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devices: Refactor to make virtqueues fully created at transport layer #514

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8352f4d
devices: Refactor to make virtio queues managed by the transport laye…
mtjhrc Jan 12, 2026
6c49559
device/gpu: Refactor queue event handling
mtjhrc Jan 14, 2026
2d21135
devices/mmio: Automatically enable device_idx feature for queues
mtjhrc Jan 15, 2026
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61 changes: 23 additions & 38 deletions src/devices/src/virtio/balloon/device.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,8 @@ use utils::eventfd::EventFd;
use vm_memory::{ByteValued, GuestMemory, GuestMemoryMmap};

use super::super::{
ActivateError, ActivateResult, BalloonError, DeviceState, Queue as VirtQueue, VirtioDevice,
ActivateError, ActivateResult, BalloonError, DeviceQueue, DeviceState, QueueConfig,
VirtioDevice,
};
use super::{defs, defs::uapi};
use crate::virtio::InterruptTransport;
Expand Down Expand Up @@ -45,8 +46,7 @@ pub struct VirtioBalloonConfig {
unsafe impl ByteValued for VirtioBalloonConfig {}

pub struct Balloon {
pub(crate) queues: Vec<VirtQueue>,
pub(crate) queue_events: Vec<EventFd>,
pub(crate) queues: Option<Vec<DeviceQueue>>,
pub(crate) avail_features: u64,
pub(crate) acked_features: u64,
pub(crate) activate_evt: EventFd,
Expand All @@ -55,35 +55,18 @@ pub struct Balloon {
}

impl Balloon {
pub(crate) fn with_queues(queues: Vec<VirtQueue>) -> super::Result<Balloon> {
let mut queue_events = Vec::new();
for _ in 0..queues.len() {
queue_events
.push(EventFd::new(utils::eventfd::EFD_NONBLOCK).map_err(BalloonError::EventFd)?);
}

let config = VirtioBalloonConfig::default();

pub fn new() -> super::Result<Balloon> {
Ok(Balloon {
queues,
queue_events,
queues: None,
avail_features: AVAIL_FEATURES,
acked_features: 0,
activate_evt: EventFd::new(utils::eventfd::EFD_NONBLOCK)
.map_err(BalloonError::EventFd)?,
device_state: DeviceState::Inactive,
config,
config: VirtioBalloonConfig::default(),
})
}

pub fn new() -> super::Result<Balloon> {
let queues: Vec<VirtQueue> = defs::QUEUE_SIZES
.iter()
.map(|&max_size| VirtQueue::new(max_size))
.collect();
Self::with_queues(queues)
}

pub fn id(&self) -> &str {
defs::BALLOON_DEV_ID
}
Expand All @@ -96,9 +79,13 @@ impl Balloon {
DeviceState::Inactive => unreachable!(),
};

let queues = self
.queues
.as_mut()
.expect("queues should exist when activated");
let mut have_used = false;

while let Some(head) = self.queues[FRQ_INDEX].pop(mem) {
while let Some(head) = queues[FRQ_INDEX].queue.pop(mem) {
let index = head.index;
for desc in head.into_iter() {
let host_addr = mem.get_host_address(desc.addr).unwrap();
Expand All @@ -116,7 +103,7 @@ impl Balloon {
}

have_used = true;
if let Err(e) = self.queues[FRQ_INDEX].add_used(mem, index, 0) {
if let Err(e) = queues[FRQ_INDEX].queue.add_used(mem, index, 0) {
error!("failed to add used elements to the queue: {e:?}");
}
}
Expand Down Expand Up @@ -146,16 +133,8 @@ impl VirtioDevice for Balloon {
"balloon"
}

fn queues(&self) -> &[VirtQueue] {
&self.queues
}

fn queues_mut(&mut self) -> &mut [VirtQueue] {
&mut self.queues
}

fn queue_events(&self) -> &[EventFd] {
&self.queue_events
fn queue_config(&self) -> &[QueueConfig] {
&defs::QUEUE_CONFIG
}

