vm-virtio: Add virtio-vsock skeleton

This is the first commit introducing the support for virtio-vsock.

This is based off of Firecracker commit
1e1cb6f8f8003e0bdce11d265f0feb23249a03f6

Fixes #102

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

vm-virtio/src/lib.rs

@@ -27,6 +27,7 @@ pub mod net;
 mod pmem;
 mod queue;
 mod rng;
+mod vsock;
 
 pub mod transport;
 pub mod vhost_user;
@@ -38,6 +39,7 @@ pub use self::net::*;
 pub use self::pmem::*;
 pub use self::queue::*;
 pub use self::rng::*;
+pub use self::vsock::*;
 
 const DEVICE_INIT: u32 = 0x00;
 const DEVICE_ACKNOWLEDGE: u32 = 0x01;

vm-virtio/src/vsock.rs

@@ -0,0 +1,311 @@
+// Copyright 2019 Intel Corporation. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+//
+// Portions Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+//
+// Portions Copyright 2017 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the THIRD-PARTY file.
+
+/// This is the `VirtioDevice` implementation for our vsock device. It handles the virtio-level
+/// device logic: feature negociation, device configuration, and device activation.
+/// The run-time device logic (i.e. event-driven data handling) is implemented by
+/// `super::epoll_handler::EpollHandler`.
+///
+/// We aim to conform to the VirtIO v1.1 spec:
+/// https://docs.oasis-open.org/virtio/virtio/v1.1/virtio-v1.1.html
+///
+/// The vsock device has two input parameters: a CID to identify the device, and a `VsockBackend`
+/// to use for offloading vsock traffic.
+///
+/// Upon its activation, the vsock device creates its `EpollHandler`, passes it the event-interested
+/// file descriptors, and registers these descriptors with the VMM `EpollContext`. Going forward,
+/// the `EpollHandler` will get notified whenever an event occurs on the just-registered FDs:
+/// - an RX queue FD;
+/// - a TX queue FD;
+/// - an event queue FD; and
+/// - a backend FD.
+///
+use epoll;
+use libc::EFD_NONBLOCK;
+use std;
+use std::io;
+use std::os::unix::io::AsRawFd;
+use std::result;
+use std::sync::{Arc, RwLock};
+use std::thread;
+
+use super::Error as DeviceError;
+use super::{
+    ActivateError, ActivateResult, DeviceEventT, Queue, VirtioDevice, VirtioDeviceType,
+    VIRTIO_F_VERSION_1,
+};
+use crate::VirtioInterrupt;
+use byteorder::{ByteOrder, LittleEndian};
+use vm_memory::GuestMemoryMmap;
+use vmm_sys_util::eventfd::EventFd;
+
+const QUEUE_SIZE: u16 = 256;
+const NUM_QUEUES: usize = 3;
+const QUEUE_SIZES: &[u16] = &[QUEUE_SIZE; NUM_QUEUES];
+
+// New descriptors are pending on the rx queue.
+const RX_QUEUE_EVENT: DeviceEventT = 0;
+// New descriptors are pending on the tx queue.
+const TX_QUEUE_EVENT: DeviceEventT = 1;
+// New descriptors are pending on the event queue.
+const EVT_QUEUE_EVENT: DeviceEventT = 2;
+// The device has been dropped.
+const KILL_EVENT: DeviceEventT = 3;
+
+struct VsockEpollHandler {
+    _cid: u64,
+    _mem: Arc<RwLock<GuestMemoryMmap>>,
+    _queues: Vec<Queue>,
+    queue_evts: Vec<EventFd>,
+    kill_evt: EventFd,
+    _interrupt_cb: Arc<VirtioInterrupt>,
+}
+
+impl VsockEpollHandler {
+    fn run(&mut self) -> result::Result<(), DeviceError> {
+        // Create the epoll file descriptor
+        let epoll_fd = epoll::create(true).map_err(DeviceError::EpollCreateFd)?;
+
+        // Add events
+        epoll::ctl(
+            epoll_fd,
+            epoll::ControlOptions::EPOLL_CTL_ADD,
+            self.queue_evts[0].as_raw_fd(),
+            epoll::Event::new(epoll::Events::EPOLLIN, u64::from(RX_QUEUE_EVENT)),
+        )
+        .map_err(DeviceError::EpollCtl)?;
+        epoll::ctl(
+            epoll_fd,
+            epoll::ControlOptions::EPOLL_CTL_ADD,
+            self.queue_evts[1].as_raw_fd(),
+            epoll::Event::new(epoll::Events::EPOLLIN, u64::from(TX_QUEUE_EVENT)),
