cloud-hypervisor/vm-virtio/src/pmem.rs

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// Copyright 2019 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 file.
//
// Copyright © 2019 Intel Corporation
//
// SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
use super::Error as DeviceError;
use super::{
ActivateError, ActivateResult, DescriptorChain, DeviceEventT, Queue, UserspaceMapping,
VirtioDevice, VirtioDeviceType, VIRTIO_F_IOMMU_PLATFORM, VIRTIO_F_VERSION_1,
};
use crate::{VirtioInterrupt, VirtioInterruptType};
use anyhow::anyhow;
use epoll;
use libc::EFD_NONBLOCK;
use serde::ser::{Serialize, SerializeStruct, Serializer};
use std::cmp;
use std::fmt::{self, Display};
use std::fs::File;
use std::io::{self, Write};
use std::mem::size_of;
use std::os::unix::io::AsRawFd;
use std::result;
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::Arc;
use std::thread;
use vm_memory::{
Address, ByteValued, Bytes, GuestAddress, GuestAddressSpace, GuestMemoryAtomic,
GuestMemoryError, GuestMemoryMmap, MmapRegion,
};
use vm_migration::{
Migratable, MigratableError, Pausable, Snapshot, SnapshotDataSection, Snapshottable,
Transportable,
};
use vmm_sys_util::eventfd::EventFd;
const QUEUE_SIZE: u16 = 256;
const NUM_QUEUES: usize = 1;
const QUEUE_SIZES: &[u16] = &[QUEUE_SIZE];
const VIRTIO_PMEM_REQ_TYPE_FLUSH: u32 = 0;
const VIRTIO_PMEM_RESP_TYPE_OK: u32 = 0;
const VIRTIO_PMEM_RESP_TYPE_EIO: u32 = 1;
// New descriptors are pending on the virtio queue.
const QUEUE_AVAIL_EVENT: DeviceEventT = 0;
// The device has been dropped.
const KILL_EVENT: DeviceEventT = 1;
// The device should be paused.
const PAUSE_EVENT: DeviceEventT = 2;
#[derive(Copy, Clone, Debug, Default, Deserialize)]
#[repr(C, packed)]
struct VirtioPmemConfig {
start: u64,
size: u64,
}
// We must explicitly implement Serialize since the structure is packed and
// it's unsafe to borrow from a packed structure. And by default, if we derive
// Serialize from serde, it will borrow the values from the structure.
// That's why this implementation copies each field separately before it
// serializes the entire structure field by field.
impl Serialize for VirtioPmemConfig {
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
S: Serializer,
{
let start = self.start;
let size = self.size;
let mut virtio_pmem_config = serializer.serialize_struct("VirtioPmemConfig", 16)?;
virtio_pmem_config.serialize_field("start", &start)?;
virtio_pmem_config.serialize_field("size", &size)?;
virtio_pmem_config.end()
}
}
// Safe because it only has data and has no implicit padding.
unsafe impl ByteValued for VirtioPmemConfig {}
#[derive(Copy, Clone, Debug, Default)]
#[repr(C)]
struct VirtioPmemReq {
type_: u32,
}
// Safe because it only has data and has no implicit padding.
unsafe impl ByteValued for VirtioPmemReq {}
#[derive(Copy, Clone, Debug, Default)]
#[repr(C)]
struct VirtioPmemResp {
ret: u32,
}
// Safe because it only has data and has no implicit padding.
unsafe impl ByteValued for VirtioPmemResp {}
#[derive(Debug)]
enum Error {
/// Guest gave us bad memory addresses.
GuestMemory(GuestMemoryError),
/// 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 buffer that was too short to use.
BufferLengthTooSmall,
/// Guest sent us invalid request.
InvalidRequest,
}
impl Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
use self::Error::*;
match self {
BufferLengthTooSmall => write!(f, "buffer length too small"),
DescriptorChainTooShort => write!(f, "descriptor chain too short"),
GuestMemory(e) => write!(f, "bad guest memory address: {}", e),
InvalidRequest => write!(f, "invalid request"),
UnexpectedReadOnlyDescriptor => write!(f, "unexpected read-only descriptor"),
UnexpectedWriteOnlyDescriptor => write!(f, "unexpected write-only descriptor"),
}
}
}
#[derive(Debug, PartialEq)]
enum RequestType {
Flush,
}
struct Request {
type_: RequestType,
status_addr: GuestAddress,
}
impl Request {
fn parse(
avail_desc: &DescriptorChain,
mem: &GuestMemoryMmap,
) -> result::Result<Request, Error> {
// The head contains the request type which MUST be readable.
