[edk2-devel] [PATCH v3 5/6] MdeModulePkg/SMM: Support to unregister SMI handler in SMI handlers

["Zhiguang Liu" <zhiguang.liu@intel.com>]

Unregistering SMI handler will free the SMI_HANDLER. However, the
SmiManage() may be using the link node from SMI_HANDLER for loop if
the unregistering happens in SMI handlers.
To avoid that, the idea is to inform SmiHandlerUnRegister() whether
it's running or not running on the stack of SmiManage(), and to
postpone SMI_HANDLER deletion before SmiManage() returns.
Noted SmiManage() may be called recursively, the SmiHandlerUnRegister()
won't take effect until the root SmiManage() returns.

Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Jiaxin Wu <jiaxin.wu@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Zhiguang Liu <zhiguang.liu@intel.com>
---
 MdeModulePkg/Core/PiSmmCore/PiSmmCore.h |   1 +
 MdeModulePkg/Core/PiSmmCore/Smi.c       | 161 ++++++++++++++++++++----
 2 files changed, 137 insertions(+), 25 deletions(-)

diff --git a/MdeModulePkg/Core/PiSmmCore/PiSmmCore.h b/MdeModulePkg/Core/PiSmmCore/PiSmmCore.h
index b8a490a8c3..60073c78b4 100644
--- a/MdeModulePkg/Core/PiSmmCore/PiSmmCore.h
+++ b/MdeModulePkg/Core/PiSmmCore/PiSmmCore.h
@@ -93,6 +93,7 @@ typedef struct {
   SMI_ENTRY                       *SmiEntry;
   VOID                            *Context;    // for profile
   UINTN                           ContextSize; // for profile
+  BOOLEAN                         ToRemove;    // To remove this SMI_HANDLER later
 } SMI_HANDLER;
 
 //
diff --git a/MdeModulePkg/Core/PiSmmCore/Smi.c b/MdeModulePkg/Core/PiSmmCore/Smi.c
index 2985f989c3..53bec7600c 100644
--- a/MdeModulePkg/Core/PiSmmCore/Smi.c
+++ b/MdeModulePkg/Core/PiSmmCore/Smi.c
@@ -8,6 +8,11 @@
 
 #include "PiSmmCore.h"
 
+//
+// mSmiManageCallingDepth is used to track the depth of recursive calls of SmiManage.
+//
+UINTN  mSmiManageCallingDepth = 0;
+
 LIST_ENTRY  mSmiEntryList = INITIALIZE_LIST_HEAD_VARIABLE (mSmiEntryList);
 
 SMI_ENTRY  mRootSmiEntry = {
@@ -79,6 +84,40 @@ SmmCoreFindSmiEntry (
   return SmiEntry;
 }
 
+/**
+  Remove SmiHandler and free the memory it used.
+  If SmiEntry is empty, remove SmiEntry and free the memory it used.
+
+  @param  SmiHandler Points to SMI handler.
+  @param  SmiEntry   Points to SMI Entry or NULL for root SMI handlers.
+
+  @retval TRUE        SmiEntry is removed.
+  @retval FALSE       SmiEntry is not removed.
+**/
+BOOLEAN
+RemoveSmiHandler (
+  IN SMI_HANDLER  *SmiHandler,
+  IN SMI_ENTRY    *SmiEntry
+  )
+{
+  ASSERT (SmiHandler->ToRemove);
+  RemoveEntryList (&SmiHandler->Link);
+  FreePool (SmiHandler);
+
+  //
+  // Remove the SMI_ENTRY if all handlers have been removed.
+  //
+  if (SmiEntry != NULL) {
+    if (IsListEmpty (&SmiEntry->SmiHandlers)) {
+      RemoveEntryList (&SmiEntry->AllEntries);
+      FreePool (SmiEntry);
+      return TRUE;
+    }
+  }
+
+  return FALSE;
+}
+
 /**
   Manage SMI of a particular type.
 
@@ -104,15 +143,17 @@ SmiManage (
 {
   LIST_ENTRY   *Link;
   LIST_ENTRY   *Head;
+  LIST_ENTRY   *EntryLink;
   SMI_ENTRY    *SmiEntry;
   SMI_HANDLER  *SmiHandler;
-  BOOLEAN      SuccessReturn;
+  EFI_STATUS   ReturnStatus;
+  BOOLEAN      WillReturn;
   EFI_STATUS   Status;
 
   PERF_FUNCTION_BEGIN ();
-
-  Status        = EFI_NOT_FOUND;
-  SuccessReturn = FALSE;
+  mSmiManageCallingDepth++;
+  Status       = EFI_NOT_FOUND;
+  ReturnStatus = Status;
   if (HandlerType == NULL) {
     //
     // Root SMI handler
@@ -152,7 +193,16 @@ SmiManage (
         //
         if (HandlerType != NULL) {
           PERF_FUNCTION_END ();
-          return EFI_INTERRUPT_PENDING;
+          ReturnStatus = EFI_INTERRUPT_PENDING;
+          WillReturn   = TRUE;
+        } else {
+          //
+          // If any other handler's result sets ReturnStatus as EFI_SUCCESS, the return status
+          // will be EFI_SUCCESS.
+          //
+          if (ReturnStatus != EFI_SUCCESS) {
+            ReturnStatus = Status;
+          }
         }
 
         break;
@@ -165,10 +215,10 @@ SmiManage (
         //
         if (HandlerType != NULL) {
           PERF_FUNCTION_END ();
-          return EFI_SUCCESS;
+          WillReturn = TRUE;
         }
 
