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vhost_user_backend: Allow for proper error propagation

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Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This commit is contained in:
Sebastien Boeuf 2019-09-16 15:37:07 -07:00
parent 36de390caf
commit 5f076923d3
1 changed files with 185 additions and 96 deletions
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281
vhost_user_backend/src/lib.rs
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@ -4,6 +4,7 @@
// Copyright 2019 Alibaba Cloud Computing. All rights reserved.
// SPDX-License-Identifier: Apache-2.0
use std::error;
use std::fs::File;
use std::io;
use std::num::Wrapping;
@ -27,6 +28,8 @@ use vmm_sys_util::eventfd::EventFd;
#[derive(Debug)]
/// Errors related to vhost-user daemon.
pub enum Error {
/// Failed to create a new vhost-user handler.
NewVhostUserHandler(VhostUserHandlerError),
/// Failed creating vhost-user slave handler.
CreateSlaveReqHandler(VhostUserError),
/// Failed starting daemon thread.
@ -35,20 +38,18 @@ pub enum Error {
WaitDaemon(std::boxed::Box<dyn std::any::Any + std::marker::Send>),
/// Failed handling a vhost-user request.
HandleRequest(VhostUserError),
/// Could not find the mapping from memory regions.
MissingMemoryMapping,
/// Failed to create epoll file descriptor.
EpollCreateFd(io::Error),
/// Failed to add a file descriptor to the epoll handler.
EpollCtl(io::Error),
/// Failed while waiting for events.
EpollWait(io::Error),
/// Failed to signal used queue.
SignalUsedQueue(io::Error),
/// Failed to handle the event.
HandleEvent(io::Error),
/// Failed to process queue.
ProcessQueue(VringEpollHandlerError),
/// Failed to register listener.
RegisterListener(io::Error),
/// Failed to unregister listener.
UnregisterListener(io::Error),
}
/// Result of vhost-user daemon operations.
pub type Result<T> = std::result::Result<T, Error>;
pub type Result<T> = result::Result<T, Error>;
/// This trait must be implemented by the caller in order to provide backend
/// specific implementation.
@ -66,7 +67,11 @@ pub trait VhostUserBackend: Send + Sync + 'static {
/// listeners onto specific file descriptors. The library can handle
/// virtqueues on its own, but does not know what to do with events
/// happening on custom listeners.
fn handle_event(&mut self, device_event: u16, evset: epoll::Events) -> Result<bool>;
fn handle_event(
&mut self,
device_event: u16,
evset: epoll::Events,
) -> result::Result<bool, io::Error>;
/// This function is responsible for the actual processing that needs to
/// happen when one of the virtqueues is available.
@ -75,13 +80,13 @@ pub trait VhostUserBackend: Send + Sync + 'static {
q_idx: u16,
avail_desc: &DescriptorChain,
mem: &GuestMemoryMmap,
) -> Result<u32>;
) -> result::Result<u32, io::Error>;
/// Get virtio device configuration.
fn get_config(&self, offset: u32, size: u32) -> Vec<u8>;
/// Set virtio device configuration.
fn set_config(&mut self, offset: u32, buf: &[u8]);
fn set_config(&mut self, offset: u32, buf: &[u8]) -> result::Result<(), io::Error>;
}
/// This structure is the public API the backend is allowed to interact with
@ -102,7 +107,9 @@ impl<S: VhostUserBackend> VhostUserDaemon<S> {
/// custom events from the backend, but they get to be registered later
/// during the sequence.
pub fn new(name: String, sock_path: String, backend: S) -> Result<Self> {
let handler = Arc::new(Mutex::new(VhostUserHandler::new(backend)));
let handler = Arc::new(Mutex::new(
VhostUserHandler::new(backend).map_err(Error::NewVhostUserHandler)?,
));
let vring_handler = handler.lock().unwrap().get_vring_handler();
Ok(VhostUserDaemon {
@ -151,31 +158,23 @@ impl<S: VhostUserBackend> VhostUserDaemon<S> {
/// This lets entire control to the caller about what needs to be done for
/// this special event, without forcing it to run its own dedicated epoll
/// loop for it.