+        )
+        .map_err(DeviceError::EpollCtl)?;
+        epoll::ctl(
+            epoll_fd,
+            epoll::ControlOptions::EPOLL_CTL_ADD,
+            self.queue_evts[2].as_raw_fd(),
+            epoll::Event::new(epoll::Events::EPOLLIN, u64::from(EVT_QUEUE_EVENT)),
+        )
+        .map_err(DeviceError::EpollCtl)?;
+        epoll::ctl(
+            epoll_fd,
+            epoll::ControlOptions::EPOLL_CTL_ADD,
+            self.kill_evt.as_raw_fd(),
+            epoll::Event::new(epoll::Events::EPOLLIN, u64::from(KILL_EVENT)),
+        )
+        .map_err(DeviceError::EpollCtl)?;
+
+        let mut events = vec![epoll::Event::new(epoll::Events::empty(), 0); 4];
+
+        'epoll: loop {
+            let num_events = match epoll::wait(epoll_fd, -1, &mut events[..]) {
+                Ok(res) => res,
+                Err(e) => {
+                    if e.kind() == io::ErrorKind::Interrupted {
+                        // It's well defined from the epoll_wait() syscall
+                        // documentation that the epoll loop can be interrupted
+                        // before any of the requested events occurred or the
+                        // timeout expired. In both those cases, epoll_wait()
+                        // returns an error of type EINTR, but this should not
+                        // be considered as a regular error. Instead it is more
+                        // appropriate to retry, by calling into epoll_wait().
+                        continue;
+                    }
+                    return Err(DeviceError::EpollWait(e));
+                }
+            };
+
+            for event in events.iter().take(num_events) {
+                let ev_type = event.data as u16;
+
+                match ev_type {
+                    RX_QUEUE_EVENT => {
+                        if let Err(e) = self.queue_evts[0].read() {
+                            error!("Failed to get queue event: {:?}", e);
+                            break 'epoll;
+                        }
+
+                        debug!("RX queue event received");
+                    }
+                    TX_QUEUE_EVENT => {
+                        if let Err(e) = self.queue_evts[1].read() {
+                            error!("Failed to get queue event: {:?}", e);
+                            break 'epoll;
+                        }
+
+                        debug!("TX queue event received");
+                    }
+                    EVT_QUEUE_EVENT => {
+                        if let Err(e) = self.queue_evts[2].read() {
+                            error!("Failed to get queue event: {:?}", e);
+                            break 'epoll;
+                        }
+
+                        debug!("EVT queue event received");
+                    }
+                    KILL_EVENT => {
+                        debug!("KILL_EVENT received, stopping epoll loop");
+                        break 'epoll;
+                    }
+                    _ => {
+                        error!("Unknown event for virtio-vsock");
+                    }
+                }
+            }
+        }
+
+        Ok(())
+    }
+}
+
+/// Virtio device exposing virtual socket to the guest.
+pub struct Vsock {
+    cid: u64,
+    kill_evt: Option<EventFd>,
+    avail_features: u64,
+    acked_features: u64,
+}
+
+impl Vsock {
+    pub fn new(cid: u64) -> io::Result<Vsock> {
+        let avail_features = 1u64 << VIRTIO_F_VERSION_1;
+
+        Ok(Vsock {
+            cid,
+            kill_evt: None,
+            avail_features,
+            acked_features: 0u64,
+        })
+    }
+}
+
+impl Drop for Vsock {
+    fn drop(&mut self) {
+        if let Some(kill_evt) = self.kill_evt.take() {
+            // Ignore the result because there is nothing we can do about it.
