virtio-devices: vhost-user: Port to EpollHelper

Migrate all vhost-user devices to EpollHelper so as to remove code that
is duplicated between multiple virtio devices.

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

virtio-devices/src/vhost_user/blk.rs

@@ -1,10 +1,11 @@
 // Copyright 2019 Intel Corporation. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 
-use super::super::{ActivateError, ActivateResult, Queue, VirtioDevice, VirtioDeviceType};
+use super::super::{
+    ActivateError, ActivateResult, EpollHelperError, Queue, VirtioDevice, VirtioDeviceType,
+};
 use super::handler::*;
 use super::vu_common_ctrl::*;
-use super::Error as DeviceError;
 use super::{Error, Result};
 use crate::VirtioInterrupt;
 use block_util::VirtioBlockConfig;
@@ -41,7 +42,7 @@ pub struct Blk {
     queue_sizes: Vec<u16>,
     queue_evts: Option<Vec<EventFd>>,
     interrupt_cb: Option<Arc<dyn VirtioInterrupt>>,
-    epoll_threads: Option<Vec<thread::JoinHandle<result::Result<(), DeviceError>>>>,
+    epoll_threads: Option<Vec<thread::JoinHandle<result::Result<(), EpollHelperError>>>>,
     paused: Arc<AtomicBool>,
 }
 

virtio-devices/src/vhost_user/fs.rs

@@ -2,12 +2,11 @@
 // SPDX-License-Identifier: Apache-2.0
 
 use super::vu_common_ctrl::{reset_vhost_user, setup_vhost_user, update_mem_table};
-use super::Error as DeviceError;
 use super::{Error, Result};
 use crate::vhost_user::handler::{VhostUserEpollConfig, VhostUserEpollHandler};
 use crate::{
-    ActivateError, ActivateResult, Queue, UserspaceMapping, VirtioDevice, VirtioDeviceType,
-    VirtioInterrupt, VirtioSharedMemoryList, VIRTIO_F_VERSION_1,
+    ActivateError, ActivateResult, EpollHelperError, Queue, UserspaceMapping, VirtioDevice,
+    VirtioDeviceType, VirtioInterrupt, VirtioSharedMemoryList, VIRTIO_F_VERSION_1,
 };
 use libc::{self, c_void, off64_t, pread64, pwrite64, EFD_NONBLOCK};
 use std::io;
@@ -279,7 +278,7 @@ pub struct Fs {
     slave_req_support: bool,
     queue_evts: Option<Vec<EventFd>>,
     interrupt_cb: Option<Arc<dyn VirtioInterrupt>>,
-    epoll_threads: Option<Vec<thread::JoinHandle<result::Result<(), DeviceError>>>>,
+    epoll_threads: Option<Vec<thread::JoinHandle<result::Result<(), EpollHelperError>>>>,
     paused: Arc<AtomicBool>,
 }
 

virtio-devices/src/vhost_user/handler.rs

@@ -7,17 +7,17 @@
 //
 // SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
 
-use super::super::{Queue, VirtioInterruptType};
+use super::super::{
+    EpollHelper, EpollHelperError, EpollHelperHandler, Queue, VirtioInterruptType,
+    EPOLL_HELPER_EVENT_LAST,
+};
 use super::{Error, Result};
 use vmm_sys_util::eventfd::EventFd;
 
 use crate::VirtioInterrupt;
-use std::fs::File;
-use std::io;
-use std::os::unix::io::{AsRawFd, FromRawFd};
-use std::sync::atomic::{AtomicBool, Ordering};
+use std::os::unix::io::AsRawFd;
+use std::sync::atomic::AtomicBool;
 use std::sync::Arc;
-use std::thread;
 use vhost_rs::vhost_user::{MasterReqHandler, VhostUserMasterReqHandler};
 
 /// Collection of common parameters required by vhost-user devices while
@@ -37,6 +37,8 @@ pub struct VhostUserEpollConfig<S: VhostUserMasterReqHandler> {
 
 pub struct VhostUserEpollHandler<S: VhostUserMasterReqHandler> {
     vu_epoll_cfg: VhostUserEpollConfig<S>,
+    queue_evt_start_idx: u16,
+    slave_evt_idx: u16,
 }
 
 impl<S: VhostUserMasterReqHandler> VhostUserEpollHandler<S> {
@@ -48,7 +50,14 @@ impl<S: VhostUserMasterReqHandler> VhostUserEpollHandler<S> {
     /// # Return
     /// * `VhostUserEpollHandler` - epoll handler for vhost-user based devices
     pub fn new(vu_epoll_cfg: VhostUserEpollConfig<S>) -> VhostUserEpollHandler<S> {
-        VhostUserEpollHandler { vu_epoll_cfg }
+        let queue_evt_start_idx = EPOLL_HELPER_EVENT_LAST + 1;
+        let slave_evt_idx = queue_evt_start_idx + vu_epoll_cfg.vu_interrupt_list.len() as u16;
+
+        VhostUserEpollHandler {
+            vu_epoll_cfg,
+            queue_evt_start_idx,
+            slave_evt_idx,
+        }
     }
 
     fn signal_used_queue(&self, queue: &Queue) -> Result<()> {
@@ -58,139 +67,59 @@ impl<S: VhostUserMasterReqHandler> VhostUserEpollHandler<S> {
             .map_err(Error::FailedSignalingUsedQueue)
     }
 
