mirror of
https://github.com/cloud-hypervisor/cloud-hypervisor.git
synced 2024-10-28 07:33:09 +00:00
b45264af75
If writing to the TAP returns EAGAIN then listen for the TAP to be writable. When the TAP becomes writable attempt to process the TX queue again. Fixes: #2807 Signed-off-by: Rob Bradford <robert.bradford@intel.com>
369 lines
12 KiB
Rust
369 lines
12 KiB
Rust
// Copyright (c) 2020 Intel Corporation. All rights reserved.
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//
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// SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
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use super::{register_listener, unregister_listener, vnet_hdr_len, Tap};
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use crate::GuestMemoryMmap;
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use rate_limiter::{RateLimiter, TokenType};
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use std::io;
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use std::num::Wrapping;
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use std::os::unix::io::{AsRawFd, RawFd};
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use std::sync::atomic::{AtomicU64, Ordering};
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use std::sync::Arc;
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use vm_memory::{Bytes, GuestAddressSpace, GuestMemory, GuestMemoryAtomic};
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use vm_virtio::Queue;
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#[derive(Clone)]
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pub struct TxVirtio {
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pub counter_bytes: Wrapping<u64>,
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pub counter_frames: Wrapping<u64>,
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}
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impl Default for TxVirtio {
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fn default() -> Self {
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Self::new()
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}
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}
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impl TxVirtio {
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pub fn new() -> Self {
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TxVirtio {
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counter_bytes: Wrapping(0),
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counter_frames: Wrapping(0),
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}
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}
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pub fn process_desc_chain(
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&mut self,
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mem: &GuestMemoryMmap,
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tap: &mut Tap,
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queue: &mut Queue,
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rate_limiter: &mut Option<RateLimiter>,
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) -> Result<bool, NetQueuePairError> {
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let mut retry_write = false;
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while let Some(avail_desc) = queue.iter(mem).next() {
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let head_index = avail_desc.index;
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let mut next_desc = Some(avail_desc);
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if let Some(rate_limiter) = rate_limiter {
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if !rate_limiter.consume(1, TokenType::Ops) {
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queue.go_to_previous_position();
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break;
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}
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let mut bytes = Wrapping(0);
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let mut tmp_next_desc = next_desc.clone();
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while let Some(desc) = tmp_next_desc {
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if !desc.is_write_only() {
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bytes += Wrapping(desc.len as u64);
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}
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tmp_next_desc = desc.next_descriptor();
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}
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bytes -= Wrapping(vnet_hdr_len() as u64);
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if !rate_limiter.consume(bytes.0, TokenType::Bytes) {
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// Revert the OPS consume().
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rate_limiter.manual_replenish(1, TokenType::Ops);
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queue.go_to_previous_position();
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break;
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}
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}
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let mut iovecs = Vec::new();
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while let Some(desc) = next_desc {
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if !desc.is_write_only() && desc.len > 0 {
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let buf = mem
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.get_slice(desc.addr, desc.len as usize)
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.map_err(NetQueuePairError::GuestMemory)?
