cloud-hypervisor/virtio-devices/src/block_io_uring.rs
Rob Bradford dc9f1e4cdf virtio-devices: block_io_uring: Port to VirtioCommon for feature handling
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
2020-09-03 17:00:32 +02:00

701 lines
24 KiB
Rust

// Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
//
// 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 LICENSE-BSD-3-Clause file.
//
// Copyright © 2020 Intel Corporation
//
// SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
use super::Error as DeviceError;
use super::{
ActivateError, ActivateResult, EpollHelper, EpollHelperError, EpollHelperHandler, Queue,
VirtioCommon, VirtioDevice, VirtioDeviceType, VirtioInterruptType, EPOLL_HELPER_EVENT_LAST,
};
use crate::VirtioInterrupt;
use anyhow::anyhow;
use block_util::{build_disk_image_id, Request, RequestType, VirtioBlockConfig};
use io_uring::IoUring;
use libc::EFD_NONBLOCK;
use std::collections::HashMap;
use std::fs::File;
use std::io::{self, Seek, SeekFrom};
use std::num::Wrapping;
use std::os::unix::io::{AsRawFd, RawFd};
use std::path::PathBuf;
use std::result;
use std::sync::atomic::{AtomicBool, AtomicU64, Ordering};
use std::sync::{Arc, Barrier};
use std::thread;
use virtio_bindings::bindings::virtio_blk::*;
use vm_memory::{
ByteValued, Bytes, GuestAddress, GuestAddressSpace, GuestMemoryAtomic, GuestMemoryError,
GuestMemoryMmap,
};
use vm_migration::{
Migratable, MigratableError, Pausable, Snapshot, SnapshotDataSection, Snapshottable,
Transportable,
};
use vmm_sys_util::eventfd::EventFd;
const SECTOR_SHIFT: u8 = 9;
pub const SECTOR_SIZE: u64 = (0x01 as u64) << SECTOR_SHIFT;
// New descriptors are pending on the virtio queue.
const QUEUE_AVAIL_EVENT: u16 = EPOLL_HELPER_EVENT_LAST + 1;
// New completed tasks are pending on the completion ring.
const IO_URING_EVENT: u16 = EPOLL_HELPER_EVENT_LAST + 2;
#[derive(Debug)]
pub enum Error {
/// Guest gave us bad memory addresses.
GuestMemory(GuestMemoryError),
/// Guest gave us offsets that would have overflowed a usize.
CheckedOffset(GuestAddress, usize),
/// Guest gave us a write only descriptor that protocol says to read from.
UnexpectedWriteOnlyDescriptor,
/// Guest gave us a read only descriptor that protocol says to write to.
UnexpectedReadOnlyDescriptor,
/// Guest gave us too few descriptors in a descriptor chain.
DescriptorChainTooShort,
/// Guest gave us a descriptor that was too short to use.
DescriptorLengthTooSmall,
/// Getting a block's metadata fails for any reason.
GetFileMetadata,
/// The requested operation would cause a seek beyond disk end.
InvalidOffset,
/// Unsupported operation on the disk.
Unsupported(u32),
/// Failed to parse the request.
RequestParsing(block_util::Error),
/// Failed to execute the request.
RequestExecuting(block_util::ExecuteError),
/// Missing the expected entry in the list of requests.
MissingEntryRequestList,
/// The asynchronous request returned with failure.
AsyncRequestFailure,
}
pub type Result<T> = result::Result<T, Error>;
#[derive(Default, Clone)]
pub struct BlockCounters {
read_bytes: Arc<AtomicU64>,
read_ops: Arc<AtomicU64>,
write_bytes: Arc<AtomicU64>,
write_ops: Arc<AtomicU64>,
}
struct BlockIoUringEpollHandler {
queue: Queue,
mem: GuestMemoryAtomic<GuestMemoryMmap>,
disk_image_fd: RawFd,
disk_nsectors: u64,
interrupt_cb: Arc<dyn VirtioInterrupt>,
disk_image_id: Vec<u8>,
kill_evt: EventFd,
pause_evt: EventFd,
writeback: Arc<AtomicBool>,
counters: BlockCounters,
queue_evt: EventFd,
io_uring: IoUring,
io_uring_evt: EventFd,
request_list: HashMap<u16, Request>,
}
impl BlockIoUringEpollHandler {
fn process_queue_submit(&mut self) -> Result<bool> {
let queue = &mut self.queue;
let mem = self.mem.memory();
let mut used_desc_heads = Vec::new();
let mut used_count = 0;
for avail_desc in queue.iter(&mem) {
let mut request = Request::parse(&avail_desc, &mem).map_err(Error::RequestParsing)?;
request.set_writeback(self.writeback.load(Ordering::SeqCst));
if request
.execute_io_uring(
&mem,
&mut self.io_uring,
self.disk_nsectors,
self.disk_image_fd,
&self.disk_image_id,
avail_desc.index as u64,
)
.map_err(Error::RequestExecuting)?
