VirtioLib.h File Reference

Data Structures
struct	DESC_INDICES

Functions
EFI_STATUS EFIAPI	VirtioRingInit (IN VIRTIO_DEVICE_PROTOCOL *VirtIo, IN UINT16 QueueSize, OUT VRING *Ring)
EFI_STATUS EFIAPI	VirtioRingMap (IN VIRTIO_DEVICE_PROTOCOL *VirtIo, IN VRING *Ring, OUT UINT64 *RingBaseShift, OUT VOID **Mapping)
VOID EFIAPI	VirtioRingUninit (IN VIRTIO_DEVICE_PROTOCOL *VirtIo, IN OUT VRING *Ring)
VOID EFIAPI	VirtioPrepare (IN OUT VRING *Ring, OUT DESC_INDICES *Indices)
VOID EFIAPI	VirtioAppendDesc (IN OUT VRING *Ring, IN UINT64 BufferDeviceAddress, IN UINT32 BufferSize, IN UINT16 Flags, IN OUT DESC_INDICES *Indices)
EFI_STATUS EFIAPI	VirtioFlush (IN VIRTIO_DEVICE_PROTOCOL *VirtIo, IN UINT16 VirtQueueId, IN OUT VRING *Ring, IN DESC_INDICES *Indices, OUT UINT32 *UsedLen)
EFI_STATUS EFIAPI	Virtio10WriteFeatures (IN VIRTIO_DEVICE_PROTOCOL *VirtIo, IN UINT64 Features, IN OUT UINT8 *DeviceStatus)
EFI_STATUS EFIAPI	VirtioMapAllBytesInSharedBuffer (IN VIRTIO_DEVICE_PROTOCOL *VirtIo, IN VIRTIO_MAP_OPERATION Operation, IN VOID *HostAddress, IN UINTN NumberOfBytes, OUT EFI_PHYSICAL_ADDRESS *DeviceAddress, OUT VOID **Mapping)

Detailed Description

Declarations of utility functions used by virtio device drivers.

Copyright (C) 2012-2016, Red Hat, Inc. Copyright (C) 2017, AMD Inc, All rights reserved.

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

Function Documentation

EFI_STATUS EFIAPI Virtio10WriteFeatures	(	IN VIRTIO_DEVICE_PROTOCOL *	VirtIo,
		IN UINT64	Features,
		IN OUT UINT8 *	DeviceStatus
	)

Report the feature bits to the VirtIo 1.0 device that the VirtIo 1.0 driver understands.

In VirtIo 1.0, a device can reject a self-inconsistent feature bitmap through the new VSTAT_FEATURES_OK status bit. (For example if the driver requests a higher level feature but clears a prerequisite feature.) This function is a small wrapper around VIRTIO_DEVICE_PROTOCOL.SetGuestFeatures() that also verifies if the VirtIo 1.0 device accepts the feature bitmap.

Parameters

[in]	VirtIo	Report feature bits to this device.
[in]	Features	The set of feature bits that the driver wishes to report. The caller is responsible to perform any masking before calling this function; the value is directly written with VIRTIO_DEVICE_PROTOCOL.SetGuestFeatures().
[in,out]	DeviceStatus	On input, the status byte most recently written to the device's status register. On output (even on error), DeviceStatus will be updated so that it is suitable for further status bit manipulation and writing to the device's status register.

Return values

EFI_SUCCESS

The device accepted the configuration in Features.

Returns

EFI_UNSUPPORTED The device rejected the configuration in Features.

Return values

EFI_UNSUPPORTED

VirtIo->Revision is smaller than 1.0.0.

Returns

Error codes from the SetGuestFeatures(), SetDeviceStatus(), GetDeviceStatus() member functions.

VOID EFIAPI VirtioAppendDesc	(	IN OUT VRING *	Ring,
		IN UINT64	BufferDeviceAddress,
		IN UINT32	BufferSize,
		IN UINT16	Flags,
		IN OUT DESC_INDICES *	Indices
	)

Append a contiguous buffer for transmission / reception via the virtio ring.

This function implements the following section from virtio-0.9.5:

• 2.4.1.1 Placing Buffers into the Descriptor Table

Free space is taken as granted, since the individual drivers support only synchronous requests and host side status is processed in lock-step with request submission. It is the calling driver's responsibility to verify the ring size in advance.

The caller is responsible for initializing *Indices with VirtioPrepare() first.

Parameters

[in,out]	Ring	The virtio ring to append the buffer to, as a descriptor.
[in]	BufferDeviceAddress	(Bus master device) start address of the transmit / receive buffer.
[in]	BufferSize	Number of bytes to transmit or receive.
[in]	Flags	A bitmask of VRING_DESC_F_* flags. The caller computes this mask dependent on further buffers to append and transfer direction. VRING_DESC_F_INDIRECT is unsupported. The VRING_DESC.Next field is always set, but the host only interprets it dependent on VRING_DESC_F_NEXT.
[in,out]	Indices	Indices->HeadDescIdx is not accessed. On input, Indices->NextDescIdx identifies the next descriptor to carry the buffer. On output, Indices->NextDescIdx is incremented by one, modulo 2^16.

