IntelSiliconPkg/Feature/VTd/IntelVTdDxe/BmDma.c - edk2 - Git at Google

 /** @file
   BmDma related function

   Copyright (c) 2017 - 2018, 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 "DmaProtection.h"

 // TBD: May make it a policy
 #define DMA_MEMORY_TOP          MAX_UINTN
 //#define DMA_MEMORY_TOP          0x0000000001FFFFFFULL

 #define MAP_INFO_SIGNATURE  SIGNATURE_32 ('D', 'M', 'A', 'P')
 typedef struct {
   UINT32                                    Signature;
   LIST_ENTRY                                Link;
   EDKII_IOMMU_OPERATION                     Operation;
   UINTN                                     NumberOfBytes;
   UINTN                                     NumberOfPages;
   EFI_PHYSICAL_ADDRESS                      HostAddress;
   EFI_PHYSICAL_ADDRESS                      DeviceAddress;
 } MAP_INFO;
 #define MAP_INFO_FROM_LINK(a) CR (a, MAP_INFO, Link, MAP_INFO_SIGNATURE)

 LIST_ENTRY                        gMaps = INITIALIZE_LIST_HEAD_VARIABLE(gMaps);

 /**
   Provides the controller-specific addresses required to access system memory from a
   DMA bus master.

   @param  This                  The protocol instance pointer.
   @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 PCI 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 PCI controller to use to
                                 access the hosts HostAddress.
   @param  Mapping               A resulting value to pass to Unmap().

   @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
 IoMmuMap (
   IN     EDKII_IOMMU_PROTOCOL                       *This,
   IN     EDKII_IOMMU_OPERATION                      Operation,
   IN     VOID                                       *HostAddress,
   IN OUT UINTN                                      *NumberOfBytes,
   OUT    EFI_PHYSICAL_ADDRESS                       *DeviceAddress,
   OUT    VOID                                       **Mapping
   )
 {
   EFI_STATUS                                        Status;
   EFI_PHYSICAL_ADDRESS                              PhysicalAddress;
   MAP_INFO                                          *MapInfo;
   EFI_PHYSICAL_ADDRESS                              DmaMemoryTop;
   BOOLEAN                                           NeedRemap;
   EFI_TPL                                           OriginalTpl;

   if (NumberOfBytes == NULL || DeviceAddress == NULL ||
       Mapping == NULL) {
     DEBUG ((DEBUG_ERROR, "IoMmuMap: %r\n", EFI_INVALID_PARAMETER));
     return EFI_INVALID_PARAMETER;
   }

   DEBUG ((DEBUG_VERBOSE, "IoMmuMap: ==> 0x%08x - 0x%08x (%x)\n", HostAddress, *NumberOfBytes, Operation));

   //
   // Make sure that Operation is valid
   //
   if ((UINT32) Operation >= EdkiiIoMmuOperationMaximum) {
     DEBUG ((DEBUG_ERROR, "IoMmuMap: %r\n", EFI_INVALID_PARAMETER));
     return EFI_INVALID_PARAMETER;
   }
   NeedRemap = FALSE;
   PhysicalAddress = (EFI_PHYSICAL_ADDRESS) (UINTN) HostAddress;

   DmaMemoryTop = DMA_MEMORY_TOP;

   //
   // Alignment check
   //
   if ((*NumberOfBytes != ALIGN_VALUE(*NumberOfBytes, SIZE_4KB)) ||
       (PhysicalAddress != ALIGN_VALUE(PhysicalAddress, SIZE_4KB))) {
     if ((Operation == EdkiiIoMmuOperationBusMasterCommonBuffer) ||
         (Operation == EdkiiIoMmuOperationBusMasterCommonBuffer64)) {
       //
       // The input buffer might be a subset from IoMmuAllocateBuffer.
       // Skip the check.
       //
     } else {
       NeedRemap = TRUE;
     }
   }

   if ((PhysicalAddress + *NumberOfBytes) >= DMA_MEMORY_TOP) {
     NeedRemap = TRUE;
   }

   if (((Operation != EdkiiIoMmuOperationBusMasterRead64 &&
         Operation != EdkiiIoMmuOperationBusMasterWrite64 &&
         Operation != EdkiiIoMmuOperationBusMasterCommonBuffer64)) &&
       ((PhysicalAddress + *NumberOfBytes) > SIZE_4GB)) {
     //
     // If the root bridge or the device cannot handle performing DMA above
     // 4GB but any part of the DMA transfer being mapped is above 4GB, then
     // map the DMA transfer to a buffer below 4GB.
     //
     NeedRemap = TRUE;
     DmaMemoryTop = MIN (DmaMemoryTop, SIZE_4GB - 1);
   }