{
self.request_list.insert(avail_desc.index, request);
} else {
// We use unwrap because the request parsing process already
// checked that the status_addr was valid.
mem.write_obj(VIRTIO_BLK_S_OK, request.status_addr).unwrap();
// If no asynchronous operation has been submitted, we can
// simply return the used descriptor.
used_desc_heads.push((avail_desc.index, 0));
used_count += 1;
}
}
for &(desc_index, len) in used_desc_heads.iter() {
queue.add_used(&mem, desc_index, len);
}
Ok(used_count > 0)
}
fn process_queue_complete(&mut self) -> Result<bool> {
let queue = &mut self.queue;
let mut used_desc_heads = Vec::new();
let mut used_count = 0;
let mem = self.mem.memory();
let mut read_bytes = Wrapping(0);
let mut write_bytes = Wrapping(0);
let mut read_ops = Wrapping(0);
let mut write_ops = Wrapping(0);
let cq = self.io_uring.completion();
for cq_entry in cq.available() {
let result = cq_entry.result();
let desc_index = cq_entry.user_data() as u16;
let request = self
.request_list
.remove(&desc_index)
.ok_or(Error::MissingEntryRequestList)?;
let (status, len) = if result >= 0 {
match request.request_type {
RequestType::In => {
read_bytes += Wrapping(request.data_len as u64);
read_ops += Wrapping(1);
}
RequestType::Out => {
if !request.writeback {
unsafe { libc::fsync(self.disk_image_fd) };
}
write_bytes += Wrapping(request.data_len as u64);
write_ops += Wrapping(1);
}
_ => {}
}
(VIRTIO_BLK_S_OK, result as u32)
} else {
error!(
"Request failed: {:?}",
io::Error::from_raw_os_error(-result)
);
return Err(Error::AsyncRequestFailure);
};
// We use unwrap because the request parsing process already
// checked that the status_addr was valid.
mem.write_obj(status, request.status_addr).unwrap();
used_desc_heads.push((desc_index, len));
used_count += 1;
}
for &(desc_index, len) in used_desc_heads.iter() {
queue.add_used(&mem, desc_index, len);
}
self.counters
.write_bytes
.fetch_add(write_bytes.0, Ordering::AcqRel);
self.counters
.write_ops
.fetch_add(write_ops.0, Ordering::AcqRel);
self.counters
.read_bytes
.fetch_add(read_bytes.0, Ordering::AcqRel);
self.counters
.read_ops
.fetch_add(read_ops.0, Ordering::AcqRel);
Ok(used_count > 0)
}
fn signal_used_queue(&self) -> result::Result<(), DeviceError> {
self.interrupt_cb
.trigger(&VirtioInterruptType::Queue, Some(&self.queue))
.map_err(|e| {
error!("Failed to signal used queue: {:?}", e);
DeviceError::FailedSignalingUsedQueue(e)
})
}
fn run(
&mut self,
paused: Arc<AtomicBool>,
paused_sync: Arc<Barrier>,
) -> result::Result<(), EpollHelperError> {
let mut helper = EpollHelper::new(&self.kill_evt, &self.pause_evt)?;
helper.add_event(self.queue_evt.as_raw_fd(), QUEUE_AVAIL_EVENT)?;
helper.add_event(self.io_uring_evt.as_raw_fd(), IO_URING_EVENT)?;
helper.run(paused, paused_sync, self)?;
Ok(())
}
}
impl EpollHelperHandler for BlockIoUringEpollHandler {
fn handle_event(&mut self, _helper: &mut EpollHelper, event: &epoll::Event) -> bool {
let ev_type = event.data as u16;
match ev_type {
QUEUE_AVAIL_EVENT => {
if let Err(e) = self.queue_evt.read() {
error!("Failed to get queue event: {:?}", e);
return true;
}
match self.process_queue_submit() {
Ok(needs_notification) => {
if needs_notification {
if let Err(e) = self.signal_used_queue() {
error!("Failed to signal used queue: {:?}", e);
return true;
}
}
}
Err(e) => {
error!("Failed to process queue (submit): {:?}", e);
return true;
}
}
}
IO_URING_EVENT => {
if let Err(e) = self.io_uring_evt.read() {
error!("Failed to get queue event: {:?}", e);
return true;
}
match self.process_queue_complete() {
Ok(needs_notification) => {
if needs_notification {
if let Err(e) = self.signal_used_queue() {
error!("Failed to signal used queue: {:?}", e);
return true;
}
}
}
Err(e) => {
error!("Failed to process queue (complete): {:?}", e);
return true;
}
}
}
_ => {
error!("Unexpected event: {}", ev_type);
return true;
}
}
false
}
}
/// Virtio device for exposing block level read/write operations on a host file.
