MdeModulePkg: Skip invalid bus number scanning in PciBusDxe driver

When PcdPciDisableBusEnumeration is enabled, the PciBus driver
might get into a dead loop if the secondary bus register on PCI
bridge is not programmed or programmed improperly. Adding this
check to avoid any potential dead loop caused by this.

Cc: Feng Tian <feng.tian@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Maurice Ma <maurice.ma@intel.com>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>
Reviewed-by: Lee Leahy <Leroy.p.leahy@intel.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c b/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
index a6ade26..086c481 100644
--- a/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
+++ b/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
@@ -165,6 +165,14 @@ PciPciDeviceInfoCollector (
           }

 

           //

+          // Ensure secondary bus number is greater than the primary bus number to avoid

+          // any potential dead loop when PcdPciDisableBusEnumeration is set to TRUE

+          //

+          if (SecBus <= StartBusNumber) {

+            break;

+          }

+

+          //

           // Get resource padding for PPB

           //

           GetResourcePaddingPpb (PciIoDevice);