#include <Library/PcdLib.h>
#include <ConfidentialComputingGuestAttr.h>
#include "CcIoMmu.h"
#include "IoMmuInternal.h"

Functions
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)

STATIC EFI_STATUS EFIAPI	IoMmuUnmapWorker (IN EDKII_IOMMU_PROTOCOL This, IN VOID Mapping, IN BOOLEAN MemoryMapLocked)

EFI_STATUS EFIAPI	IoMmuUnmap (IN EDKII_IOMMU_PROTOCOL This, IN VOID Mapping)

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 EFIAPI	IoMmuFreeBuffer (IN EDKII_IOMMU_PROTOCOL This, IN UINTN Pages, IN VOID HostAddress)

EFI_STATUS EFIAPI	IoMmuSetAttribute (IN EDKII_IOMMU_PROTOCOL This, IN EFI_HANDLE DeviceHandle, IN VOID Mapping, IN UINT64 IoMmuAccess)

STATIC VOID EFIAPI	IoMmuExitBoot (IN EFI_EVENT Event, IN VOID *EventToSignal)

STATIC VOID EFIAPI	IoMmuUnmapAllMappings (IN EFI_EVENT Event, IN VOID *Context)

EFI_STATUS EFIAPI	InstallIoMmuProtocol (VOID)

Variables
STATIC LIST_ENTRY	mMapInfos = INITIALIZE_LIST_HEAD_VARIABLE (mMapInfos)

BOOLEAN	mReservedSharedMemSupported = FALSE

STATIC CONST CHAR8 *CONST	mBusMasterOperationName [EdkiiIoMmuOperationMaximum]

EDKII_IOMMU_PROTOCOL	mIoMmu

Detailed Description

The protocol provides support to allocate, free, map and umap a DMA buffer for bus master (e.g PciHostBridge). When SEV or TDX is enabled, the DMA operations must be performed on unencrypted buffer hence we use a bounce buffer to map the guest buffer into an unencrypted DMA buffer.

SPDX-License-Identifier: BSD-2-Clause-Patent

Definition in file CcIoMmu.c.

Function Documentation

◆ InstallIoMmuProtocol()

EFI_STATUS EFIAPI InstallIoMmuProtocol ( VOID )

Initialize Iommu Protocol.

Definition at line 929 of file CcIoMmu.c.

◆ IoMmuAllocateBuffer()

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
	)

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

Parameters

This	The protocol instance pointer.
Type	This parameter is not used and must be ignored.
MemoryType	The type of memory to allocate, EfiBootServicesData or EfiRuntimeServicesData.
Pages	The number of pages to allocate.
HostAddress	A pointer to store the base system memory address of the allocated range.
Attributes	The requested bit mask of attributes for the allocated range.

Return values

EFI_SUCCESS	The requested memory pages were allocated.
EFI_UNSUPPORTED	Attributes is unsupported. The only legal attribute bits are MEMORY_WRITE_COMBINE and MEMORY_CACHED.
EFI_INVALID_PARAMETER	One or more parameters are invalid.
EFI_OUT_OF_RESOURCES	The memory pages could not be allocated.

Definition at line 521 of file CcIoMmu.c.

◆ IoMmuExitBoot()

STATIC VOID EFIAPI IoMmuExitBoot	(	IN EFI_EVENT	Event,
		IN VOID *	EventToSignal
	)

Notification function that is queued when gBS->ExitBootServices() signals the EFI_EVENT_GROUP_EXIT_BOOT_SERVICES event group. This function signals another event, received as Context, and returns.

Signaling an event in this context is safe. The UEFI spec allows gBS->SignalEvent() to return EFI_SUCCESS only; EFI_OUT_OF_RESOURCES is not listed, hence memory is not allocated. The edk2 implementation also does not release memory (and we only have to care about the edk2 implementation because EDKII_IOMMU_PROTOCOL is edk2-specific anyway).

Parameters

[in]	Event	Event whose notification function is being invoked. Event is permitted to request the queueing of this function at TPL_CALLBACK or TPL_NOTIFY task priority level.
[in]	EventToSignal	Identifies the EFI_EVENT to signal. EventToSignal is permitted to request the queueing of its notification function only at TPL_CALLBACK level.