pub struct BlockIoUring {
common: VirtioCommon,
id: String,
kill_evt: Option<EventFd>,
disk_image: File,
disk_path: PathBuf,
disk_nsectors: u64,
config: VirtioBlockConfig,
queue_evts: Option<Vec<EventFd>>,
interrupt_cb: Option<Arc<dyn VirtioInterrupt>>,
epoll_threads: Option<Vec<thread::JoinHandle<()>>>,
pause_evt: Option<EventFd>,
paused: Arc<AtomicBool>,
paused_sync: Arc<Barrier>,
queue_size: Vec<u16>,
writeback: Arc<AtomicBool>,
counters: BlockCounters,
}
#[derive(Serialize, Deserialize)]
pub struct BlockState {
pub disk_path: PathBuf,
pub disk_nsectors: u64,
pub avail_features: u64,
pub acked_features: u64,
pub config: VirtioBlockConfig,
}
impl BlockIoUring {
/// Create a new virtio block device that operates on the given file.
pub fn new(
id: String,
mut disk_image: File,
disk_path: PathBuf,
is_disk_read_only: bool,
iommu: bool,
num_queues: usize,
queue_size: u16,
) -> io::Result<Self> {
let disk_size = disk_image.seek(SeekFrom::End(0))? as u64;
if disk_size % SECTOR_SIZE != 0 {
warn!(
"Disk size {} is not a multiple of sector size {}; \
the remainder will not be visible to the guest.",
disk_size, SECTOR_SIZE
);
}
let mut avail_features = (1u64 << VIRTIO_F_VERSION_1)
| (1u64 << VIRTIO_BLK_F_FLUSH)
| (1u64 << VIRTIO_BLK_F_CONFIG_WCE);
if iommu {
avail_features |= 1u64 << VIRTIO_F_IOMMU_PLATFORM;
}
if is_disk_read_only {
avail_features |= 1u64 << VIRTIO_BLK_F_RO;
}
let disk_nsectors = disk_size / SECTOR_SIZE;
let mut config = VirtioBlockConfig {
capacity: disk_nsectors,
writeback: 1,
..Default::default()
};
if num_queues > 1 {
avail_features |= 1u64 << VIRTIO_BLK_F_MQ;
config.num_queues = num_queues as u16;
}
Ok(BlockIoUring {
common: VirtioCommon {
avail_features,
acked_features: 0u64,
},
id,
kill_evt: None,
disk_image,
disk_path,
disk_nsectors,
config,
queue_evts: None,
interrupt_cb: None,
epoll_threads: None,
pause_evt: None,
paused: Arc::new(AtomicBool::new(false)),
paused_sync: Arc::new(Barrier::new(num_queues + 1)),
queue_size: vec![queue_size; num_queues],
writeback: Arc::new(AtomicBool::new(true)),
counters: BlockCounters::default(),
})
}
fn state(&self) -> BlockState {
BlockState {
disk_path: self.disk_path.clone(),
disk_nsectors: self.disk_nsectors,
avail_features: self.common.avail_features,
acked_features: self.common.acked_features,
config: self.config,
}
}
fn set_state(&mut self, state: &BlockState) -> io::Result<()> {
self.disk_path = state.disk_path.clone();
self.disk_nsectors = state.disk_nsectors;
self.common.avail_features = state.avail_features;
self.common.acked_features = state.acked_features;
self.config = state.config;
Ok(())
}
fn update_writeback(&mut self) {
// Use writeback from config if VIRTIO_BLK_F_CONFIG_WCE
let writeback = if self.common.feature_acked(VIRTIO_BLK_F_CONFIG_WCE.into()) {