   if (Operation == EdkiiIoMmuOperationBusMasterCommonBuffer ||
       Operation == EdkiiIoMmuOperationBusMasterCommonBuffer64) {
     if (NeedRemap) {
       //
       // Common Buffer operations can not be remapped.  If the common buffer
       // is above 4GB, then it is not possible to generate a mapping, so return
       // an error.
       //
       DEBUG ((DEBUG_ERROR, "IoMmuMap: %r\n", EFI_UNSUPPORTED));
       return EFI_UNSUPPORTED;
     }
   }

   //
   // Allocate a MAP_INFO structure to remember the mapping when Unmap() is
   // called later.
   //
   MapInfo = AllocatePool (sizeof (MAP_INFO));
   if (MapInfo == NULL) {
     *NumberOfBytes = 0;
     DEBUG ((DEBUG_ERROR, "IoMmuMap: %r\n", EFI_OUT_OF_RESOURCES));
     return EFI_OUT_OF_RESOURCES;
   }

   //
   // Initialize the MAP_INFO structure
   //
   MapInfo->Signature         = MAP_INFO_SIGNATURE;
   MapInfo->Operation         = Operation;
   MapInfo->NumberOfBytes     = *NumberOfBytes;
   MapInfo->NumberOfPages     = EFI_SIZE_TO_PAGES (MapInfo->NumberOfBytes);
   MapInfo->HostAddress       = PhysicalAddress;
   MapInfo->DeviceAddress     = DmaMemoryTop;

   //
   // Allocate a buffer below 4GB to map the transfer to.
   //
   if (NeedRemap) {
     Status = gBS->AllocatePages (
                     AllocateMaxAddress,
                     EfiBootServicesData,
                     MapInfo->NumberOfPages,
                     &MapInfo->DeviceAddress
                     );
     if (EFI_ERROR (Status)) {
       FreePool (MapInfo);
       *NumberOfBytes = 0;
       DEBUG ((DEBUG_ERROR, "IoMmuMap: %r\n", Status));
       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 == EdkiiIoMmuOperationBusMasterRead ||
         Operation == EdkiiIoMmuOperationBusMasterRead64) {
       CopyMem (
         (VOID *) (UINTN) MapInfo->DeviceAddress,
         (VOID *) (UINTN) MapInfo->HostAddress,
         MapInfo->NumberOfBytes
         );
     }
   } else {
     MapInfo->DeviceAddress = MapInfo->HostAddress;
   }

   OriginalTpl = gBS->RaiseTPL (VTD_TPL_LEVEL);
   InsertTailList (&gMaps, &MapInfo->Link);
   gBS->RestoreTPL (OriginalTpl);

   //
   // The DeviceAddress is the address of the maped buffer below 4GB
   //
   *DeviceAddress = MapInfo->DeviceAddress;
   //
   // Return a pointer to the MAP_INFO structure in Mapping
   //
   *Mapping       = MapInfo;

   DEBUG ((DEBUG_VERBOSE, "IoMmuMap: 0x%08x - 0x%08x <==\n", *DeviceAddress, *Mapping));

   return EFI_SUCCESS;
 }

 /**
   Completes the Map() operation and releases any corresponding resources.

   @param  This                  The protocol instance pointer.
   @param  Mapping               The mapping value returned from Map().

   @retval EFI_SUCCESS           The range was unmapped.
   @retval EFI_INVALID_PARAMETER Mapping is not a value that was returned by Map().
   @retval EFI_DEVICE_ERROR      The data was not committed to the target system memory.
 **/
 EFI_STATUS
 EFIAPI
 IoMmuUnmap (
   IN  EDKII_IOMMU_PROTOCOL                     *This,
   IN  VOID                                     *Mapping
   )
 {
   MAP_INFO                 *MapInfo;
   LIST_ENTRY               *Link;
   EFI_TPL                  OriginalTpl;

   DEBUG ((DEBUG_VERBOSE, "IoMmuUnmap: 0x%08x\n", Mapping));

   if (Mapping == NULL) {
     DEBUG ((DEBUG_ERROR, "IoMmuUnmap: %r\n", EFI_INVALID_PARAMETER));
     return EFI_INVALID_PARAMETER;
   }

