vm-virtio: Add vhost-user-fs support

The vhost-user-fs or virtio-fs device allows files and directories to
be shared between host and guest. This patch adds the implementation
of this device to the cloud-hypervisor device model.

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

Cargo.lock

@@ -629,6 +629,15 @@ name = "vec_map"
 version = "0.8.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "vhost_rs"
+version = "0.1.0"
+dependencies = [
+ "bitflags 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.58 (registry+https://github.com/rust-lang/crates.io-index)",
+ "vmm-sys-util 0.1.0 (git+https://github.com/rust-vmm/vmm-sys-util)",
+]
+
 [[package]]
 name = "virtio-bindings"
 version = "0.1.0"
@@ -663,6 +672,7 @@ dependencies = [
  "net_util 0.1.0",
  "pci 0.1.0",
  "tempfile 3.0.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "vhost_rs 0.1.0",
  "virtio-bindings 0.1.0",
  "vm-allocator 0.1.0",
  "vm-memory 0.1.0 (git+https://github.com/rust-vmm/vm-memory)",

vm-virtio/Cargo.toml

@@ -18,6 +18,10 @@ virtio-bindings = { path = "../virtio-bindings" }
 vm-allocator = { path = "../vm-allocator" }
 vmm-sys-util = { git = "https://github.com/rust-vmm/vmm-sys-util" }
 
+[dependencies.vhost_rs]
+path = "../vhost_rs"
+features = ["vhost-user-master"]
+
 [dependencies.vm-memory]
 git = "https://github.com/rust-vmm/vm-memory"
 features = ["backend-mmap"]

