Re: [PATCH RFC 05/14] OvmfPkg/Library: add XenPciHostBridgeLib

[Laszlo Ersek <lersek@redhat.com>]

On 12/08/16 16:33, Anthony PERARD wrote:
> A copy of OvmfPkg/Library/PciHostBridgeLib
> 
> Removing support for pci bus enumeration, I think, and only use scan of
> already enumerated pci bus.
> 
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
> ---
>  .../Library/XenPciHostBridgeLib/XenPciHostBridge.h |  75 ++++
>  .../XenPciHostBridgeLib/XenPciHostBridgeLib.c      | 291 +++++++++++++
>  .../XenPciHostBridgeLib/XenPciHostBridgeLib.inf    |  58 +++
>  OvmfPkg/Library/XenPciHostBridgeLib/XenSupport.c   | 456 +++++++++++++++++++++
>  4 files changed, 880 insertions(+)
>  create mode 100644 OvmfPkg/Library/XenPciHostBridgeLib/XenPciHostBridge.h
>  create mode 100644 OvmfPkg/Library/XenPciHostBridgeLib/XenPciHostBridgeLib.c
>  create mode 100644 OvmfPkg/Library/XenPciHostBridgeLib/XenPciHostBridgeLib.inf
>  create mode 100644 OvmfPkg/Library/XenPciHostBridgeLib/XenSupport.c

(1) I think the following subject line is more idiomatic:

  OvmfPkg: add XenPciHostBridgeLib

Then, I'll practically repeat my comments for the previous patch:

(2) You might want to add Citrix copyright notices to new files.

(3) The Xen-related code that remains in the original PciHostBridgeLib
instance should be possible to remove later; if that's the case, can you
please write a subsequent patch for that too?

(4) The removed functionality should be named more precisely in the
commit message:

- PciHostBridgeGetRootBridges(): the search for extra PCI root buses
(which come from QEMU's pxb and pxb-pcie devices) is removed (hence the
"etc/extra-pci-roots" fw_cfg file is no longer consulted either, which
is otherwise used to speed up the search).

The Xen-specific ScanForRootBridges() function call is hardwired.

(5) It would be nice to hint at the reason (which is implemented in a
later patch) why a separate module is a good idea here. That is, why the
expected PVH2 functionality is best not added to the current
PciHostBridgeLib instance.

More below:

> diff --git a/OvmfPkg/Library/XenPciHostBridgeLib/XenPciHostBridge.h b/OvmfPkg/Library/XenPciHostBridgeLib/XenPciHostBridge.h
> new file mode 100644
> index 0000000..c23d40c
> --- /dev/null
> +++ b/OvmfPkg/Library/XenPciHostBridgeLib/XenPciHostBridge.h
> @@ -0,0 +1,75 @@
> +/** @file
> +  Header file of OVMF instance of PciHostBridgeLib.
> +
> +  Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>
> +
> +  This program and the accompanying materials are licensed and made available
> +  under the terms and conditions of the BSD License which accompanies this
> +  distribution.  The full text of the license may be found at
> +  http://opensource.org/licenses/bsd-license.php.
> +
> +  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
> +  WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> +
> +**/
> +
> +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/XenPciHostBridgeLib/XenPciHostBridgeLib.c b/OvmfPkg/Library/XenPciHostBridgeLib/XenPciHostBridgeLib.c
> new file mode 100644
> index 0000000..efcd830
> --- /dev/null
> +++ b/OvmfPkg/Library/XenPciHostBridgeLib/XenPciHostBridgeLib.c
> @@ -0,0 +1,291 @@
> +/** @file
> +  OVMF's instance of the PCI Host Bridge Library.
> +
> +  Copyright (C) 2016, Red Hat, Inc.
> +  Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>
> +
> +  This program and the accompanying materials are licensed and made available
> +  under the terms and conditions of the BSD License which accompanies this
> +  distribution.  The full text of the license may be found at
> +  http://opensource.org/licenses/bsd-license.php.
> +
> +  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
> +  WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> +
> +**/
> +#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/PciLib.h>
> +#include <Library/QemuFwCfgLib.h>
> +#include "XenPciHostBridge.h"
> +
> +
> +#pragma pack(1)
> +typedef struct {
> +  ACPI_HID_DEVICE_PATH     AcpiDevicePath;
> +  EFI_DEVICE_PATH_PROTOCOL EndDevicePath;
> +} OVMF_PCI_ROOT_BRIDGE_DEVICE_PATH;
> +#pragma pack ()
> +
> +
> +GLOBAL_REMOVE_IF_UNREFERENCED
> +CHAR16 *mPciHostBridgeLibAcpiAddressSpaceTypeStr[] = {
> +  L"Mem", L"I/O", L"Bus"
> +};
> +
> +
> +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
> +    }
> +  }
> +};
> +
> +/**
> +  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 ((EFI_D_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 ((EFI_D_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.
> +
> +  @param Count  Return the count of root bridge instances.
> +
> +  @return All the root bridge instances in an array.
> +          The array should be passed into PciHostBridgeFreeRootBridges()
> +          when it's not used.
> +**/
> +PCI_ROOT_BRIDGE *
> +EFIAPI
> +PciHostBridgeGetRootBridges (
> +  UINTN *Count
> +  )
> +{
> +  ASSERT (PcdGetBool (PcdPciDisableBusEnumeration));
> +  return ScanForRootBridges (Count);
> +}
> +
> +
> +/**
> +  Free the root bridge instances array returned from
> +  PciHostBridgeGetRootBridges().
> +
> +  @param  The root bridge instances array.
> +  @param  The count of the array.
> +**/
> +VOID
> +EFIAPI
> +PciHostBridgeFreeRootBridges (
> +  PCI_ROOT_BRIDGE *Bridges,
> +  UINTN           Count
> +  )
> +{
> +  if (Bridges == NULL && Count == 0) {
> +    return;
> +  }
> +  ASSERT (Bridges != NULL && Count > 0);
> +
> +  do {
> +    --Count;
> +    UninitRootBridge (&Bridges[Count]);
> +  } while (Count > 0);
> +
> +  FreePool (Bridges);
> +}
> +
> +
> +/**
> +  Inform the platform that the resource conflict happens.
> +
> +  @param HostBridgeHandle Handle of the Host Bridge.
