Re: [RFC 1/6] MdeModulePkg: Add DxeBmDmaLib library

["Duran, Leo" <leo.duran@amd.com>]

> -----Original Message-----
> From: afish@apple.com [mailto:afish@apple.com]
> Sent: Monday, January 09, 2017 6:47 PM
> To: Duran, Leo <leo.duran@amd.com>
> Cc: edk2-devel <edk2-devel@lists.01.org>; Tian, Feng
> <feng.tian@intel.com>; Singh, Brijesh <brijesh.singh@amd.com>; Ard
> Biesheuvel <ard.biesheuvel@linaro.org>; Jordan Justen
> <jordan.l.justen@intel.com>; Agyeman, Prince
> <prince.agyeman@intel.com>; lersek@redhat.com; star.zeng@intel.com
> Subject: Re: [edk2] [RFC 1/6] MdeModulePkg: Add DxeBmDmaLib library
> 
> 
> > On Jan 9, 2017, at 4:16 PM, Leo Duran <leo.duran@amd.com> wrote:
> >
> > This patch provides an abstraction layer for DMA operations
> > implemented by the PciHostBridgeDxe driver. The intent is to then
> > allow override of this library as may be required by specific hardware
> > implementations, such as AMD's Secure Encrypted Virtualization (SEV).
> >
> > This new (BmDmaLib class) library is modeled after the existing DmaLib
> > plus an extra DmaAbove4GB (BOOLEAN) parameter in the Map and
> Allocate
> > interfaces, so that decisions can be made about the need to allocate
> > DMA buffers below the 4GB boundary.
> >
[Duran, Leo] 
Hi Andrew,

Yes, I believe a version of this library class could be used for IOMMU mappings.
The DMA API in the Linux kernel does exactly that.

Regards,
Leo.

> 
> Leo,
> 
> Sorry to jump in late, and maybe this is a phase 2 kind of thing, but should we
> support a generic IOMMU architecture via this library?
> 
> I'm not really familiar with AMD's SEV, but in general an IO MMU can restrict
> a DMA buffer to a specific PCI device, and block other PCI devices from
> having access to that buffer. That would seem to imply it would be good to
> have the option of passing the PCI device via these library APIs or I guess we
> could add an Ex version of the APIs that include the PCI device? You could
> always implement the Ex versions of the API by ignoring the PCI device (if
> you don't care about per device IOMMU pertection) and calling the non-Ex
> version.
> 
> To be honest it is kind of hard to fully implement an IOMMU with the current
> UEFI spec as is, but I thought it be worth asking the question?
> 
> Thanks,
> 
> Andrew Fish
> 
> 
> > Cc: Feng Tian <feng.tian@intel.com>
> > Cc: Star Zeng <star.zeng@intel.com>
> > Contributed-under: TianoCore Contribution Agreement 1.0
> > Signed-off-by: Leo Duran  <leo.duran@amd.com>
> > ---
> > MdeModulePkg/Include/Library/BmDmaLib.h          | 161 +++++++++++
> > MdeModulePkg/Library/DxeBmDmaLib/DxeBmDmaLib.c   | 351
> +++++++++++++++++++++++
> > MdeModulePkg/Library/DxeBmDmaLib/DxeBmDmaLib.inf |  41 +++
> > MdeModulePkg/MdeModulePkg.dsc                    |   1 +
> > 4 files changed, 554 insertions(+)
> > create mode 100644 MdeModulePkg/Include/Library/BmDmaLib.h
> > create mode 100644
> MdeModulePkg/Library/DxeBmDmaLib/DxeBmDmaLib.c
> > create mode 100644
> MdeModulePkg/Library/DxeBmDmaLib/DxeBmDmaLib.inf
> >
> > diff --git a/MdeModulePkg/Include/Library/BmDmaLib.h
> > b/MdeModulePkg/Include/Library/BmDmaLib.h
> > new file mode 100644
> > index 0000000..2c0e50f
> > --- /dev/null
> > +++ b/MdeModulePkg/Include/Library/BmDmaLib.h
> > @@ -0,0 +1,161 @@
> > +/** @file
> > +  DMA abstraction library APIs. Based on PCI IO protocol DMA abstractions.
