[PATCH v4 3/9] OvmfPkg/PciHostBridgeLib: Extract InitRootBridge/UninitRootBridge

["Jiahui Cen" <cenjiahui@huawei.com>]

Extract InitRootBridge/UninitRootBridge to PciHostBridgeUtilityLib as
common utility functions. No change of functionality.

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>
Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: Julien Grall <julien@xen.org>
Signed-off-by: Jiahui Cen <cenjiahui@huawei.com>
Signed-off-by: Yubo Miao <miaoyubo@huawei.com>
---
 OvmfPkg/Library/PciHostBridgeLib/PciHostBridgeLib.inf               |   2 -
 OvmfPkg/Library/PciHostBridgeUtilityLib/PciHostBridgeUtilityLib.inf |   7 +
 OvmfPkg/Include/Library/PciHostBridgeUtilityLib.h                   |  75 ++++++++++
 OvmfPkg/Library/PciHostBridgeLib/PciHostBridge.h                    |  56 -------
 OvmfPkg/Library/PciHostBridgeLib/PciHostBridgeLib.c                 | 158 +-------------------
 OvmfPkg/Library/PciHostBridgeLib/XenSupport.c                       |   3 +-
 OvmfPkg/Library/PciHostBridgeUtilityLib/PciHostBridgeUtilityLib.c   | 155 +++++++++++++++++++
 7 files changed, 243 insertions(+), 213 deletions(-)

diff --git a/OvmfPkg/Library/PciHostBridgeLib/PciHostBridgeLib.inf b/OvmfPkg/Library/PciHostBridgeLib/PciHostBridgeLib.inf
index 4c56f3c90b3b..d09429d9f0fb 100644
--- a/OvmfPkg/Library/PciHostBridgeLib/PciHostBridgeLib.inf
+++ b/OvmfPkg/Library/PciHostBridgeLib/PciHostBridgeLib.inf
@@ -37,7 +37,6 @@ [Packages]
 [LibraryClasses]
   BaseMemoryLib
   DebugLib
-  DevicePathLib
   MemoryAllocationLib
   PciHostBridgeUtilityLib
   PciLib
@@ -50,5 +49,4 @@ [Pcd]
   gUefiOvmfPkgTokenSpaceGuid.PcdPciMmio32Size
   gUefiOvmfPkgTokenSpaceGuid.PcdPciMmio64Base
   gUefiOvmfPkgTokenSpaceGuid.PcdPciMmio64Size
-  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfHostBridgePciDevId
   gEfiMdeModulePkgTokenSpaceGuid.PcdPciDisableBusEnumeration
diff --git a/OvmfPkg/Library/PciHostBridgeUtilityLib/PciHostBridgeUtilityLib.inf b/OvmfPkg/Library/PciHostBridgeUtilityLib/PciHostBridgeUtilityLib.inf
index 1ba8ec3e03c7..32a10e99c3e0 100644
--- a/OvmfPkg/Library/PciHostBridgeUtilityLib/PciHostBridgeUtilityLib.inf
+++ b/OvmfPkg/Library/PciHostBridgeUtilityLib/PciHostBridgeUtilityLib.inf
@@ -30,8 +30,15 @@ [Sources]
   PciHostBridgeUtilityLib.c
 
 [Packages]
+  MdeModulePkg/MdeModulePkg.dec
   MdePkg/MdePkg.dec
   OvmfPkg/OvmfPkg.dec
 
 [LibraryClasses]
+  BaseMemoryLib
   DebugLib
+  DevicePathLib
+  MemoryAllocationLib
+
+[Pcd]
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfHostBridgePciDevId
diff --git a/OvmfPkg/Include/Library/PciHostBridgeUtilityLib.h b/OvmfPkg/Include/Library/PciHostBridgeUtilityLib.h
index f932d412aa10..f02cec812a50 100644
--- a/OvmfPkg/Include/Library/PciHostBridgeUtilityLib.h
+++ b/OvmfPkg/Include/Library/PciHostBridgeUtilityLib.h
@@ -14,6 +14,81 @@
 #define __PCI_HOST_BRIDGE_UTILITY_LIB_H__
 