> +  @param Configuration    Pointer to PCI I/O and PCI memory resource
> +                          descriptors. The Configuration contains the resources
> +                          for all the root bridges. The resource for each root
> +                          bridge is terminated with END descriptor and an
> +                          additional END is appended indicating the end of the
> +                          entire resources. The resource descriptor field
> +                          values follow the description in
> +                          EFI_PCI_HOST_BRIDGE_RESOURCE_ALLOCATION_PROTOCOL
> +                          .SubmitResources().
> +**/
> +VOID
> +EFIAPI
> +PciHostBridgeResourceConflict (
> +  EFI_HANDLE                        HostBridgeHandle,
> +  VOID                              *Configuration
> +  )
> +{
> +  EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR *Descriptor;
> +  UINTN                             RootBridgeIndex;
> +  DEBUG ((EFI_D_ERROR, "PciHostBridge: Resource conflict happens!\n"));
> +
> +  RootBridgeIndex = 0;
> +  Descriptor = (EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR *) Configuration;
> +  while (Descriptor->Desc == ACPI_ADDRESS_SPACE_DESCRIPTOR) {
> +    DEBUG ((EFI_D_ERROR, "RootBridge[%d]:\n", RootBridgeIndex++));
> +    for (; Descriptor->Desc == ACPI_ADDRESS_SPACE_DESCRIPTOR; Descriptor++) {
> +      ASSERT (Descriptor->ResType <
> +              ARRAY_SIZE (mPciHostBridgeLibAcpiAddressSpaceTypeStr)
> +              );
> +      DEBUG ((EFI_D_ERROR, " %s: Length/Alignment = 0x%lx / 0x%lx\n",
> +              mPciHostBridgeLibAcpiAddressSpaceTypeStr[Descriptor->ResType],
> +              Descriptor->AddrLen, Descriptor->AddrRangeMax
> +              ));
> +      if (Descriptor->ResType == ACPI_ADDRESS_SPACE_TYPE_MEM) {
> +        DEBUG ((EFI_D_ERROR, "     Granularity/SpecificFlag = %ld / %02x%s\n",
> +                Descriptor->AddrSpaceGranularity, Descriptor->SpecificFlag,
> +                ((Descriptor->SpecificFlag &
> +                  EFI_ACPI_MEMORY_RESOURCE_SPECIFIC_FLAG_CACHEABLE_PREFETCHABLE
> +                  ) != 0) ? L" (Prefetchable)" : L""
> +                ));
> +      }
> +    }
> +    //
> +    // Skip the END descriptor for root bridge
> +    //
> +    ASSERT (Descriptor->Desc == ACPI_END_TAG_DESCRIPTOR);
> +    Descriptor = (EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR *)(
> +                   (EFI_ACPI_END_TAG_DESCRIPTOR *)Descriptor + 1
> +                   );
> +  }
> +}
> diff --git a/OvmfPkg/Library/XenPciHostBridgeLib/XenPciHostBridgeLib.inf b/OvmfPkg/Library/XenPciHostBridgeLib/XenPciHostBridgeLib.inf
> new file mode 100644
> index 0000000..3b8f003
> --- /dev/null
> +++ b/OvmfPkg/Library/XenPciHostBridgeLib/XenPciHostBridgeLib.inf
> @@ -0,0 +1,58 @@
> +## @file
> +#  OVMF's instance of the PCI Host Bridge Library.
> +#
> +#  Copyright (C) 2016, Red Hat, Inc.
> +#  Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>
> +#
> +#  This program and the accompanying materials are licensed and made available
> +#  under the terms and conditions of the BSD License which accompanies this
> +#  distribution. The full text of the license may be found at
> +#  http://opensource.org/licenses/bsd-license.php
> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR
> +#  IMPLIED.
> +#
> +#
> +##
> +
> +[Defines]
> +  INF_VERSION                    = 0x00010005
> +  BASE_NAME                      = XenPciHostBridgeLib
> +  FILE_GUID                      = 9F2BC05E-51EA-4AED-9A3E-7699641734E8

