Struct vmm_vhost::backend_client::BackendClient

pub struct BackendClient {
    connection: Connection<FrontendReq>,
    virtio_features: u64,
    acked_virtio_features: u64,
    acked_protocol_features: u64,
}

Client for a vhost-user device. The API is a thin abstraction over the vhost-user protocol.

Fields

connection: Connection<FrontendReq>

virtio_features: u64

acked_virtio_features: u64

acked_protocol_features: u64

Implementations

impl BackendClient

pub fn new(connection: Connection<FrontendReq>) -> Self

Create a new instance.

pub fn get_features(&mut self) -> Result<u64>

Get a bitmask of supported virtio/vhost features.

pub fn set_features(&mut self, features: u64) -> Result<()>

Inform the vhost subsystem which features to enable. This should be a subset of supported features from get_features().

pub fn set_owner(&self) -> Result<()>

Set the current process as the owner of the vhost backend. This must be run before any other vhost commands.

pub fn reset_owner(&self) -> Result<()>

Used to be sent to request disabling all rings This is no longer used.

pub fn set_mem_table(&self, regions: &[VhostUserMemoryRegionInfo]) -> Result<()>

Set the memory map regions on the backend so it can translate the vring addresses. In the ancillary data there is an array of file descriptors

pub fn set_log_base(&self, base: u64, fd: Option<RawDescriptor>) -> Result<()>

Set base address for page modification logging.

pub fn set_log_fd(&self, fd: RawDescriptor) -> Result<()>

Specify an event file descriptor to signal on log write.

pub fn set_vring_num(&self, queue_index: usize, num: u16) -> Result<()>

Set the number of descriptors in the vring.

pub fn set_vring_addr( &self, queue_index: usize, config_data: &VringConfigData ) -> Result<()>

Set the addresses for a given vring.

pub fn set_vring_base(&self, queue_index: usize, base: u16) -> Result<()>

Set the first index to look for available descriptors.

pub fn get_vring_base(&self, queue_index: usize) -> Result<u32>

Get the available vring base offset.

pub fn set_vring_call(&self, queue_index: usize, event: &Event) -> Result<()>

Set the event to trigger when buffers have been used by the host.

Bits (0-7) of the payload contain the vring index. Bit 8 is the invalid FD flag. This flag is set when there is no file descriptor in the ancillary data. This signals that polling will be used instead of waiting for the call.

pub fn set_vring_kick(&self, queue_index: usize, event: &Event) -> Result<()>

Set the event that will be signaled by the guest when buffers are available for the host to process.

Bits (0-7) of the payload contain the vring index. Bit 8 is the invalid FD flag. This flag is set when there is no file descriptor in the ancillary data. This signals that polling should be used instead of waiting for a kick.

pub fn set_vring_err(&self, queue_index: usize, event: &Event) -> Result<()>

Set the event that will be signaled by the guest when error happens.

Bits (0-7) of the payload contain the vring index. Bit 8 is the invalid FD flag. This flag is set when there is no file descriptor in the ancillary data.

pub fn set_device_state_fd( &self, transfer_direction: VhostUserTransferDirection, migration_phase: VhostUserMigrationPhase, fd: &impl AsRawDescriptor ) -> Result<Option<File>>

Front-end and back-end negotiate a channel over which to transfer the back-end’s internal state during migration.

Requires VHOST_USER_PROTOCOL_F_DEVICE_STATE to be negotiated.

pub fn check_device_state(&self) -> Result<()>

After transferring the back-end’s internal state during migration, check whether the back-end was able to successfully fully process the state.

pub fn get_protocol_features(&self) -> Result<VhostUserProtocolFeatures>

Get the protocol feature bitmask from the underlying vhost implementation.

pub fn set_protocol_features( &mut self, features: VhostUserProtocolFeatures ) -> Result<()>

Enable protocol features in the underlying vhost implementation.

pub fn get_queue_num(&self) -> Result<u64>

Query how many queues the backend supports.

pub fn set_vring_enable(&self, queue_index: usize, enable: bool) -> Result<()>

Signal backend to enable or disable corresponding vring.

