// 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 file.
use std;
use std::fmt::{self, Display};
use std::os::unix::io::{AsRawFd, RawFd};
use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::Arc;
use std::thread;
use data_model::{DataInit, Le32};
use msg_socket::MsgReceiver;
use sys_util::{
self, error, info, warn, EventFd, GuestAddress, GuestMemory, PollContext, PollToken,
};
use vm_control::{BalloonControlCommand, BalloonControlResponseSocket};
use super::{
copy_config, Interrupt, Queue, Reader, VirtioDevice, TYPE_BALLOON, VIRTIO_F_VERSION_1,
};
#[derive(Debug)]
pub enum BalloonError {
/// Request to adjust memory size can't provide the number of pages requested.
NotEnoughPages,
/// Failure wriitng the config notification event.
WritingConfigEvent(sys_util::Error),
}
pub type Result<T> = std::result::Result<T, BalloonError>;
impl Display for BalloonError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
use self::BalloonError::*;
match self {
NotEnoughPages => write!(f, "not enough pages"),
WritingConfigEvent(e) => write!(f, "failed to write config event: {}", e),
}
}
}
// Balloon has three virt IO queues: Inflate, Deflate, and Stats.
// Stats is currently not used.
const QUEUE_SIZE: u16 = 128;
const QUEUE_SIZES: &[u16] = &[QUEUE_SIZE, QUEUE_SIZE];
const VIRTIO_BALLOON_PFN_SHIFT: u32 = 12;
// The feature bitmap for virtio balloon
const VIRTIO_BALLOON_F_MUST_TELL_HOST: u32 = 0; // Tell before reclaiming pages
const VIRTIO_BALLOON_F_DEFLATE_ON_OOM: u32 = 2; // Deflate balloon on OOM
// virtio_balloon_config is the ballon device configuration space defined by the virtio spec.
#[derive(Copy, Clone, Debug, Default)]
#[repr(C)]
struct virtio_balloon_config {
num_pages: Le32,
actual: Le32,
}
// Safe because it only has data and has no implicit padding.
unsafe impl DataInit for virtio_balloon_config {}
// BalloonConfig is modified by the worker and read from the device thread.
#[derive(Default)]
struct BalloonConfig {
num_pages: AtomicUsize,
actual_pages: AtomicUsize,
}
struct Worker {
interrupt: Interrupt,
mem: GuestMemory,
inflate_queue: Queue,
deflate_queue: Queue,
config: Arc<BalloonConfig>,
command_socket: BalloonControlResponseSocket,
}
impl Worker {
fn process_inflate_deflate(&mut self, inflate: bool) -> bool {
let queue = if inflate {
&mut self.inflate_queue
} else {
&mut self.deflate_queue
};
let mut needs_interrupt = false;
while let Some(avail_desc) = queue.pop(&self.mem) {
let index = avail_desc.index;
if inflate {
let mut reader = match Reader::new(&self.mem, avail_desc) {
Ok(r) => r,
Err(e) => {
error!("balloon: failed to create reader: {}", e);
queue.add_used(&self.mem, index, 0);
needs_interrupt = true;
continue;
}
};
let data_length = reader.available_bytes();
if data_length % 4 != 0 {
error!("invalid inflate buffer size: {}", data_length);
queue.add_used(&self.mem, index, 0);
needs_interrupt = true;
continue;
}
let num_addrs = data_length / 4;
for _ in 0..num_addrs as usize {
let guest_input = match reader.read_obj::<Le32>() {
Ok(a) => a.to_native(),
Err(err) => {
error!("error while reading unused pages: {}", err);
break;
}
};
let guest_address =
GuestAddress((u64::from(guest_input)) << VIRTIO_BALLOON_PFN_SHIFT);
if self
.mem
.remove_range(guest_address, 1 << VIRTIO_BALLOON_PFN_SHIFT)
.is_err()
{
warn!("Marking pages unused failed; addr={}", guest_address);
continue;
}
}
}
queue.add_used(&self.mem, index, 0);
needs_interrupt = true;
}
needs_interrupt
}
fn run(&mut self, mut queue_evts: Vec<EventFd>, kill_evt: EventFd) {
#[derive(PartialEq, PollToken)]
enum Token {
Inflate,
Deflate,
CommandSocket,
InterruptResample,
Kill,
}
let inflate_queue_evt = queue_evts.remove(0);
let deflate_queue_evt = queue_evts.remove(0);
let poll_ctx: PollContext<Token> = match PollContext::build_with(&[
(&inflate_queue_evt, Token::Inflate),
(&deflate_queue_evt, Token::Deflate),
(&self.command_socket, Token::CommandSocket),
(self.interrupt.get_resample_evt(), Token::InterruptResample),
(&kill_evt, Token::Kill),
]) {
Ok(pc) => pc,
Err(e) => {
error!("failed creating PollContext: {}", e);
return;
}
};
'poll: loop {
let events = match poll_ctx.wait() {
Ok(v) => v,
Err(e) => {
error!("failed polling for events: {}", e);
break;
}
};
let mut needs_interrupt_inflate = false;
let mut needs_interrupt_deflate = false;
for event in events.iter_readable() {
match event.token() {
Token::Inflate => {
if let Err(e) = inflate_queue_evt.read() {
error!("failed reading inflate queue EventFd: {}", e);
break 'poll;
}
needs_interrupt_inflate |= self.process_inflate_deflate(true);
}
Token::Deflate => {
if let Err(e) = deflate_queue_evt.read() {
error!("failed reading deflate queue EventFd: {}", e);
break 'poll;
}
needs_interrupt_deflate |= self.process_inflate_deflate(false);
}
Token::CommandSocket => {
if let Ok(req) = self.command_socket.recv() {
match req {
BalloonControlCommand::Adjust { num_bytes } => {
let num_pages =
(num_bytes >> VIRTIO_BALLOON_PFN_SHIFT) as usize;
info!("ballon config changed to consume {} pages", num_pages);
self.config.num_pages.store(num_pages, Ordering::Relaxed);
self.interrupt.signal_config_changed();
}
};
}
}
Token::InterruptResample => {
self.interrupt.interrupt_resample();
}
Token::Kill => break 'poll,
}
}
for event in events.iter_hungup() {
if event.token() == Token::CommandSocket && !event.readable() {
// If this call fails, the command socket was already removed from the
// PollContext.
