cloud-hypervisor/virtio-devices/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, EpollHelper, EpollHelperError,
EpollHelperHandler, Queue, UserspaceMapping, VirtioCommon, VirtioDevice, VirtioDeviceType,
EPOLL_HELPER_EVENT_LAST, VIRTIO_F_IOMMU_PLATFORM, VIRTIO_F_VERSION_1,
};
use crate::seccomp_filters::{get_seccomp_filter, Thread};
use crate::{VirtioInterrupt, VirtioInterruptType};
use seccomp::{SeccompAction, SeccompFilter};
use std::fmt::{self, Display};
use std::fs::File;
use std::io;
use std::mem::size_of;
use std::os::unix::io::AsRawFd;
use std::result;
use std::sync::atomic::AtomicBool;
use std::sync::{Arc, Barrier};
use std::thread;
use vm_memory::{
Address, ByteValued, Bytes, GuestAddress, GuestAddressSpace, GuestMemoryAtomic,
GuestMemoryError, GuestMemoryMmap, MmapRegion,
};
use vm_migration::{Migratable, MigratableError, Pausable, Snapshot, Snapshottable, Transportable};
use vmm_sys_util::eventfd::EventFd;
const QUEUE_SIZE: u16 = 256;
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: u16 = EPOLL_HELPER_EVENT_LAST + 1;
#[derive(Copy, Clone, Debug, Default, Serialize, Deserialize)]
#[repr(C)]
struct VirtioPmemConfig {
start: u64,
size: u64,
}
// 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>,
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.run(paused, paused_sync, self)?;
Ok(())
}
}
impl EpollHelperHandler for PmemEpollHandler {
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;
} else if self.process_queue() {
if let Err(e) = self.signal_used_queue() {
error!("Failed to signal used queue: {:?}", e);
return true;
}
}
}
_ => {
error!("Unexpected event: {}", ev_type);
return true;
}
}
false
}
}
pub struct Pmem {
common: VirtioCommon,
id: String,
disk: Option<File>,
config: VirtioPmemConfig,
mapping: UserspaceMapping,
seccomp_action: SeccompAction,
// 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,
seccomp_action: SeccompAction,
) -> 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 {
common: VirtioCommon {
device_type: VirtioDeviceType::Pmem as u32,
queue_sizes: QUEUE_SIZES.to_vec(),
paused_sync: Some(Arc::new(Barrier::new(2))),
avail_features,
min_queues: 1,
..Default::default()
},
id,
disk: Some(disk),
config,
mapping,
seccomp_action,
_region,
})
}
fn state(&self) -> PmemState {
PmemState {
avail_features: self.common.avail_features,
acked_features: self.common.acked_features,
config: self.config,
}
}
fn set_state(&mut self, state: &PmemState) {
self.common.avail_features = state.avail_features;
self.common.acked_features = state.acked_features;
self.config = state.config;
}
}
impl Drop for Pmem {
fn drop(&mut self) {
if let Some(kill_evt) = self.common.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 {
self.common.device_type
}
fn queue_max_sizes(&self) -> &[u16] {
&self.common.queue_sizes
}
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 activate(
&mut self,
mem: GuestMemoryAtomic<GuestMemoryMmap>,
interrupt_cb: Arc<dyn VirtioInterrupt>,
mut queues: Vec<Queue>,
mut queue_evts: Vec<EventFd>,
) -> ActivateResult {
self.common.activate(&queues, &queue_evts, &interrupt_cb)?;
let kill_evt = self
.common
.kill_evt
.as_ref()
.unwrap()
.try_clone()
.map_err(|e| {
error!("failed to clone kill_evt eventfd: {}", e);
ActivateError::BadActivate
})?;
let pause_evt = self
.common
.pause_evt
.as_ref()
.unwrap()
.try_clone()
.map_err(|e| {
error!("failed to clone pause_evt eventfd: {}", e);
ActivateError::BadActivate
})?;
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.common.paused.clone();
let paused_sync = self.common.paused_sync.clone();
let mut epoll_threads = Vec::new();
// Retrieve seccomp filter for virtio_pmem thread
let virtio_pmem_seccomp_filter =
get_seccomp_filter(&self.seccomp_action, Thread::VirtioPmem)
.map_err(ActivateError::CreateSeccompFilter)?;
thread::Builder::new()
.name(self.id.clone())
.spawn(move || {
if let Err(e) = SeccompFilter::apply(virtio_pmem_seccomp_filter) {
error!("Error applying seccomp filter: {:?}", e);
} else if let Err(e) = handler.run(paused, paused_sync.unwrap()) {
error!("Error running worker: {:?}", e);
}
})
.map(|thread| epoll_threads.push(thread))
.map_err(|e| {
error!("failed to clone virtio-pmem epoll thread: {}", e);
ActivateError::BadActivate
})?;
self.common.epoll_threads = Some(epoll_threads);
event!("virtio-device", "activated", "id", &self.id);
return Ok(());
}
Err(ActivateError::BadActivate)
}
fn reset(&mut self) -> Option<Arc<dyn VirtioInterrupt>> {
let result = self.common.reset();
event!("virtio-device", "reset", "id", &self.id);
result
}
fn userspace_mappings(&self) -> Vec<UserspaceMapping> {
vec![self.mapping.clone()]
}
}
impl Pausable for Pmem {
fn pause(&mut self) -> result::Result<(), MigratableError> {
self.common.pause()
}
fn resume(&mut self) -> result::Result<(), MigratableError> {
self.common.resume()
}
}
impl Snapshottable for Pmem {
fn id(&self) -> String {
self.id.clone()
}
fn snapshot(&mut self) -> std::result::Result<Snapshot, MigratableError> {
Snapshot::new_from_state(&self.id, &self.state())
}
fn restore(&mut self, snapshot: Snapshot) -> std::result::Result<(), MigratableError> {
self.set_state(&snapshot.to_state(&self.id)?);
Ok(())
}
}
impl Transportable for Pmem {}
impl Migratable for Pmem {}