fn read_config(&self, offset: u64, mut data: &mut [u8]) {
Expand All @@ -180,12 +159,17 @@ impl VirtioDevice for Balloon {
);
}

fn activate(&mut self, mem: GuestMemoryMmap, interrupt: InterruptTransport) -> ActivateResult {
if self.queues.len() != defs::NUM_QUEUES {
fn activate(
&mut self,
mem: GuestMemoryMmap,
interrupt: InterruptTransport,
queues: Vec<DeviceQueue>,
) -> ActivateResult {
if queues.len() != defs::NUM_QUEUES {
error!(
"Cannot perform activate. Expected {} queue(s), got {}",
defs::NUM_QUEUES,
self.queues.len()
queues.len()
);
return Err(ActivateError::BadActivate);
}
Expand All @@ -195,6 +179,7 @@ impl VirtioDevice for Balloon {
return Err(ActivateError::BadActivate);
}

self.queues = Some(queues);
self.device_state = DeviceState::Activated(mem, interrupt);

Ok(())
Expand Down
59 changes: 24 additions & 35 deletions src/devices/src/virtio/balloon/event_handler.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,10 @@ use super::device::{Balloon, DFQ_INDEX, FRQ_INDEX, IFQ_INDEX, PHQ_INDEX, STQ_IND
use crate::virtio::device::VirtioDevice;

impl Balloon {
fn queue_event(&self, idx: usize) -> &std::sync::Arc<utils::eventfd::EventFd> {
&self.queues.as_ref().expect("queues should exist")[idx].event
}

pub(crate) fn handle_ifq_event(&mut self, event: &EpollEvent) {
error!("balloon: unsupported inflate queue event");

Expand All @@ -16,7 +20,7 @@ impl Balloon {
return;
}

if let Err(e) = self.queue_events[IFQ_INDEX].read() {
if let Err(e) = self.queue_event(IFQ_INDEX).read() {
error!("Failed to read balloon inflate queue event: {e:?}");
}
}
Expand All @@ -30,7 +34,7 @@ impl Balloon {
return;
}

if let Err(e) = self.queue_events[DFQ_INDEX].read() {
if let Err(e) = self.queue_event(DFQ_INDEX).read() {
error!("Failed to read balloon inflate queue event: {e:?}");
}
}
Expand All @@ -44,7 +48,7 @@ impl Balloon {
return;
}

if let Err(e) = self.queue_events[STQ_INDEX].read() {
if let Err(e) = self.queue_event(STQ_INDEX).read() {
error!("Failed to read balloon stats queue event: {e:?}");
}
}
Expand All @@ -58,7 +62,7 @@ impl Balloon {
return;
}

if let Err(e) = self.queue_events[PHQ_INDEX].read() {
if let Err(e) = self.queue_event(PHQ_INDEX).read() {
error!("Failed to read balloon page-hinting queue event: {e:?}");
}
}
Expand All @@ -72,7 +76,7 @@ impl Balloon {
return;
}

if let Err(e) = self.queue_events[FRQ_INDEX].read() {
if let Err(e) = self.queue_event(FRQ_INDEX).read() {
error!("Failed to read balloon free-page reporting queue event: {e:?}");
} else if self.process_frq() {
self.device_state.signal_used_queue();
Expand All @@ -93,11 +97,8 @@ impl Balloon {

event_manager
.register(
self.queue_events[IFQ_INDEX].as_raw_fd(),
EpollEvent::new(
EventSet::IN,
self.queue_events[IFQ_INDEX].as_raw_fd() as u64,
),
self.queue_event(IFQ_INDEX).as_raw_fd(),
EpollEvent::new(EventSet::IN, self.queue_event(IFQ_INDEX).as_raw_fd() as u64),
self_subscriber.clone(),
)
.unwrap_or_else(|e| {
Expand All @@ -106,11 +107,8 @@ impl Balloon {

event_manager
.register(
self.queue_events[DFQ_INDEX].as_raw_fd(),
EpollEvent::new(
EventSet::IN,
self.queue_events[DFQ_INDEX].as_raw_fd() as u64,
),
self.queue_event(DFQ_INDEX).as_raw_fd(),
EpollEvent::new(EventSet::IN, self.queue_event(DFQ_INDEX).as_raw_fd() as u64),
self_subscriber.clone(),
)
.unwrap_or_else(|e| {
Expand All @@ -119,11 +117,8 @@ impl Balloon {