(6) You forgot to generate a new FILE_GUID with uuidgen.

Thanks
Laszlo

> +  MODULE_TYPE                    = DXE_DRIVER
> +  VERSION_STRING                 = 1.0
> +  LIBRARY_CLASS                  = PciHostBridgeLib
> +
> +#
> +# The following information is for reference only and not required by the build
> +# tools.
> +#
> +#  VALID_ARCHITECTURES           = IA32 X64 IPF EBC
> +#
> +
> +[Sources]
> +  XenPciHostBridgeLib.c
> +  XenSupport.c
> +  XenPciHostBridge.h
> +
> +[Packages]
> +  MdeModulePkg/MdeModulePkg.dec
> +  MdePkg/MdePkg.dec
> +  OvmfPkg/OvmfPkg.dec
> +
> +[LibraryClasses]
> +  BaseMemoryLib
> +  DebugLib
> +  DevicePathLib
> +  MemoryAllocationLib
> +  PciLib
> +
> +[Pcd]
> +  gUefiOvmfPkgTokenSpaceGuid.PcdPciIoBase
> +  gUefiOvmfPkgTokenSpaceGuid.PcdPciIoSize
> +  gUefiOvmfPkgTokenSpaceGuid.PcdPciMmio32Base
> +  gUefiOvmfPkgTokenSpaceGuid.PcdPciMmio32Size
> +  gUefiOvmfPkgTokenSpaceGuid.PcdPciMmio64Base
> +  gUefiOvmfPkgTokenSpaceGuid.PcdPciMmio64Size
> +  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfHostBridgePciDevId
> +  gEfiMdeModulePkgTokenSpaceGuid.PcdPciDisableBusEnumeration
> diff --git a/OvmfPkg/Library/XenPciHostBridgeLib/XenSupport.c b/OvmfPkg/Library/XenPciHostBridgeLib/XenSupport.c
> new file mode 100644
> index 0000000..a45945f
> --- /dev/null
> +++ b/OvmfPkg/Library/XenPciHostBridgeLib/XenSupport.c
> @@ -0,0 +1,456 @@
> +/** @file
> +  Scan the entire PCI bus for root bridges to support OVMF above Xen.
> +
> +  Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>
> +
> +  This program and the accompanying materials are licensed and made available
> +  under the terms and conditions of the BSD License which accompanies this
> +  distribution.  The full text of the license may be found at
> +  http://opensource.org/licenses/bsd-license.php.
> +
> +  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
> +  WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> +
> +**/
> +#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/MemoryAllocationLib.h>
> +#include <Library/PciHostBridgeLib.h>
> +#include <Library/PciLib.h>
> +#include "XenPciHostBridge.h"
> +
> +STATIC
> +VOID
> +PcatPciRootBridgeBarExisted (
> +  IN  UINTN                          Address,
> +  OUT UINT32                         *OriginalValue,
> +  OUT UINT32                         *Value
> +  )
> +{
> +  //
> +  // Preserve the original value
> +  //
> +  *OriginalValue = PciRead32 (Address);
> +
> +  //
> +  // Disable timer interrupt while the BAR is probed
> +  //
> +  DisableInterrupts ();
> +
> +  PciWrite32 (Address, 0xFFFFFFFF);
> +  *Value = PciRead32 (Address);
> +  PciWrite32 (Address, *OriginalValue);
> +
> +  //
> +  // Enable interrupt
> +  //
> +  EnableInterrupts ();
> +}
> +
> +STATIC
> +VOID
> +PcatPciRootBridgeParseBars (
> +  IN UINT16                         Command,
> +  IN UINTN                          Bus,
> +  IN UINTN                          Device,
> +  IN UINTN                          Function,
> +  IN UINTN                          BarOffsetBase,
> +  IN UINTN                          BarOffsetEnd,
> +  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
> +
> +)
> +{
> +  UINT32                            OriginalValue;
> +  UINT32                            Value;
> +  UINT32                            OriginalUpperValue;
> +  UINT32                            UpperValue;
> +  UINT64                            Mask;
> +  UINTN                             Offset;
> +  UINT64                            Base;
> +  UINT64                            Length;
> +  UINT64                            Limit;
> +  PCI_ROOT_BRIDGE_APERTURE          *MemAperture;
> +
> +  for (Offset = BarOffsetBase; Offset < BarOffsetEnd; Offset += sizeof (UINT32)) {
> +    PcatPciRootBridgeBarExisted (
> +      PCI_LIB_ADDRESS (Bus, Device, Function, Offset),
> +      &OriginalValue, &Value
> +    );
> +    if (Value == 0) {
> +      continue;
> +    }
> +    if ((Value & BIT0) == BIT0) {
> +      //
> +      // IO Bar
> +      //
> +      if (Command & EFI_PCI_COMMAND_IO_SPACE) {
> +        Mask = 0xfffffffc;