   OriginalTpl = gBS->RaiseTPL (VTD_TPL_LEVEL);
   MapInfo = NULL;
   for (Link = GetFirstNode (&gMaps)
        ; !IsNull (&gMaps, Link)
        ; Link = GetNextNode (&gMaps, Link)
        ) {
     MapInfo = MAP_INFO_FROM_LINK (Link);
     if (MapInfo == Mapping) {
       break;
     }
   }
   //
   // Mapping is not a valid value returned by Map()
   //
   if (MapInfo != Mapping) {
     gBS->RestoreTPL (OriginalTpl);
     DEBUG ((DEBUG_ERROR, "IoMmuUnmap: %r\n", EFI_INVALID_PARAMETER));
     return EFI_INVALID_PARAMETER;
   }
   RemoveEntryList (&MapInfo->Link);
   gBS->RestoreTPL (OriginalTpl);

   if (MapInfo->DeviceAddress != MapInfo->HostAddress) {
     //
     // 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.
     //
     if (MapInfo->Operation == EdkiiIoMmuOperationBusMasterWrite ||
         MapInfo->Operation == EdkiiIoMmuOperationBusMasterWrite64) {
       CopyMem (
         (VOID *) (UINTN) MapInfo->HostAddress,
         (VOID *) (UINTN) MapInfo->DeviceAddress,
         MapInfo->NumberOfBytes
         );
     }

     //
     // Free the mapped buffer and the MAP_INFO structure.
     //
     gBS->FreePages (MapInfo->DeviceAddress, MapInfo->NumberOfPages);
   }

   FreePool (Mapping);
   return EFI_SUCCESS;
 }

 /**
   Allocates pages that are suitable for an OperationBusMasterCommonBuffer or
   OperationBusMasterCommonBuffer64 mapping.

   @param  This                  The protocol instance pointer.
   @param  Type                  This parameter is not used and must be ignored.
   @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.
   @param  Attributes            The requested bit mask of attributes for 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, MEMORY_CACHED and DUAL_ADDRESS_CYCLE.
   @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
 IoMmuAllocateBuffer (
   IN     EDKII_IOMMU_PROTOCOL                     *This,
   IN     EFI_ALLOCATE_TYPE                        Type,
   IN     EFI_MEMORY_TYPE                          MemoryType,
   IN     UINTN                                    Pages,
   IN OUT VOID                                     **HostAddress,
   IN     UINT64                                   Attributes
   )
 {
   EFI_STATUS                Status;
   EFI_PHYSICAL_ADDRESS      PhysicalAddress;

   DEBUG ((DEBUG_VERBOSE, "IoMmuAllocateBuffer: ==> 0x%08x\n", Pages));

   //
   // Validate Attributes
   //
   if ((Attributes & EDKII_IOMMU_ATTRIBUTE_INVALID_FOR_ALLOCATE_BUFFER) != 0) {
     DEBUG ((DEBUG_ERROR, "IoMmuAllocateBuffer: %r\n", EFI_UNSUPPORTED));
     return EFI_UNSUPPORTED;
   }

   //
   // Check for invalid inputs
   //
   if (HostAddress == NULL) {
     DEBUG ((DEBUG_ERROR, "IoMmuAllocateBuffer: %r\n", EFI_INVALID_PARAMETER));
     return EFI_INVALID_PARAMETER;
   }

   //
   // The only valid memory types are EfiBootServicesData and
   // EfiRuntimeServicesData
   //
   if (MemoryType != EfiBootServicesData &&
       MemoryType != EfiRuntimeServicesData) {
     DEBUG ((DEBUG_ERROR, "IoMmuAllocateBuffer: %r\n", EFI_INVALID_PARAMETER));
     return EFI_INVALID_PARAMETER;
   }

   PhysicalAddress = DMA_MEMORY_TOP;
   if ((Attributes & EDKII_IOMMU_ATTRIBUTE_DUAL_ADDRESS_CYCLE) == 0) {
     //
     // Limit allocations to memory below 4GB
     //
     PhysicalAddress = MIN (PhysicalAddress, SIZE_4GB - 1);
   }
   Status = gBS->AllocatePages (
                   AllocateMaxAddress,
                   MemoryType,
                   Pages,
                   &PhysicalAddress
                   );
   if (!EFI_ERROR (Status)) {
     *HostAddress = (VOID *) (UINTN) PhysicalAddress;
   }

   DEBUG ((DEBUG_VERBOSE, "IoMmuAllocateBuffer: 0x%08x <==\n", *HostAddress));

   return Status;
 }

 /**
   Frees memory that was allocated with AllocateBuffer().