Backend must not pass data to/from the ring until ring is enabled by VHOST_USER_SET_VRING_ENABLE with parameter 1, or after it has been disabled by VHOST_USER_SET_VRING_ENABLE with parameter 0.

pub fn get_config( &self, offset: u32, size: u32, flags: VhostUserConfigFlags, buf: &[u8] ) -> Result<(VhostUserConfig, VhostUserConfigPayload)>

Fetch the contents of the virtio device configuration space.

pub fn set_config( &self, offset: u32, flags: VhostUserConfigFlags, buf: &[u8] ) -> Result<()>

Change the virtio device configuration space. It also can be used for live migration on the destination host to set readonly configuration space fields.

pub fn set_backend_req_fd(&self, fd: &dyn AsRawDescriptor) -> Result<()>

Setup backend communication channel.

pub fn get_inflight_fd( &self, inflight: &VhostUserInflight ) -> Result<(VhostUserInflight, File)>

Retrieve shared buffer for inflight I/O tracking.

pub fn set_inflight_fd( &self, inflight: &VhostUserInflight, fd: RawDescriptor ) -> Result<()>

Set shared buffer for inflight I/O tracking.

pub fn get_max_mem_slots(&self) -> Result<u64>

Query the maximum amount of memory slots supported by the backend.

pub fn add_mem_region(&self, region: &VhostUserMemoryRegionInfo) -> Result<()>

Add a new guest memory mapping for vhost to use.

pub fn remove_mem_region( &self, region: &VhostUserMemoryRegionInfo ) -> Result<()>

Remove a guest memory mapping from vhost.

pub fn get_shared_memory_regions(&self) -> Result<Vec<VhostSharedMemoryRegion>>

Gets the shared memory regions used by the device.

fn send_request_header( &self, code: FrontendReq, fds: Option<&[RawDescriptor]> ) -> VhostUserResult<VhostUserMsgHeader<FrontendReq>>

fn send_request_with_body<T: Sized + AsBytes>( &self, code: FrontendReq, msg: &T, fds: Option<&[RawDescriptor]> ) -> VhostUserResult<VhostUserMsgHeader<FrontendReq>>

fn send_request_with_payload<T: Sized + AsBytes>( &self, code: FrontendReq, msg: &T, payload: &[u8], fds: Option<&[RawDescriptor]> ) -> VhostUserResult<VhostUserMsgHeader<FrontendReq>>

fn send_fd_for_vring( &self, code: FrontendReq, queue_index: usize, fd: RawDescriptor ) -> VhostUserResult<VhostUserMsgHeader<FrontendReq>>

fn recv_reply<T: Sized + FromBytes + AsBytes + Default + VhostUserMsgValidator>( &self, hdr: &VhostUserMsgHeader<FrontendReq> ) -> VhostUserResult<T>

fn recv_reply_with_files<T: Sized + AsBytes + FromBytes + Default + VhostUserMsgValidator>( &self, hdr: &VhostUserMsgHeader<FrontendReq> ) -> VhostUserResult<(T, Vec<File>)>

fn recv_reply_with_payload<T: Sized + AsBytes + FromBytes + Default + VhostUserMsgValidator>( &self, hdr: &VhostUserMsgHeader<FrontendReq> ) -> VhostUserResult<(T, Vec<u8>, Vec<File>)>

fn wait_for_ack( &self, hdr: &VhostUserMsgHeader<FrontendReq> ) -> VhostUserResult<()>

fn is_feature_mq_available(&self) -> bool

fn new_request_header( &self, request: FrontendReq, size: u32 ) -> VhostUserMsgHeader<FrontendReq>

Trait Implementations

impl ReadNotifier for BackendClient

fn get_read_notifier(&self) -> &dyn AsRawDescriptor

Gets a descriptor that can be used in EventContext to wait for events to be available (e.g. to avoid receive_events blocking).