SecurityPkg: Tcg2Smm: Remove Memory Clear SMI Handler

Remove unused MemoryClear SMI Handler, which is no longer used due to _DSM Memory Clear no longer being used. _DSM Memory Clear was deprecated in 2019 by TCG PC Client Platform Reset Attack Mitigation Spec Version 1.10 revision 17 Family "2.0". Signed-off-by: Oliver Smith-Denny <[email protected]>
NVIDIA · Sep 4, 2024 · a4245b2 · a4245b2
1 parent 559affa
commit a4245b2
Showing 1 changed file with 0 additions and 85 deletions.
diff --git a/SecurityPkg/Tcg/Tcg2Smm/Tcg2Smm.c b/SecurityPkg/Tcg/Tcg2Smm/Tcg2Smm.c
@@ -170,81 +170,6 @@ PhysicalPresenceCallback (
   return EFI_SUCCESS;
 }
 
-/**
-  Software SMI callback for MemoryClear which is called from ACPI method.
-
-  Caution: This function may receive untrusted input.
-  Variable and ACPINvs are external input, so this function will validate
-  its data structure to be valid value.
-
-  @param[in]      DispatchHandle  The unique handle assigned to this handler by SmiHandlerRegister().
-  @param[in]      Context         Points to an optional handler context which was specified when the
-                                  handler was registered.
-  @param[in, out] CommBuffer      A pointer to a collection of data in memory that will
-                                  be conveyed from a non-SMM environment into an SMM environment.
-  @param[in, out] CommBufferSize  The size of the CommBuffer.
-
-  @retval EFI_SUCCESS             The interrupt was handled successfully.
-
-**/
-EFI_STATUS
-EFIAPI
-MemoryClearCallback (
-  IN EFI_HANDLE  DispatchHandle,
-  IN CONST VOID  *Context,
-  IN OUT VOID    *CommBuffer,
-  IN OUT UINTN   *CommBufferSize
-  )
-{
-  EFI_STATUS  Status;
-  UINTN       DataSize;
-  UINT8       MorControl;
-
-  mTcgNvs->MemoryClear.ReturnCode = MOR_REQUEST_SUCCESS;
-  if (mTcgNvs->MemoryClear.Parameter == ACPI_FUNCTION_DSM_MEMORY_CLEAR_INTERFACE) {
-    MorControl = (UINT8)mTcgNvs->MemoryClear.Request;
-  } else if (mTcgNvs->MemoryClear.Parameter == ACPI_FUNCTION_PTS_CLEAR_MOR_BIT) {
-    DataSize = sizeof (UINT8);
-    Status   = mSmmVariable->SmmGetVariable (
-                               MEMORY_OVERWRITE_REQUEST_VARIABLE_NAME,
-                               &gEfiMemoryOverwriteControlDataGuid,
-                               NULL,
-                               &DataSize,
-                               &MorControl
-                               );
-    if (EFI_ERROR (Status)) {
-      mTcgNvs->MemoryClear.ReturnCode = MOR_REQUEST_GENERAL_FAILURE;
-      DEBUG ((DEBUG_ERROR, "[TPM] Get MOR variable failure! Status = %r\n", Status));
-      return EFI_SUCCESS;
-    }
-
-    if (MOR_CLEAR_MEMORY_VALUE (MorControl) == 0x0) {
-      return EFI_SUCCESS;
-    }
-
-    MorControl &= ~MOR_CLEAR_MEMORY_BIT_MASK;
-  } else {
-    mTcgNvs->MemoryClear.ReturnCode = MOR_REQUEST_GENERAL_FAILURE;
-    DEBUG ((DEBUG_ERROR, "[TPM] MOR Parameter error! Parameter = %x\n", mTcgNvs->MemoryClear.Parameter));
-    return EFI_SUCCESS;
-  }
-
-  DataSize = sizeof (UINT8);
-  Status   = mSmmVariable->SmmSetVariable (
-                             MEMORY_OVERWRITE_REQUEST_VARIABLE_NAME,
-                             &gEfiMemoryOverwriteControlDataGuid,
-                             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
-                             DataSize,
-                             &MorControl
-                             );
-  if (EFI_ERROR (Status)) {
-    mTcgNvs->MemoryClear.ReturnCode = MOR_REQUEST_GENERAL_FAILURE;
-    DEBUG ((DEBUG_ERROR, "[TPM] Set MOR variable failure! Status = %r\n", Status));
-  }
-
-  return EFI_SUCCESS;
-}
-
 /**
   Notification for SMM ReadyToLock protocol.
 
@@ -337,16 +262,6 @@ InitializeTcgCommon (
 
   mPpSoftwareSmi = SwContext.SwSmiInputValue;
 
-  SwContext.SwSmiInputValue = (UINTN)-1;
-  Status                    = SwDispatch->Register (SwDispatch, MemoryClearCallback, &SwContext, &McSwHandle);
-  ASSERT_EFI_ERROR (Status);
-  if (EFI_ERROR (Status)) {
-    DEBUG ((DEBUG_ERROR, "[%a] Failed to register MC callback as SW MM handler - %r!\n", __func__, Status));
-    goto Cleanup;
-  }
-
-  mMcSoftwareSmi = SwContext.SwSmiInputValue;
-
   //
   // Locate SmmVariableProtocol.
   //