   @param  This                  The protocol instance pointer.
   @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 AllocateBuffer().

 **/
 EFI_STATUS
 EFIAPI
 IoMmuFreeBuffer (
   IN  EDKII_IOMMU_PROTOCOL                     *This,
   IN  UINTN                                    Pages,
   IN  VOID                                     *HostAddress
   )
 {
   DEBUG ((DEBUG_VERBOSE, "IoMmuFreeBuffer: 0x%\n", Pages));
   return gBS->FreePages ((EFI_PHYSICAL_ADDRESS) (UINTN) HostAddress, Pages);
 }

 /**
   Get device information from mapping.

   @param[in]  Mapping        The mapping.
   @param[out] DeviceAddress  The device address of the mapping.
   @param[out] NumberOfPages  The number of pages of the mapping.

   @retval EFI_SUCCESS            The device information is returned.
   @retval EFI_INVALID_PARAMETER  The mapping is invalid.
 **/
 EFI_STATUS
 GetDeviceInfoFromMapping (
   IN  VOID                                     *Mapping,
   OUT EFI_PHYSICAL_ADDRESS                     *DeviceAddress,
   OUT UINTN                                    *NumberOfPages
   )
 {
   MAP_INFO                 *MapInfo;
   LIST_ENTRY               *Link;

   if (Mapping == NULL) {
     return EFI_INVALID_PARAMETER;
   }

   MapInfo = NULL;
   for (Link = GetFirstNode (&gMaps)
        ; !IsNull (&gMaps, Link)
        ; Link = GetNextNode (&gMaps, Link)
        ) {
     MapInfo = MAP_INFO_FROM_LINK (Link);
     if (MapInfo == Mapping) {
       break;
     }
   }
   //
   // Mapping is not a valid value returned by Map()
   //
   if (MapInfo != Mapping) {
     return EFI_INVALID_PARAMETER;
   }

   *DeviceAddress = MapInfo->DeviceAddress;
   *NumberOfPages = MapInfo->NumberOfPages;
   return EFI_SUCCESS;
 }
	/** @file
	BmDma related function

	Copyright (c) 2017 - 2018, 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 "DmaProtection.h"

	// TBD: May make it a policy
	#define DMA_MEMORY_TOP MAX_UINTN
	//#define DMA_MEMORY_TOP 0x0000000001FFFFFFULL

	#define MAP_INFO_SIGNATURE SIGNATURE_32 ('D', 'M', 'A', 'P')
	typedef struct {
	UINT32 Signature;
	LIST_ENTRY Link;
	EDKII_IOMMU_OPERATION Operation;
	UINTN NumberOfBytes;
	UINTN NumberOfPages;
	EFI_PHYSICAL_ADDRESS HostAddress;
	EFI_PHYSICAL_ADDRESS DeviceAddress;
	} MAP_INFO;
	#define MAP_INFO_FROM_LINK(a) CR (a, MAP_INFO, Link, MAP_INFO_SIGNATURE)

	LIST_ENTRY gMaps = INITIALIZE_LIST_HEAD_VARIABLE(gMaps);

	/**
	Provides the controller-specific addresses required to access system memory from a
	DMA bus master.

	@param This The protocol instance pointer.
	@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 PCI 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 PCI controller to use to
	access the hosts HostAddress.
	@param Mapping A resulting value to pass to Unmap().