-        SuccessReturn = TRUE;
+        ReturnStatus = EFI_SUCCESS;
         break;
 
       case EFI_WARN_INTERRUPT_SOURCE_QUIESCED:
@@ -176,7 +226,7 @@ SmiManage (
         // If at least one of the handlers returns EFI_WARN_INTERRUPT_SOURCE_QUIESCED
         // then the function will return EFI_SUCCESS.
         //
-        SuccessReturn = TRUE;
+        ReturnStatus = EFI_SUCCESS;
         break;
 
       case EFI_WARN_INTERRUPT_SOURCE_PENDING:
@@ -184,6 +234,10 @@ SmiManage (
         // If all the handlers returned EFI_WARN_INTERRUPT_SOURCE_PENDING
         // then EFI_WARN_INTERRUPT_SOURCE_PENDING will be returned.
         //
+        if (ReturnStatus != EFI_SUCCESS) {
+          ReturnStatus = Status;
+        }
+
         break;
 
       default:
@@ -193,14 +247,74 @@ SmiManage (
         ASSERT (FALSE);
         break;
     }
+
+    if (WillReturn) {
+      break;
+    }
   }
 
-  if (SuccessReturn) {
-    Status = EFI_SUCCESS;
+  ASSERT (mSmiManageCallingDepth > 0);
+  mSmiManageCallingDepth--;
+
+  //
+  // SmiHandlerUnRegister() calls from SMI handlers are deferred till this point.
+  // Before returned from SmiManage, delete the SmiHandler which is
+  // marked as ToRemove.
+  // Note that SmiManage can be called recursively.
+  //
+  if (mSmiManageCallingDepth == 0) {
+    //
+    // Go through all SmiHandler in root SMI handlers
+    //
+    for ( Link = GetFirstNode (&mRootSmiEntry.SmiHandlers)
+          ; !IsNull (&mRootSmiEntry.SmiHandlers, Link);
+          )
+    {
+      //
+      // SmiHandler might be removed in below, so cache the next link in Link
+      //
+      SmiHandler = CR (Link, SMI_HANDLER, Link, SMI_HANDLER_SIGNATURE);
+      Link       = GetNextNode (&mRootSmiEntry.SmiHandlers, Link);
+      if (SmiHandler->ToRemove) {
+        //
+        // Remove SmiHandler if the ToRemove is set.
+        //
+        RemoveSmiHandler (SmiHandler, NULL);
+      }
+    }
+
+    //
+    // Go through all SmiHandler in non-root SMI handlers
+    //
+    for ( EntryLink = GetFirstNode (&mSmiEntryList)
+          ; !IsNull (&mSmiEntryList, EntryLink);
+          )
+    {
+      //
+      // SmiEntry might be removed in below, so cache the next link in EntryLink
+      //
+      SmiEntry  = CR (EntryLink, SMI_ENTRY, AllEntries, SMI_ENTRY_SIGNATURE);
+      EntryLink = GetNextNode (&mSmiEntryList, EntryLink);
+      for ( Link = GetFirstNode (&SmiEntry->SmiHandlers)
+            ; !IsNull (&SmiEntry->SmiHandlers, Link);
+            )
+      {
+        //
+        // SmiHandler might be removed in below, so cache the next link in Link
+        //
+        SmiHandler = CR (Link, SMI_HANDLER, Link, SMI_HANDLER_SIGNATURE);
+        Link       = GetNextNode (&SmiEntry->SmiHandlers, Link);
+        if (SmiHandler->ToRemove) {
+          if (RemoveSmiHandler (SmiHandler, SmiEntry)) {
+            break;
+          }
+        }
+      }
+    }
   }
 
   PERF_FUNCTION_END ();
-  return Status;
+  return ReturnStatus;
 }
 
 /**
@@ -238,6 +352,7 @@ SmiHandlerRegister (
   SmiHandler->Signature  = SMI_HANDLER_SIGNATURE;
   SmiHandler->Handler    = Handler;
   SmiHandler->CallerAddr = (UINTN)RETURN_ADDRESS (0);
+  SmiHandler->ToRemove   = FALSE;
 
   if (HandlerType == NULL) {
     //
@@ -322,26 +437,22 @@ SmiHandlerUnRegister (
     return EFI_INVALID_PARAMETER;
   }
 
-  SmiEntry = SmiHandler->SmiEntry;
+  SmiHandler->ToRemove = TRUE;
 
-  RemoveEntryList (&SmiHandler->Link);
-  FreePool (SmiHandler);
-
-  if (SmiEntry == NULL) {
+  if (mSmiManageCallingDepth > 0) {
     //
-    // This is root SMI handler
+    // This function is called from SmiManage()
+    // Do not delete or remove SmiHandler or SmiEntry now.
+    // SmiManage will handle it later
     //
     return EFI_SUCCESS;
   }
 
-  if (IsListEmpty (&SmiEntry->SmiHandlers)) {
-    //
-    // No handler registered for this interrupt now, remove the SMI_ENTRY
-    //
-    RemoveEntryList (&SmiEntry->AllEntries);
-
-    FreePool (SmiEntry);
-  }
+  SmiEntry = SmiHandler->SmiEntry;
 
+  //
+  // For root SMI handler, use NULL for SmiEntry
+  //
+  RemoveSmiHandler (SmiHandler, (SmiEntry == &mRootSmiEntry) ? NULL : SmiEntry);
   return EFI_SUCCESS;
 }
-- 
2.31.1.windows.1



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