+            let _ = kill_evt.write(1);
+        }
+    }
+}
+
+impl VirtioDevice for Vsock {
+    fn device_type(&self) -> u32 {
+        VirtioDeviceType::TYPE_VSOCK as u32
+    }
+
+    fn queue_max_sizes(&self) -> &[u16] {
+        QUEUE_SIZES
+    }
+
+    fn features(&self, page: u32) -> u32 {
+        match page {
+            // Get the lower 32-bits of the features bitfield.
+            0 => self.avail_features as u32,
+            // Get the upper 32-bits of the features bitfield.
+            1 => (self.avail_features >> 32) as u32,
+            _ => {
+                warn!("Received request for unknown features page.");
+                0u32
+            }
+        }
+    }
+
+    fn ack_features(&mut self, page: u32, value: u32) {
+        let mut v = match page {
+            0 => u64::from(value),
+            1 => u64::from(value) << 32,
+            _ => {
+                warn!("Cannot acknowledge unknown features page.");
+                0u64
+            }
+        };
+
+        // Check if the guest is ACK'ing a feature that we didn't claim to have.
+        let unrequested_features = v & !self.avail_features;
+        if unrequested_features != 0 {
+            warn!("Received acknowledge request for unknown feature.");
+
+            // Don't count these features as acked.
+            v &= !unrequested_features;
+        }
+        self.acked_features |= v;
+    }
+
+    fn read_config(&self, offset: u64, data: &mut [u8]) {
+        match offset {
+            0 if data.len() == 8 => LittleEndian::write_u64(data, self.cid),
+            0 if data.len() == 4 => LittleEndian::write_u32(data, (self.cid & 0xffff_ffff) as u32),
+            4 if data.len() == 4 => {
+                LittleEndian::write_u32(data, ((self.cid >> 32) & 0xffff_ffff) as u32)
+            }
+            _ => warn!(
+                "vsock: virtio-vsock received invalid read request of {} bytes at offset {}",
+                data.len(),
+                offset
+            ),
+        }
+    }
+
+    fn write_config(&mut self, offset: u64, data: &[u8]) {
+        warn!(
+            "vsock: guest driver attempted to write device config (offset={:x}, len={:x})",
+            offset,
+            data.len()
+        );
+    }
+
+    fn activate(
+        &mut self,
+        mem: Arc<RwLock<GuestMemoryMmap>>,
+        interrupt_cb: Arc<VirtioInterrupt>,
+        queues: Vec<Queue>,
+        queue_evts: Vec<EventFd>,
+    ) -> ActivateResult {
+        if queues.len() != NUM_QUEUES || queue_evts.len() != NUM_QUEUES {
+            error!(
+                "Cannot perform activate. Expected {} queue(s), got {}",
+                NUM_QUEUES,
+                queues.len()
+            );
+            return Err(ActivateError::BadActivate);
+        }
+
+        let (self_kill_evt, kill_evt) =
+            match EventFd::new(EFD_NONBLOCK).and_then(|e| Ok((e.try_clone()?, e))) {
+                Ok(v) => v,
+                Err(e) => {
+                    error!("failed creating kill EventFd pair: {}", e);
+                    return Err(ActivateError::BadActivate);
+                }
+            };
+        self.kill_evt = Some(self_kill_evt);
+
+        let mut handler = VsockEpollHandler {
+            _cid: self.cid,
+            _mem: mem,
+            _queues: queues,
+            queue_evts,
+            kill_evt,
+            _interrupt_cb: interrupt_cb,
+        };
+
+        let worker_result = thread::Builder::new()
+            .name("virtio_vsock".to_string())
+            .spawn(move || handler.run());
+
+        if let Err(e) = worker_result {
+            error!("failed to spawn virtio_vsock worker: {}", e);
+            return Err(ActivateError::BadActivate);;
+        }
+
+        Ok(())
+    }
+}