> > +
> > +  Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR>
> > + Copyright (c) 2017, AMD Inc. All rights reserved.<BR>
> > +
> > +  DMA Bus Master Read Operation:
> > +    Call BmDmaMap() for DmaOperationBusMasterRead.
> > +    Program the DMA Bus Master with the DeviceAddress returned by
> BmDmaMap().
> > +    Start the DMA Bus Master.
> > +    Wait for DMA Bus Master to complete the read operation.
> > +    Call BmDmaUnmap().
> > +
> > +  DMA Bus Master Write Operation:
> > +    Call BmDmaMap() for DmaOperationBusMasterWrite.
> > +    Program the DMA Bus Master with the DeviceAddress returned by
> BmDmaMap().
> > +    Start the DMA Bus Master.
> > +    Wait for DMA Bus Master to complete the write operation.
> > +    Call BmDmaUnmap().
> > +
> > +  DMA Bus Master Common Buffer Operation:
> > +    Call BmDmaAllocateBuffer() to allocate a common buffer.
> > +    Call BmDmaMap() for DmaOperationBusMasterCommonBuffer.
> > +    Program the DMA Bus Master with the DeviceAddress returned by
> BmDmaMap().
> > +    The common buffer can now be accessed equally by the processor and
> the DMA bus master.
> > +    Call BmDmaUnmap().
> > +    Call BmDmaFreeBuffer().
> > +
> > +  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.
> > +
> > + Derived from:
> > +   EmbeddedPkg/Include/Library/DmaLib.h
> > +
> > +**/
> > +
> > +#ifndef __BM_DMA_LIB_H__
> > +#define __BM_DMA_LIB_H__
> > +
> > +
> > +typedef enum {
> > +  ///
> > +  /// A read operation from system memory by a bus master.
> > +  ///
> > +  DmaOperationBusMasterRead,
> > +  ///
> > +  /// A write operation from system memory by a bus master.
> > +  ///
> > +  DmaOperationBusMasterWrite,
> > +  ///
> > +  /// Provides both read and write access to system memory by both
> > +the processor and a
> > +  /// bus master. The buffer is coherent from both the processor's and the
> bus master's point of view.
> > +  ///
> > +  DmaOperationBusMasterCommonBuffer,
> > +  DmaOperationBusMasterMaximum
> > +} BM_DMA_OPERATION;
> > +
> > +
> > +/**
> > +  Provides the DMA controller-specific addresses needed to access system
> memory.
> > +
> > +  Operation is relative to the DMA bus master.
> > +
> > +  @param  DmaAbove4GB           Indicates capability of DMA operations
> above 4GB.
> > +  @param  Operation             Indicates if the bus master is going to read or
> write to system memory.
> > +  @param  HostAddress           The system memory address to map to the
> DMA controller.
> > +  @param  NumberOfBytes         On input the number of bytes to map. On
> output the number of bytes
> > +                                that were mapped.
> > +  @param  DeviceAddress         The resulting map address for the bus
> master controller to use to
> > +                                access the hosts HostAddress.
> > +  @param  Mapping               A resulting value to pass to BmDmaUnmap().
> > +
> > +  @retval EFI_SUCCESS           The range was mapped for the returned
> NumberOfBytes.
> > +  @retval EFI_UNSUPPORTED       The HostAddress cannot be mapped as a
> common buffer.
> > +  @retval EFI_INVALID_PARAMETER One or more parameters are invalid.
> > +  @retval EFI_OUT_OF_RESOURCES  The request could not be completed
> due to a lack of resources.
> > +  @retval EFI_DEVICE_ERROR      The system hardware could not map the
> requested address.