if avail_desc.is_write_only() {
return Err(Error::UnexpectedWriteOnlyDescriptor);
}
if avail_desc.len as usize != size_of::<VirtioPmemReq>() {
return Err(Error::InvalidRequest);
}
let request: VirtioPmemReq = mem.read_obj(avail_desc.addr).map_err(Error::GuestMemory)?;
let request_type = match request.type_ {
VIRTIO_PMEM_REQ_TYPE_FLUSH => RequestType::Flush,
_ => return Err(Error::InvalidRequest),
};
let status_desc = avail_desc
.next_descriptor()
.ok_or(Error::DescriptorChainTooShort)?;
// The status MUST always be writable
if !status_desc.is_write_only() {
return Err(Error::UnexpectedReadOnlyDescriptor);
}
if (status_desc.len as usize) < size_of::<VirtioPmemResp>() {
return Err(Error::BufferLengthTooSmall);
}
Ok(Request {
type_: request_type,
status_addr: status_desc.addr,
})
}
}
struct PmemEpollHandler {
queue: Queue,
mem: GuestMemoryAtomic<GuestMemoryMmap>,
disk: File,
interrupt_cb: Arc<dyn VirtioInterrupt>,
queue_evt: EventFd,
kill_evt: EventFd,
pause_evt: EventFd,
}
impl PmemEpollHandler {
fn process_queue(&mut self) -> bool {
let mut used_desc_heads = [(0, 0); QUEUE_SIZE as usize];
let mut used_count = 0;
let mem = self.mem.memory();
for avail_desc in self.queue.iter(&mem) {
let len = match Request::parse(&avail_desc, &mem) {
Ok(ref req) if (req.type_ == RequestType::Flush) => {
let status_code = match self.disk.sync_all() {
Ok(()) => VIRTIO_PMEM_RESP_TYPE_OK,
Err(e) => {
error!("failed flushing disk image: {}", e);
VIRTIO_PMEM_RESP_TYPE_EIO
}
};
let resp = VirtioPmemResp { ret: status_code };
match mem.write_obj(resp, req.status_addr) {
Ok(_) => size_of::<VirtioPmemResp>() as u32,
Err(e) => {
error!("bad guest memory address: {}", e);
0
}
}
}
Ok(ref req) => {
// Currently, there is only one virtio-pmem request, FLUSH.
error!("Invalid virtio request type {:?}", req.type_);
0
}
Err(e) => {
error!("Failed to parse available descriptor chain: {:?}", e);
0
}
};
used_desc_heads[used_count] = (avail_desc.index, len);
used_count += 1;
}
for &(desc_index, len) in &used_desc_heads[..used_count] {
self.queue.add_used(&mem, desc_index, len);
}
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>) -> 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_evt.as_raw_fd(),
epoll::Event::new(epoll::Events::EPOLLIN, u64::from(QUEUE_AVAIL_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)?;
epoll::ctl(
epoll_fd,
epoll::ControlOptions::EPOLL_CTL_ADD,
self.pause_evt.as_raw_fd(),
epoll::Event::new(epoll::Events::EPOLLIN, u64::from(PAUSE_EVENT)),
)
.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 = 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 {
QUEUE_AVAIL_EVENT => {
if let Err(e) = self.queue_evt.read() {
error!("Failed to get queue event: {:?}", e);
break 'epoll;
} else if self.process_queue() {
if let Err(e) = self.signal_used_queue() {
error!("Failed to signal used queue: {:?}", e);
break 'epoll;
}
}
}
KILL_EVENT => {
debug!("kill_evt received, stopping epoll loop");
break 'epoll;
}
PAUSE_EVENT => {
// Drain pause event
let _ = self.pause_evt.read();
debug!("PAUSE_EVENT received, pausing virtio-pmem 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();
}
}
_ => {
error!("Unknown event for virtio-block");
}
}
}
}
Ok(())
}
}
pub struct Pmem {
id: String,
kill_evt: Option<EventFd>,
pause_evt: Option<EventFd>,
disk: Option<File>,
avail_features: u64,
acked_features: u64,
config: VirtioPmemConfig,
queue_evts: Option<Vec<EventFd>>,
interrupt_cb: Option<Arc<dyn VirtioInterrupt>>,
epoll_threads: Option<Vec<thread::JoinHandle<result::Result<(), DeviceError>>>>,
paused: Arc<AtomicBool>,
mapping: UserspaceMapping,
// Hold ownership of the memory that is allocated for the device
// which will be automatically dropped when the device is dropped
_region: MmapRegion,
}
#[derive(Serialize, Deserialize)]
pub struct PmemState {
avail_features: u64,
acked_features: u64,
config: VirtioPmemConfig,
}
impl Pmem {
pub fn new(
