diff --git a/OvmfPkg/Library/PciHostBridgeLib/PciHostBridgeLib.c b/OvmfPkg/Library/PciHostBridgeLib/PciHostBridgeLib.c
index f1cefe4169..b238a8544d 100644
--- a/OvmfPkg/Library/PciHostBridgeLib/PciHostBridgeLib.c
+++ b/OvmfPkg/Library/PciHostBridgeLib/PciHostBridgeLib.c
@@ -17,6 +17,7 @@
 
 #include <IndustryStandard/Pci.h>
 
+#include <Protocol/PciHostBridgeResourceAllocation.h>
 #include <Protocol/PciRootBridgeIo.h>
 
 #include <Library/BaseMemoryLib.h>
@@ -84,6 +85,14 @@ InitRootBridge (
 
   RootBus->DmaAbove4G = FALSE;
 
+  RootBus->AllocationAttributes = EFI_PCI_HOST_BRIDGE_COMBINE_MEM_PMEM;
+  RootBus->PMem.Base            = 0;
+  RootBus->PMem.Limit           = 0;
+  RootBus->PMemAbove4G.Base     = 0;
+  RootBus->PMemAbove4G.Limit    = 0;
+  RootBus->MemAbove4G.Base      = 0;
+  RootBus->MemAbove4G.Limit     = 0;
+
   return EFI_OUT_OF_RESOURCES;
 }