 
+#include <Library/PciHostBridgeLib.h>
+
+
+/**
+  Utility function to initialize a PCI_ROOT_BRIDGE structure.
+
+  @param[in]  Supports         Supported attributes.
+
+  @param[in]  Attributes       Initial attributes.
+
+  @param[in]  AllocAttributes  Allocation attributes.
+
+  @param[in]  RootBusNumber    The bus number to store in RootBus.
+
+  @param[in]  MaxSubBusNumber  The inclusive maximum bus number that can be
+                               assigned to any subordinate bus found behind any
+                               PCI bridge hanging off this root bus.
+
+                               The caller is repsonsible for ensuring that
+                               RootBusNumber <= MaxSubBusNumber. If
+                               RootBusNumber equals MaxSubBusNumber, then the
+                               root bus has no room for subordinate buses.
+
+  @param[in]  Io               IO aperture.
+
+  @param[in]  Mem              MMIO aperture.
+
+  @param[in]  MemAbove4G       MMIO aperture above 4G.
+
+  @param[in]  PMem             Prefetchable MMIO aperture.
+
+  @param[in]  PMemAbove4G      Prefetchable MMIO aperture above 4G.
+
+  @param[out] RootBus          The PCI_ROOT_BRIDGE structure (allocated by the
+                               caller) that should be filled in by this
+                               function.
+
+  @retval EFI_SUCCESS           Initialization successful. A device path
+                                consisting of an ACPI device path node, with
+                                UID = RootBusNumber, has been allocated and
+                                linked into RootBus.
+
+  @retval EFI_OUT_OF_RESOURCES  Memory allocation failed.
+**/
+EFI_STATUS
+PciHostBridgeUtilityInitRootBridge (
+  IN  UINT64                   Supports,
+  IN  UINT64                   Attributes,
+  IN  UINT64                   AllocAttributes,
+  IN  UINT8                    RootBusNumber,
+  IN  UINT8                    MaxSubBusNumber,
+  IN  PCI_ROOT_BRIDGE_APERTURE *Io,
+  IN  PCI_ROOT_BRIDGE_APERTURE *Mem,
+  IN  PCI_ROOT_BRIDGE_APERTURE *MemAbove4G,
+  IN  PCI_ROOT_BRIDGE_APERTURE *PMem,
+  IN  PCI_ROOT_BRIDGE_APERTURE *PMemAbove4G,
+  OUT PCI_ROOT_BRIDGE          *RootBus
+  );
+
+
+/**
+  Utility function to uninitialize a PCI_ROOT_BRIDGE structure set up with
+  PciHostBridgeUtilityInitRootBridge().
+
+  param[in] RootBus  The PCI_ROOT_BRIDGE structure, allocated by the caller and
+                     initialized with PciHostBridgeUtilityInitRootBridge(),
+                     that should be uninitialized. This function doesn't free
+                     RootBus.
+**/
+VOID
+PciHostBridgeUtilityUninitRootBridge (
+  IN PCI_ROOT_BRIDGE *RootBus
+  );
+
+
 /**
   Utility function to inform the platform that the resource conflict happens.
 