pub fn register_listener(
&self,
fd: RawFd,
ev_type: epoll::Events,
data: u64,
) -> result::Result<(), io::Error> {
pub fn register_listener(&self, fd: RawFd, ev_type: epoll::Events, data: u64) -> Result<()> {
self.vring_handler
.read()
.unwrap()
.register_listener(fd, ev_type, data)
.map_err(Error::RegisterListener)
}
/// Unregister a custom event. If the custom event is triggered after this
/// function has been called, nothing will happen as it will be removed
/// from the list of file descriptors the epoll loop is listening to.
pub fn unregister_listener(
&self,
fd: RawFd,
ev_type: epoll::Events,
data: u64,
) -> result::Result<(), io::Error> {
pub fn unregister_listener(&self, fd: RawFd, ev_type: epoll::Events, data: u64) -> Result<()> {
self.vring_handler
.read()
.unwrap()
.unregister_listener(fd, ev_type, data)
.map_err(Error::RegisterListener)
}
/// Trigger the processing of a virtqueue. This function is meant to be
@ -189,7 +188,11 @@ impl<S: VhostUserBackend> VhostUserDaemon<S> {
/// of `process_queue`. With this twisted trick, all common parts related
/// to the virtqueues can remain part of the library.
pub fn process_queue(&self, q_idx: u16) -> Result<()> {
self.vring_handler.write().unwrap().process_queue(q_idx)
self.vring_handler
.write()
.unwrap()
.process_queue(q_idx)
.map_err(Error::ProcessQueue)
}
}
@ -224,6 +227,53 @@ impl Vring {
}
}
#[derive(Debug)]
/// Errors related to vring epoll handler.
pub enum VringEpollHandlerError {
/// Failed to process the queue from the backend.
ProcessQueueBackendProcessing(io::Error),
/// Failed to signal used queue.
SignalUsedQueue(io::Error),
/// Failed to read the event from kick EventFd.
HandleEventReadKick(io::Error),
/// Failed to handle the event from the backend.
HandleEventBackendHandling(io::Error),
/// Failed to register vring listener.
RegisterVringListener(io::Error),
/// Failed to unregister vring listener.
UnregisterVringListener(io::Error),
}
impl std::fmt::Display for VringEpollHandlerError {
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
match self {
VringEpollHandlerError::ProcessQueueBackendProcessing(e) => {
write!(f, "failed processing queue from backend: {}", e)
}
VringEpollHandlerError::SignalUsedQueue(e) => {
write!(f, "failed signalling used queue: {}", e)
}
VringEpollHandlerError::HandleEventReadKick(e) => {
write!(f, "failed reading from kick eventfd: {}", e)
}
VringEpollHandlerError::HandleEventBackendHandling(e) => {
write!(f, "failed handling event from backend: {}", e)
}
VringEpollHandlerError::RegisterVringListener(e) => {
write!(f, "failed registering vring listener: {}", e)
}
VringEpollHandlerError::UnregisterVringListener(e) => {
write!(f, "failed unregistering vring listener: {}", e)
}
}
}
}
impl error::Error for VringEpollHandlerError {}
/// Result of vring epoll handler operations.