event_manager
.register(
self.queue_events[STQ_INDEX].as_raw_fd(),
EpollEvent::new(
EventSet::IN,
self.queue_events[STQ_INDEX].as_raw_fd() as u64,
),
self.queue_event(STQ_INDEX).as_raw_fd(),
EpollEvent::new(EventSet::IN, self.queue_event(STQ_INDEX).as_raw_fd() as u64),
self_subscriber.clone(),
)
.unwrap_or_else(|e| {
Expand All @@ -132,11 +127,8 @@ impl Balloon {

event_manager
.register(
self.queue_events[PHQ_INDEX].as_raw_fd(),
EpollEvent::new(
EventSet::IN,
self.queue_events[PHQ_INDEX].as_raw_fd() as u64,
),
self.queue_event(PHQ_INDEX).as_raw_fd(),
EpollEvent::new(EventSet::IN, self.queue_event(PHQ_INDEX).as_raw_fd() as u64),
self_subscriber.clone(),
)
.unwrap_or_else(|e| {
Expand All @@ -145,11 +137,8 @@ impl Balloon {

event_manager
.register(
self.queue_events[FRQ_INDEX].as_raw_fd(),
EpollEvent::new(
EventSet::IN,
self.queue_events[FRQ_INDEX].as_raw_fd() as u64,
),
self.queue_event(FRQ_INDEX).as_raw_fd(),
EpollEvent::new(EventSet::IN, self.queue_event(FRQ_INDEX).as_raw_fd() as u64),
self_subscriber.clone(),
)
.unwrap_or_else(|e| {
Expand All @@ -167,11 +156,11 @@ impl Balloon {
impl Subscriber for Balloon {
fn process(&mut self, event: &EpollEvent, event_manager: &mut EventManager) {
let source = event.fd();
let ifq = self.queue_events[IFQ_INDEX].as_raw_fd();
let dfq = self.queue_events[DFQ_INDEX].as_raw_fd();
let stq = self.queue_events[STQ_INDEX].as_raw_fd();
let phq = self.queue_events[PHQ_INDEX].as_raw_fd();
let frq = self.queue_events[FRQ_INDEX].as_raw_fd();
let ifq = self.queue_event(IFQ_INDEX).as_raw_fd();
let dfq = self.queue_event(DFQ_INDEX).as_raw_fd();
let stq = self.queue_event(STQ_INDEX).as_raw_fd();
let phq = self.queue_event(PHQ_INDEX).as_raw_fd();
let frq = self.queue_event(FRQ_INDEX).as_raw_fd();
let activate_evt = self.activate_evt.as_raw_fd();

if self.is_activated() {
Expand Down
5 changes: 4 additions & 1 deletion src/devices/src/virtio/balloon/mod.rs
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -5,9 +5,12 @@ pub use self::defs::uapi::VIRTIO_ID_BALLOON as TYPE_BALLOON;
pub use self::device::Balloon;

mod defs {
use super::super::QueueConfig;

pub const BALLOON_DEV_ID: &str = "virtio_balloon";
pub const NUM_QUEUES: usize = 5;
pub const QUEUE_SIZES: &[u16] = &[256; NUM_QUEUES];
pub const QUEUE_SIZE: u16 = 256;
pub static QUEUE_CONFIG: [QueueConfig; NUM_QUEUES] = [QueueConfig::new(QUEUE_SIZE); NUM_QUEUES];

pub mod uapi {
pub const VIRTIO_F_VERSION_1: u32 = 32;
Expand Down
40 changes: 15 additions & 25 deletions src/devices/src/virtio/block/device.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -31,8 +31,8 @@ use vm_memory::{ByteValued, GuestMemoryMmap};

use super::worker::BlockWorker;
use super::{
super::{ActivateResult, DeviceState, Queue, VirtioDevice, TYPE_BLOCK},
Error, QUEUE_SIZES, SECTOR_SHIFT, SECTOR_SIZE,
super::{ActivateResult, DeviceQueue, DeviceState, QueueConfig, VirtioDevice, TYPE_BLOCK},
Error, NUM_QUEUES, QUEUE_CONFIG, SECTOR_SHIFT, SECTOR_SIZE,
};

use crate::virtio::{
Expand Down Expand Up @@ -216,8 +216,6 @@ pub struct Block {
config: VirtioBlkConfig,