Definition at line 840 of file CcIoMmu.c.

◆ IoMmuFreeBuffer()

EFI_STATUS EFIAPI IoMmuFreeBuffer	(	IN EDKII_IOMMU_PROTOCOL *	This,
		IN UINTN	Pages,
		IN VOID *	HostAddress
	)

Frees memory that was allocated with AllocateBuffer().

Parameters

This	The protocol instance pointer.
Pages	The number of pages to free.
HostAddress	The base system memory address of the allocated range.

Return values

EFI_SUCCESS	The requested memory pages were freed.
EFI_INVALID_PARAMETER	The memory range specified by HostAddress and Pages was not allocated with AllocateBuffer().

Definition at line 654 of file CcIoMmu.c.

◆ IoMmuMap()

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
	)

Provides the controller-specific addresses required to access system memory from a DMA bus master. On SEV/TDX guest, the DMA operations must be performed on shared buffer hence we allocate a bounce buffer to map the HostAddress to a DeviceAddress. The Encryption attribute is removed from the DeviceAddress buffer.

Parameters

This	The protocol instance pointer.
Operation	Indicates if the bus master is going to read or write to system memory.
HostAddress	The system memory address to map to the PCI controller.
NumberOfBytes	On input the number of bytes to map. On output the number of bytes that were mapped.
DeviceAddress	The resulting map address for the bus master PCI controller to use to access the hosts HostAddress.
Mapping	A resulting value to pass to Unmap().

Return values

EFI_SUCCESS	The range was mapped for the returned NumberOfBytes.
EFI_UNSUPPORTED	The HostAddress cannot be mapped as a common buffer.
EFI_INVALID_PARAMETER	One or more parameters are invalid.
EFI_OUT_OF_RESOURCES	The request could not be completed due to a lack of resources.
EFI_DEVICE_ERROR	The system hardware could not map the requested address.

Definition at line 77 of file CcIoMmu.c.

◆ IoMmuSetAttribute()

EFI_STATUS EFIAPI IoMmuSetAttribute	(	IN EDKII_IOMMU_PROTOCOL *	This,
		IN EFI_HANDLE	DeviceHandle,
		IN VOID *	Mapping,
		IN UINT64	IoMmuAccess
	)

Set IOMMU attribute for a system memory.

If the IOMMU protocol exists, the system memory cannot be used for DMA by default.

When a device requests a DMA access for a system memory, the device driver need use SetAttribute() to update the IOMMU attribute to request DMA access (read and/or write).

The DeviceHandle is used to identify which device submits the request. The IOMMU implementation need translate the device path to an IOMMU device ID, and set IOMMU hardware register accordingly. 1) DeviceHandle can be a standard PCI device. The memory for BusMasterRead need set EDKII_IOMMU_ACCESS_READ. The memory for BusMasterWrite need set EDKII_IOMMU_ACCESS_WRITE. The memory for BusMasterCommonBuffer need set EDKII_IOMMU_ACCESS_READ|EDKII_IOMMU_ACCESS_WRITE. After the memory is used, the memory need set 0 to keep it being protected. 2) DeviceHandle can be an ACPI device (ISA, I2C, SPI, etc). The memory for DMA access need set EDKII_IOMMU_ACCESS_READ and/or EDKII_IOMMU_ACCESS_WRITE.

Parameters

[in]	This	The protocol instance pointer.
[in]	DeviceHandle	The device who initiates the DMA access request.
[in]	Mapping	The mapping value returned from Map().
[in]	IoMmuAccess	The IOMMU access.

Return values

EFI_SUCCESS	The IoMmuAccess is set for the memory range specified by DeviceAddress and Length.
EFI_INVALID_PARAMETER	DeviceHandle is an invalid handle.
EFI_INVALID_PARAMETER	Mapping is not a value that was returned by Map().
EFI_INVALID_PARAMETER	IoMmuAccess specified an illegal combination of access.
EFI_UNSUPPORTED	DeviceHandle is unknown by the IOMMU.
EFI_UNSUPPORTED	The bit mask of IoMmuAccess is not supported by the IOMMU.
EFI_UNSUPPORTED	The IOMMU does not support the memory range specified by Mapping.
EFI_OUT_OF_RESOURCES	There are not enough resources available to modify the IOMMU access.
EFI_DEVICE_ERROR	The IOMMU device reported an error while attempting the operation.

