vhost_user_net: Use NetQueuePair from vm-virtio

The logic for handling the networking queues can now be shared between
the version running in vhost-user-net and vm-virtio.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

vhost_user_backend/src/lib.rs

@@ -310,6 +310,12 @@ pub struct VringWorker {
     epoll_file: File,
 }
 
+impl AsRawFd for VringWorker {
+    fn as_raw_fd(&self) -> RawFd {
+        self.epoll_file.as_raw_fd()
+    }
+}
+
 impl VringWorker {
     fn run<S: VhostUserBackend>(&self, handler: VringEpollHandler<S>) -> VringWorkerResult<()> {
         const EPOLL_EVENTS_LEN: usize = 100;

vhost_user_net/src/lib.rs

@@ -13,11 +13,10 @@ extern crate vhost_user_backend;
 extern crate vm_virtio;
 extern crate vmm;
 
-use libc::{self, EAGAIN, EFD_NONBLOCK};
+use libc::{self, EFD_NONBLOCK};
 use log::*;
 use net_util::{MacAddr, Tap};
 use std::fmt;
-use std::io::Read;
 use std::io::{self};
 use std::net::Ipv4Addr;
 use std::os::unix::io::AsRawFd;
@@ -28,9 +27,9 @@ use vhost_rs::vhost_user::message::*;
 use vhost_rs::vhost_user::{Error as VhostUserError, Listener};
 use vhost_user_backend::{VhostUserBackend, VhostUserDaemon, Vring, VringWorker};
 use virtio_bindings::bindings::virtio_net::*;
-use vm_memory::GuestMemoryMmap;
+use vm_memory::{GuestMemoryAtomic, GuestMemoryMmap};
 use vm_virtio::net_util::{open_tap, RxVirtio, TxVirtio};
-use vm_virtio::Queue;
+use vm_virtio::NetQueuePair;
 use vmm::config::{OptionParser, OptionParserError};
 use vmm_sys_util::eventfd::EventFd;
 
@@ -55,7 +54,7 @@ pub enum Error {
     /// Failed to parse configuration string
     FailedConfigParse(OptionParserError),
     /// Failed to signal used queue.
-    FailedSignalingUsedQueue,
+    FailedSignalingUsedQueue(io::Error),
     /// Failed to handle event other than input event.
     HandleEventNotEpollIn,
     /// Failed to handle unknown event.
@@ -70,6 +69,8 @@ pub enum Error {
     OpenTap(vm_virtio::net_util::Error),
     /// No socket provided
     SocketParameterMissing,
+    /// Underlying QueuePair error
+    NetQueuePair(vm_virtio::Error),
 }
 
 pub const SYNTAX: &str = "vhost-user-net backend parameters \
@@ -91,121 +92,30 @@ impl std::convert::From<Error> for std::io::Error {
 }
 
 struct VhostUserNetThread {
-    mem: Option<GuestMemoryMmap>,
+    net: NetQueuePair,
     vring_worker: Option<Arc<VringWorker>>,
     kill_evt: EventFd,
-    tap: Tap,
-    rx: RxVirtio,
-    tx: TxVirtio,
-    rx_tap_listening: bool,
 }
 
 impl VhostUserNetThread {
     /// Create a new virtio network device with the given TAP interface.
     fn new(tap: Tap) -> Result<Self> {
         Ok(VhostUserNetThread {
-            mem: None,
             vring_worker: None,
             kill_evt: EventFd::new(EFD_NONBLOCK).map_err(Error::CreateKillEventFd)?,
-            tap,
-            rx: RxVirtio::new(),
-            tx: TxVirtio::new(),
-            rx_tap_listening: false,
+            net: NetQueuePair {
+                mem: None,
+                tap,
+                rx: RxVirtio::new(),
+                tx: TxVirtio::new(),
+                rx_tap_listening: false,
+                epoll_fd: None,
+            },
         })
     }
 