diff --git a/OvmfPkg/Library/PciHostBridgeLib/PciHostBridge.h b/OvmfPkg/Library/PciHostBridgeLib/PciHostBridge.h
index 134d7411214d..a2e4d8696281 100644
--- a/OvmfPkg/Library/PciHostBridgeLib/PciHostBridge.h
+++ b/OvmfPkg/Library/PciHostBridgeLib/PciHostBridge.h
@@ -11,59 +11,3 @@ PCI_ROOT_BRIDGE *
 ScanForRootBridges (
   UINTN      *NumberOfRootBridges
 );
-
-/**
-  Initialize a PCI_ROOT_BRIDGE structure.
-
-  @param[in]  Supports         Supported attributes.
-
-  @param[in]  Attributes       Initial attributes.
-
-  @param[in]  AllocAttributes  Allocation attributes.
-
-  @param[in]  RootBusNumber    The bus number to store in RootBus.
-
-  @param[in]  MaxSubBusNumber  The inclusive maximum bus number that can be
-                               assigned to any subordinate bus found behind any
-                               PCI bridge hanging off this root bus.
-
-                               The caller is repsonsible for ensuring that
-                               RootBusNumber <= MaxSubBusNumber. If
-                               RootBusNumber equals MaxSubBusNumber, then the
-                               root bus has no room for subordinate buses.
-
-  @param[in]  Io               IO aperture.
-
-  @param[in]  Mem              MMIO aperture.
-
-  @param[in]  MemAbove4G       MMIO aperture above 4G.
-
-  @param[in]  PMem             Prefetchable MMIO aperture.
-
-  @param[in]  PMemAbove4G      Prefetchable MMIO aperture above 4G.
-
-  @param[out] RootBus          The PCI_ROOT_BRIDGE structure (allocated by the
-                               caller) that should be filled in by this
-                               function.
-
-  @retval EFI_SUCCESS           Initialization successful. A device path
-                                consisting of an ACPI device path node, with
-                                UID = RootBusNumber, has been allocated and
-                                linked into RootBus.
-
-  @retval EFI_OUT_OF_RESOURCES  Memory allocation failed.
-**/
-EFI_STATUS
-InitRootBridge (
-  IN  UINT64                   Supports,
-  IN  UINT64                   Attributes,
-  IN  UINT64                   AllocAttributes,
-  IN  UINT8                    RootBusNumber,
-  IN  UINT8                    MaxSubBusNumber,
-  IN  PCI_ROOT_BRIDGE_APERTURE *Io,
-  IN  PCI_ROOT_BRIDGE_APERTURE *Mem,
-  IN  PCI_ROOT_BRIDGE_APERTURE *MemAbove4G,
-  IN  PCI_ROOT_BRIDGE_APERTURE *PMem,
-  IN  PCI_ROOT_BRIDGE_APERTURE *PMemAbove4G,
-  OUT PCI_ROOT_BRIDGE          *RootBus
-  );
diff --git a/OvmfPkg/Library/PciHostBridgeLib/PciHostBridgeLib.c b/OvmfPkg/Library/PciHostBridgeLib/PciHostBridgeLib.c
index 4a176347fd49..f284244448bb 100644
--- a/OvmfPkg/Library/PciHostBridgeLib/PciHostBridgeLib.c
+++ b/OvmfPkg/Library/PciHostBridgeLib/PciHostBridgeLib.c
@@ -10,14 +10,12 @@
 #include <PiDxe.h>
 
 #include <IndustryStandard/Pci.h>
-#include <IndustryStandard/Q35MchIch9.h>
 
 #include <Protocol/PciHostBridgeResourceAllocation.h>
 #include <Protocol/PciRootBridgeIo.h>
 
 #include <Library/BaseMemoryLib.h>
 #include <Library/DebugLib.h>
-#include <Library/DevicePathLib.h>
 #include <Library/MemoryAllocationLib.h>
 #include <Library/PciHostBridgeLib.h>
 #include <Library/PciHostBridgeUtilityLib.h>
@@ -26,156 +24,8 @@
 #include "PciHostBridge.h"
 
 
-#pragma pack(1)
-typedef struct {
-  ACPI_HID_DEVICE_PATH     AcpiDevicePath;
-  EFI_DEVICE_PATH_PROTOCOL EndDevicePath;
-} OVMF_PCI_ROOT_BRIDGE_DEVICE_PATH;
-#pragma pack ()
-
-
-STATIC
-CONST
-OVMF_PCI_ROOT_BRIDGE_DEVICE_PATH mRootBridgeDevicePathTemplate = {
-  {
-    {
-      ACPI_DEVICE_PATH,
-      ACPI_DP,
-      {
-        (UINT8) (sizeof(ACPI_HID_DEVICE_PATH)),
-        (UINT8) ((sizeof(ACPI_HID_DEVICE_PATH)) >> 8)
-      }
-    },
-    EISA_PNP_ID(0x0A03), // HID
-    0                    // UID
-  },
-
-  {
-    END_DEVICE_PATH_TYPE,
-    END_ENTIRE_DEVICE_PATH_SUBTYPE,
-    {
-      END_DEVICE_PATH_LENGTH,
-      0
-    }
-  }
-};
-
 STATIC PCI_ROOT_BRIDGE_APERTURE mNonExistAperture = { MAX_UINT64, 0 };
 