> > +
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +BmDmaMap (
> > +  IN     BOOLEAN           DmaAbove4GB,
> > +  IN     BM_DMA_OPERATION  Operation,
> > +  IN     VOID              *HostAddress,
> > +  IN OUT UINTN             *NumberOfBytes,
> > +  OUT    PHYSICAL_ADDRESS  *DeviceAddress,
> > +  OUT    VOID              **Mapping
> > +  );
> > +
> > +
> > +/**
> > +  Completes the DmaOperationBusMasterRead/Write/CommonBuffer
> > +operation
> > +  and releases any corresponding resources.
> > +
> > +  @param  Mapping               The mapping value returned from
> BmDmaMap().
> > +
> > +  @retval EFI_SUCCESS           The range was unmapped.
> > +  @retval EFI_DEVICE_ERROR      The data was not committed to the target
> system memory.
> > +
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +BmDmaUnmap (
> > +  IN  VOID                 *Mapping
> > +  );
> > +
> > +
> > +/**
> > +  Allocates pages that are suitable for a BmDmaMap() of type
> DmaOperationBusMasterCommonBuffer.
> > +
> > +  @param  DmaAbove4GB           Indicates capability of DMA operations
> above 4GB.
> > +  @param  MemoryType            The type of memory to allocate:
> EfiBootServicesData or
> > +                                EfiRuntimeServicesData.
> > +  @param  Pages                 The number of pages to allocate.
> > +  @param  HostAddress           A pointer to store the base system memory
> address of the
> > +                                allocated range.
> > +
> > +  @retval EFI_SUCCESS           The requested memory pages were allocated.
> > +  @retval EFI_UNSUPPORTED       Attributes is unsupported. The only legal
> attribute bits are
> > +                                MEMORY_WRITE_COMBINE and MEMORY_CACHED.
> > +  @retval EFI_INVALID_PARAMETER One or more parameters are invalid.
> > +  @retval EFI_OUT_OF_RESOURCES  The memory pages could not be
> allocated.
> > +
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +BmDmaAllocateBuffer (
> > +  IN  BOOLEAN              DmaAbove4GB,
> > +  IN  EFI_MEMORY_TYPE      MemoryType,
> > +  IN  UINTN                Pages,
> > +  OUT VOID                 **HostAddress
> > +  );
> > +
> > +
> > +/**
> > +  Frees memory that was allocated with BmDmaAllocateBuffer().
> > +
> > +  @param  Pages                 The number of pages to free.
> > +  @param  HostAddress           The base system memory address of the
> allocated range.
> > +
> > +  @retval EFI_SUCCESS           The requested memory pages were freed.
> > +  @retval EFI_INVALID_PARAMETER The memory range specified by
> HostAddress and Pages
> > +                                was not allocated with BmDmaAllocateBuffer().
> > +
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +BmDmaFreeBuffer (
> > +  IN  UINTN                Pages,
> > +  IN  VOID                 *HostAddress
> > +  );
> > +
> > +
> > +#endif
> > +
> > diff --git a/MdeModulePkg/Library/DxeBmDmaLib/DxeBmDmaLib.c
> > b/MdeModulePkg/Library/DxeBmDmaLib/DxeBmDmaLib.c
> > new file mode 100644
> > index 0000000..824b51f
> > --- /dev/null
> > +++ b/MdeModulePkg/Library/DxeBmDmaLib/DxeBmDmaLib.c
> > @@ -0,0 +1,351 @@
> > +/** @file
> > +  DMA abstraction library APIs. Based on PCI IO protocol DMA abstractions.
> > +
> > +  Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR>
> > + Copyright (c) 2017, AMD Inc. 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.
