamFirmwareVolumes) ||
        (Private->HobList.HandoffInformationTable->BootMode != BOOT_ON_S3_RESUME) ||
@@ -1621,6 +1967,13 @@ PeiDispatcher (
             }
           }
         }
+
+        // Dispatch pending delalyed dispatch requests
+        if (NULL != Private->DelayedDispatchTable) {
+          if (DelayedDispatchDispatcher (Private->DelayedDispatchTable, NULL)) {
+            ProcessDispatchNotifyList (Private);
+          }
+        }
       }
 
       //
diff --git a/MdeModulePkg/Core/Pei/PeiMain/PeiMain.c b/MdeModulePkg/Core/Pei/PeiMain/PeiMain.c
index bf1719d7941a..e5643adf7027 100644
--- a/MdeModulePkg/Core/Pei/PeiMain/PeiMain.c
+++ b/MdeModulePkg/Core/Pei/PeiMain/PeiMain.c
@@ -277,6 +277,9 @@ PeiCore (
         OldCoreData->TempFileHandles = (EFI_PEI_FILE_HANDLE *)((UINT8 *)OldCoreData->TempFileHandles - OldCoreData->HeapOffset);
       }
 
+      // Force relocating the dispatch table
+      OldCoreData->DelayedDispatchTable = NULL;
+
       //
       // Fixup for PeiService's address
       //
diff --git a/MdeModulePkg/Core/Pei/PeiMain.h b/MdeModulePkg/Core/Pei/PeiMain.h
index 556beddad533..3b8bbe7f25a1 100644
--- a/MdeModulePkg/Core/Pei/PeiMain.h
+++ b/MdeModulePkg/Core/Pei/PeiMain.h
@@ -11,6 +11,8 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 
 #include <PiPei.h>
 #include <Ppi/DxeIpl.h>
+#include <Ppi/DelayedDispatch.h>
+#include <Ppi/EndOfPeiPhase.h>
 #include <Ppi/MemoryDiscovered.h>
 #include <Ppi/StatusCode.h>
 #include <Ppi/Reset.h>
@@ -41,6 +43,7 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 #include <IndustryStandard/PeImage.h>
 #include <Library/PeiServicesTablePointerLib.h>
 #include <Library/MemoryAllocationLib.h>
+#include <Library/TimerLib.h>
 #include <Guid/FirmwareFileSystem2.h>
 #include <Guid/FirmwareFileSystem3.h>
 #include <Guid/AprioriFileName.h>
@@ -207,6 +210,29 @@ EFI_STATUS
 
 #define PEI_CORE_HANDLE_SIGNATURE  SIGNATURE_32('P','e','i','C')
 
+#define GET_TIME_IN_US()  ((UINT32)DivU64x32(GetTimeInNanoSecond(GetPerformanceCounter ()), 1000))
+
+//
+// Internal structure for delayed dispatch entries.
+//
+#pragma pack (push, 1)
+
+typedef struct {
+  EFI_GUID                         UniqueId;
+  UINT64                           Context;
+  EFI_DELAYED_DISPATCH_FUNCTION    Function;
+  UINT32                           DispatchTime;
+  UINT32                           MicrosecondDelay;
+} DELAYED_DISPATCH_ENTRY;
+
+typedef struct {
+  UINT32                    Count;
+  UINT32                    DispCount;
+  DELAYED_DISPATCH_ENTRY    Entry[1];     // Actual size based on PCD PcdDelayedDispatchMaxEntries;
+} DELAYED_DISPATCH_TABLE;
+
+#pragma pack (pop)
+
 ///
 /// Pei Core private data structure instance
 ///
@@ -307,6 +333,11 @@ struct _PEI_CORE_INSTANCE {
   // Those Memory Range will be migrated into physical memory.
   //
   HOLE_MEMORY_DATA                  HoleData[HOLE_MAX_NUMBER];
+
+  //
+  // Table of delayed dispatch requests
+  //
+  DELAYED_DISPATCH_TABLE            *DelayedDispatchTable;
 };
 
 ///
@@ -2038,4 +2069,49 @@ PeiReinitializeFv (
   IN  PEI_CORE_INSTANCE  *PrivateData
   );
 
+/**
+Register a callback to be called after a minimum delay has occurred.
+
+This service is the single member function of the EFI_DELAYED_DISPATCH_PPI
+
+  @param[in] This           Pointer to the EFI_DELAYED_DISPATCH_PPI instance
+  @param[in] Function       Function to call back
+  @param[in] Context        Context data
+  @param[in] UniqueId       GUID for this Delayed Dispatch request.
+  @param[in] Delay          Delay interval
+
+  @retval EFI_SUCCESS               Function successfully loaded
+  @retval EFI_INVALID_PARAMETER     One of the Arguments is not supported
+  @retval EFI_OUT_OF_RESOURCES      No more entries
+
+**/
+EFI_STATUS
+EFIAPI
+PeiDelayedDispatchRegister (
+  IN  EFI_DELAYED_DISPATCH_PPI       *This,
+  IN  EFI_DELAYED_DISPATCH_FUNCTION  Function,
+  IN  UINT64                         Context,
+  IN  EFI_GUID                       *UniqueId   OPTIONAL,
+  IN  UINT32                         Delay
+  );
+
+/**
+  Wait on a registered Delayed Dispatch unit that has a UniqueId.  Continue
+  to dispatch all registered delayed dispatch entries until *ALL* entries with
+  UniqueId have completed.
+
+  @param[in]     This            The Delayed Dispatch PPI pointer.
+  @param[in]     UniqueId        UniqueId of delayed dispatch entry.
+
+  @retval EFI_SUCCESS            The operation succeeds.
+  @retval EFI_INVALID_PARAMETER  The parameters are invalid.
+
+**/
+EFI_STATUS
+EFIAPI
+PeiDelayedDispatchWaitOnUniqueId (
+  IN EFI_DELAYED_DISPATCH_PPI  *This,
+  IN EFI_GUID                  *UniqueId
+  );
+
 #endif
diff --git a/MdeModulePkg/Core/Pei/PeiMain.inf b/MdeModulePkg/Core/Pei/PeiMain.inf
index 0cf357371a16..73738c939ac7 100644
--- a/MdeModulePkg/Core/Pei/PeiMain.inf
+++ b/MdeModulePkg/Core/Pei/PeiMain.inf
@@ -66,6 +66,7 @@ [LibraryClasses]
   PeCoffLib
   PeiServicesTablePointerLib
   PcdLib
+  TimerLib
 