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.as_ptr();
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let iovec = libc::iovec {
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iov_base: buf as *mut libc::c_void,
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iov_len: desc.len as libc::size_t,
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};
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iovecs.push(iovec);
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}
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next_desc = desc.next_descriptor();
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}
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if !iovecs.is_empty() {
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let result = unsafe {
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libc::writev(
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tap.as_raw_fd() as libc::c_int,
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iovecs.as_ptr() as *const libc::iovec,
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iovecs.len() as libc::c_int,
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)
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};
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if result < 0 {
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let e = std::io::Error::last_os_error();
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/* EAGAIN */
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if e.kind() == std::io::ErrorKind::WouldBlock {
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warn!("net: tx: (recoverable) failed writing to tap: {}", e);
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queue.go_to_previous_position();
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retry_write = true;
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break;
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}
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error!("net: tx: failed writing to tap: {}", e);
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return Err(NetQueuePairError::WriteTap(e));
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}
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self.counter_bytes += Wrapping(result as u64 - vnet_hdr_len() as u64);
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self.counter_frames += Wrapping(1);
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}
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queue.add_used(mem, head_index, 0);
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queue.update_avail_event(mem);
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}
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Ok(retry_write)
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}
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}
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#[derive(Clone)]
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pub struct RxVirtio {
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pub counter_bytes: Wrapping<u64>,
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pub counter_frames: Wrapping<u64>,
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}
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impl Default for RxVirtio {
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fn default() -> Self {
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Self::new()
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}
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}
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impl RxVirtio {
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pub fn new() -> Self {
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RxVirtio {
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counter_bytes: Wrapping(0),
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counter_frames: Wrapping(0),
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}
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}
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pub fn process_desc_chain(
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&mut self,
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mem: &GuestMemoryMmap,
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tap: &mut Tap,
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queue: &mut Queue,
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rate_limiter: &mut Option<RateLimiter>,
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) -> Result<bool, NetQueuePairError> {
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let mut exhausted_descs = true;
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let mut rate_limit_reached = false;
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while let Some(avail_desc) = queue.iter(mem).next() {
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if rate_limit_reached {
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exhausted_descs = false;
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queue.go_to_previous_position();
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break;
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}
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let head_index = avail_desc.index;
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let num_buffers_addr = mem.checked_offset(avail_desc.addr, 10).unwrap();
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let mut next_desc = Some(avail_desc);
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let mut iovecs = Vec::new();
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while let Some(desc) = next_desc {
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if desc.is_write_only() && desc.len > 0 {
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let buf = mem
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.get_slice(desc.addr, desc.len as usize)
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.map_err(NetQueuePairError::GuestMemory)?
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.as_ptr();
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let iovec = libc::iovec {
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iov_base: buf as *mut libc::c_void,
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iov_len: desc.len as libc::size_t,
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};
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iovecs.push(iovec);
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}
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next_desc = desc.next_descriptor();
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}
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let len = if !iovecs.is_empty() {
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let result = unsafe {
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libc::readv(
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tap.as_raw_fd() as libc::c_int,
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iovecs.as_ptr() as *const libc::iovec,
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iovecs.len() as libc::c_int,
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)
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};
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if result < 0 {
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let e = std::io::Error::last_os_error();
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exhausted_descs = false;
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queue.go_to_previous_position();
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/* EAGAIN */
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if e.kind() == std::io::ErrorKind::WouldBlock {
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break;
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}
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error!("net: rx: failed reading from tap: {}", e);
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return Err(NetQueuePairError::ReadTap(e));
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}
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// Write num_buffers to guest memory. We simply write 1 as we
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// never spread the frame over more than one descriptor chain.
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mem.write_obj(1u16, num_buffers_addr)
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.map_err(NetQueuePairError::GuestMemory)?;
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self.counter_bytes += Wrapping(result as u64 - vnet_hdr_len() as u64);
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self.counter_frames += Wrapping(1);
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result as u32
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} else {
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0
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};
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queue.add_used(mem, head_index, len);
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queue.update_avail_event(mem);
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// For the sake of simplicity (keeping the handling of RX_QUEUE_EVENT and
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// RX_TAP_EVENT totally asynchronous), we always let the 'last' descriptor
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// chain go-through even if it was over the rate limit, and simply stop
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// processing oncoming `avail_desc` if any.
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if let Some(rate_limiter) = rate_limiter {
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rate_limit_reached = !rate_limiter.consume(1, TokenType::Ops)
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|| !rate_limiter.consume(len as u64, TokenType::Bytes);
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}
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}
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Ok(exhausted_descs)
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}
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}
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#[derive(Default, Clone)]
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pub struct NetCounters {
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pub tx_bytes: Arc<AtomicU64>,
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pub tx_frames: Arc<AtomicU64>,
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pub rx_bytes: Arc<AtomicU64>,
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pub rx_frames: Arc<AtomicU64>,
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}
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#[derive(Debug)]
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pub enum NetQueuePairError {
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/// No memory configured
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NoMemoryConfigured,
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/// Error registering listener
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RegisterListener(io::Error),
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/// Error unregistering listener
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UnregisterListener(io::Error),
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/// Error writing to the TAP device
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WriteTap(io::Error),
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/// Error reading from the TAP device
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ReadTap(io::Error),
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/// Error related to guest memory
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GuestMemory(vm_memory::GuestMemoryError),
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}
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pub struct NetQueuePair {
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pub mem: Option<GuestMemoryAtomic<GuestMemoryMmap>>,
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pub tap: Tap,
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// With epoll each FD must be unique. So in order to filter the
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// events we need to get a second FD responding to the original
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// device so that we can send EPOLLOUT and EPOLLIN to separate
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// events.