> +        Base = OriginalValue & Mask;
> +        Length = ((~(Value & Mask)) & Mask) + 0x04;
> +        if (!(Value & 0xFFFF0000)) {
> +          Length &= 0x0000FFFF;
> +        }
> +        Limit = Base + Length - 1;
> +
> +        if (Base < Limit) {
> +          if (Io->Base > Base) {
> +            Io->Base = Base;
> +          }
> +          if (Io->Limit < Limit) {
> +            Io->Limit = Limit;
> +          }
> +        }
> +      }
> +    } else {
> +      //
> +      // Mem Bar
> +      //
> +      if (Command & EFI_PCI_COMMAND_MEMORY_SPACE) {
> +
> +        Mask = 0xfffffff0;
> +        Base = OriginalValue & Mask;
> +        Length = Value & Mask;
> +
> +        if ((Value & (BIT1 | BIT2)) == 0) {
> +          //
> +          // 32bit
> +          //
> +          Length = ((~Length) + 1) & 0xffffffff;
> +
> +          if ((Value & BIT3) == BIT3) {
> +            MemAperture = PMem;
> +          } else {
> +            MemAperture = Mem;
> +          }
> +        } else {
> +          //
> +          // 64bit
> +          //
> +          Offset += 4;
> +          PcatPciRootBridgeBarExisted (
> +            PCI_LIB_ADDRESS (Bus, Device, Function, Offset),
> +            &OriginalUpperValue,
> +            &UpperValue
> +          );
> +
> +          Base = Base | LShiftU64 ((UINT64) OriginalUpperValue, 32);
> +          Length = Length | LShiftU64 ((UINT64) UpperValue, 32);
> +          Length = (~Length) + 1;
> +
> +          if ((Value & BIT3) == BIT3) {
> +            MemAperture = PMemAbove4G;
> +          } else {
> +            MemAperture = MemAbove4G;
> +          }
> +        }
> +
> +        Limit = Base + Length - 1;
> +        if (Base < Limit) {
> +          if (MemAperture->Base > Base) {
> +            MemAperture->Base = Base;
> +          }
> +          if (MemAperture->Limit < Limit) {
> +            MemAperture->Limit = Limit;
> +          }
> +        }
> +      }
> +    }
> +  }
> +}
> +
> +PCI_ROOT_BRIDGE *
> +ScanForRootBridges (
> +  UINTN      *NumberOfRootBridges
> +  )
> +{
> +  UINTN      PrimaryBus;
> +  UINTN      SubBus;
> +  UINT8      Device;
> +  UINT8      Function;
> +  UINTN      NumberOfDevices;
> +  UINTN      Address;
> +  PCI_TYPE01 Pci;
> +  UINT64     Attributes;
> +  UINT64     Base;
> +  UINT64     Limit;
> +  UINT64     Value;
> +  PCI_ROOT_BRIDGE_APERTURE Io, Mem, MemAbove4G, PMem, PMemAbove4G, *MemAperture;
> +  PCI_ROOT_BRIDGE *RootBridges;
> +  UINTN      BarOffsetEnd;
> +
> +
> +  *NumberOfRootBridges = 0;
> +  RootBridges = NULL;
> +
> +  //
> +  // After scanning all the PCI devices on the PCI root bridge's primary bus,
> +  // update the Primary Bus Number for the next PCI root bridge to be this PCI
> +  // root bridge's subordinate bus number + 1.
> +  //
> +  for (PrimaryBus = 0; PrimaryBus <= PCI_MAX_BUS; PrimaryBus = SubBus + 1) {
> +    SubBus = PrimaryBus;
> +    Attributes = 0;
> +    Io.Base = Mem.Base = MemAbove4G.Base = PMem.Base = PMemAbove4G.Base = MAX_UINT64;
> +    Io.Limit = Mem.Limit = MemAbove4G.Limit = PMem.Limit = PMemAbove4G.Limit = 0;
> +    //
> +    // Scan all the PCI devices on the primary bus of the PCI root bridge
> +    //
> +    for (Device = 0, NumberOfDevices = 0; Device <= PCI_MAX_DEVICE; Device++) {
> +
> +      for (Function = 0; Function <= PCI_MAX_FUNC; Function++) {
> +
> +        //
> +        // Compute the PCI configuration address of the PCI device to probe
> +        //
> +        Address = PCI_LIB_ADDRESS (PrimaryBus, Device, Function, 0);
> +
> +        //
> +        // Read the Vendor ID from the PCI Configuration Header
> +        //
> +        if (PciRead16 (Address) == MAX_UINT16) {
> +          if (Function == 0) {
> +            //
> +            // If the PCI Configuration Read fails, or a PCI device does not
> +            // exist, then skip this entire PCI device
> +            //
> +            break;
> +          } else {
> +            //
> +            // If PCI function != 0, VendorId == 0xFFFF, we continue to search
> +            // PCI function.
> +            //
> +            continue;
> +          }