self.config.writeback == 1
} else {
// Else check if VIRTIO_BLK_F_FLUSH negotiated
self.common.feature_acked(VIRTIO_BLK_F_FLUSH.into())
};
info!(
"Changing cache mode to {}",
if writeback {
"writeback"
} else {
"writethrough"
}
);
self.writeback.store(writeback, Ordering::SeqCst);
}
}
impl Drop for BlockIoUring {
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 BlockIoUring {
fn device_type(&self) -> u32 {
VirtioDeviceType::TYPE_BLOCK as u32
}
fn queue_max_sizes(&self) -> &[u16] {
self.queue_size.as_slice()
}
fn features(&self) -> u64 {
self.common.avail_features
}
fn ack_features(&mut self, value: u64) {
self.common.ack_features(value)
}
fn read_config(&self, offset: u64, data: &mut [u8]) {
self.read_config_from_slice(self.config.as_slice(), offset, data);
}
fn write_config(&mut self, offset: u64, data: &[u8]) {
// The "writeback" field is the only mutable field
let writeback_offset =
(&self.config.writeback as *const _ as u64) - (&self.config as *const _ as u64);
if offset != writeback_offset || data.len() != std::mem::size_of_val(&self.config.writeback)
{
error!(
"Attempt to write to read-only field: offset {:x} length {}",
offset,
data.len()
);
return;
}
self.config.writeback = data[0];
self.update_writeback();
}
fn activate(
&mut self,
mem: GuestMemoryAtomic<GuestMemoryMmap>,
interrupt_cb: Arc<dyn VirtioInterrupt>,
mut queues: Vec<Queue>,
mut queue_evts: Vec<EventFd>,
) -> ActivateResult {
if queues.len() != self.queue_size.len() || queue_evts.len() != self.queue_size.len() {
error!(
"Cannot perform activate. Expected {} queue(s), got {}",
self.queue_size.len(),
queues.len()
);
return Err(ActivateError::BadActivate);
}
let (self_kill_evt, kill_evt) = EventFd::new(EFD_NONBLOCK)
.and_then(|e| Ok((e.try_clone()?, e)))
.map_err(|e| {
error!("failed creating kill EventFd pair: {}", e);
ActivateError::BadActivate
})?;
self.kill_evt = Some(self_kill_evt);
let (self_pause_evt, pause_evt) = EventFd::new(EFD_NONBLOCK)
.and_then(|e| Ok((e.try_clone()?, e)))
.map_err(|e| {
error!("failed creating pause EventFd pair: {}", e);
ActivateError::BadActivate
})?;
self.pause_evt = Some(self_pause_evt);
let disk_image_id = build_disk_image_id(&self.disk_path);
let mut tmp_queue_evts: Vec<EventFd> = Vec::new();
for queue_evt in queue_evts.iter() {
// Save the queue EventFD as we need to return it on reset
// but clone it to pass into the thread.
tmp_queue_evts.push(queue_evt.try_clone().map_err(|e| {
error!("failed to clone queue EventFd: {}", e);
ActivateError::BadActivate
})?);
}
self.queue_evts = Some(tmp_queue_evts);
let mut tmp_queue_evts: Vec<EventFd> = Vec::new();
for queue_evt in queue_evts.iter() {
// Save the queue EventFD as we need to return it on reset
// but clone it to pass into the thread.