	@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
	IoMmuMap (
	IN EDKII_IOMMU_PROTOCOL *This,
	IN EDKII_IOMMU_OPERATION Operation,
	IN VOID *HostAddress,
	IN OUT UINTN *NumberOfBytes,
	OUT EFI_PHYSICAL_ADDRESS *DeviceAddress,
	OUT VOID **Mapping
	)
	{
	EFI_STATUS Status;
	EFI_PHYSICAL_ADDRESS PhysicalAddress;
	MAP_INFO *MapInfo;
	EFI_PHYSICAL_ADDRESS DmaMemoryTop;
	BOOLEAN NeedRemap;
	EFI_TPL OriginalTpl;

	if (NumberOfBytes == NULL \|\| DeviceAddress == NULL \|\|
	Mapping == NULL) {
	DEBUG ((DEBUG_ERROR, "IoMmuMap: %r\n", EFI_INVALID_PARAMETER));
	return EFI_INVALID_PARAMETER;
	}

	DEBUG ((DEBUG_VERBOSE, "IoMmuMap: ==> 0x%08x - 0x%08x (%x)\n", HostAddress, *NumberOfBytes, Operation));

	//
	// Make sure that Operation is valid
	//
	if ((UINT32) Operation >= EdkiiIoMmuOperationMaximum) {
	DEBUG ((DEBUG_ERROR, "IoMmuMap: %r\n", EFI_INVALID_PARAMETER));
	return EFI_INVALID_PARAMETER;
	}
	NeedRemap = FALSE;
	PhysicalAddress = (EFI_PHYSICAL_ADDRESS) (UINTN) HostAddress;

	DmaMemoryTop = DMA_MEMORY_TOP;

	//
	// Alignment check
	//
	if ((NumberOfBytes != ALIGN_VALUE(NumberOfBytes, SIZE_4KB)) \|\|
	(PhysicalAddress != ALIGN_VALUE(PhysicalAddress, SIZE_4KB))) {
	if ((Operation == EdkiiIoMmuOperationBusMasterCommonBuffer) \|\|
	(Operation == EdkiiIoMmuOperationBusMasterCommonBuffer64)) {
	//
	// The input buffer might be a subset from IoMmuAllocateBuffer.
	// Skip the check.
	//
	} else {
	NeedRemap = TRUE;
	}
	}

	if ((PhysicalAddress + *NumberOfBytes) >= DMA_MEMORY_TOP) {
	NeedRemap = TRUE;
	}

	if (((Operation != EdkiiIoMmuOperationBusMasterRead64 &&
	Operation != EdkiiIoMmuOperationBusMasterWrite64 &&
	Operation != EdkiiIoMmuOperationBusMasterCommonBuffer64)) &&
	((PhysicalAddress + *NumberOfBytes) > SIZE_4GB)) {
	//
	// If the root bridge or the device cannot handle performing DMA above
	// 4GB but any part of the DMA transfer being mapped is above 4GB, then
	// map the DMA transfer to a buffer below 4GB.
	//
	NeedRemap = TRUE;
	DmaMemoryTop = MIN (DmaMemoryTop, SIZE_4GB - 1);
	}

	if (Operation == EdkiiIoMmuOperationBusMasterCommonBuffer \|\|
	Operation == EdkiiIoMmuOperationBusMasterCommonBuffer64) {
	if (NeedRemap) {
	//
	// Common Buffer operations can not be remapped. If the common buffer
	// is above 4GB, then it is not possible to generate a mapping, so return
	// an error.
	//
	DEBUG ((DEBUG_ERROR, "IoMmuMap: %r\n", EFI_UNSUPPORTED));
	return EFI_UNSUPPORTED;
	}
	}

	//
	// Allocate a MAP_INFO structure to remember the mapping when Unmap() is
	// called later.
	//
	MapInfo = AllocatePool (sizeof (MAP_INFO));
	if (MapInfo == NULL) {
	*NumberOfBytes = 0;
	DEBUG ((DEBUG_ERROR, "IoMmuMap: %r\n", EFI_OUT_OF_RESOURCES));
	return EFI_OUT_OF_RESOURCES;
	}

	//
	// Initialize the MAP_INFO structure
	//
	MapInfo->Signature = MAP_INFO_SIGNATURE;
	MapInfo->Operation = Operation;
	MapInfo->NumberOfBytes = *NumberOfBytes;
	MapInfo->NumberOfPages = EFI_SIZE_TO_PAGES (MapInfo->NumberOfBytes);
	MapInfo->HostAddress = PhysicalAddress;
	MapInfo->DeviceAddress = DmaMemoryTop;