> +        }
> +
> +        //
> +        // Read the entire PCI Configuration Header
> +        //
> +        PciReadBuffer (Address, sizeof (Pci), &Pci);
> +
> +        //
> +        // Increment the number of PCI device found on the primary bus of the
> +        // PCI root bridge
> +        //
> +        NumberOfDevices++;
> +
> +        //
> +        // Look for devices with the VGA Palette Snoop enabled in the COMMAND
> +        // register of the PCI Config Header
> +        //
> +        if ((Pci.Hdr.Command & EFI_PCI_COMMAND_VGA_PALETTE_SNOOP) != 0) {
> +          Attributes |= EFI_PCI_ATTRIBUTE_VGA_PALETTE_IO;
> +          Attributes |= EFI_PCI_ATTRIBUTE_VGA_PALETTE_IO_16;
> +        }
> +
> +        BarOffsetEnd = 0;
> +
> +        //
> +        // PCI-PCI Bridge
> +        //
> +        if (IS_PCI_BRIDGE (&Pci)) {
> +          //
> +          // Get the Bus range that the PPB is decoding
> +          //
> +          if (Pci.Bridge.SubordinateBus > SubBus) {
> +            //
> +            // If the suborinate bus number of the PCI-PCI bridge is greater
> +            // than the PCI root bridge's current subordinate bus number,
> +            // then update the PCI root bridge's subordinate bus number
> +            //
> +            SubBus = Pci.Bridge.SubordinateBus;
> +          }
> +
> +          //
> +          // Get the I/O range that the PPB is decoding
> +          //
> +          Value = Pci.Bridge.IoBase & 0x0f;
> +          Base = ((UINT32) Pci.Bridge.IoBase & 0xf0) << 8;
> +          Limit = (((UINT32) Pci.Bridge.IoLimit & 0xf0) << 8) | 0x0fff;
> +          if (Value == BIT0) {
> +            Base |= ((UINT32) Pci.Bridge.IoBaseUpper16 << 16);
> +            Limit |= ((UINT32) Pci.Bridge.IoLimitUpper16 << 16);
> +          }
> +          if (Base < Limit) {
> +            if (Io.Base > Base) {
> +              Io.Base = Base;
> +            }
> +            if (Io.Limit < Limit) {
> +              Io.Limit = Limit;
> +            }
> +          }
> +
> +          //
> +          // Get the Memory range that the PPB is decoding
> +          //
> +          Base = ((UINT32) Pci.Bridge.MemoryBase & 0xfff0) << 16;
> +          Limit = (((UINT32) Pci.Bridge.MemoryLimit & 0xfff0) << 16) | 0xfffff;
> +          if (Base < Limit) {
> +            if (Mem.Base > Base) {
> +              Mem.Base = Base;
> +            }
> +            if (Mem.Limit < Limit) {
> +              Mem.Limit = Limit;
> +            }
> +          }
> +
> +          //
> +          // Get the Prefetchable Memory range that the PPB is decoding
> +          //
> +          Value = Pci.Bridge.PrefetchableMemoryBase & 0x0f;
> +          Base = ((UINT32) Pci.Bridge.PrefetchableMemoryBase & 0xfff0) << 16;
> +          Limit = (((UINT32) Pci.Bridge.PrefetchableMemoryLimit & 0xfff0)
> +                   << 16) | 0xfffff;
> +          MemAperture = &PMem;
> +          if (Value == BIT0) {
> +            Base |= LShiftU64 (Pci.Bridge.PrefetchableBaseUpper32, 32);
> +            Limit |= LShiftU64 (Pci.Bridge.PrefetchableLimitUpper32, 32);
> +            MemAperture = &PMemAbove4G;
> +          }
> +          if (Base < Limit) {
> +            if (MemAperture->Base > Base) {
> +              MemAperture->Base = Base;
> +            }
> +            if (MemAperture->Limit < Limit) {
> +              MemAperture->Limit = Limit;
> +            }
> +          }
> +
> +          //
> +          // Look at the PPB Configuration for legacy decoding attributes
> +          //
> +          if ((Pci.Bridge.BridgeControl & EFI_PCI_BRIDGE_CONTROL_ISA)
> +              == EFI_PCI_BRIDGE_CONTROL_ISA) {
> +            Attributes |= EFI_PCI_ATTRIBUTE_ISA_IO;
> +            Attributes |= EFI_PCI_ATTRIBUTE_ISA_IO_16;
> +            Attributes |= EFI_PCI_ATTRIBUTE_ISA_MOTHERBOARD_IO;
> +          }
> +          if ((Pci.Bridge.BridgeControl & EFI_PCI_BRIDGE_CONTROL_VGA)
> +              == EFI_PCI_BRIDGE_CONTROL_VGA) {
> +            Attributes |= EFI_PCI_ATTRIBUTE_VGA_PALETTE_IO;
> +            Attributes |= EFI_PCI_ATTRIBUTE_VGA_MEMORY;
> +            Attributes |= EFI_PCI_ATTRIBUTE_VGA_IO;