vm-virtio/src/fs.rs

@@ -0,0 +1,438 @@
+// Copyright 2019 Intel Corporation. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+use super::Error as DeviceError;
+use super::{
+    ActivateError, ActivateResult, Queue, VirtioDevice, VirtioDeviceType,
+    INTERRUPT_STATUS_USED_RING,
+};
+use crate::{VirtioInterrupt, VIRTIO_F_VERSION_1_BITMASK};
+use epoll;
+use libc::EFD_NONBLOCK;
+use std::cmp;
+use std::io;
+use std::io::Write;
+use std::os::unix::io::AsRawFd;
+use std::result;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::sync::Arc;
+use std::thread;
+use vhost_rs::vhost_user::message::{VhostUserProtocolFeatures, VhostUserVirtioFeatures};
+use vhost_rs::vhost_user::{Master, VhostUserMaster};
+use vhost_rs::{VhostBackend, VhostUserMemoryRegionInfo, VringConfigData};
+use vm_memory::{Address, Error as MmapError, GuestMemory, GuestMemoryMmap, GuestMemoryRegion};
+use vmm_sys_util::EventFd;
+
+const CONFIG_SPACE_TAG_SIZE: usize = 36;
+const CONFIG_SPACE_NUM_QUEUES_SIZE: usize = 4;
+const CONFIG_SPACE_SIZE: usize = CONFIG_SPACE_TAG_SIZE + CONFIG_SPACE_NUM_QUEUES_SIZE;
+const NUM_QUEUE_OFFSET: usize = 1;
+
+#[derive(Debug)]
+pub enum Error {
+    /// common
+
+    /// Invalid descriptor table address.
+    DescriptorTableAddress,
+    /// Invalid used address.
+    UsedAddress,
+    /// Invalid available address.
+    AvailAddress,
+
+    /// vhost
+
+    /// Creating kill eventfd failed.
+    CreateKillEventFd(io::Error),
+    /// Cloning kill eventfd failed.
+    CloneKillEventFd(io::Error),
+    /// Error while polling for events.
+    PollError(io::Error),
+    /// Failed to create irq eventfd.
+    IrqEventCreate(io::Error),
+    /// Failed to read vhost eventfd.
+    VhostIrqRead(io::Error),
+
+    /// vhost-user
+
+    /// Connection to socket failed.
+    VhostUserConnect(vhost_rs::Error),
+    /// Get features failed.
+    VhostUserGetFeatures(vhost_rs::Error),
+    /// Get protocol features failed.
+    VhostUserGetProtocolFeatures(vhost_rs::Error),
+    /// Set owner failed.
+    VhostUserSetOwner(vhost_rs::Error),
+    /// Set features failed.
+    VhostUserSetFeatures(vhost_rs::Error),
+    /// Set protocol features failed.
+    VhostUserSetProtocolFeatures(vhost_rs::Error),
+    /// Set mem table failed.
+    VhostUserSetMemTable(vhost_rs::Error),
+    /// Set vring num failed.
+    VhostUserSetVringNum(vhost_rs::Error),
+    /// Set vring addr failed.
+    VhostUserSetVringAddr(vhost_rs::Error),
+    /// Set vring base failed.
+    VhostUserSetVringBase(vhost_rs::Error),
+    /// Set vring call failed.
+    VhostUserSetVringCall(vhost_rs::Error),
+    /// Set vring kick failed.
+    VhostUserSetVringKick(vhost_rs::Error),
+
+    /// Invalid features provided from vhost-user backend.
+    InvalidFeatures,
+
+    /// Missing file descriptor.
+    FdMissing,
+
+    /// Failure going through memory regions.
+    MemoryRegions(MmapError),
+}
+type Result<T> = result::Result<T, Error>;
+
+struct FsEpollHandler {
+    vu_call_evt_queue_list: Vec<(EventFd, Queue)>,
+    interrupt_status: Arc<AtomicUsize>,
+    interrupt_cb: Arc<VirtioInterrupt>,
+    kill_evt: EventFd,
+}
+
+impl FsEpollHandler {
+    fn run(&mut self) -> result::Result<(), DeviceError> {
+        // Create the epoll file descriptor
+        let epoll_fd = epoll::create(true).map_err(DeviceError::EpollCreateFd)?;
+
+        for (evt_index, vu_call_evt_queue) in self.vu_call_evt_queue_list.iter().enumerate() {
+            // Add events
+            epoll::ctl(
+                epoll_fd,
+                epoll::ControlOptions::EPOLL_CTL_ADD,
+                vu_call_evt_queue.0.as_raw_fd(),
+                epoll::Event::new(epoll::Events::EPOLLIN, evt_index as u64),
+            )
+            .map_err(DeviceError::EpollCtl)?;
+        }
+
+        let kill_evt_index = self.vu_call_evt_queue_list.len();
+        epoll::ctl(
+            epoll_fd,
+            epoll::ControlOptions::EPOLL_CTL_ADD,
+            self.kill_evt.as_raw_fd(),
+            epoll::Event::new(epoll::Events::EPOLLIN, kill_evt_index as u64),
+        )
+        .map_err(DeviceError::EpollCtl)?;
+
+        const EPOLL_EVENTS_LEN: usize = 100;
+        let mut events = vec![epoll::Event::new(epoll::Events::empty(), 0); EPOLL_EVENTS_LEN];
+
+        'epoll: loop {
+            let num_events =
+                epoll::wait(epoll_fd, -1, &mut events[..]).map_err(DeviceError::EpollWait)?;
+
+            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 Err(e) = self.vu_call_evt_queue_list[x].0.read() {
+                            error!("Failed to get queue event: {:?}", e);
+                            break 'epoll;
+                        } else {
+                            self.interrupt_status
+                                .fetch_or(INTERRUPT_STATUS_USED_RING as usize, Ordering::SeqCst);
+                            if let Err(e) = (self.interrupt_cb)(&self.vu_call_evt_queue_list[x].1) {
+                                error!(
+                                    "Failed to signal used queue: {:?}",
+                                    DeviceError::FailedSignalingUsedQueue(e)
+                                );
+                                break 'epoll;
+                            }
+                        }
+                    }
+                    x if (x == kill_evt_index) => {
+                        debug!("KILL_EVENT received, stopping epoll loop");
+                        break 'epoll;
+                    }
+                    _ => {
+                        error!("Unknown event for virtio-fs");
+                    }
+                }
+            }
+        }
+
+        Ok(())
+    }
+}
+
+pub struct Fs {
+    vu: Master,
+    queue_sizes: Vec<u16>,
+    avail_features: u64,
+    acked_features: u64,
+    config_space: Vec<u8>,
+    kill_evt: Option<EventFd>,
+}
+
+impl Fs {
+    /// Create a new virtio-fs device.
+    pub fn new(path: &str, tag: &str, req_num_queues: usize, queue_size: u16) -> Result<Fs> {
+        // Calculate the actual number of queues needed.
+        let num_queues = NUM_QUEUE_OFFSET + req_num_queues;
+        // Connect to the vhost-user socket.
+        let mut master =
+            Master::connect(path, num_queues as u64).map_err(Error::VhostUserConnect)?;
+        // Retrieve available features only when connecting the first time.
+        let mut avail_features = master.get_features().map_err(Error::VhostUserGetFeatures)?;
+        // Let only ack features we expect, that is VIRTIO_F_VERSION_1.
+        if (avail_features & VIRTIO_F_VERSION_1_BITMASK) != VIRTIO_F_VERSION_1_BITMASK {
+            return Err(Error::InvalidFeatures);
+        }
+        avail_features =
+            VIRTIO_F_VERSION_1_BITMASK | VhostUserVirtioFeatures::PROTOCOL_FEATURES.bits();
+        master
+            .set_features(avail_features)
+            .map_err(Error::VhostUserSetFeatures)?;
+        // Identify if protocol features are supported by the slave.
+        if (avail_features & VhostUserVirtioFeatures::PROTOCOL_FEATURES.bits())