-/**
-  Initialize a PCI_ROOT_BRIDGE structure.
-
-  @param[in]  Supports         Supported attributes.
-
-  @param[in]  Attributes       Initial attributes.
-
-  @param[in]  AllocAttributes  Allocation attributes.
-
-  @param[in]  RootBusNumber    The bus number to store in RootBus.
-
-  @param[in]  MaxSubBusNumber  The inclusive maximum bus number that can be
-                               assigned to any subordinate bus found behind any
-                               PCI bridge hanging off this root bus.
-
-                               The caller is repsonsible for ensuring that
-                               RootBusNumber <= MaxSubBusNumber. If
-                               RootBusNumber equals MaxSubBusNumber, then the
-                               root bus has no room for subordinate buses.
-
-  @param[in]  Io               IO aperture.
-
-  @param[in]  Mem              MMIO aperture.
-
-  @param[in]  MemAbove4G       MMIO aperture above 4G.
-
-  @param[in]  PMem             Prefetchable MMIO aperture.
-
-  @param[in]  PMemAbove4G      Prefetchable MMIO aperture above 4G.
-
-  @param[out] RootBus          The PCI_ROOT_BRIDGE structure (allocated by the
-                               caller) that should be filled in by this
-                               function.
-
-  @retval EFI_SUCCESS           Initialization successful. A device path
-                                consisting of an ACPI device path node, with
-                                UID = RootBusNumber, has been allocated and
-                                linked into RootBus.
-
-  @retval EFI_OUT_OF_RESOURCES  Memory allocation failed.
-**/
-EFI_STATUS
-InitRootBridge (
-  IN  UINT64                   Supports,
-  IN  UINT64                   Attributes,
-  IN  UINT64                   AllocAttributes,
-  IN  UINT8                    RootBusNumber,
-  IN  UINT8                    MaxSubBusNumber,
-  IN  PCI_ROOT_BRIDGE_APERTURE *Io,
-  IN  PCI_ROOT_BRIDGE_APERTURE *Mem,
-  IN  PCI_ROOT_BRIDGE_APERTURE *MemAbove4G,
-  IN  PCI_ROOT_BRIDGE_APERTURE *PMem,
-  IN  PCI_ROOT_BRIDGE_APERTURE *PMemAbove4G,
-  OUT PCI_ROOT_BRIDGE          *RootBus
-  )
-{
-  OVMF_PCI_ROOT_BRIDGE_DEVICE_PATH *DevicePath;
-
-  //
-  // Be safe if other fields are added to PCI_ROOT_BRIDGE later.
-  //
-  ZeroMem (RootBus, sizeof *RootBus);
-
-  RootBus->Segment = 0;
-
-  RootBus->Supports   = Supports;
-  RootBus->Attributes = Attributes;
-
-  RootBus->DmaAbove4G = FALSE;
-
-  RootBus->AllocationAttributes = AllocAttributes;
-  RootBus->Bus.Base  = RootBusNumber;
-  RootBus->Bus.Limit = MaxSubBusNumber;
-  CopyMem (&RootBus->Io, Io, sizeof (*Io));
-  CopyMem (&RootBus->Mem, Mem, sizeof (*Mem));
-  CopyMem (&RootBus->MemAbove4G, MemAbove4G, sizeof (*MemAbove4G));
-  CopyMem (&RootBus->PMem, PMem, sizeof (*PMem));
-  CopyMem (&RootBus->PMemAbove4G, PMemAbove4G, sizeof (*PMemAbove4G));
-
-  RootBus->NoExtendedConfigSpace = (PcdGet16 (PcdOvmfHostBridgePciDevId) !=
-                                    INTEL_Q35_MCH_DEVICE_ID);
-
-  DevicePath = AllocateCopyPool (sizeof mRootBridgeDevicePathTemplate,
-                 &mRootBridgeDevicePathTemplate);
-  if (DevicePath == NULL) {
-    DEBUG ((DEBUG_ERROR, "%a: %r\n", __FUNCTION__, EFI_OUT_OF_RESOURCES));
-    return EFI_OUT_OF_RESOURCES;
-  }
-  DevicePath->AcpiDevicePath.UID = RootBusNumber;
-  RootBus->DevicePath = (EFI_DEVICE_PATH_PROTOCOL *)DevicePath;
-
-  DEBUG ((DEBUG_INFO,
-    "%a: populated root bus %d, with room for %d subordinate bus(es)\n",
-    __FUNCTION__, RootBusNumber, MaxSubBusNumber - RootBusNumber));
-  return EFI_SUCCESS;
-}
-
-
-/**
-  Uninitialize a PCI_ROOT_BRIDGE structure set up with InitRootBridge().
-
-  param[in] RootBus  The PCI_ROOT_BRIDGE structure, allocated by the caller and
-                     initialized with InitRootBridge(), that should be
-                     uninitialized. This function doesn't free RootBus.
-**/
-STATIC
-VOID
-UninitRootBridge (
-  IN PCI_ROOT_BRIDGE *RootBus
-  )
-{
-  FreePool (RootBus->DevicePath);
-}
-
 