type VringEpollHandlerResult<T> = std::result::Result<T, VringEpollHandlerError>;
struct VringEpollHandler<S: VhostUserBackend> {
backend: Arc<RwLock<S>>,
vrings: Vec<Arc<RwLock<Vring>>>,
@ -236,7 +286,7 @@ impl<S: VhostUserBackend> VringEpollHandler<S> {
self.mem = mem;
}
fn process_queue(&mut self, q_idx: u16) -> Result<()> {
fn process_queue(&mut self, q_idx: u16) -> VringEpollHandlerResult<()> {
let vring = &mut self.vrings[q_idx as usize].write().unwrap();
let mut used_desc_heads = vec![(0, 0); vring.queue.size as usize];
let mut used_count = 0;
@ -247,7 +297,7 @@ impl<S: VhostUserBackend> VringEpollHandler<S> {
.write()
.unwrap()
.process_queue(q_idx, &avail_desc, &mem)
.unwrap();
.map_err(VringEpollHandlerError::ProcessQueueBackendProcessing)?;
used_desc_heads[used_count] = (avail_desc.index, used_len);
used_count += 1;
@ -260,44 +310,52 @@ impl<S: VhostUserBackend> VringEpollHandler<S> {
if used_count > 0 {
if let Some(call) = &vring.call {
return call.write(1).map_err(Error::SignalUsedQueue);
call.write(1)
.map_err(VringEpollHandlerError::SignalUsedQueue)?;
}
}
Ok(())
}
fn handle_event(&mut self, device_event: u16, evset: epoll::Events) -> Result<bool> {
fn handle_event(
&mut self,
device_event: u16,
evset: epoll::Events,
) -> VringEpollHandlerResult<bool> {
let num_queues = self.vrings.len();
match device_event as usize {
x if x < num_queues => {
if let Some(kick) = &self.vrings[device_event as usize].read().unwrap().kick {
kick.read().unwrap();
kick.read()
.map_err(VringEpollHandlerError::HandleEventReadKick)?;
}
self.process_queue(device_event).unwrap();
self.process_queue(device_event)?;
Ok(false)
}
_ => self
.backend
.write()
.unwrap()
.handle_event(device_event, evset),
.handle_event(device_event, evset)
.map_err(VringEpollHandlerError::HandleEventBackendHandling),
}
}
fn register_vring_listener(&self, q_idx: usize) -> result::Result<(), io::Error> {
fn register_vring_listener(&self, q_idx: usize) -> VringEpollHandlerResult<()> {
if let Some(fd) = &self.vrings[q_idx].read().unwrap().kick {
self.register_listener(fd.as_raw_fd(), epoll::Events::EPOLLIN, q_idx as u64)
.map_err(VringEpollHandlerError::RegisterVringListener)
} else {
Ok(())
}
}
fn unregister_vring_listener(&self, q_idx: usize) -> result::Result<(), io::Error> {
fn unregister_vring_listener(&self, q_idx: usize) -> VringEpollHandlerResult<()> {
if let Some(fd) = &self.vrings[q_idx].read().unwrap().kick {
self.unregister_listener(fd.as_raw_fd(), epoll::Events::EPOLLIN, q_idx as u64)
.map_err(VringEpollHandlerError::UnregisterVringListener)
} else {
Ok(())
}
@ -332,12 +390,24 @@ impl<S: VhostUserBackend> VringEpollHandler<S> {
}
}
#[derive(Debug)]
/// Errors related to vring worker.
enum VringWorkerError {
/// Failed while waiting for events.
EpollWait(io::Error),
/// Failed to handle event.
HandleEvent(VringEpollHandlerError),
}
/// Result of vring worker operations.
type VringWorkerResult<T> = std::result::Result<T, VringWorkerError>;
struct VringWorker<S: VhostUserBackend> {
handler: Arc<RwLock<VringEpollHandler<S>>>,
}
impl<S: VhostUserBackend> VringWorker<S> {
fn run(&self, epoll_fd: RawFd) -> Result<()> {
fn run(&self, epoll_fd: RawFd) -> VringWorkerResult<()> {
const EPOLL_EVENTS_LEN: usize = 100;
let mut events = vec![epoll::Event::new(epoll::Events::empty(), 0); EPOLL_EVENTS_LEN];
@ -355,7 +425,7 @@ impl<S: VhostUserBackend> VringWorker<S> {
// appropriate to retry, by calling into epoll_wait().
continue;
}
return Err(Error::EpollWait(e));
return Err(VringWorkerError::EpollWait(e));
}
};
@ -371,7 +441,13 @@ impl<S: VhostUserBackend> VringWorker<S> {
let ev_type = event.data as u16;
if self.handler.write().unwrap().handle_event(ev_type, evset)? {
if self
.handler
.write()
.unwrap()
.handle_event(ev_type, evset)
.map_err(VringWorkerError::HandleEvent)?
{
break 'epoll;
}
}
@ -381,6 +457,34 @@ impl<S: VhostUserBackend> VringWorker<S> {
}
}
#[derive(Debug)]
/// Errors related to vhost-user handler.
pub enum VhostUserHandlerError {
/// Failed to create epoll file descriptor.
EpollCreateFd(io::Error),
/// Failed to spawn vring worker.
SpawnVringWorker(io::Error),
/// Could not find the mapping from memory regions.