let _ = poll_ctx.delete(&self.command_socket);
}
}
if needs_interrupt_inflate {
self.interrupt.signal_used_queue(self.inflate_queue.vector);
}
if needs_interrupt_deflate {
self.interrupt.signal_used_queue(self.deflate_queue.vector);
}
}
}
}
/// Virtio device for memory balloon inflation/deflation.
pub struct Balloon {
command_socket: Option<BalloonControlResponseSocket>,
config: Arc<BalloonConfig>,
features: u64,
kill_evt: Option<EventFd>,
worker_thread: Option<thread::JoinHandle<Worker>>,
}
impl Balloon {
/// Create a new virtio balloon device.
pub fn new(command_socket: BalloonControlResponseSocket) -> Result<Balloon> {
Ok(Balloon {
command_socket: Some(command_socket),
config: Arc::new(BalloonConfig {
num_pages: AtomicUsize::new(0),
actual_pages: AtomicUsize::new(0),
}),
kill_evt: None,
worker_thread: None,
// TODO(dgreid) - Add stats queue feature.
features: 1 << VIRTIO_BALLOON_F_MUST_TELL_HOST | 1 << VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
})
}
fn get_config(&self) -> virtio_balloon_config {
let num_pages = self.config.num_pages.load(Ordering::Relaxed) as u32;
let actual_pages = self.config.actual_pages.load(Ordering::Relaxed) as u32;
virtio_balloon_config {
num_pages: num_pages.into(),
actual: actual_pages.into(),
}
}
}
impl Drop for Balloon {
fn drop(&mut self) {
if let Some(kill_evt) = self.kill_evt.take() {
// Ignore the result because there is nothing we can do with a failure.
let _ = kill_evt.write(1);
}
if let Some(worker_thread) = self.worker_thread.take() {
let _ = worker_thread.join();
}
}
}
impl VirtioDevice for Balloon {
fn keep_fds(&self) -> Vec<RawFd> {
vec![self.command_socket.as_ref().unwrap().as_raw_fd()]
}
fn device_type(&self) -> u32 {
TYPE_BALLOON
}
fn queue_max_sizes(&self) -> &[u16] {
QUEUE_SIZES
}
fn read_config(&self, offset: u64, data: &mut [u8]) {
copy_config(data, 0, self.get_config().as_slice(), offset);
}
fn write_config(&mut self, offset: u64, data: &[u8]) {
let mut config = self.get_config();
copy_config(config.as_mut_slice(), offset, data, 0);
self.config
.actual_pages
.store(config.actual.to_native() as usize, Ordering::Relaxed);
}
fn features(&self) -> u64 {
1 << VIRTIO_BALLOON_F_MUST_TELL_HOST
| 1 << VIRTIO_BALLOON_F_DEFLATE_ON_OOM
| 1 << VIRTIO_F_VERSION_1
}
fn ack_features(&mut self, value: u64) {
self.features &= value;
}
fn activate(
&mut self,
mem: GuestMemory,
interrupt: Interrupt,
mut queues: Vec<Queue>,
queue_evts: Vec<EventFd>,
) {
if queues.len() != QUEUE_SIZES.len() || queue_evts.len() != QUEUE_SIZES.len() {
return;
}
let (self_kill_evt, kill_evt) = match EventFd::new().and_then(|e| Ok((e.try_clone()?, e))) {
Ok(v) => v,
Err(e) => {
error!("failed to create kill EventFd pair: {}", e);
return;
}
};
self.kill_evt = Some(self_kill_evt);
let config = self.config.clone();
let command_socket = self.command_socket.take().unwrap();
let worker_result = thread::Builder::new()
.name("virtio_balloon".to_string())
.spawn(move || {
let mut worker = Worker {
interrupt,
mem,
inflate_queue: queues.remove(0),
deflate_queue: queues.remove(0),
command_socket,
config,
};
worker.run(queue_evts, kill_evt);
worker
});
match worker_result {
Err(e) => {
error!("failed to spawn virtio_balloon worker: {}", e);
}
Ok(join_handle) => {
self.worker_thread = Some(join_handle);
}
}
}
fn reset(&mut self) -> bool {
if let Some(kill_evt) = self.kill_evt.take() {
if kill_evt.write(1).is_err() {
error!("{}: failed to notify the kill event", self.debug_label());
return false;
}
}
if let Some(worker_thread) = self.worker_thread.take() {
match worker_thread.join() {
Err(_) => {
error!("{}: failed to get back resources", self.debug_label());
return false;
}
Ok(worker) => {
self.command_socket = Some(worker.command_socket);
return true;
}
}
}
false
}
}