 /**
   Return all the root bridge instances in an array.
@@ -296,7 +146,7 @@ PciHostBridgeGetRootBridges (
       // because now we know how big a bus number range *that* one has, for any
       // subordinate buses that might exist behind PCI bridges hanging off it.
       //
-      Status = InitRootBridge (
+      Status = PciHostBridgeUtilityInitRootBridge (
         Attributes,
         Attributes,
         AllocationAttributes,
@@ -321,7 +171,7 @@ PciHostBridgeGetRootBridges (
   // Install the last root bus (which might be the only, ie. main, root bus, if
   // we've found no extra root buses).
   //
-  Status = InitRootBridge (
+  Status = PciHostBridgeUtilityInitRootBridge (
     Attributes,
     Attributes,
     AllocationAttributes,
@@ -345,7 +195,7 @@ PciHostBridgeGetRootBridges (
 FreeBridges:
   while (Initialized > 0) {
     --Initialized;
-    UninitRootBridge (&Bridges[Initialized]);
+    PciHostBridgeUtilityUninitRootBridge (&Bridges[Initialized]);
   }
 
   FreePool (Bridges);
@@ -374,7 +224,7 @@ PciHostBridgeFreeRootBridges (
 
   do {
     --Count;
-    UninitRootBridge (&Bridges[Count]);
+    PciHostBridgeUtilityUninitRootBridge (&Bridges[Count]);
   } while (Count > 0);
 
   FreePool (Bridges);
diff --git a/OvmfPkg/Library/PciHostBridgeLib/XenSupport.c b/OvmfPkg/Library/PciHostBridgeLib/XenSupport.c
index e161f14375ca..4bd27211ec37 100644
--- a/OvmfPkg/Library/PciHostBridgeLib/XenSupport.c
+++ b/OvmfPkg/Library/PciHostBridgeLib/XenSupport.c
@@ -18,6 +18,7 @@
 #include <Library/DebugLib.h>
 #include <Library/MemoryAllocationLib.h>
 #include <Library/PciHostBridgeLib.h>
+#include <Library/PciHostBridgeUtilityLib.h>
 #include <Library/PciLib.h>
 #include "PciHostBridge.h"
 