MissingMemoryMapping,
}
impl std::fmt::Display for VhostUserHandlerError {
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
match self {
VhostUserHandlerError::EpollCreateFd(e) => write!(f, "failed creating epoll fd: {}", e),
VhostUserHandlerError::SpawnVringWorker(e) => {
write!(f, "failed spawning the vring worker: {}", e)
}
VhostUserHandlerError::MissingMemoryMapping => write!(f, "Missing memory mapping"),
}
}
}
impl error::Error for VhostUserHandlerError {}
/// Result of vhost-user handler operations.
type VhostUserHandlerResult<T> = std::result::Result<T, VhostUserHandlerError>;
struct VhostUserHandler<S: VhostUserBackend> {
backend: Arc<RwLock<S>>,
vring_handler: Arc<RwLock<VringEpollHandler<S>>>,
@ -395,14 +499,14 @@ struct VhostUserHandler<S: VhostUserBackend> {
}
impl<S: VhostUserBackend> VhostUserHandler<S> {
fn new(backend: S) -> Self {
fn new(backend: S) -> VhostUserHandlerResult<Self> {
let num_queues = backend.num_queues();
let max_queue_size = backend.max_queue_size();
let arc_backend = Arc::new(RwLock::new(backend));
let vrings = vec![Arc::new(RwLock::new(Vring::new(max_queue_size as u16))); num_queues];
// Create the epoll file descriptor
let epoll_fd = epoll::create(true).unwrap();
let epoll_fd = epoll::create(true).map_err(VhostUserHandlerError::EpollCreateFd)?;
let vring_handler = Arc::new(RwLock::new(VringEpollHandler {
backend: arc_backend.clone(),
@ -415,11 +519,11 @@ impl<S: VhostUserBackend> VhostUserHandler<S> {
};
thread::Builder::new()
.name("vring_epoll_handler".to_string())
.name("vring_worker".to_string())
.spawn(move || worker.run(epoll_fd))
.unwrap();
.map_err(VhostUserHandlerError::SpawnVringWorker)?;
VhostUserHandler {
Ok(VhostUserHandler {
backend: arc_backend,
vring_handler,
owned: false,
@ -430,14 +534,14 @@ impl<S: VhostUserBackend> VhostUserHandler<S> {
max_queue_size,
memory: None,
vrings,
}
})
}
fn get_vring_handler(&self) -> Arc<RwLock<VringEpollHandler<S>>> {
self.vring_handler.clone()
}
fn vmm_va_to_gpa(&self, vmm_va: u64) -> Result<u64> {
fn vmm_va_to_gpa(&self, vmm_va: u64) -> VhostUserHandlerResult<u64> {
if let Some(memory) = &self.memory {
for mapping in memory.mappings.iter() {
if vmm_va >= mapping.vmm_addr && vmm_va < mapping.vmm_addr + mapping.size {
@ -446,7 +550,7 @@ impl<S: VhostUserBackend> VhostUserHandler<S> {
}
}
Err(Error::MissingMemoryMapping)
Err(VhostUserHandlerError::MissingMemoryMapping)
}
}
@ -532,7 +636,9 @@ impl<S: VhostUserBackend> VhostUserSlaveReqHandler for VhostUserHandler<S> {
});
}
let mem = GuestMemoryMmap::with_files(regions).unwrap();
let mem = GuestMemoryMmap::with_files(regions).map_err(|e| {
VhostUserError::ReqHandlerError(io::Error::new(io::ErrorKind::Other, e))
})?;
self.vring_handler.write().unwrap().update_memory(Some(mem));
self.memory = Some(Memory { mappings });
@ -565,9 +671,15 @@ impl<S: VhostUserBackend> VhostUserSlaveReqHandler for VhostUserHandler<S> {
}
if self.memory.is_some() {
let desc_table = self.vmm_va_to_gpa(descriptor).unwrap();
let avail_ring = self.vmm_va_to_gpa(available).unwrap();
let used_ring = self.vmm_va_to_gpa(used).unwrap();
let desc_table = self.vmm_va_to_gpa(descriptor).map_err(|e| {
VhostUserError::ReqHandlerError(io::Error::new(io::ErrorKind::Other, e))
})?;
let avail_ring = self.vmm_va_to_gpa(available).map_err(|e| {
VhostUserError::ReqHandlerError(io::Error::new(io::ErrorKind::Other, e))
})?;
let used_ring = self.vmm_va_to_gpa(used).map_err(|e| {
VhostUserError::ReqHandlerError(io::Error::new(io::ErrorKind::Other, e))
})?;
self.vrings[index as usize]
.write()
.unwrap()
@ -609,7 +721,9 @@ impl<S: VhostUserBackend> VhostUserSlaveReqHandler for VhostUserHandler<S> {
.read()
.unwrap()
.unregister_vring_listener(index as usize)
.unwrap();
.map_err(|e| {
VhostUserError::ReqHandlerError(io::Error::new(io::ErrorKind::Other, e))
})?;
let next_avail = self.vrings[index as usize]
.read()
@ -626,22 +740,12 @@ impl<S: VhostUserBackend> VhostUserSlaveReqHandler for VhostUserHandler<S> {
return Err(VhostUserError::InvalidParam);
}
if self.vrings[index as usize].read().unwrap().kick.is_some() {
if let Some(kick) = self.vrings[index as usize].write().unwrap().kick.take() {
// Close file descriptor set by previous operations.