> > +
> > +  Derived from:
> > +   MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c
> > +
> > +**/
> > +
> > +#include <PiDxe.h>
> > +#include <Library/BaseLib.h>
> > +#include <Library/BaseMemoryLib.h>
> > +#include <Library/DebugLib.h>
> > +#include <Library/DxeServicesTableLib.h> #include
> > +<Library/MemoryAllocationLib.h> #include
> > +<Library/UefiBootServicesTableLib.h>
> > +#include <Library/BmDmaLib.h>
> > +
> > +
> > +#define FORCE_BELOW_4GB_TRUE   TRUE
> > +#define FORCE_BELOW_4GB_FALSE  FALSE
> > +#define NO_MAPPING             (VOID *) (UINTN) -1
> > +
> > +
> > +typedef struct {
> > +  BM_DMA_OPERATION      Operation;
> > +  UINTN                 NumberOfBytes;
> > +  UINTN                 NumberOfPages;
> > +  EFI_PHYSICAL_ADDRESS  HostAddress;
> > +  EFI_PHYSICAL_ADDRESS  MappedHostAddress; } MAP_INFO;
> > +
> > +
> > +EFI_STATUS
> > +AllocateBounceBuffer (
> > +  IN     BOOLEAN               ForceBelow4GB,
> > +  IN     BM_DMA_OPERATION      Operation,
> > +  IN     EFI_PHYSICAL_ADDRESS  HostAddress,
> > +  IN OUT UINTN                 *NumberOfBytes,
> > +  OUT    PHYSICAL_ADDRESS      *DeviceAddress,
> > +  OUT    VOID                  **Mapping
> > +  )
> > +{
> > +  EFI_STATUS         Status;
> > +  MAP_INFO           *MapInfo;
> > +  EFI_ALLOCATE_TYPE  AllocateType;
> > +
> > +  //
> > +  // Allocate a MAP_INFO structure to remember the mapping when
> > + Unmap() is  // called later.
> > +  //
> > +  MapInfo = AllocatePool (sizeof (MAP_INFO));  if (MapInfo == NULL) {
> > +    *NumberOfBytes = 0;
> > +    return EFI_OUT_OF_RESOURCES;
> > +  }
> > +
> > +  //
> > +  // Initialize the MAP_INFO structure  //
> > +  MapInfo->Operation     = Operation;
> > +  MapInfo->NumberOfBytes = *NumberOfBytes;  MapInfo-
> >NumberOfPages =
> > + EFI_SIZE_TO_PAGES (MapInfo->NumberOfBytes);
> > +  MapInfo->HostAddress   = HostAddress;
> > +
> > +  if (ForceBelow4GB) {
> > +    //
> > +    // Limit allocations to memory below 4GB
> > +    //
> > +    AllocateType = AllocateMaxAddress;
> > +    MapInfo->MappedHostAddress = SIZE_4GB - 1;  } else {
> > +    AllocateType = AllocateAnyPages;
> > +  }
> > +
> > +  //
> > +  // Allocate DMA bounce buffer
> > +  //
> > +  Status = gBS->AllocatePages (
> > +                  AllocateType,
> > +                  EfiBootServicesData,
> > +                  MapInfo->NumberOfPages,
> > +                  &MapInfo->MappedHostAddress
> > +                  );
> > +
> > +  if (EFI_ERROR (Status)) {
> > +    FreePool (MapInfo);
> > +    *NumberOfBytes = 0;
> > +    return Status;
> > +  }
> > +
> > +  //
> > +  // If this is a read operation from the Bus Master's point of view,
> > + // then copy the contents of the real buffer into the mapped buffer
> > + // so the Bus Master can read the contents of the real buffer.
> > +  //
> > +  if (Operation ==  DmaOperationBusMasterRead) {
> > +    CopyMem (
> > +      (VOID *) (UINTN) MapInfo->MappedHostAddress,
> > +      (VOID *) (UINTN) MapInfo->HostAddress,
> > +      MapInfo->NumberOfBytes
> > +      );
> > +  }
> > +
> > +  //
> > +  // The DeviceAddress is the address of the mapped buffer  //
> > + *DeviceAddress = MapInfo->MappedHostAddress;
> > +
> > +  //
> > +  // Return a pointer to the MAP_INFO structure in Mapping  //
> > + *Mapping = MapInfo;
> > +
> > +  return EFI_SUCCESS;
> > +}
> > +
> > +
> > +/**
> > +  Provides the DMA controller-specific addresses needed to access system
> memory.
