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Diffstat (limited to 'vhost_rs/src/vhost_user/mod.rs')
| -rw-r--r-- | vhost_rs/src/vhost_user/mod.rs | 251 |
1 files changed, 251 insertions, 0 deletions
diff --git a/vhost_rs/src/vhost_user/mod.rs b/vhost_rs/src/vhost_user/mod.rs new file mode 100644 index 0000000..af2c6d1 --- /dev/null +++ b/vhost_rs/src/vhost_user/mod.rs @@ -0,0 +1,251 @@ +// Copyright (C) 2019 Alibaba Cloud Computing. All rights reserved. +// SPDX-License-Identifier: Apache-2.0 + +//! The protocol for vhost-user is based on the existing implementation of vhost for the Linux +//! Kernel. The protocol defines two sides of the communication, master and slave. Master is +//! the application that shares its virtqueues. Slave is the consumer of the virtqueues. +//! +//! The communication channel between the master and the slave includes two sub channels. One is +//! used to send requests from the master to the slave and optional replies from the slave to the +//! master. This sub channel is created on master startup by connecting to the slave service +//! endpoint. The other is used to send requests from the slave to the master and optional replies +//! from the master to the slave. This sub channel is created by the master issuing a +//! VHOST_USER_SET_SLAVE_REQ_FD request to the slave with an auxiliary file descriptor. +//! +//! Unix domain socket is used as the underlying communication channel because the master needs to +//! send file descriptors to the slave. +//! +//! Most messages that can be sent via the Unix domain socket implementing vhost-user have an +//! equivalent ioctl to the kernel implementation. + +use libc; +use std::io::Error as IOError; + +mod connection; +pub mod message; +pub use self::connection::Listener; +#[cfg(feature = "vhost-user-master")] +mod master; +#[cfg(feature = "vhost-user-master")] +pub use self::master::{Master, VhostUserMaster}; +#[cfg(feature = "vhost-user-master")] +mod master_req_handler; +#[cfg(feature = "vhost-user-master")] +pub use self::master_req_handler::{MasterReqHandler, VhostUserMasterReqHandler}; + +#[cfg(feature = "vhost-user-slave")] +mod slave; +#[cfg(feature = "vhost-user-slave")] +pub use self::slave::SlaveListener; +#[cfg(feature = "vhost-user-slave")] +mod slave_req_handler; +#[cfg(feature = "vhost-user-slave")] +pub use self::slave_req_handler::{SlaveReqHandler, VhostUserSlaveReqHandler}; + +pub mod sock_ctrl_msg; + +/// Errors for vhost-user operations +#[derive(Debug)] +pub enum Error { + /// Invalid parameters. + InvalidParam, + /// Unsupported operations due to that the protocol feature hasn't been negotiated. + InvalidOperation, + /// Invalid message format, flag or content. + InvalidMessage, + /// Only part of a message have been sent or received successfully + PartialMessage, + /// Message is too large + OversizedMsg, + /// Fd array in question is too big or too small + IncorrectFds, + /// Can't connect to peer. + SocketConnect(std::io::Error), + /// Generic socket errors. + SocketError(std::io::Error), + /// The socket is broken or has been closed. + SocketBroken(std::io::Error), + /// Should retry the socket operation again. + SocketRetry(std::io::Error), + /// Failure from the slave side. + SlaveInternalError, + /// Virtio/protocol features mismatch. + FeatureMismatch, + /// Error from request handler + ReqHandlerError(IOError), +} + +impl std::fmt::Display for Error { + fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result { + match self { + Error::InvalidParam => write!(f, "invalid parameters"), + Error::InvalidOperation => write!(f, "invalid operation"), + Error::InvalidMessage => write!(f, "invalid message"), + Error::PartialMessage => write!(f, "partial message"), + Error::OversizedMsg => write!(f, "oversized message"), + Error::IncorrectFds => write!(f, "wrong number of attached fds"), + Error::SocketError(e) => write!(f, "socket error: {}", e), + Error::SocketConnect(e) => write!(f, "can't connect to peer: {}", e), + Error::SocketBroken(e) => write!(f, "socket is broken: {}", e), + Error::SocketRetry(e) => write!(f, "temporary socket error: {}", e), + Error::SlaveInternalError => write!(f, "slave internal error"), + Error::FeatureMismatch => write!(f, "virtio/protocol features mismatch"), + Error::ReqHandlerError(e) => write!(f, "handler failed to handle request: {}", e), + } + } +} + +impl Error { + /// Determine whether to rebuild the underline communication channel. + pub fn should_reconnect(&self) -> bool { + match *self { + // Should reconnect because it may be caused by temporary network errors. + Error::PartialMessage => true, + // Should reconnect because the underline socket is broken. + Error::SocketBroken(_) => true, + // Slave internal error, hope it recovers on reconnect. + Error::SlaveInternalError => true, + // Should just retry the IO operation instead of rebuilding the underline connection. + Error::SocketRetry(_) => false, + Error::InvalidParam | Error::InvalidOperation => false, + Error::InvalidMessage | Error::IncorrectFds | Error::OversizedMsg => false, + Error::SocketError(_) | Error::SocketConnect(_) => false, + Error::FeatureMismatch => false, + Error::ReqHandlerError(_) => false, + } + } +} + +impl std::convert::From<vmm_sys_util::errno::Error> for Error { + /// Convert raw socket errors into meaningful vhost-user errors. + /// + /// The vmm_sys_util::errno::Error is a simple wrapper over the raw errno, which doesn't means much + /// to the vhost-user connection manager. So convert it into meaningful errors to simplify + /// the connection manager logic. + /// + /// # Return: + /// * - Error::SocketRetry: temporary error caused by signals or short of resources. + /// * - Error::SocketBroken: the underline socket is broken. + /// * - Error::SocketError: other socket related errors. + #[allow(unreachable_patterns)] // EWOULDBLOCK equals to EGAIN on linux + fn from(err: vmm_sys_util::errno::Error) -> Self { + match err.errno() { + // The socket is marked nonblocking and the requested operation would block. + libc::EAGAIN => Error::SocketRetry(IOError::from_raw_os_error(libc::EAGAIN)), + // The socket is marked nonblocking and the requested operation would block. + libc::EWOULDBLOCK => Error::SocketRetry(IOError::from_raw_os_error(libc::EWOULDBLOCK)), + // A signal occurred before any data was transmitted + libc::EINTR => Error::SocketRetry(IOError::from_raw_os_error(libc::EINTR)), + // The output queue for a network interface was full. This generally indicates + // that the interface has stopped sending, but may be caused by transient congestion. + libc::ENOBUFS => Error::SocketRetry(IOError::from_raw_os_error(libc::ENOBUFS)), + // No memory available. + libc::ENOMEM => Error::SocketRetry(IOError::from_raw_os_error(libc::ENOMEM)), + // Connection reset by peer. + libc::ECONNRESET => Error::SocketBroken(IOError::from_raw_os_error(libc::ECONNRESET)), + // The local end has been shut down on a connection oriented socket. In this case the + // process will also receive a SIGPIPE unless MSG_NOSIGNAL is set. + libc::EPIPE => Error::SocketBroken(IOError::from_raw_os_error(libc::EPIPE)), + // Write permission is denied on the destination socket file, or search permission is + // denied for one of the directories the path prefix. + libc::EACCES => Error::SocketConnect(IOError::from_raw_os_error(libc::EACCES)), + // Catch all other errors + e => Error::SocketError(IOError::from_raw_os_error(e)), + } + } +} + +/// Result of vhost-user operations +pub type Result<T> = std::result::Result<T, Error>; + +/// Result of request handler. +pub type HandlerResult<T> = std::result::Result<T, IOError>; + +#[cfg(all(test, feature = "vhost-user-master", feature = "vhost-user-slave"))] +mod dummy_slave; + +#[cfg(all(test, feature = "vhost-user-master", feature = "vhost-user-slave"))] +mod tests { + use super::dummy_slave::{DummySlaveReqHandler, VIRTIO_FEATURES}; + use super::message::*; + use super::*; + use crate::backend::VhostBackend; + use std::sync::{Arc, Barrier, Mutex}; + use std::thread; + + fn create_slave<S: VhostUserSlaveReqHandler>( + path: &str, + backend: Arc<Mutex<S>>, + ) -> (Master, SlaveReqHandler<S>) { + let mut slave_listener = SlaveListener::new(path, true, backend).unwrap(); + let master = Master::connect(path).unwrap(); + (master, slave_listener.accept().unwrap().unwrap()) + } + + #[test] + fn create_dummy_slave() { + let mut slave = DummySlaveReqHandler::new(); + + slave.set_owner().unwrap(); + assert!(slave.set_owner().is_err()); + } + + #[test] + fn test_set_owner() { + let slave_be = Arc::new(Mutex::new(DummySlaveReqHandler::new())); + let (mut master, mut slave) = + create_slave("/tmp/vhost_user_lib_unit_test_owner", slave_be.clone()); + + assert_eq!(slave_be.lock().unwrap().owned, false); + master.set_owner().unwrap(); + slave.handle_request().unwrap(); + assert_eq!(slave_be.lock().unwrap().owned, true); + master.set_owner().unwrap(); + assert!(slave.handle_request().is_err()); + assert_eq!(slave_be.lock().unwrap().owned, true); + } + + #[test] + fn test_set_features() { + let mbar = Arc::new(Barrier::new(2)); + let sbar = mbar.clone(); + let slave_be = Arc::new(Mutex::new(DummySlaveReqHandler::new())); + let (mut master, mut slave) = + create_slave("/tmp/vhost_user_lib_unit_test_feature", slave_be.clone()); + + thread::spawn(move || { + slave.handle_request().unwrap(); + assert_eq!(slave_be.lock().unwrap().owned, true); + + slave.handle_request().unwrap(); + slave.handle_request().unwrap(); + assert_eq!( + slave_be.lock().unwrap().acked_features, + VIRTIO_FEATURES & !0x1 + ); + + slave.handle_request().unwrap(); + slave.handle_request().unwrap(); + assert_eq!( + slave_be.lock().unwrap().acked_protocol_features, + VhostUserProtocolFeatures::all().bits() + ); + + sbar.wait(); + }); + + master.set_owner().unwrap(); + + // set virtio features + let features = master.get_features().unwrap(); + assert_eq!(features, VIRTIO_FEATURES); + master.set_features(VIRTIO_FEATURES & !0x1).unwrap(); + + // set vhost protocol features + let features = master.get_protocol_features().unwrap(); + assert_eq!(features.bits(), VhostUserProtocolFeatures::all().bits()); + master.set_protocol_features(features).unwrap(); + + mbar.wait(); + } +} |