OvmfPkg/PciHostBridgeUtilityLib: Extend GetRootBridges() with BusMin/BusMax

Extend parameter list of PciHostBridgeUtilityGetRootBridges() with BusMin/
BusMax, so that the utility function could be compatible with ArmVirtPkg
who uses mutable bus range [BusMin, BusMax] insteand of [0, PCI_MAX_BUS].

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3059

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Signed-off-by: Jiahui Cen <cenjiahui@huawei.com>
Message-Id: <20210119011302.10908-10-cenjiahui@huawei.com>
[lersek@redhat.com: fix logging of UINTN values BusMin, BusMax]
[lersek@redhat.com: keep zeroing of (*Count) centralized]
[lersek@redhat.com: fix typos in ExtraRootBridges comment]
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

1 files changed, 24 insertions, 5 deletions

diff --git a/OvmfPkg/Library/PciHostBridgeUtilityLib/PciHostBridgeUtilityLib.c b/OvmfPkg/Library/PciHostBridgeUtilityLib/PciHostBridgeUtilityLib.c
index b59da78700..d2296f3308 100644
--- a/OvmfPkg/Library/PciHostBridgeUtilityLib/PciHostBridgeUtilityLib.c
+++ b/OvmfPkg/Library/PciHostBridgeUtilityLib/PciHostBridgeUtilityLib.c
@@ -200,6 +200,10 @@ PciHostBridgeUtilityUninitRootBridge (
 

   @param[in]  NoExtendedConfigSpace  No Extended Config Space.

 

+  @param[in]  BusMin                 Minimum Bus number, inclusive.

+

+  @param[in]  BusMax                 Maximum Bus number, inclusive.

+

   @param[in]  Io                     IO aperture.

 

   @param[in]  Mem                    MMIO aperture.

@@ -220,6 +224,8 @@ PciHostBridgeUtilityGetRootBridges (
   IN  UINT64                   AllocationAttributes,

   IN  BOOLEAN                  DmaAbove4G,

   IN  BOOLEAN                  NoExtendedConfigSpace,

+  IN  UINTN                    BusMin,

+  IN  UINTN                    BusMax,

   IN  PCI_ROOT_BRIDGE_APERTURE *Io,

   IN  PCI_ROOT_BRIDGE_APERTURE *Mem,

   IN  PCI_ROOT_BRIDGE_APERTURE *MemAbove4G,

@@ -238,6 +244,12 @@ PciHostBridgeUtilityGetRootBridges (
 

   *Count = 0;

 

+  if (BusMin > BusMax || BusMax > PCI_MAX_BUS) {

+    DEBUG ((DEBUG_ERROR, "%a: invalid bus range with BusMin %Lu and BusMax "

+      "%Lu\n", __FUNCTION__, (UINT64)BusMin, (UINT64)BusMax));

+    return NULL;

+  }

+

   //

   // QEMU provides the number of extra root buses, shortening the exhaustive

   // search below. If there is no hint, the feature is missing.

@@ -249,7 +261,14 @@ PciHostBridgeUtilityGetRootBridges (
     QemuFwCfgSelectItem (FwCfgItem);

     QemuFwCfgReadBytes (FwCfgSize, &ExtraRootBridges);

 

-    if (ExtraRootBridges > PCI_MAX_BUS) {

+    //

+    // Validate the number of extra root bridges. As BusMax is inclusive, the

+    // max bus count is (BusMax - BusMin + 1). From that, the "main" root bus

+    // is always a given, so the max count for the "extra" root bridges is one

+    // less, i.e. (BusMax - BusMin). If the QEMU hint exceeds that, we have

+    // invalid behavior.

+    //

+    if (ExtraRootBridges > BusMax - BusMin) {

       DEBUG ((DEBUG_ERROR, "%a: invalid count of extra root buses (%Lu) "

         "reported by QEMU\n", __FUNCTION__, ExtraRootBridges));

       return NULL;

@@ -271,15 +290,15 @@ PciHostBridgeUtilityGetRootBridges (
   //

   // The "main" root bus is always there.

   //

-  LastRootBridgeNumber = 0;

+  LastRootBridgeNumber = BusMin;

 

   //

   // Scan all other root buses. If function 0 of any device on a bus returns a

   // VendorId register value different from all-bits-one, then that bus is

   // alive.

   //

-  for (RootBridgeNumber = 1;

-       RootBridgeNumber <= PCI_MAX_BUS && Initialized < ExtraRootBridges;

+  for (RootBridgeNumber = BusMin + 1;

+       RootBridgeNumber <= BusMax && Initialized < ExtraRootBridges;

        ++RootBridgeNumber) {

     UINTN Device;

 

@@ -329,7 +348,7 @@ PciHostBridgeUtilityGetRootBridges (
     DmaAbove4G,

     NoExtendedConfigSpace,

     (UINT8) LastRootBridgeNumber,

-    PCI_MAX_BUS,

+    (UINT8) BusMax,

     Io,

     Mem,

     MemAbove4G,