-    pub fn run(&mut self, paused: Arc<AtomicBool>) -> Result<()> {
-        // Create the epoll file descriptor
-        let epoll_fd = epoll::create(true).map_err(Error::EpollCreateFd)?;
-        // Use 'File' to enforce closing on 'epoll_fd'
-        let epoll_file = unsafe { File::from_raw_fd(epoll_fd) };
+    pub fn run(&mut self, paused: Arc<AtomicBool>) -> std::result::Result<(), EpollHelperError> {
+        let mut helper =
+            EpollHelper::new(&self.vu_epoll_cfg.kill_evt, &self.vu_epoll_cfg.pause_evt)?;
 
-        for (index, vhost_user_interrupt) in self.vu_epoll_cfg.vu_interrupt_list.iter().enumerate()
-        {
+        for (i, vhost_user_interrupt) in self.vu_epoll_cfg.vu_interrupt_list.iter().enumerate() {
             if let Some(eventfd) = &vhost_user_interrupt.0 {
-                // Add events
-                epoll::ctl(
-                    epoll_file.as_raw_fd(),
-                    epoll::ControlOptions::EPOLL_CTL_ADD,
-                    eventfd.as_raw_fd(),
-                    epoll::Event::new(epoll::Events::EPOLLIN, index as u64),
-                )
-                .map_err(Error::EpollCtl)?;
+                helper.add_event(eventfd.as_raw_fd(), self.queue_evt_start_idx + i as u16)?;
             }
         }
 
-        let kill_evt_index = self.vu_epoll_cfg.vu_interrupt_list.len();
-
-        epoll::ctl(
-            epoll_file.as_raw_fd(),
-            epoll::ControlOptions::EPOLL_CTL_ADD,
-            self.vu_epoll_cfg.kill_evt.as_raw_fd(),
-            epoll::Event::new(epoll::Events::EPOLLIN, kill_evt_index as u64),
-        )
-        .map_err(Error::EpollCtl)?;
-
-        let pause_evt_index = kill_evt_index + 1;
-
-        epoll::ctl(
-            epoll_file.as_raw_fd(),
-            epoll::ControlOptions::EPOLL_CTL_ADD,
-            self.vu_epoll_cfg.pause_evt.as_raw_fd(),
-            epoll::Event::new(epoll::Events::EPOLLIN, pause_evt_index as u64),
-        )
-        .map_err(Error::EpollCtl)?;
-
-        let mut index = pause_evt_index;
-
-        let slave_evt_index = if let Some(self_req_handler) = &self.vu_epoll_cfg.slave_req_handler {
-            index = pause_evt_index + 1;
-            epoll::ctl(
-                epoll_file.as_raw_fd(),
-                epoll::ControlOptions::EPOLL_CTL_ADD,
-                self_req_handler.as_raw_fd(),
-                epoll::Event::new(epoll::Events::EPOLLIN, index as u64),
-            )
-            .map_err(Error::EpollCtl)?;
-
-            Some(index)
-        } else {
-            None
-        };
-
-        let mut events = vec![epoll::Event::new(epoll::Events::empty(), 0); index + 1];
-
-        // Before jumping into the epoll loop, check if the device is expected
-        // to be in a paused state. This is helpful for the restore code path
-        // as the device thread should not start processing anything before the
-        // device has been resumed.
-        while paused.load(Ordering::SeqCst) {
-            thread::park();
+        if let Some(self_req_handler) = &self.vu_epoll_cfg.slave_req_handler {
+            helper.add_event(self_req_handler.as_raw_fd(), self.slave_evt_idx)?;
         }
 
-        'poll: loop {
-            let num_events = match epoll::wait(epoll_file.as_raw_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(Error::EpollWait(e));
-                }
-            };
+        helper.run(paused, self)?;
 
