diff --git a/OvmfPkg/PlatformPei/Platform.c b/OvmfPkg/PlatformPei/Platform.c
index 743044d29e..d4df0c60e7 100644
--- a/OvmfPkg/PlatformPei/Platform.c
+++ b/OvmfPkg/PlatformPei/Platform.c
@@ -384,9 +384,7 @@ InitializePlatform (
 
   PublishPeiMemory ();
 
-  if (mXen) {
-    PcdSetBool (PcdPciDisableBusEnumeration, TRUE);
-  } else {
+  if (!mXen) {
     TopOfMemory = MemDetect ();
   }
 
diff --git a/OvmfPkg/PlatformPei/Xen.c b/OvmfPkg/PlatformPei/Xen.c
index 3a2e358661..1886326f20 100644
--- a/OvmfPkg/PlatformPei/Xen.c
+++ b/OvmfPkg/PlatformPei/Xen.c
@@ -225,5 +225,7 @@ InitializeXen (
   //
   AddReservedMemoryBaseSizeHob (0xFC000000, 0x1000000);
 
+  PcdSetBool (PcdPciDisableBusEnumeration, TRUE);
+
   return EFI_SUCCESS;
 }