+            == VhostUserVirtioFeatures::PROTOCOL_FEATURES.bits()
+        {
+            let mut protocol_features = master
+                .get_protocol_features()
+                .map_err(Error::VhostUserGetProtocolFeatures)?;
+            protocol_features &= VhostUserProtocolFeatures::MQ;
+            master
+                .set_protocol_features(protocol_features)
+                .map_err(Error::VhostUserSetProtocolFeatures)?;
+        }
+        // Create virtio device config space.
+        // First by adding the tag.
+        let mut config_space = tag.to_string().into_bytes();
+        config_space.resize(CONFIG_SPACE_SIZE, 0);
+        // And then by copying the number of queues.
+        let num_queues_slice = (req_num_queues as u32).to_le_bytes();
+        config_space[CONFIG_SPACE_TAG_SIZE..CONFIG_SPACE_SIZE].copy_from_slice(&num_queues_slice);
+
+        Ok(Fs {
+            vu: master,
+            queue_sizes: vec![queue_size; num_queues],
+            avail_features,
+            acked_features: 0u64,
+            config_space,
+            kill_evt: None,
+        })
+    }
+
+    fn setup_vu(
+        &mut self,
+        mem: &GuestMemoryMmap,
+        queues: Vec<Queue>,
+        queue_evts: Vec<EventFd>,
+    ) -> Result<Vec<(EventFd, Queue)>> {
+        // Set vhost-user owner.
+        self.vu.set_owner().map_err(Error::VhostUserSetOwner)?;
+
+        // Set backend features.
+        self.vu
+            .set_features(self.acked_features)
+            .map_err(Error::VhostUserSetFeatures)?;
+
+        let mut regions: Vec<VhostUserMemoryRegionInfo> = Vec::new();
+
+        mem.with_regions_mut(|_, region| {
+            let (mmap_handle, mmap_offset) = match region.file_offset() {
+                Some(fo) => (fo.file().as_raw_fd(), fo.start()),
+                None => return Err(MmapError::NoMemoryRegion),
+            };
+
+            let vu_mem_reg = VhostUserMemoryRegionInfo {
+                guest_phys_addr: region.start_addr().raw_value(),
+                memory_size: region.len() as u64,
+                userspace_addr: region.as_ptr() as u64,
+                mmap_offset,
+                mmap_handle,
+            };
+
+            regions.push(vu_mem_reg);
+
+            Ok(())
+        })
+        .map_err(Error::MemoryRegions)?;
+
+        self.vu
+            .set_mem_table(regions.as_slice())
+            .map_err(Error::VhostUserSetMemTable)?;
+
+        let mut result = Vec::new();
+        for (queue_index, queue) in queues.into_iter().enumerate() {
+            self.vu
+                .set_vring_num(queue_index, queue.get_max_size())
+                .map_err(Error::VhostUserSetVringNum)?;
+
+            let vring_config = VringConfigData {
+                queue_max_size: queue.get_max_size(),
+                queue_size: queue.size,
+                flags: 0u32,
+                desc_table_addr: mem
+                    .get_host_address(queue.desc_table)
+                    .ok_or_else(|| Error::DescriptorTableAddress)?
+                    as u64,
+                used_ring_addr: mem
+                    .get_host_address(queue.used_ring)
+                    .ok_or_else(|| Error::UsedAddress)? as u64,
+                avail_ring_addr: mem
+                    .get_host_address(queue.avail_ring)
+                    .ok_or_else(|| Error::AvailAddress)? as u64,
+                log_addr: None,
+            };
+
+            self.vu
+                .set_vring_addr(queue_index, &vring_config)
+                .map_err(Error::VhostUserSetVringAddr)?;
+
+            self.vu
+                .set_vring_base(queue_index, 0u16)
+                .map_err(Error::VhostUserSetVringBase)?;
+
+            let vu_call_evt = EventFd::new(EFD_NONBLOCK).map_err(Error::IrqEventCreate)?;
+
+            self.vu
+                .set_vring_call(queue_index, &vu_call_evt)
+                .map_err(Error::VhostUserSetVringCall)?;
+
+            result.push((vu_call_evt, queue));
+
+            self.vu
+                .set_vring_kick(queue_index, &queue_evts[queue_index])
+                .map_err(Error::VhostUserSetVringKick)?;
+        }
+
+        Ok(result)
+    }
+}
+
+impl Drop for Fs {
+    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 Fs {
+    fn device_type(&self) -> u32 {
+        VirtioDeviceType::TYPE_FS as u32
+    }
+
+    fn queue_max_sizes(&self) -> &[u16] {
+        &self.queue_sizes.as_slice()
+    }
+
+    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!("fs: Received request for unknown features page: {}", 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!("fs: Cannot acknowledge unknown features page: {}", 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!("fs: virtio-fs got unknown feature ack: {:x}", v);
+
+            // Don't count these features as acked.
+            v &= !unrequested_features;
+        }
+        self.acked_features |= v;
+    }
+
+    fn read_config(&self, offset: u64, mut data: &mut [u8]) {
+        let config_len = self.config_space.len() as u64;
+        if offset >= config_len {
+            error!("Failed to read config space");
+            return;
+        }
+        if let Some(end) = offset.checked_add(data.len() as u64) {
+            // This write can't fail, offset and end are checked against config_len.
+            data.write_all(&self.config_space[offset as usize..cmp::min(end, config_len) as usize])
+                .unwrap();
+        }
+    }
+
+    fn write_config(&mut self, offset: u64, data: &[u8]) {
+        let data_len = data.len() as u64;
+        let config_len = self.config_space.len() as u64;
+        if offset + data_len > config_len {
+            error!("Failed to write config space");
+            return;
+        }
+        let (_, right) = self.config_space.split_at_mut(offset as usize);
+        right.copy_from_slice(&data[..]);
+    }
+
+    fn activate(
+        &mut self,
+        mem: GuestMemoryMmap,
+        interrupt_cb: Arc<VirtioInterrupt>,
+        status: Arc<AtomicUsize>,
+        queues: Vec<Queue>,
+        queue_evts: Vec<EventFd>,
+    ) -> ActivateResult {
+        if queues.len() != self.queue_sizes.len() || queue_evts.len() != self.queue_sizes.len() {
+            error!(
+                "Cannot perform activate. Expected {} queue(s), got {}",
+                self.queue_sizes.len(),
+                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 vu_call_evt_queue_list = self
+            .setup_vu(&mem, queues, queue_evts)
+            .map_err(ActivateError::VhostUserSetup)?;
+
+        let mut handler = FsEpollHandler {
+            vu_call_evt_queue_list,
+            interrupt_status: status,
+            interrupt_cb,
+            kill_evt,
+        };
+
+        let worker_result = thread::Builder::new()
+            .name("virtio_fs".to_string())
+            .spawn(move || handler.run());
+
+        if let Err(e) = worker_result {
+            error!("failed to spawn virtio_blk worker: {}", e);
+            return Err(ActivateError::BadActivate);
+        }
+
+        Ok(())
+    }
+}