tmp_queue_evts.push(queue_evt.try_clone().map_err(|e| {
error!("failed to clone queue EventFd: {}", e);
ActivateError::BadActivate
})?);
}
self.queue_evts = Some(tmp_queue_evts);
self.update_writeback();
let mut epoll_threads = Vec::new();
for i in 0..self.queue_size.len() {
let queue_size = self.queue_size[i] as usize;
let queue_evt = queue_evts.remove(0);
let io_uring = IoUring::new(queue_size as u32).map_err(|e| {
error!("failed to create io_uring instance: {}", e);
ActivateError::BadActivate
})?;
let mut handler = BlockIoUringEpollHandler {
queue: queues.remove(0),
mem: mem.clone(),
disk_image_fd: self.disk_image.as_raw_fd(),
disk_nsectors: self.disk_nsectors,
interrupt_cb: interrupt_cb.clone(),
disk_image_id: disk_image_id.clone(),
kill_evt: kill_evt.try_clone().map_err(|e| {
error!("failed to clone kill_evt eventfd: {}", e);
ActivateError::BadActivate
})?,
pause_evt: pause_evt.try_clone().map_err(|e| {
error!("failed to clone pause_evt eventfd: {}", e);
ActivateError::BadActivate
})?,
writeback: self.writeback.clone(),
counters: self.counters.clone(),
queue_evt,
io_uring,
io_uring_evt: EventFd::new(EFD_NONBLOCK).map_err(|e| {
error!("failed to create io_uring eventfd: {}", e);
ActivateError::BadActivate
})?,
request_list: HashMap::with_capacity(queue_size),
};
let paused = self.paused.clone();
let paused_sync = self.paused_sync.clone();
// Register the io_uring eventfd that will notify the epoll loop
// when something in the completion queue is ready.
handler
.io_uring
.submitter()
.register_eventfd(handler.io_uring_evt.as_raw_fd())
.map_err(|e| {
error!("failed to register eventfd for io_uring: {}", e);
ActivateError::BadActivate
})?;
thread::Builder::new()
.name("virtio_blk".to_string())
.spawn(move || {
if let Err(e) = handler.run(paused, paused_sync) {
error!("Error running worker: {:?}", e);
}
})
.map(|thread| epoll_threads.push(thread))
.map_err(|e| {
error!("failed to clone the virtio-blk epoll thread: {}", e);
ActivateError::BadActivate
})?;
}
// Save the interrupt EventFD as we need to return it on reset
// but clone it to pass into the thread.
self.interrupt_cb = Some(interrupt_cb);
self.epoll_threads = Some(epoll_threads);
Ok(())
}
fn reset(&mut self) -> Option<(Arc<dyn VirtioInterrupt>, Vec<EventFd>)> {
// We first must resume the virtio thread if it was paused.
if self.pause_evt.take().is_some() {
self.resume().ok()?;
}
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);
}
// Return the interrupt and queue EventFDs
Some((
self.interrupt_cb.take().unwrap(),
self.queue_evts.take().unwrap(),
))
}
fn counters(&self) -> Option<HashMap<&'static str, Wrapping<u64>>> {
let mut counters = HashMap::new();
counters.insert(
"read_bytes",
Wrapping(self.counters.read_bytes.load(Ordering::Acquire)),
);
counters.insert(
"write_bytes",
Wrapping(self.counters.write_bytes.load(Ordering::Acquire)),
);
counters.insert(
"read_ops",
Wrapping(self.counters.read_ops.load(Ordering::Acquire)),
);
counters.insert(
"write_ops",
Wrapping(self.counters.write_ops.load(Ordering::Acquire)),
);
Some(counters)
}
}
virtio_pausable!(BlockIoUring);
impl Snapshottable for BlockIoUring {
fn id(&self) -> String {
self.id.clone()
}
fn snapshot(&mut self) -> std::result::Result<Snapshot, MigratableError> {
let snapshot =
serde_json::to_vec(&self.state()).map_err(|e| MigratableError::Snapshot(e.into()))?;
let mut block_snapshot = Snapshot::new(self.id.as_str());
block_snapshot.add_data_section(SnapshotDataSection {
id: format!("{}-section", self.id),
snapshot,
});
Ok(block_snapshot)
}
fn restore(&mut self, snapshot: Snapshot) -> std::result::Result<(), MigratableError> {
if let Some(block_section) = snapshot.snapshot_data.get(&format!("{}-section", self.id)) {
let block_state = match serde_json::from_slice(&block_section.snapshot) {
Ok(state) => state,
Err(error) => {
return Err(MigratableError::Restore(anyhow!(
"Could not deserialize BLOCK {}",
error
)))
}
};
return self.set_state(&block_state).map_err(|e| {
MigratableError::Restore(anyhow!("Could not restore BLOCK state {:?}", e))
});
}
Err(MigratableError::Restore(anyhow!(
"Could not find BLOCK snapshot section"
)))
}
}
impl Transportable for BlockIoUring {}
impl Migratable for BlockIoUring {}