id: String,
disk: File,
addr: GuestAddress,
mapping: UserspaceMapping,
_region: MmapRegion,
iommu: bool,
) -> io::Result<Pmem> {
let config = VirtioPmemConfig {
start: addr.raw_value().to_le(),
size: (_region.size() as u64).to_le(),
};
let mut avail_features = 1u64 << VIRTIO_F_VERSION_1;
if iommu {
avail_features |= 1u64 << VIRTIO_F_IOMMU_PLATFORM;
}
Ok(Pmem {
id,
kill_evt: None,
pause_evt: None,
disk: Some(disk),
avail_features,
acked_features: 0u64,
config,
queue_evts: None,
interrupt_cb: None,
epoll_threads: None,
paused: Arc::new(AtomicBool::new(false)),
mapping,
_region,
})
}
fn state(&self) -> PmemState {
PmemState {
avail_features: self.avail_features,
acked_features: self.acked_features,
config: self.config,
}
}
fn set_state(&mut self, state: &PmemState) -> io::Result<()> {
self.avail_features = state.avail_features;
self.acked_features = state.acked_features;
self.config = state.config;
Ok(())
}
}
impl Drop for Pmem {
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 Pmem {
fn device_type(&self) -> u32 {
VirtioDeviceType::TYPE_PMEM as u32
}
fn queue_max_sizes(&self) -> &[u16] {
QUEUE_SIZES
}
fn features(&self) -> u64 {
self.avail_features
}
fn ack_features(&mut self, value: u64) {
let mut v = value;
// 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, mut data: &mut [u8]) {
let config_slice = self.config.as_slice();
let config_len = config_slice.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(&config_slice[offset as usize..cmp::min(end, config_len) as usize])
.unwrap();
}
}
fn write_config(&mut self, _offset: u64, _data: &[u8]) {
warn!("virtio-pmem device configuration is read-only");
}
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() != 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) = 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);
// 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.clone());
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);
if let Some(disk) = self.disk.as_ref() {
let disk = disk.try_clone().map_err(|e| {
error!("failed cloning pmem disk: {}", e);
ActivateError::BadActivate
})?;
let mut handler = PmemEpollHandler {
queue: queues.remove(0),
mem,
disk,
interrupt_cb,
queue_evt: queue_evts.remove(0),
kill_evt,
pause_evt,
};
let paused = self.paused.clone();
let mut epoll_threads = Vec::new();
thread::Builder::new()
.name("virtio_pmem".to_string())
.spawn(move || handler.run(paused))
.map(|thread| epoll_threads.push(thread))
.map_err(|e| {
error!("failed to clone virtio-pmem epoll thread: {}", e);
ActivateError::BadActivate
})?;
self.epoll_threads = Some(epoll_threads);
return Ok(());
}
Err(ActivateError::BadActivate)
}
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 userspace_mappings(&self) -> Vec<UserspaceMapping> {
vec![self.mapping.clone()]
}
}
virtio_pausable!(Pmem);
impl Snapshottable for Pmem {
fn id(&self) -> String {
self.id.clone()
}
fn snapshot(&self) -> std::result::Result<Snapshot, MigratableError> {
let snapshot =
serde_json::to_vec(&self.state()).map_err(|e| MigratableError::Snapshot(e.into()))?;
let mut pmem_snapshot = Snapshot::new(self.id.as_str());
pmem_snapshot.add_data_section(SnapshotDataSection {
id: format!("{}-section", self.id),
snapshot,
});
Ok(pmem_snapshot)
}
fn restore(&mut self, snapshot: Snapshot) -> std::result::Result<(), MigratableError> {
if let Some(pmem_section) = snapshot.snapshot_data.get(&format!("{}-section", self.id)) {
let pmem_state = match serde_json::from_slice(&pmem_section.snapshot) {
Ok(state) => state,
Err(error) => {
return Err(MigratableError::Restore(anyhow!(
"Could not deserialize PMEM {}",
error
)))
}
};
return self.set_state(&pmem_state).map_err(|e| {
MigratableError::Restore(anyhow!("Could not restore PMEM state {:?}", e))
});
}
Err(MigratableError::Restore(anyhow!(
"Could not find PMEM snapshot section"
)))
}
}
impl Transportable for Pmem {}
impl Migratable for Pmem {}