-            for event in events.iter().take(num_events) {
-                let ev_type = event.data as usize;
-
-                match ev_type {
-                    x if x < kill_evt_index => {
-                        if let Some(eventfd) = &self.vu_epoll_cfg.vu_interrupt_list[x].0 {
-                            eventfd.read().map_err(Error::FailedReadingQueue)?;
-                            if let Err(e) =
-                                self.signal_used_queue(&self.vu_epoll_cfg.vu_interrupt_list[x].1)
-                            {
-                                error!("Failed to signal used queue: {:?}", e);
-                                break 'poll;
-                            }
-                        }
-                    }
-                    x if kill_evt_index == x => {
-                        debug!("KILL_EVENT received, stopping epoll loop");
-                        break 'poll;
-                    }
-                    x if pause_evt_index == x => {
-                        debug!("PAUSE_EVENT received, pausing vhost-user epoll loop");
-                        // We loop here to handle spurious park() returns.
-                        // Until we have not resumed, the paused boolean will
-                        // be true.
-                        while paused.load(Ordering::SeqCst) {
-                            thread::park();
-                        }
-
-                        // Drain pause event after the device has been resumed.
-                        // This ensures the pause event has been seen by each
-                        // and every thread related to this virtio device.
-                        let _ = self.vu_epoll_cfg.pause_evt.read();
-                    }
-                    x if (slave_evt_index.is_some() && slave_evt_index.unwrap() == x) => {
-                        if let Some(slave_req_handler) =
-                            self.vu_epoll_cfg.slave_req_handler.as_mut()
-                        {
-                            slave_req_handler
-                                .handle_request()
-                                .map_err(Error::VhostUserSlaveRequest)?;
-                        }
-                    }
-                    _ => {
-                        error!("Unknown event for vhost-user");
-                    }
-                }
-            }
-        }
         Ok(())
     }
 }
+
+impl<S: VhostUserMasterReqHandler> EpollHelperHandler for VhostUserEpollHandler<S> {
+    fn handle_event(&mut self, _helper: &mut EpollHelper, event: &epoll::Event) -> bool {
+        let ev_type = event.data as u16;
+        match ev_type {
+            x if (x >= self.queue_evt_start_idx && x < self.slave_evt_idx) => {
+                let idx = (x - self.queue_evt_start_idx) as usize;
+                if let Some(eventfd) = &self.vu_epoll_cfg.vu_interrupt_list[idx].0 {
+                    if let Err(e) = eventfd.read() {
+                        error!("Failed to read queue: {:?}", e);
+                        return true;
+                    }
+                    if let Err(e) =
+                        self.signal_used_queue(&self.vu_epoll_cfg.vu_interrupt_list[idx].1)
+                    {
+                        error!("Failed to signal used queue: {:?}", e);
+                        return true;
+                    }
+                }
+            }
+            x if x == self.slave_evt_idx => {
+                if let Some(slave_req_handler) = self.vu_epoll_cfg.slave_req_handler.as_mut() {
+                    if let Err(e) = slave_req_handler.handle_request() {
+                        error!("Failed to handle vhost-user request: {:?}", e);
+                        return true;
+                    }
+                }
+            }
+            _ => {
+                error!("Unknown event for vhost-user");
+                return true;
+            }
+        }
+
+        false
+    }
+}

virtio-devices/src/vhost_user/mod.rs

@@ -34,14 +34,6 @@ pub enum Error {
     CloneKillEventFd(io::Error),
     /// Invalid descriptor table address.
     DescriptorTableAddress,
-    /// Create Epoll eventfd failed
-    EpollCreateFd(io::Error),
-    /// Epoll ctl error
-    EpollCtl(io::Error),
-    /// Epoll wait error
-    EpollWait(io::Error),
-    /// Read queue failed.
-    FailedReadingQueue(io::Error),
     /// Signal used queue failed.
     FailedSignalingUsedQueue(io::Error),
     /// Failed to read vhost eventfd.
@@ -88,8 +80,6 @@ pub enum Error {
     VhostIrqRead(io::Error),
     /// Failed to read vhost eventfd.
     VhostUserMemoryRegion(MmapError),
-    /// Failed to handle vhost-user slave request.
-    VhostUserSlaveRequest(vhost_rs::vhost_user::Error),
     /// Failed to create the master request handler from slave.
     MasterReqHandlerCreation(vhost_rs::vhost_user::Error),
     /// Set slave request fd failed.

virtio-devices/src/vhost_user/net.rs

@@ -5,10 +5,11 @@ use super::super::net_util::{
     build_net_config_space, CtrlVirtio, NetCtrlEpollHandler, VirtioNetConfig,
 };
 use super::super::Error as CtrlError;
-use super::super::{ActivateError, ActivateResult, Queue, VirtioDevice, VirtioDeviceType};
+use super::super::{
+    ActivateError, ActivateResult, EpollHelperError, Queue, VirtioDevice, VirtioDeviceType,
+};
 use super::handler::*;
 use super::vu_common_ctrl::*;
-use super::Error as DeviceError;
 use super::{Error, Result};
 use crate::VirtioInterrupt;
 use libc::EFD_NONBLOCK;
@@ -45,7 +46,7 @@ pub struct Net {
     queue_sizes: Vec<u16>,
     queue_evts: Option<Vec<EventFd>>,
     interrupt_cb: Option<Arc<dyn VirtioInterrupt>>,
-    epoll_threads: Option<Vec<thread::JoinHandle<result::Result<(), DeviceError>>>>,
+    epoll_threads: Option<Vec<thread::JoinHandle<result::Result<(), EpollHelperError>>>>,
     ctrl_queue_epoll_thread: Option<thread::JoinHandle<result::Result<(), CtrlError>>>,
     paused: Arc<AtomicBool>,
 }