@@ -452,7 +453,7 @@ ScanForRootBridges (
         RootBridges
       );
       ASSERT (RootBridges != NULL);
-      InitRootBridge (
+      PciHostBridgeUtilityInitRootBridge (
         Attributes, Attributes, 0,
         (UINT8) PrimaryBus, (UINT8) SubBus,
         &Io, &Mem, &MemAbove4G, &mNonExistAperture, &mNonExistAperture,
diff --git a/OvmfPkg/Library/PciHostBridgeUtilityLib/PciHostBridgeUtilityLib.c b/OvmfPkg/Library/PciHostBridgeUtilityLib/PciHostBridgeUtilityLib.c
index bbaa5f830c98..e3db4b766181 100644
--- a/OvmfPkg/Library/PciHostBridgeUtilityLib/PciHostBridgeUtilityLib.c
+++ b/OvmfPkg/Library/PciHostBridgeUtilityLib/PciHostBridgeUtilityLib.c
@@ -11,16 +11,171 @@
 **/
 
 #include <IndustryStandard/Acpi10.h>
+#include <IndustryStandard/Q35MchIch9.h>
+#include <Library/BaseMemoryLib.h>
 #include <Library/DebugLib.h>
+#include <Library/DevicePathLib.h>
+#include <Library/MemoryAllocationLib.h>
 #include <Library/PciHostBridgeUtilityLib.h>
 
 
+#pragma pack(1)
+typedef struct {
+  ACPI_HID_DEVICE_PATH     AcpiDevicePath;
+  EFI_DEVICE_PATH_PROTOCOL EndDevicePath;
+} PCI_ROOT_BRIDGE_DEVICE_PATH;
+#pragma pack ()
+
+
 GLOBAL_REMOVE_IF_UNREFERENCED
 CHAR16 *mPciHostBridgeUtilityLibAcpiAddressSpaceTypeStr[] = {
   L"Mem", L"I/O", L"Bus"
 };
 