> > +
> > +  Operation is relative to the DMA bus master.
> > +
> > +  @param  DmaAbove4GB           Indicates capability of DMA operations
> above 4GB.
> > +  @param  Operation             Indicates if the bus master is going to read or
> write to system memory.
> > +  @param  HostAddress           The system memory address to map to the
> DMA controller.
> > +  @param  NumberOfBytes         On input the number of bytes to map. On
> output the number of bytes
> > +                                that were mapped.
> > +  @param  DeviceAddress         The resulting map address for the bus
> master controller to use to
> > +                                access the hosts HostAddress.
> > +  @param  Mapping               A resulting value to pass to BmDmaUnmap().
> > +
> > +  @retval EFI_SUCCESS           The range was mapped for the returned
> NumberOfBytes.
> > +  @retval EFI_UNSUPPORTED       The HostAddress cannot be mapped as a
> common buffer.
> > +  @retval EFI_INVALID_PARAMETER One or more parameters are invalid.
> > +  @retval EFI_OUT_OF_RESOURCES  The request could not be completed
> due to a lack of resources.
> > +  @retval EFI_DEVICE_ERROR      The system hardware could not map the
> requested address.
> > +
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +BmDmaMap (
> > +  IN     BOOLEAN           DmaAbove4GB,
> > +  IN     BM_DMA_OPERATION  Operation,
> > +  IN     VOID              *HostAddress,
> > +  IN OUT UINTN             *NumberOfBytes,
> > +  OUT    PHYSICAL_ADDRESS  *DeviceAddress,
> > +  OUT    VOID              **Mapping
> > +  )
> > +{
> > +  EFI_PHYSICAL_ADDRESS  PhysicalAddress;
> > +
> > +  //
> > +  // Check for invalid inputs
> > +  //
> > +  if (HostAddress == NULL || NumberOfBytes == NULL || DeviceAddress
> == NULL ||
> > +      Mapping == NULL || (UINT32) Operation >=
> DmaOperationBusMasterMaximum) {
> > +    return EFI_INVALID_PARAMETER;
> > +  }
> > +
> > +  PhysicalAddress = (EFI_PHYSICAL_ADDRESS) (UINTN) HostAddress;  if
> > + (DmaAbove4GB || (PhysicalAddress + *NumberOfBytes) <= SIZE_4GB) {
> > +    //
> > +    // If we CAN handle DMA above 4GB or the transfer is below 4GB,
> > +    // the DeviceAddress is simply the HostAddress
> > +    //
> > +    *DeviceAddress = PhysicalAddress;
> > +    *Mapping       = NO_MAPPING;
> > +
> > +    return EFI_SUCCESS;
> > +  }
> > +
> > +  //
> > +  // If we cannot handle DMA above 4GB and any part of the DMA
> > + transfer  // being is above 4GB, then map the DMA transfer to a buffer
> below 4GB.
> > +  //
> > +  if (Operation == DmaOperationBusMasterCommonBuffer) {
> > +    //
> > +    // Common Buffer operations cannot be remapped, so return an error.
> > +    //
> > +    return EFI_UNSUPPORTED;
> > +  }
> > +
> > +  return AllocateBounceBuffer (
> > +           Operation,
> > +           FORCE_BELOW_4GB_TRUE,
> > +           PhysicalAddress,
> > +           NumberOfBytes,
> > +           DeviceAddress,
> > +           Mapping
> > +           );
> > +}
> > +
> > +
> > +/**
> > +  Completes the DmaOperationBusMasterRead/Write/CommonBuffer
> > +operation
> > +  and releases any corresponding resources.
> > +
> > +  @param  Mapping               The mapping value returned from
> BmDmaMap().
> > +
> > +  @retval EFI_SUCCESS           The range was unmapped.
> > +  @retval EFI_DEVICE_ERROR      The data was not committed to the target
> system memory.