// Transport related fields.
pub(crate) queues: Vec<Queue>,
pub(crate) queue_evts: [EventFd; 1],
pub(crate) device_state: DeviceState,

// Implementation specific fields.
Expand Down Expand Up @@ -302,10 +300,6 @@ impl Block {
avail_features |= 1u64 << VIRTIO_BLK_F_RO;
};

let queue_evts = [EventFd::new(EFD_NONBLOCK)?];

let queues = QUEUE_SIZES.iter().map(|&s| Queue::new(s)).collect();

let config = VirtioBlkConfig {
capacity: disk_properties.nsectors(),
size_max: 0,
Expand All @@ -330,8 +324,6 @@ impl Block {
disk_image_id,
avail_features,
acked_features: 0u64,
queue_evts,
queues,
device_state: DeviceState::Inactive,
worker_thread: None,
worker_stopfd: EventFd::new(EFD_NONBLOCK)?,
Expand Down Expand Up @@ -363,16 +355,8 @@ impl VirtioDevice for Block {
"block"
}

fn queues(&self) -> &[Queue] {
&self.queues
}

fn queues_mut(&mut self) -> &mut [Queue] {
&mut self.queues
}

fn queue_events(&self) -> &[EventFd] {
&self.queue_evts
fn queue_config(&self) -> &[QueueConfig] {
&QUEUE_CONFIG
}

fn avail_features(&self) -> u64 {
Expand Down Expand Up @@ -409,13 +393,20 @@ impl VirtioDevice for Block {
self.device_state.is_activated()
}

fn activate(&mut self, mem: GuestMemoryMmap, interrupt: InterruptTransport) -> ActivateResult {
fn activate(
&mut self,
mem: GuestMemoryMmap,
interrupt: InterruptTransport,
queues: Vec<DeviceQueue>,
) -> ActivateResult {
if self.worker_thread.is_some() {
panic!("virtio_blk: worker thread already exists");
}

let event_idx: bool = (self.acked_features & (1 << VIRTIO_RING_F_EVENT_IDX)) != 0;
self.queues[0].set_event_idx(event_idx);
let [blk_q]: [_; NUM_QUEUES] = queues.try_into().map_err(|_| {
error!("Cannot perform activate. Expected {} queue(s)", NUM_QUEUES);
ActivateError::BadActivate
})?;

let disk = match self.disk.take() {
Some(d) => d,
Expand All @@ -428,8 +419,7 @@ impl VirtioDevice for Block {
};

let worker = BlockWorker::new(
self.queues[0].clone(),
self.queue_evts[0].try_clone().unwrap(),
blk_q,
interrupt.clone(),
mem.clone(),
disk,
Expand Down
6 changes: 4 additions & 2 deletions src/devices/src/virtio/block/mod.rs
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -8,12 +8,14 @@ pub use self::device::{Block, CacheType};

use vm_memory::GuestMemoryError;

use super::QueueConfig;

pub const CONFIG_SPACE_SIZE: usize = 8;
pub const SECTOR_SHIFT: u8 = 9;
pub const SECTOR_SIZE: u64 = (0x01_u64) << SECTOR_SHIFT;
pub const QUEUE_SIZE: u16 = 256;
const QUEUE_SIZE: u16 = 256;
pub const NUM_QUEUES: usize = 1;
pub const QUEUE_SIZES: &[u16] = &[QUEUE_SIZE];
pub static QUEUE_CONFIG: [QueueConfig; NUM_QUEUES] = [QueueConfig::new(QUEUE_SIZE)];

#[derive(Debug)]
pub enum Error {
Expand Down
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