 [Guids]
   gPeiAprioriFileNameGuid       ## SOMETIMES_CONSUMES   ## File
@@ -78,6 +79,7 @@ [Guids]
   gEfiFirmwareFileSystem3Guid
   gStatusCodeCallbackGuid
   gEdkiiMigratedFvInfoGuid                      ## SOMETIMES_PRODUCES     ## HOB
+  gEfiDelayedDispatchTableGuid                  ## SOMETIMES_PRODUCES     ## HOB
 
 [Ppis]
   gEfiPeiStatusCodePpiGuid                      ## SOMETIMES_CONSUMES # PeiReportStatusService is not ready if this PPI doesn't exist
@@ -100,6 +102,8 @@ [Ppis]
   gEfiPeiReset2PpiGuid                          ## SOMETIMES_CONSUMES
   gEfiSecHobDataPpiGuid                         ## SOMETIMES_CONSUMES
   gEfiPeiCoreFvLocationPpiGuid                  ## SOMETIMES_CONSUMES
+  gEfiPeiDelayedDispatchPpiGuid                 ## SOMETIMES_CONSUMES
+  gEfiEndOfPeiSignalPpiGuid                     ## CONSUMES
 
 [Pcd]
   gEfiMdeModulePkgTokenSpaceGuid.PcdPeiCoreMaxPeiStackSize                  ## CONSUMES
@@ -112,6 +116,9 @@ [Pcd]
   gEfiMdeModulePkgTokenSpaceGuid.PcdShadowPeimOnBoot                        ## CONSUMES
   gEfiMdeModulePkgTokenSpaceGuid.PcdInitValueInTempStack                    ## CONSUMES
   gEfiMdeModulePkgTokenSpaceGuid.PcdMigrateTemporaryRamFirmwareVolumes      ## CONSUMES
+  gEfiMdeModulePkgTokenSpaceGuid.PcdDelayedDispatchMaxDelayUs               ## CONSUMES
+  gEfiMdeModulePkgTokenSpaceGuid.PcdDelayedDispatchCompletionTimeoutUs      ## CONSUMES
+  gEfiMdeModulePkgTokenSpaceGuid.PcdDelayedDispatchMaxEntries               ## CONSUMES
 
 # [BootMode]
 # S3_RESUME             ## SOMETIMES_CONSUMES
diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec
index 0ff058b0a9da..2f4bd2f2b773 100644
--- a/MdeModulePkg/MdeModulePkg.dec
+++ b/MdeModulePkg/MdeModulePkg.dec
@@ -418,6 +418,9 @@ [Guids]
   ## Include/Guid/MigratedFvInfo.h
   gEdkiiMigratedFvInfoGuid = { 0xc1ab12f7, 0x74aa, 0x408d, { 0xa2, 0xf4, 0xc6, 0xce, 0xfd, 0x17, 0x98, 0x71 } }
 
+  ## Delayed Dispatch table GUID
+  gEfiDelayedDispatchTableGuid = { 0x4b733449, 0x8eff, 0x488c, {0x92, 0x1a, 0x15, 0x4a, 0xda, 0x25, 0x18, 0x07}}
+
   #
   # GUID defined in UniversalPayload
   #
@@ -991,6 +994,18 @@ [PcdsFixedAtBuild]
   # @ValidList  0x80000006 | 0x03058002
   gEfiMdeModulePkgTokenSpaceGuid.PcdErrorCodeSetVariable|0x03058002|UINT32|0x30001040
 
+  ## Delayed Dispatch Maximum Delay in us (microseconds)
+  # Maximum delay for any particular delay request - 5 seconds
+  gEfiMdeModulePkgTokenSpaceGuid.PcdDelayedDispatchMaxDelayUs|5000000|UINT32|0x3000104A
+
+  ## Delayed Dispatch timeout in us (microseconds)
+  # Maximum delay when waiting for completion (ie EndOfPei) - 10 seconds
+  gEfiMdeModulePkgTokenSpaceGuid.PcdDelayedDispatchCompletionTimeoutUs|10000000|UINT32|0x3000104B
+
+  ## Delayed Dispatch Max Entries
+  # Maximum number of delayed dispatch entries
+  gEfiMdeModulePkgTokenSpaceGuid.PcdDelayedDispatchMaxEntries|8|UINT32|0x3000104C
+
   ## Mask to control the NULL address detection in code for different phases.
   #  If enabled, accessing NULL address in UEFI or SMM code can be caught.<BR><BR>
   #    BIT0    - Enable NULL pointer detection for UEFI.<BR>
-- 
2.41.0.windows.2



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