> > +
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +BmDmaUnmap (
> > +  IN  VOID                 *Mapping
> > +  )
> > +{
> > +  MAP_INFO  *MapInfo;
> > +
> > +  //
> > +  // Check for invalid inputs
> > +  //
> > +  if (Mapping == NULL) {
> > +    return EFI_INVALID_PARAMETER;
> > +  }
> > +
> > +  //
> > +  // See if the Map() operation associated with this Unmap() required
> > + a mapping  // buffer. If a mapping buffer was not required, then
> > + this function simply  // returns EFI_SUCCESS.
> > +  //
> > +  if (Mapping == NO_MAPPING) {
> > +    return EFI_SUCCESS;
> > +  }
> > +
> > +  //
> > +  // If this is a write operation from the Bus Master's point of
> > + view,  // then copy the contents of the mapped buffer into the real
> > + buffer  // so the processor can read the contents of the real buffer.
> > +  //
> > +  MapInfo = (MAP_INFO *)Mapping;
> > +  if (MapInfo->Operation == DmaOperationBusMasterWrite) {
> > +    CopyMem (
> > +      (VOID *) (UINTN) MapInfo->HostAddress,
> > +      (VOID *) (UINTN) MapInfo->MappedHostAddress,
> > +      MapInfo->NumberOfBytes
> > +      );
> > +  }
> > +
> > +  //
> > +  // Free the mapped buffer and the MAP_INFO structure.
> > +  //
> > +  gBS->FreePages (MapInfo->MappedHostAddress,
> > +MapInfo->NumberOfPages);
> > +  FreePool (Mapping);
> > +  return EFI_SUCCESS;
> > +}
> > +
> > +
> > +/**
> > +  Allocates pages that are suitable for a BmDmaMap() of type
> DmaOperationBusMasterCommonBuffer.
> > +
> > +  @param  DmaAbove4GB           Indicates capability of DMA operations
> above 4GB.
> > +  @param  MemoryType            The type of memory to allocate:
> EfiBootServicesData or
> > +                                EfiRuntimeServicesData.
> > +  @param  Pages                 The number of pages to allocate.
> > +  @param  HostAddress           A pointer to store the base system memory
> address of the
> > +                                allocated range.
> > +
> > +  @retval EFI_SUCCESS           The requested memory pages were allocated.
> > +  @retval EFI_UNSUPPORTED       Attributes is unsupported. The only legal
> attribute bits are
> > +                                MEMORY_WRITE_COMBINE and MEMORY_CACHED.
> > +  @retval EFI_INVALID_PARAMETER One or more parameters are invalid.
> > +  @retval EFI_OUT_OF_RESOURCES  The memory pages could not be
> allocated.
> > +
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +BmDmaAllocateBuffer (
> > +  IN  BOOLEAN              DmaAbove4GB,
> > +  IN  EFI_MEMORY_TYPE      MemoryType,
> > +  IN  UINTN                Pages,
> > +  OUT VOID                 **HostAddress
> > +  )
> > +{
> > +  EFI_STATUS           Status;
> > +  EFI_PHYSICAL_ADDRESS PhysicalAddress;
> > +  EFI_ALLOCATE_TYPE    AllocateType;
> > +
> > +  //
> > +  // Check for invalid inputs
> > +  //
> > +  if (HostAddress == NULL) {
> > +    return EFI_INVALID_PARAMETER;
> > +  }
> > +
> > +  //
> > +  // The only valid memory types are EfiBootServicesData and  //
> > + EfiRuntimeServicesData  //  if (MemoryType != EfiBootServicesData &&
> > +      MemoryType != EfiRuntimeServicesData) {
> > +    return EFI_INVALID_PARAMETER;
> > +  }
> > +
> > +  if (DmaAbove4GB) {
> > +    AllocateType = AllocateAnyPages;
> > +  } else {
> > +    //
> > +    // Limit allocations to memory below 4GB
> > +    //
> > +    AllocateType    = AllocateMaxAddress;
> > +    PhysicalAddress = (EFI_PHYSICAL_ADDRESS) (SIZE_4GB - 1);  }
> > + Status = gBS->AllocatePages (
> > +                  AllocateType,
> > +                  MemoryType,
> > +                  Pages,
> > +                  &PhysicalAddress
> > +                  );
> > +  if (!EFI_ERROR (Status)) {
> > +    *HostAddress = (VOID *) (UINTN) PhysicalAddress;  }
> > +
> > +  return Status;
> > +}
> > +
> > +
> > +/**
> > +  Frees memory that was allocated with BmDmaAllocateBuffer().
