[PATCH] MdeModulePkg/PciBus: Fix system hang when no PCI Option ROM exists

[Ruiyu Ni <ruiyu.ni@intel.com>]

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1394

When there is no PCI option ROM exists, today's logic still creates
virtual BAR for option ROM using Length = 0, Alignment = (-1).
It causes the final MEM32 alignment requirement is as big as
0xFFFFFFFF_FFFFFFFF.

The patch fixes this issue by only creating virtual BAR for option
ROM when there is PCI option ROM.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Chiu Chasel <chasel.chiu@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
---
 MdeModulePkg/Bus/Pci/PciBusDxe/PciLib.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/MdeModulePkg/Bus/Pci/PciBusDxe/PciLib.c b/MdeModulePkg/Bus/Pci/PciBusDxe/PciLib.c
index 7255bcfbbc..ee5c77147e 100644
--- a/MdeModulePkg/Bus/Pci/PciBusDxe/PciLib.c
+++ b/MdeModulePkg/Bus/Pci/PciBusDxe/PciLib.c
@@ -515,10 +515,12 @@ PciHostBridgeResourceAllocator (
       // All devices' Option ROM share the same MEM32 resource.
       //
       MaxOptionRomSize = GetMaxOptionRomSize (RootBridgeDev);
-      RootBridgeDev->PciBar[0].BarType   = PciBarTypeOpRom;
-      RootBridgeDev->PciBar[0].Length    = MaxOptionRomSize;
-      RootBridgeDev->PciBar[0].Alignment = MaxOptionRomSize - 1;
-      GetResourceFromDevice (RootBridgeDev, IoBridge, Mem32Bridge, PMem32Bridge, Mem64Bridge, PMem64Bridge);
+      if (MaxOptionRomSize != 0) {
+        RootBridgeDev->PciBar[0].BarType   = PciBarTypeOpRom;
+        RootBridgeDev->PciBar[0].Length    = MaxOptionRomSize;
+        RootBridgeDev->PciBar[0].Alignment = MaxOptionRomSize - 1;
+        GetResourceFromDevice (RootBridgeDev, IoBridge, Mem32Bridge, PMem32Bridge, Mem64Bridge, PMem64Bridge);
+      }
 
       //
       // Create resourcemap by going through all the devices subject to this root bridge
-- 
2.16.1.windows.1