let _ = unsafe {
libc::close(
self.vrings[index as usize]
.write()
.unwrap()
.kick
.take()
.unwrap()
.as_raw_fd(),
)
};
let _ = unsafe { libc::close(kick.as_raw_fd()) };
}
self.vrings[index as usize].write().unwrap().kick =
Some(unsafe { EventFd::from_raw_fd(fd.unwrap()) });
fd.map(|x| unsafe { EventFd::from_raw_fd(x) });
// Quotation from vhost-user spec:
// Client must start ring upon receiving a kick (that is, detecting
@ -655,7 +759,9 @@ impl<S: VhostUserBackend> VhostUserSlaveReqHandler for VhostUserHandler<S> {
.read()
.unwrap()
.register_vring_listener(index as usize)
.unwrap();
.map_err(|e| {
VhostUserError::ReqHandlerError(io::Error::new(io::ErrorKind::Other, e))
})?;
Ok(())
}
@ -665,22 +771,12 @@ impl<S: VhostUserBackend> VhostUserSlaveReqHandler for VhostUserHandler<S> {
return Err(VhostUserError::InvalidParam);
}
if self.vrings[index as usize].write().unwrap().call.is_some() {
if let Some(call) = self.vrings[index as usize].write().unwrap().call.take() {
// Close file descriptor set by previous operations.
let _ = unsafe {
libc::close(
self.vrings[index as usize]
.write()
.unwrap()
.call
.take()
.unwrap()
.as_raw_fd(),
)
};
let _ = unsafe { libc::close(call.as_raw_fd()) };
}
self.vrings[index as usize].write().unwrap().call =
Some(unsafe { EventFd::from_raw_fd(fd.unwrap()) });
fd.map(|x| unsafe { EventFd::from_raw_fd(x) });
Ok(())
}
@ -690,22 +786,12 @@ impl<S: VhostUserBackend> VhostUserSlaveReqHandler for VhostUserHandler<S> {
return Err(VhostUserError::InvalidParam);
}
if self.vrings[index as usize].read().unwrap().err.is_some() {
if let Some(err) = self.vrings[index as usize].write().unwrap().err.take() {
// Close file descriptor set by previous operations.
let _ = unsafe {
libc::close(
self.vrings[index as usize]
.write()
.unwrap()
.err
.take()
.unwrap()
.as_raw_fd(),
)
};
let _ = unsafe { libc::close(err.as_raw_fd()) };
}
self.vrings[index as usize].write().unwrap().err =
Some(unsafe { EventFd::from_raw_fd(fd.unwrap()) });
fd.map(|x| unsafe { EventFd::from_raw_fd(x) });
Ok(())
}
@ -764,7 +850,10 @@ impl<S: VhostUserBackend> VhostUserSlaveReqHandler for VhostUserHandler<S> {
return Err(VhostUserError::InvalidParam);
}
self.backend.write().unwrap().set_config(offset, buf);
Ok(())
self.backend
.write()
.unwrap()
.set_config(offset, buf)
.map_err(VhostUserError::ReqHandlerError)
}
}