-    // Copies a single frame from `self.rx.frame_buf` into the guest. Returns true
-    // if a buffer was used, and false if the frame must be deferred until a buffer
-    // is made available by the driver.
-    fn rx_single_frame(&mut self, mut queue: &mut Queue) -> Result<bool> {
-        let mem = self.mem.as_ref().ok_or(Error::NoMemoryConfigured)?;
-
-        let next_desc = queue.iter(&mem).next();
-
-        if next_desc.is_none() {
-            // Queue has no available descriptors
-            if self.rx_tap_listening {
-                self.vring_worker
-                    .as_ref()
-                    .unwrap()
-                    .unregister_listener(self.tap.as_raw_fd(), epoll::Events::EPOLLIN, 2)
-                    .unwrap();
-                self.rx_tap_listening = false;
-            }
-            return Ok(false);
-        }
-
-        let write_complete = self.rx.process_desc_chain(&mem, next_desc, &mut queue);
-
-        Ok(write_complete)
-    }
-
-    fn process_rx(&mut self, vring: &mut Vring) -> Result<()> {
-        // Read as many frames as possible.
-        loop {
-            match self.read_tap() {
-                Ok(count) => {
-                    self.rx.bytes_read = count;
-                    if !self.rx_single_frame(&mut vring.mut_queue())? {
-                        self.rx.deferred_frame = true;
-                        break;
-                    }
-                }
-                Err(e) => {
-                    // The tap device is non-blocking, so any error aside from EAGAIN is
-                    // unexpected.
-                    match e.raw_os_error() {
-                        Some(err) if err == EAGAIN => (),
-                        _ => {
-                            error!("Failed to read tap: {:?}", e);
-                            return Err(Error::FailedReadTap);
-                        }
-                    };
-                    break;
-                }
-            }
-        }
-        if self.rx.deferred_irqs {
-            self.rx.deferred_irqs = false;
-            vring.signal_used_queue().unwrap();
-            Ok(())
-        } else {
-            Ok(())
-        }
-    }
-
-    fn resume_rx(&mut self, vring: &mut Vring) -> Result<()> {
-        if self.rx.deferred_frame {
-            if self.rx_single_frame(&mut vring.mut_queue())? {
-                self.rx.deferred_frame = false;
-                // process_rx() was interrupted possibly before consuming all
-                // packets in the tap; try continuing now.
-                self.process_rx(vring)
-            } else if self.rx.deferred_irqs {
-                self.rx.deferred_irqs = false;
-                vring.signal_used_queue().unwrap();
-                Ok(())
-            } else {
-                Ok(())
-            }
-        } else {
-            Ok(())
-        }
-    }
-
-    fn process_tx(&mut self, mut queue: &mut Queue) -> Result<()> {
-        let mem = self.mem.as_ref().ok_or(Error::NoMemoryConfigured)?;
-
-        self.tx.process_desc_chain(&mem, &mut self.tap, &mut queue);
-
-        Ok(())
-    }
-
-    fn read_tap(&mut self) -> io::Result<usize> {
-        self.tap.read(&mut self.rx.frame_buf)
-    }
-
     pub fn set_vring_worker(&mut self, vring_worker: Option<Arc<VringWorker>>) {
+        self.net.epoll_fd = Some(vring_worker.as_ref().unwrap().as_raw_fd());
         self.vring_worker = vring_worker;
     }
 }
@@ -280,7 +190,7 @@ impl VhostUserBackend for VhostUserNetBackend {
 
     fn update_memory(&mut self, mem: GuestMemoryMmap) -> VhostUserBackendResult<()> {
         for thread in self.threads.iter() {
-            thread.lock().unwrap().mem = Some(mem.clone());
+            thread.lock().unwrap().net.mem = Some(GuestMemoryAtomic::new(mem.clone()));
         }
         Ok(())
     }
@@ -299,37 +209,39 @@ impl VhostUserBackend for VhostUserNetBackend {
         let mut thread = self.threads[thread_id].lock().unwrap();
         match device_event {
             0 => {
-                thread.resume_rx(&mut vrings[0].write().unwrap())?;
-
-                if !thread.rx_tap_listening {
-                    thread.vring_worker.as_ref().unwrap().register_listener(
-                        thread.tap.as_raw_fd(),
-                        epoll::Events::EPOLLIN,
-                        2,
-                    )?;
-                    thread.rx_tap_listening = true;
+                let mut vring = vrings[0].write().unwrap();
+                if thread
+                    .net
+                    .resume_rx(&mut vring.mut_queue())
+                    .map_err(Error::NetQueuePair)?
+                {
+                    vring
+                        .signal_used_queue()
+                        .map_err(Error::FailedSignalingUsedQueue)?
                 }
             }
             1 => {
                 let mut vring = vrings[1].write().unwrap();
-                thread.process_tx(vring.mut_queue())?;
-                vring.signal_used_queue()?;
+                if thread
+                    .net
+                    .process_tx(&mut vring.mut_queue())
+                    .map_err(Error::NetQueuePair)?
+                {
+                    vring
+                        .signal_used_queue()
+                        .map_err(Error::FailedSignalingUsedQueue)?
+                }
             }
             2 => {
                 let mut vring = vrings[0].write().unwrap();
-                if thread.rx.deferred_frame
-                // Process a deferred frame first if available. Don't read from tap again
-                // until we manage to receive this deferred frame.
+                if thread
+                    .net
+                    .process_rx_tap(&mut vring.mut_queue())
+                    .map_err(Error::NetQueuePair)?
                 {
-                    if thread.rx_single_frame(&mut vring.mut_queue())? {
-                        thread.rx.deferred_frame = false;
-                        thread.process_rx(&mut vring)?;
-                    } else if thread.rx.deferred_irqs {
-                        thread.rx.deferred_irqs = false;
-                        vring.signal_used_queue()?;
-                    }
-                } else {
-                    thread.process_rx(&mut vring)?;
+                    vring
+                        .signal_used_queue()
+                        .map_err(Error::FailedSignalingUsedQueue)?
                 }
             }
             _ => return Err(Error::HandleEventUnknownEvent.into()),