The Migration Handdler is started using the Mp Service, which
is only designed to function during boot time. The MH needs
to run continuously. In the abscence of a generalized persitent
Mp Service, temporary alterations were made to keep the MH running.

Here, we skip registering the ExitBootServices callback that
would normally clean up the APs. Obviously this is not suitable
for production, as it does not generalize for multiple APs
(it leaves all APs untouched rather than just the MH) and it
introduces a weird dependency where the MpLib needs an
OVMF PCD.

Signed-off-by: Tobin Feldman-Fitzthum <tobin@linux.ibm.com>
---
 UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf |  2 ++
 UefiCpuPkg/Library/MpInitLib/DxeMpLib.c       | 21 ++++++++++++-------
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf b/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
index 1771575c69..71cc968de8 100644
--- a/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
+++ b/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
@@ -39,6 +39,7 @@
   MdePkg/MdePkg.dec
   MdeModulePkg/MdeModulePkg.dec
   UefiCpuPkg/UefiCpuPkg.dec
+  OvmfPkg/OvmfPkg.dec
 
 [LibraryClasses]
   BaseLib
@@ -76,3 +77,4 @@
   gUefiCpuPkgTokenSpaceGuid.PcdSevEsWorkAreaBase                       ## SOMETIMES_CONSUMES
   gEfiMdeModulePkgTokenSpaceGuid.PcdCpuStackGuard                      ## CONSUMES
   gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbBase                           ## CONSUMES
+  gUefiOvmfPkgTokenSpaceGuid.PcdStartConfidentialMigrationHandler
diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
index 7839c24976..7d59ec4a92 100644
--- a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
@@ -569,14 +569,19 @@ InitMpGlobalData (
                   );
   ASSERT_EFI_ERROR (Status);
 
-  Status = gBS->CreateEvent (
-                  EVT_SIGNAL_EXIT_BOOT_SERVICES,
-                  TPL_CALLBACK,
-                  MpInitChangeApLoopCallback,
-                  NULL,
-                  &mMpInitExitBootServicesEvent
-                  );
-  ASSERT_EFI_ERROR (Status);
+  //
+  // Workaround for persistent processes .
+  //
+  if (!PcdGetBool (PcdStartConfidentialMigrationHandler)) {
+    Status = gBS->CreateEvent (
+                    EVT_SIGNAL_EXIT_BOOT_SERVICES,
+                    TPL_CALLBACK,
+                    MpInitChangeApLoopCallback,
+                    NULL,
+                    &mMpInitExitBootServicesEvent
+                    );
+    ASSERT_EFI_ERROR (Status);
+  }
 
   Status = gBS->CreateEventEx (
                   EVT_NOTIFY_SIGNAL,
-- 
2.20.1



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