EFI_STATUS EFIAPI VirtioFlush	(	IN VIRTIO_DEVICE_PROTOCOL *	VirtIo,
		IN UINT16	VirtQueueId,
		IN OUT VRING *	Ring,
		IN DESC_INDICES *	Indices,
		OUT UINT32 *	UsedLen
	)

Notify the host about the descriptor chain just built, and wait until the host processes it.

Parameters

[in]	VirtIo	The target virtio device to notify.
[in]	VirtQueueId	Identifies the queue for the target device.
[in,out]	Ring	The virtio ring with descriptors to submit.
[in]	Indices	Indices->NextDescIdx is not accessed. Indices->HeadDescIdx identifies the head descriptor of the descriptor chain.
[out]	UsedLen	On success, the total number of bytes, consecutively across the buffers linked by the descriptor chain, that the host wrote. May be NULL if the caller doesn't care, or can compute the same information from device-specific request structures linked by the descriptor chain.

Returns

Error code from VirtIo->SetQueueNotify() if it fails.

Return values

EFI_SUCCESS

Otherwise, the host processed all descriptors.

EFI_STATUS EFIAPI VirtioMapAllBytesInSharedBuffer	(	IN VIRTIO_DEVICE_PROTOCOL *	VirtIo,
		IN VIRTIO_MAP_OPERATION	Operation,
		IN VOID *	HostAddress,
		IN UINTN	NumberOfBytes,
		OUT EFI_PHYSICAL_ADDRESS *	DeviceAddress,
		OUT VOID **	Mapping
	)

Provides the virtio device address required to access system memory from a DMA bus master.

The interface follows the same usage pattern as defined in UEFI spec 2.6 (Section 13.2 PCI Root Bridge I/O Protocol)

The VirtioMapAllBytesInSharedBuffer() is similar to VIRTIO_MAP_SHARED with exception that NumberOfBytes is IN-only parameter. The function maps all the bytes specified in NumberOfBytes param in one consecutive range.

Parameters

[in]	VirtIo	The virtio device for which the mapping is requested.
[in]	Operation	Indicates if the bus master is going to read or write to system memory.
[in]	HostAddress	The system memory address to map to shared buffer address.
[in]	NumberOfBytes	Number of bytes to map.
[out]	DeviceAddress	The resulting shared map address for the bus master to access the hosts HostAddress.
[out]	Mapping	A resulting token to pass to VIRTIO_UNMAP_SHARED.

Return values

EFI_SUCCESS	The NumberOfBytes is successfully mapped.
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. This includes the case when NumberOfBytes bytes cannot be mapped in one consecutive range.
EFI_DEVICE_ERROR	The system hardware could not map the requested address.

VOID EFIAPI VirtioPrepare	(	IN OUT VRING *	Ring,
		OUT DESC_INDICES *	Indices
	)

Turn off interrupt notifications from the host, and prepare for appending multiple descriptors to the virtio ring.

The calling driver must be in VSTAT_DRIVER_OK state.

Parameters

[in,out]	Ring	The virtio ring we intend to append descriptors to.
[out]	Indices	The DESC_INDICES structure to initialize.

EFI_STATUS EFIAPI VirtioRingInit	(	IN VIRTIO_DEVICE_PROTOCOL *	VirtIo,
		IN UINT16	QueueSize,
		OUT VRING *	Ring
	)

Configure a virtio ring.

This function sets up internal storage (the guest-host communication area) and lays out several "navigation" (ie. no-ownership) pointers to parts of that storage.

Relevant sections from the virtio-0.9.5 spec:

• 1.1 Virtqueues,
• 2.3 Virtqueue Configuration.

Parameters

[in]	VirtIo	The virtio device which will use the ring.
[in]	The	number of descriptors to allocate for the virtio ring, as requested by the host.
[out]	Ring	The virtio ring to set up.

Returns

Status codes propagated from VirtIo->AllocateSharedPages().

Return values

EFI_SUCCESS

Allocation and setup successful. Ring->Base (and nothing else) is responsible for deallocation.

EFI_STATUS EFIAPI VirtioRingMap	(	IN VIRTIO_DEVICE_PROTOCOL *	VirtIo,
		IN VRING *	Ring,
		OUT UINT64 *	RingBaseShift,
		OUT VOID **	Mapping
	)

Map the ring buffer so that it can be accessed equally by both guest and hypervisor.

Parameters

[in]	VirtIo	The virtio device instance.
[in]	Ring	The virtio ring to map.
[out]	RingBaseShift	A resulting translation offset, to be passed to VirtIo->SetQueueAddress().
[out]	Mapping	A resulting token to pass to VirtIo->UnmapSharedBuffer().

Returns

Status code from VirtIo->MapSharedBuffer()

VOID EFIAPI VirtioRingUninit	(	IN VIRTIO_DEVICE_PROTOCOL *	VirtIo,
		IN OUT VRING *	Ring
	)

Tear down the internal resources of a configured virtio ring.

The caller is responsible to stop the host from using this ring before invoking this function: the VSTAT_DRIVER_OK bit must be clear in VhdrDeviceStatus.

Parameters

[in]	VirtIo	The virtio device which was using the ring.
[out]	Ring	The virtio ring to clean up.