 
+STATIC
+CONST
+PCI_ROOT_BRIDGE_DEVICE_PATH mRootBridgeDevicePath = {
+  {
+    {
+      ACPI_DEVICE_PATH,
+      ACPI_DP,
+      {
+        (UINT8) (sizeof(ACPI_HID_DEVICE_PATH)),
+        (UINT8) ((sizeof(ACPI_HID_DEVICE_PATH)) >> 8)
+      }
+    },
+    EISA_PNP_ID(0x0A03), // HID
+    0                    // UID
+  },
+
+  {
+    END_DEVICE_PATH_TYPE,
+    END_ENTIRE_DEVICE_PATH_SUBTYPE,
+    {
+      END_DEVICE_PATH_LENGTH,
+      0
+    }
+  }
+};
+
+
+/**
+  Utility function to initialize a PCI_ROOT_BRIDGE structure.
+
+  @param[in]  Supports         Supported attributes.
+
+  @param[in]  Attributes       Initial attributes.
+
+  @param[in]  AllocAttributes  Allocation attributes.
+
+  @param[in]  RootBusNumber    The bus number to store in RootBus.
+
+  @param[in]  MaxSubBusNumber  The inclusive maximum bus number that can be
+                               assigned to any subordinate bus found behind any
+                               PCI bridge hanging off this root bus.
+
+                               The caller is repsonsible for ensuring that
+                               RootBusNumber <= MaxSubBusNumber. If
+                               RootBusNumber equals MaxSubBusNumber, then the
+                               root bus has no room for subordinate buses.
+
+  @param[in]  Io               IO aperture.
+
+  @param[in]  Mem              MMIO aperture.
+
+  @param[in]  MemAbove4G       MMIO aperture above 4G.
+
+  @param[in]  PMem             Prefetchable MMIO aperture.
+
+  @param[in]  PMemAbove4G      Prefetchable MMIO aperture above 4G.
+
+  @param[out] RootBus          The PCI_ROOT_BRIDGE structure (allocated by the
+                               caller) that should be filled in by this
+                               function.
+
+  @retval EFI_SUCCESS           Initialization successful. A device path
+                                consisting of an ACPI device path node, with
+                                UID = RootBusNumber, has been allocated and
+                                linked into RootBus.
+
+  @retval EFI_OUT_OF_RESOURCES  Memory allocation failed.
+**/
+EFI_STATUS
+PciHostBridgeUtilityInitRootBridge (
+  IN  UINT64                   Supports,
+  IN  UINT64                   Attributes,
+  IN  UINT64                   AllocAttributes,
+  IN  UINT8                    RootBusNumber,
+  IN  UINT8                    MaxSubBusNumber,
+  IN  PCI_ROOT_BRIDGE_APERTURE *Io,
+  IN  PCI_ROOT_BRIDGE_APERTURE *Mem,
+  IN  PCI_ROOT_BRIDGE_APERTURE *MemAbove4G,
+  IN  PCI_ROOT_BRIDGE_APERTURE *PMem,
+  IN  PCI_ROOT_BRIDGE_APERTURE *PMemAbove4G,
+  OUT PCI_ROOT_BRIDGE          *RootBus
+  )
+{
+  PCI_ROOT_BRIDGE_DEVICE_PATH *DevicePath;
+
+  //
+  // Be safe if other fields are added to PCI_ROOT_BRIDGE later.
+  //
+  ZeroMem (RootBus, sizeof *RootBus);
+
+  RootBus->Segment = 0;
+
+  RootBus->Supports   = Supports;
+  RootBus->Attributes = Attributes;
+
+  RootBus->DmaAbove4G = FALSE;
+
+  RootBus->AllocationAttributes = AllocAttributes;
+  RootBus->Bus.Base  = RootBusNumber;
+  RootBus->Bus.Limit = MaxSubBusNumber;
+  CopyMem (&RootBus->Io, Io, sizeof (*Io));
+  CopyMem (&RootBus->Mem, Mem, sizeof (*Mem));
+  CopyMem (&RootBus->MemAbove4G, MemAbove4G, sizeof (*MemAbove4G));
+  CopyMem (&RootBus->PMem, PMem, sizeof (*PMem));
+  CopyMem (&RootBus->PMemAbove4G, PMemAbove4G, sizeof (*PMemAbove4G));
+
+  RootBus->NoExtendedConfigSpace = (PcdGet16 (PcdOvmfHostBridgePciDevId) !=
+                                    INTEL_Q35_MCH_DEVICE_ID);
+
+  DevicePath = AllocateCopyPool (sizeof mRootBridgeDevicePath,
+                 &mRootBridgeDevicePath);
+  if (DevicePath == NULL) {
+    DEBUG ((DEBUG_ERROR, "%a: %r\n", __FUNCTION__, EFI_OUT_OF_RESOURCES));
+    return EFI_OUT_OF_RESOURCES;
+  }
+  DevicePath->AcpiDevicePath.UID = RootBusNumber;
+  RootBus->DevicePath = (EFI_DEVICE_PATH_PROTOCOL *)DevicePath;
+
+  DEBUG ((DEBUG_INFO,
+    "%a: populated root bus %d, with room for %d subordinate bus(es)\n",
+    __FUNCTION__, RootBusNumber, MaxSubBusNumber - RootBusNumber));
+  return EFI_SUCCESS;
+}
+
+
+/**
+  Utility function to uninitialize a PCI_ROOT_BRIDGE structure set up with
+  PciHostBridgeUtilityInitRootBridge().
+
+  param[in] RootBus  The PCI_ROOT_BRIDGE structure, allocated by the caller and
+                     initialized with PciHostBridgeUtilityInitRootBridge(),
+                     that should be uninitialized. This function doesn't free
+                     RootBus.
+**/
+VOID
+PciHostBridgeUtilityUninitRootBridge (
+  IN PCI_ROOT_BRIDGE *RootBus
+  )
+{
+  FreePool (RootBus->DevicePath);
+}
+
+
 /**
   Utility function to inform the platform that the resource conflict happens.
 
-- 
2.29.2