vm-virtio/src/lib.rs

@@ -21,6 +21,7 @@ use std::io;
 
 mod block;
 mod device;
+pub mod fs;
 pub mod net;
 mod queue;
 mod rng;
@@ -29,6 +30,7 @@ pub mod transport;
 
 pub use self::block::*;
 pub use self::device::*;
+pub use self::fs::*;
 pub use self::net::*;
 pub use self::queue::*;
 pub use self::rng::*;
@@ -40,8 +42,8 @@ const DEVICE_DRIVER_OK: u32 = 0x04;
 const DEVICE_FEATURES_OK: u32 = 0x08;
 const DEVICE_FAILED: u32 = 0x80;
 
-#[allow(dead_code)]
 const VIRTIO_F_VERSION_1: u32 = 32;
+const VIRTIO_F_VERSION_1_BITMASK: u64 = 1 << VIRTIO_F_VERSION_1;
 
 // Types taken from linux/virtio_ids.h
 #[derive(Copy, Clone)]
@@ -57,6 +59,7 @@ enum VirtioDeviceType {
     TYPE_GPU = 16,
     TYPE_INPUT = 18,
     TYPE_VSOCK = 19,
+    TYPE_FS = 26,
 }
 
 // In order to use the `{}` marker, the trait `fmt::Display` must be implemented
@@ -72,6 +75,7 @@ impl fmt::Display for VirtioDeviceType {
             VirtioDeviceType::TYPE_GPU => "gpu",
             VirtioDeviceType::TYPE_9P => "9p",
             VirtioDeviceType::TYPE_VSOCK => "vsock",
+            VirtioDeviceType::TYPE_FS => "fs",
             _ => return Err(std::fmt::Error),
         };
         write!(f, "{}", output)
@@ -87,6 +91,9 @@ const INTERRUPT_STATUS_CONFIG_CHANGED: u32 = 0x2;
 pub enum ActivateError {
     EpollCtl(std::io::Error),
     BadActivate,
+
+    /// Failed to setup vhost-user daemon.
+    VhostUserSetup(fs::Error),
 }
 
 pub type ActivateResult = std::result::Result<(), ActivateError>;