> +            if ((Pci.Bridge.BridgeControl & EFI_PCI_BRIDGE_CONTROL_VGA_16)
> +                != 0) {
> +              Attributes |= EFI_PCI_ATTRIBUTE_VGA_PALETTE_IO_16;
> +              Attributes |= EFI_PCI_ATTRIBUTE_VGA_IO_16;
> +            }
> +          }
> +
> +          BarOffsetEnd = OFFSET_OF (PCI_TYPE01, Bridge.Bar[2]);
> +        } else {
> +          //
> +          // Parse the BARs of the PCI device to get what I/O Ranges, Memory
> +          // Ranges, and Prefetchable Memory Ranges the device is decoding
> +          //
> +          if ((Pci.Hdr.HeaderType & HEADER_LAYOUT_CODE) == HEADER_TYPE_DEVICE) {
> +            BarOffsetEnd = OFFSET_OF (PCI_TYPE00, Device.Bar[6]);
> +          }
> +        }
> +
> +        PcatPciRootBridgeParseBars (
> +          Pci.Hdr.Command,
> +          PrimaryBus,
> +          Device,
> +          Function,
> +          OFFSET_OF (PCI_TYPE00, Device.Bar),
> +          BarOffsetEnd,
> +          &Io,
> +          &Mem, &MemAbove4G,
> +          &PMem, &PMemAbove4G
> +        );
> +
> +        //
> +        // See if the PCI device is an IDE controller
> +        //
> +        if (IS_CLASS2 (&Pci, PCI_CLASS_MASS_STORAGE,
> +                       PCI_CLASS_MASS_STORAGE_IDE)) {
> +          if (Pci.Hdr.ClassCode[0] & 0x80) {
> +            Attributes |= EFI_PCI_ATTRIBUTE_IDE_PRIMARY_IO;
> +            Attributes |= EFI_PCI_ATTRIBUTE_IDE_SECONDARY_IO;
> +          }
> +          if (Pci.Hdr.ClassCode[0] & 0x01) {
> +            Attributes |= EFI_PCI_ATTRIBUTE_IDE_PRIMARY_IO;
> +          }
> +          if (Pci.Hdr.ClassCode[0] & 0x04) {
> +            Attributes |= EFI_PCI_ATTRIBUTE_IDE_SECONDARY_IO;
> +          }
> +        }
> +
> +        //
> +        // See if the PCI device is a legacy VGA controller or
> +        // a standard VGA controller
> +        //
> +        if (IS_CLASS2 (&Pci, PCI_CLASS_OLD, PCI_CLASS_OLD_VGA) ||
> +            IS_CLASS2 (&Pci, PCI_CLASS_DISPLAY, PCI_CLASS_DISPLAY_VGA)
> +            ) {
> +          Attributes |= EFI_PCI_ATTRIBUTE_VGA_PALETTE_IO;
> +          Attributes |= EFI_PCI_ATTRIBUTE_VGA_PALETTE_IO_16;
> +          Attributes |= EFI_PCI_ATTRIBUTE_VGA_MEMORY;
> +          Attributes |= EFI_PCI_ATTRIBUTE_VGA_IO;
> +          Attributes |= EFI_PCI_ATTRIBUTE_VGA_IO_16;
> +        }
> +
> +        //
> +        // See if the PCI Device is a PCI - ISA or PCI - EISA
> +        // or ISA_POSITIVIE_DECODE Bridge device
> +        //
> +        if (Pci.Hdr.ClassCode[2] == PCI_CLASS_BRIDGE) {
> +          if (Pci.Hdr.ClassCode[1] == PCI_CLASS_BRIDGE_ISA ||
> +              Pci.Hdr.ClassCode[1] == PCI_CLASS_BRIDGE_EISA ||
> +              Pci.Hdr.ClassCode[1] == PCI_CLASS_BRIDGE_ISA_PDECODE) {
> +            Attributes |= EFI_PCI_ATTRIBUTE_ISA_IO;
> +            Attributes |= EFI_PCI_ATTRIBUTE_ISA_IO_16;
> +            Attributes |= EFI_PCI_ATTRIBUTE_ISA_MOTHERBOARD_IO;
> +          }
> +        }
> +
> +        //
> +        // If this device is not a multi function device, then skip the rest
> +        // of this PCI device
> +        //
> +        if (Function == 0 && !IS_PCI_MULTI_FUNC (&Pci)) {
> +          break;
> +        }
> +      }
> +    }
> +
> +    //
> +    // If at least one PCI device was found on the primary bus of this PCI
> +    // root bridge, then the PCI root bridge exists.
> +    //
> +    if (NumberOfDevices > 0) {
> +      RootBridges = ReallocatePool (
> +        (*NumberOfRootBridges) * sizeof (PCI_ROOT_BRIDGE),
> +        (*NumberOfRootBridges + 1) * sizeof (PCI_ROOT_BRIDGE),
> +        RootBridges
> +      );
> +      ASSERT (RootBridges != NULL);
> +      InitRootBridge (
> +        Attributes, Attributes, 0,
> +        (UINT8) PrimaryBus, (UINT8) SubBus,
> +        &Io, &Mem, &MemAbove4G, &PMem, &PMemAbove4G,
> +        &RootBridges[*NumberOfRootBridges]
> +      );
> +      RootBridges[*NumberOfRootBridges].ResourceAssigned = TRUE;
> +      //
> +      // Increment the index for the next PCI Root Bridge
> +      //
> +      (*NumberOfRootBridges)++;
> +    }
> +  }
> +
> +  return RootBridges;
> +}
>