Definition at line 747 of file CcIoMmu.c.

◆ IoMmuUnmap()

EFI_STATUS EFIAPI IoMmuUnmap	(	IN EDKII_IOMMU_PROTOCOL *	This,
		IN VOID *	Mapping
	)

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

Parameters

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

Return values

EFI_SUCCESS	The range was unmapped.
EFI_INVALID_PARAMETER	Mapping is not a value that was returned by Map().
EFI_DEVICE_ERROR	The data was not committed to the target system memory.

Definition at line 485 of file CcIoMmu.c.

◆ IoMmuUnmapAllMappings()

STATIC VOID EFIAPI IoMmuUnmapAllMappings	(	IN EFI_EVENT	Event,
		IN VOID *	Context
	)

Notification function that is queued after the notification functions of all events in the EFI_EVENT_GROUP_EXIT_BOOT_SERVICES event group. The same memory map restrictions apply.

This function unmaps all currently existing IOMMU mappings.

Parameters

[in]	Event	Event whose notification function is being invoked. Event is permitted to request the queueing of this function only at TPL_CALLBACK task priority level.
[in]	Context	Ignored.

Definition at line 892 of file CcIoMmu.c.

◆ IoMmuUnmapWorker()

STATIC EFI_STATUS EFIAPI IoMmuUnmapWorker	(	IN EDKII_IOMMU_PROTOCOL *	This,
		IN VOID *	Mapping,
		IN BOOLEAN	MemoryMapLocked
	)

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

This is an internal worker function that only extends the Map() API with the MemoryMapLocked parameter.

Parameters

This	The protocol instance pointer.
Mapping	The mapping value returned from Map().
MemoryMapLocked	The function is executing on the stack of gBS->ExitBootServices(); changes to the UEFI memory map are forbidden.

Return values

EFI_SUCCESS	The range was unmapped.
EFI_INVALID_PARAMETER	Mapping is not a value that was returned by Map().
EFI_DEVICE_ERROR	The data was not committed to the target system memory.

Definition at line 331 of file CcIoMmu.c.

Variable Documentation

◆ mBusMasterOperationName

STATIC CONST CHAR8* CONST mBusMasterOperationName[EdkiiIoMmuOperationMaximum]

Initial value:

= {
  "Read",
  "Write",
  "CommonBuffer",
  "Read64",
  "Write64",
  "CommonBuffer64"
}

Definition at line 36 of file CcIoMmu.c.

◆ mIoMmu

EDKII_IOMMU_PROTOCOL mIoMmu

Initial value:

= {
  EDKII_IOMMU_PROTOCOL_REVISION,
  IoMmuSetAttribute,
  IoMmuMap,
  IoMmuUnmap,
  IoMmuAllocateBuffer,
  IoMmuFreeBuffer,
}

Definition at line 808 of file CcIoMmu.c.

◆ mMapInfos

STATIC LIST_ENTRY mMapInfos = INITIALIZE_LIST_HEAD_VARIABLE (mMapInfos)

Definition at line 25 of file CcIoMmu.c.

◆ mReservedSharedMemSupported

BOOLEAN mReservedSharedMemSupported = FALSE

Definition at line 30 of file CcIoMmu.c.

Functions

Variables

Detailed Description

Function Documentation

◆ InstallIoMmuProtocol()

◆ IoMmuAllocateBuffer()

◆ IoMmuExitBoot()

◆ IoMmuFreeBuffer()

◆ IoMmuMap()

◆ IoMmuSetAttribute()

◆ IoMmuUnmap()

◆ IoMmuUnmapAllMappings()

◆ IoMmuUnmapWorker()

Variable Documentation

◆ mBusMasterOperationName

◆ mIoMmu

◆ mMapInfos

◆ mReservedSharedMemSupported