> > +
> > +  @param  Pages                 The number of pages to free.
> > +  @param  HostAddress           The base system memory address of the
> allocated range.
> > +
> > +  @retval EFI_SUCCESS           The requested memory pages were freed.
> > +  @retval EFI_INVALID_PARAMETER The memory range specified by
> HostAddress and Pages
> > +                                was not allocated with BmDmaAllocateBuffer().
> > +
> > +**/
> > +EFI_STATUS
> > +EFIAPI
> > +BmDmaFreeBuffer (
> > +  IN  UINTN                Pages,
> > +  IN  VOID                 *HostAddress
> > +  )
> > +{
> > +  return gBS->FreePages ((EFI_PHYSICAL_ADDRESS) (UINTN)
> HostAddress,
> > +Pages); }
> > +
> > diff --git a/MdeModulePkg/Library/DxeBmDmaLib/DxeBmDmaLib.inf
> > b/MdeModulePkg/Library/DxeBmDmaLib/DxeBmDmaLib.inf
> > new file mode 100644
> > index 0000000..06bb8b1
> > --- /dev/null
> > +++ b/MdeModulePkg/Library/DxeBmDmaLib/DxeBmDmaLib.inf
> > @@ -0,0 +1,41 @@
> > +## @file
> > +#
> > +# DMA abstraction library APIs. Based on PCI IO protocol DMA
> abstractions.
> > +#
> > +#  Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR> #
> > +Copyright (c) 2017, AMD Inc. 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                      = DxeBmDmaLib
> > +  FILE_GUID                      = daa403e0-071d-44ef-95cf-7f2472e4a4d5
> > +  MODULE_TYPE                    = DXE_DRIVER
> > +  VERSION_STRING                 = 1.0
> > +  LIBRARY_CLASS                  = BmDmaLib
> > +
> > +[Sources.common]
> > +  DxeBmDmaLib.c
> > +
> > +[Packages]
> > +  MdePkg/MdePkg.dec
> > +  MdeModulePkg/MdeModulePkg.dec
> > +
> > +[LibraryClasses]
> > +  BaseLib
> > +  BaseMemoryLib
> > +  DebugLib
> > +  DxeServicesTableLib
> > +  MemoryAllocationLib
> > +  UefiBootServicesTableLib
> > +
> > +
> > diff --git a/MdeModulePkg/MdeModulePkg.dsc
> > b/MdeModulePkg/MdeModulePkg.dsc index 5996fe5..311922e 100644
> > --- a/MdeModulePkg/MdeModulePkg.dsc
> > +++ b/MdeModulePkg/MdeModulePkg.dsc
> > @@ -275,6 +275,7 @@ [Components]
> >   MdeModulePkg/Core/Pei/PeiMain.inf
> >   MdeModulePkg/Core/RuntimeDxe/RuntimeDxe.inf
> >
> > +  MdeModulePkg/Library/DxeBmDmaLib/DxeBmDmaLib.inf
> >   MdeModulePkg/Library/DxeCapsuleLibNull/DxeCapsuleLibNull.inf
> >
> MdeModulePkg/Library/UefiMemoryAllocationProfileLib/UefiMemoryAlloca
> tionProfileLib.inf
> >
> >
> MdeModulePkg/Library/DxeCoreMemoryAllocationLib/DxeCoreMemoryAllo
> catio
> > nLib.inf
> > --
> > 1.9.1
> >
> > _______________________________________________
> > edk2-devel mailing list
> > edk2-devel@lists.01.org
> > https://lists.01.org/mailman/listinfo/edk2-devel