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pub tap_for_write_epoll: Tap,
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pub rx: RxVirtio,
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pub tx: TxVirtio,
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pub epoll_fd: Option<RawFd>,
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pub rx_tap_listening: bool,
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pub tx_tap_listening: bool,
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pub counters: NetCounters,
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pub tap_rx_event_id: u16,
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pub tap_tx_event_id: u16,
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pub rx_desc_avail: bool,
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pub rx_rate_limiter: Option<RateLimiter>,
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pub tx_rate_limiter: Option<RateLimiter>,
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}
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impl NetQueuePair {
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pub fn process_tx(&mut self, mut queue: &mut Queue) -> Result<bool, NetQueuePairError> {
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let mem = self
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.mem
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.as_ref()
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.ok_or(NetQueuePairError::NoMemoryConfigured)
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.map(|m| m.memory())?;
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let tx_tap_retry = self.tx.process_desc_chain(
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&mem,
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&mut self.tap,
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&mut queue,
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&mut self.tx_rate_limiter,
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)?;
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// We got told to try again when writing to the tap. Wait for the TAP to be writable
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if tx_tap_retry && !self.tx_tap_listening {
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register_listener(
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self.epoll_fd.unwrap(),
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self.tap_for_write_epoll.as_raw_fd(),
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epoll::Events::EPOLLOUT,
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u64::from(self.tap_tx_event_id),
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)
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.map_err(NetQueuePairError::RegisterListener)?;
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self.tx_tap_listening = true;
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info!("Writing to TAP returned EAGAIN. Listening for TAP to become writable.");
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} else if !tx_tap_retry && self.tx_tap_listening {
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unregister_listener(
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self.epoll_fd.unwrap(),
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self.tap_for_write_epoll.as_raw_fd(),
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epoll::Events::EPOLLOUT,
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u64::from(self.tap_tx_event_id),
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)
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.map_err(NetQueuePairError::UnregisterListener)?;
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self.tx_tap_listening = false;
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info!("Writing to TAP succeeded. No longer listening for TAP to become writable.");
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}
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self.counters
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.tx_bytes
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.fetch_add(self.tx.counter_bytes.0, Ordering::AcqRel);
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self.counters
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.tx_frames
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.fetch_add(self.tx.counter_frames.0, Ordering::AcqRel);
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self.tx.counter_bytes = Wrapping(0);
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self.tx.counter_frames = Wrapping(0);
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Ok(queue.needs_notification(&mem, queue.next_used))
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}
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pub fn process_rx(&mut self, mut queue: &mut Queue) -> Result<bool, NetQueuePairError> {
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let mem = self
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.mem
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.as_ref()
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.ok_or(NetQueuePairError::NoMemoryConfigured)
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.map(|m| m.memory())?;
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self.rx_desc_avail = !self.rx.process_desc_chain(
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&mem,
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&mut self.tap,
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&mut queue,
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&mut self.rx_rate_limiter,
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)?;
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let rate_limit_reached = self
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.rx_rate_limiter
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.as_ref()
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.map_or(false, |r| r.is_blocked());
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// Stop listening on the `RX_TAP_EVENT` when:
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// 1) there is no available describles, or
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// 2) the RX rate limit is reached.
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if self.rx_tap_listening && (!self.rx_desc_avail || rate_limit_reached) {
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unregister_listener(
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self.epoll_fd.unwrap(),
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self.tap.as_raw_fd(),
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epoll::Events::EPOLLIN,
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u64::from(self.tap_rx_event_id),
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)
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.map_err(NetQueuePairError::UnregisterListener)?;
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self.rx_tap_listening = false;
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}
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self.counters
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.rx_bytes
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.fetch_add(self.rx.counter_bytes.0, Ordering::AcqRel);
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self.counters
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.rx_frames
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.fetch_add(self.rx.counter_frames.0, Ordering::AcqRel);
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self.rx.counter_bytes = Wrapping(0);
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self.rx.counter_frames = Wrapping(0);
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Ok(queue.needs_notification(&mem, queue.next_used))
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}
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}
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