	//
	// Allocate a buffer below 4GB to map the transfer to.
	//
	if (NeedRemap) {
	Status = gBS->AllocatePages (
	AllocateMaxAddress,
	EfiBootServicesData,
	MapInfo->NumberOfPages,
	&MapInfo->DeviceAddress
	);
	if (EFI_ERROR (Status)) {
	FreePool (MapInfo);
	*NumberOfBytes = 0;
	DEBUG ((DEBUG_ERROR, "IoMmuMap: %r\n", Status));
	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 == EdkiiIoMmuOperationBusMasterRead \|\|
	Operation == EdkiiIoMmuOperationBusMasterRead64) {
	CopyMem (
	(VOID *) (UINTN) MapInfo->DeviceAddress,
	(VOID *) (UINTN) MapInfo->HostAddress,
	MapInfo->NumberOfBytes
	);
	}
	} else {
	MapInfo->DeviceAddress = MapInfo->HostAddress;
	}

	OriginalTpl = gBS->RaiseTPL (VTD_TPL_LEVEL);
	InsertTailList (&gMaps, &MapInfo->Link);
	gBS->RestoreTPL (OriginalTpl);

	//
	// The DeviceAddress is the address of the maped buffer below 4GB
	//
	*DeviceAddress = MapInfo->DeviceAddress;
	//
	// Return a pointer to the MAP_INFO structure in Mapping
	//
	*Mapping = MapInfo;

	DEBUG ((DEBUG_VERBOSE, "IoMmuMap: 0x%08x - 0x%08x <==\n", DeviceAddress, Mapping));

	return EFI_SUCCESS;
	}

	/**
	Completes the Map() operation and releases any corresponding resources.

	@param This The protocol instance pointer.
	@param Mapping The mapping value returned from Map().

	@retval EFI_SUCCESS The range was unmapped.
	@retval EFI_INVALID_PARAMETER Mapping is not a value that was returned by Map().
	@retval EFI_DEVICE_ERROR The data was not committed to the target system memory.
	**/
	EFI_STATUS
	EFIAPI
	IoMmuUnmap (
	IN EDKII_IOMMU_PROTOCOL *This,
	IN VOID *Mapping
	)
	{
	MAP_INFO *MapInfo;
	LIST_ENTRY *Link;
	EFI_TPL OriginalTpl;

	DEBUG ((DEBUG_VERBOSE, "IoMmuUnmap: 0x%08x\n", Mapping));

	if (Mapping == NULL) {
	DEBUG ((DEBUG_ERROR, "IoMmuUnmap: %r\n", EFI_INVALID_PARAMETER));
	return EFI_INVALID_PARAMETER;
	}

	OriginalTpl = gBS->RaiseTPL (VTD_TPL_LEVEL);
	MapInfo = NULL;
	for (Link = GetFirstNode (&gMaps)
	; !IsNull (&gMaps, Link)
	; Link = GetNextNode (&gMaps, Link)
	) {
	MapInfo = MAP_INFO_FROM_LINK (Link);
	if (MapInfo == Mapping) {
	break;
	}
	}
	//
	// Mapping is not a valid value returned by Map()
	//
	if (MapInfo != Mapping) {
	gBS->RestoreTPL (OriginalTpl);
	DEBUG ((DEBUG_ERROR, "IoMmuUnmap: %r\n", EFI_INVALID_PARAMETER));
	return EFI_INVALID_PARAMETER;
	}
	RemoveEntryList (&MapInfo->Link);
	gBS->RestoreTPL (OriginalTpl);

	if (MapInfo->DeviceAddress != MapInfo->HostAddress) {
	//
	// 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.
	//
	if (MapInfo->Operation == EdkiiIoMmuOperationBusMasterWrite \|\|
	MapInfo->Operation == EdkiiIoMmuOperationBusMasterWrite64) {
	CopyMem (
	(VOID *) (UINTN) MapInfo->HostAddress,
	(VOID *) (UINTN) MapInfo->DeviceAddress,
	MapInfo->NumberOfBytes
	);
	}

	//
	// Free the mapped buffer and the MAP_INFO structure.
	//
	gBS->FreePages (MapInfo->DeviceAddress, MapInfo->NumberOfPages);
	}

	FreePool (Mapping);
	return EFI_SUCCESS;
	}

	/**
	Allocates pages that are suitable for an OperationBusMasterCommonBuffer or
	OperationBusMasterCommonBuffer64 mapping.

