[PATCH 5/5] UefiCpuPkg: Uninstall EFI_SMM_CONFIGURATION_PROTOCOL at end of Dxe.

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

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2317
To avoid leaking information from SMM, uninstall
EFI_SMM_CONFIGURATION_PROTOCOL at end of Dxe.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Signed-off-by: Zhiguang Liu <zhiguang.liu@intel.com>
---
 UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c   | 37 +++++++++++++++++++++++++++++++++++++
 UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf |  1 +
 2 files changed, 38 insertions(+)

diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c
index db68e1316e..a1b209e125 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c
@@ -520,6 +520,33 @@ SmmReadyToLockEventNotify (
   return EFI_SUCCESS;
 }
 
+/**
+  SMM End of Dxe event notification handler.
+
+  To avoid leaking information from SMM, uninstall EFI_SMM_CONFIGURATION_PROTOCOL
+  at end of Dxe.
+
+  @param[in] Protocol   Points to the protocol's unique identifier.
+  @param[in] Interface  Points to the interface instance.
+  @param[in] Handle     The handle on which the interface was installed.
+
+  @retval EFI_SUCCESS   Notification handler runs successfully.
+ **/
+EFI_STATUS
+EFIAPI
+SmmEndOfDxeNotify (
+  IN CONST EFI_GUID  *Protocol,
+  IN VOID            *Interface,
+  IN EFI_HANDLE      Handle
+  )
+{
+  gBS->UninstallProtocolInterface (
+         gSmmCpuPrivate->SmmCpuHandle,
+         &gEfiSmmConfigurationProtocolGuid, &gSmmCpuPrivate->SmmConfiguration
+         );
+  return EFI_SUCCESS;
+}
+
 /**
   The module Entry Point of the CPU SMM driver.
 
@@ -1038,6 +1065,16 @@ PiCpuSmmEntry (
                     );
   ASSERT_EFI_ERROR (Status);
 
+  //
+  // register SMM End of Dxe notification
+  //
+  Status = gSmst->SmmRegisterProtocolNotify (
+                    &gEfiSmmEndOfDxeProtocolGuid,
+                    SmmEndOfDxeNotify,
+                    &Registration
+                    );
+  ASSERT_EFI_ERROR (Status);
+
   //
   // Initialize SMM Profile feature
   //
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf
index 76b1462996..bb994814d6 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.inf
@@ -105,6 +105,7 @@
   gEfiSmmConfigurationProtocolGuid         ## PRODUCES
   gEfiSmmCpuProtocolGuid                   ## PRODUCES
   gEfiSmmReadyToLockProtocolGuid           ## NOTIFY
+  gEfiSmmEndOfDxeProtocolGuid              ## NOTIFY
   gEfiSmmCpuServiceProtocolGuid            ## PRODUCES
   gEdkiiSmmMemoryAttributeProtocolGuid     ## PRODUCES
   gEfiMmMpProtocolGuid                    ## PRODUCES
-- 
2.25.1.windows.1