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virtio-devices, vmm: Optimised async virtio device activation

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In order to ensure that the virtio device thread is spawned from the vmm
thread we use an asynchronous activation mechanism for the virtio
devices. This change optimises that code so that we do not need to
iterate through all virtio devices on the platform in order to find the
one that requires activation. We solve this by creating a separate short
lived VirtioPciDeviceActivator that holds the required state for the
activation (e.g. the clones of the queues) this can then be stored onto
the device manager ready for asynchronous activation.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>
This commit is contained in:
Rob Bradford
2022-05-17 15:33:33 +01:00
committed by Sebastien Boeuf
parent 15e2763753
commit ade3a9c8f6
3 changed files with 84 additions and 46 deletions
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2
virtio-devices/src/transport/mod.rs
View File

@@ -6,7 +6,7 @@ use vmm_sys_util::eventfd::EventFd;
mod pci_common_config;
mod pci_device;
pub use pci_common_config::VirtioPciCommonConfig;
pub use pci_device::VirtioPciDevice;
pub use pci_device::{VirtioPciDevice, VirtioPciDeviceActivator};
pub trait VirtioTransport {
fn ioeventfds(&self, base_addr: u64) -> Vec<(&EventFd, u64)>;

99
virtio-devices/src/transport/pci_device.rs
View File

@@ -287,6 +287,37 @@ struct VirtioPciDeviceState {
impl VersionMapped for VirtioPciDeviceState {}
pub struct VirtioPciDeviceActivator {
interrupt: Option<Arc<dyn VirtioInterrupt>>,
memory: Option<GuestMemoryAtomic<GuestMemoryMmap>>,
device: Arc<Mutex<dyn VirtioDevice>>,
device_activated: Arc<AtomicBool>,
queues: Option<Vec<Queue<GuestMemoryAtomic<GuestMemoryMmap>>>>,
queue_evts: Option<Vec<EventFd>>,
barrier: Option<Arc<Barrier>>,
id: String,
}
impl VirtioPciDeviceActivator {
pub fn activate(&mut self) -> ActivateResult {
self.device.lock().unwrap().activate(
self.memory.take().unwrap(),
self.interrupt.take().unwrap(),
self.queues.take().unwrap(),
self.queue_evts.take().unwrap(),
)?;
self.device_activated.store(true, Ordering::SeqCst);
if let Some(barrier) = self.barrier.take() {
info!("{}: Waiting for barrier", self.id);
barrier.wait();
info!("{}: Barrier released", self.id);
}
Ok(())
}
}
pub struct VirtioPciDevice {
id: String,
@@ -338,11 +369,11 @@ pub struct VirtioPciDevice {
// EventFd to signal on to request activation
activate_evt: EventFd,
// Barrier that is used to wait on for activation
activate_barrier: Arc<Barrier>,
// Optional DMA handler
dma_handler: Option<Arc<dyn ExternalDmaMapping>>,
// Pending activations
pending_activations: Arc<Mutex<Vec<VirtioPciDeviceActivator>>>,
}
impl VirtioPciDevice {
@@ -359,6 +390,7 @@ impl VirtioPciDevice {
activate_evt: EventFd,
use_64bit_bar: bool,
dma_handler: Option<Arc<dyn ExternalDmaMapping>>,
pending_activations: Arc<Mutex<Vec<VirtioPciDeviceActivator>>>,
) -> Result<Self> {
let device_clone = device.clone();
let mut locked_device = device_clone.lock().unwrap();
@@ -458,8 +490,8 @@ impl VirtioPciDevice {
cap_pci_cfg_info: VirtioPciCfgCapInfo::default(),
bar_regions: vec![],
activate_evt,
activate_barrier: Arc::new(Barrier::new(2)),
dma_handler,
pending_activations,
};
if let Some(msix_config) = &virtio_pci_device.msix_config {
@@ -666,37 +698,37 @@ impl VirtioPciDevice {
self.device.clone()
}
fn activate(&mut self) -> ActivateResult {
if let Some(virtio_interrupt) = self.virtio_interrupt.take() {
if self.memory.is_some() {
let mem = self.memory.as_ref().unwrap().clone();
let mut device = self.device.lock().unwrap();
let mut queue_evts = Vec::new();
let mut queues: Vec<Queue<GuestMemoryAtomic<GuestMemoryMmap>>> =
self.queues.iter().map(vm_virtio::clone_queue).collect();
queues.retain(|q| q.state.ready);
for (i, queue) in queues.iter().enumerate() {
queue_evts.push(self.queue_evts[i].try_clone().unwrap());
if !queue.is_valid() {
error!("Queue {} is not valid", i);
}
}
return device.activate(mem, virtio_interrupt, queues, queue_evts);
fn prepare_activator(&mut self, barrier: Option<Arc<Barrier>>) -> VirtioPciDeviceActivator {
let mut queue_evts = Vec::new();
let mut queues: Vec<Queue<GuestMemoryAtomic<GuestMemoryMmap>>> =
self.queues.iter().map(vm_virtio::clone_queue).collect();
queues.retain(|q| q.state.ready);
for (i, queue) in queues.iter().enumerate() {
queue_evts.push(self.queue_evts[i].try_clone().unwrap());
if !queue.is_valid() {
error!("Queue {} is not valid", i);
}
}
Ok(())
VirtioPciDeviceActivator {
interrupt: self.virtio_interrupt.take(),
memory: self.memory.clone(),
device: self.device.clone(),
queues: Some(queues),
device_activated: self.device_activated.clone(),
queue_evts: Some(
queue_evts
.iter()
.map(|fd| fd.try_clone().unwrap())
.collect(),
),
barrier,
id: self.id.clone(),
}
}
pub fn maybe_activate(&mut self) {
if self.needs_activation() {
self.activate().expect("Failed to activate device");
self.device_activated.store(true, Ordering::SeqCst);
info!("{}: Waiting for barrier", self.id);
self.activate_barrier.wait();
info!("{}: Barrier released", self.id);
} else {
info!("{}: Device does not need activation", self.id)
}
fn activate(&mut self) -> ActivateResult {
self.prepare_activator(None).activate()
}
fn needs_activation(&self) -> bool {
@@ -1058,13 +1090,16 @@ impl PciDevice for VirtioPciDevice {
// Try and activate the device if the driver status has changed
if self.needs_activation() {
let barrier = Arc::new(Barrier::new(2));
let activator = self.prepare_activator(Some(barrier.clone()));
self.pending_activations.lock().unwrap().push(activator);
info!(
"{}: Needs activation; writing to activate event fd",
self.id
);
self.activate_evt.write(1).ok();
info!("{}: Needs activation; returning barrier", self.id);
return Some(self.activate_barrier.clone());
return Some(barrier);
}
// Device has been reset by the driver