	@param This The protocol instance pointer.
	@param Type This parameter is not used and must be ignored.
	@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.
	@param Attributes The requested bit mask of attributes for 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, MEMORY_CACHED and DUAL_ADDRESS_CYCLE.
	@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
	IoMmuAllocateBuffer (
	IN EDKII_IOMMU_PROTOCOL *This,
	IN EFI_ALLOCATE_TYPE Type,
	IN EFI_MEMORY_TYPE MemoryType,
	IN UINTN Pages,
	IN OUT VOID **HostAddress,
	IN UINT64 Attributes
	)
	{
	EFI_STATUS Status;
	EFI_PHYSICAL_ADDRESS PhysicalAddress;

	DEBUG ((DEBUG_VERBOSE, "IoMmuAllocateBuffer: ==> 0x%08x\n", Pages));

	//
	// Validate Attributes
	//
	if ((Attributes & EDKII_IOMMU_ATTRIBUTE_INVALID_FOR_ALLOCATE_BUFFER) != 0) {
	DEBUG ((DEBUG_ERROR, "IoMmuAllocateBuffer: %r\n", EFI_UNSUPPORTED));
	return EFI_UNSUPPORTED;
	}

	//
	// Check for invalid inputs
	//
	if (HostAddress == NULL) {
	DEBUG ((DEBUG_ERROR, "IoMmuAllocateBuffer: %r\n", EFI_INVALID_PARAMETER));
	return EFI_INVALID_PARAMETER;
	}

	//
	// The only valid memory types are EfiBootServicesData and
	// EfiRuntimeServicesData
	//
	if (MemoryType != EfiBootServicesData &&
	MemoryType != EfiRuntimeServicesData) {
	DEBUG ((DEBUG_ERROR, "IoMmuAllocateBuffer: %r\n", EFI_INVALID_PARAMETER));
	return EFI_INVALID_PARAMETER;
	}

	PhysicalAddress = DMA_MEMORY_TOP;
	if ((Attributes & EDKII_IOMMU_ATTRIBUTE_DUAL_ADDRESS_CYCLE) == 0) {
	//
	// Limit allocations to memory below 4GB
	//
	PhysicalAddress = MIN (PhysicalAddress, SIZE_4GB - 1);
	}
	Status = gBS->AllocatePages (
	AllocateMaxAddress,
	MemoryType,
	Pages,
	&PhysicalAddress
	);
	if (!EFI_ERROR (Status)) {
	HostAddress = (VOID ) (UINTN) PhysicalAddress;
	}

	DEBUG ((DEBUG_VERBOSE, "IoMmuAllocateBuffer: 0x%08x <==\n", *HostAddress));

	return Status;
	}

	/**
	Frees memory that was allocated with AllocateBuffer().

	@param This The protocol instance pointer.
	@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 AllocateBuffer().

	**/
	EFI_STATUS
	EFIAPI
	IoMmuFreeBuffer (
	IN EDKII_IOMMU_PROTOCOL *This,
	IN UINTN Pages,
	IN VOID *HostAddress
	)
	{
	DEBUG ((DEBUG_VERBOSE, "IoMmuFreeBuffer: 0x%\n", Pages));
	return gBS->FreePages ((EFI_PHYSICAL_ADDRESS) (UINTN) HostAddress, Pages);
	}

	/**
	Get device information from mapping.

	@param[in] Mapping The mapping.
	@param[out] DeviceAddress The device address of the mapping.
	@param[out] NumberOfPages The number of pages of the mapping.

	@retval EFI_SUCCESS The device information is returned.
	@retval EFI_INVALID_PARAMETER The mapping is invalid.
	**/
	EFI_STATUS
	GetDeviceInfoFromMapping (
	IN VOID *Mapping,
	OUT EFI_PHYSICAL_ADDRESS *DeviceAddress,
	OUT UINTN *NumberOfPages
	)
	{
	MAP_INFO *MapInfo;
	LIST_ENTRY *Link;

	if (Mapping == NULL) {
	return EFI_INVALID_PARAMETER;
	}

	MapInfo = NULL;
	for (Link = GetFirstNode (&gMaps)
	; !IsNull (&gMaps, Link)
	; Link = GetNextNode (&gMaps, Link)
	) {
	MapInfo = MAP_INFO_FROM_LINK (Link);
	if (MapInfo == Mapping) {
	break;
	}
	}
	//
	// Mapping is not a valid value returned by Map()
	//
	if (MapInfo != Mapping) {
	return EFI_INVALID_PARAMETER;
	}

	*DeviceAddress = MapInfo->DeviceAddress;
	*NumberOfPages = MapInfo->NumberOfPages;
	return EFI_SUCCESS;
	}