cloud-hypervisor/net_util/src/ctrl_queue.rs

// Copyright (c) 2021 Intel Corporation. All rights reserved.
//
// SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause

use crate::GuestMemoryMmap;
use crate::Tap;
use libc::c_uint;
use std::sync::Arc;
use virtio_bindings::bindings::virtio_net::{
    VIRTIO_NET_CTRL_GUEST_OFFLOADS, VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET, VIRTIO_NET_CTRL_MQ,
    VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MAX, VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MIN,
    VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET, VIRTIO_NET_ERR, VIRTIO_NET_F_GUEST_CSUM,
    VIRTIO_NET_F_GUEST_ECN, VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6,
    VIRTIO_NET_F_GUEST_UFO, VIRTIO_NET_OK,
};
use virtio_queue::{Queue, QueueOwnedT, QueueT};
use vm_memory::{ByteValued, Bytes, GuestMemoryError};
use vm_virtio::{AccessPlatform, Translatable};

#[derive(Debug)]
pub enum Error {
    /// Read queue failed.
    GuestMemory(GuestMemoryError),
    /// No control header descriptor
    NoControlHeaderDescriptor,
    /// Missing the data descriptor in the chain.
    NoDataDescriptor,
    /// No status descriptor
    NoStatusDescriptor,
    /// Failed adding used index
    QueueAddUsed(virtio_queue::Error),
    /// Failed creating an iterator over the queue
    QueueIterator(virtio_queue::Error),
    /// Failed enabling notification for the queue
    QueueEnableNotification(virtio_queue::Error),
}

type Result<T> = std::result::Result<T, Error>;

#[repr(C, packed)]
#[derive(Debug, Clone, Copy, Default)]
pub struct ControlHeader {
    pub class: u8,
    pub cmd: u8,
}

// SAFETY: ControlHeader only contains a series of integers
unsafe impl ByteValued for ControlHeader {}

pub struct CtrlQueue {
    pub taps: Vec<Tap>,
}

impl CtrlQueue {
    pub fn new(taps: Vec<Tap>) -> Self {
        CtrlQueue { taps }
    }

    pub fn process(
        &mut self,
        mem: &GuestMemoryMmap,
        queue: &mut Queue,
        access_platform: Option<&Arc<dyn AccessPlatform>>,
    ) -> Result<()> {
        let mut used_desc_heads = Vec::new();
        loop {
            for mut desc_chain in queue.iter(mem).map_err(Error::QueueIterator)? {
                let ctrl_desc = desc_chain.next().ok_or(Error::NoControlHeaderDescriptor)?;

                let ctrl_hdr: ControlHeader = desc_chain
                    .memory()
                    .read_obj(
                        ctrl_desc
                            .addr()
                            .translate_gva(access_platform, ctrl_desc.len() as usize),
                    )
                    .map_err(Error::GuestMemory)?;
                let data_desc = desc_chain.next().ok_or(Error::NoDataDescriptor)?;

                let data_desc_addr = data_desc
                    .addr()
                    .translate_gva(access_platform, data_desc.len() as usize);

                let status_desc = desc_chain.next().ok_or(Error::NoStatusDescriptor)?;

                let ok = match u32::from(ctrl_hdr.class) {
                    VIRTIO_NET_CTRL_MQ => {
                        let queue_pairs = desc_chain
                            .memory()
                            .read_obj::<u16>(data_desc_addr)
                            .map_err(Error::GuestMemory)?;
                        if u32::from(ctrl_hdr.cmd) != VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET {
                            warn!("Unsupported command: {}", ctrl_hdr.cmd);
                            false
                        } else if (queue_pairs < VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MIN as u16)
                            || (queue_pairs > VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MAX as u16)
                        {
                            warn!("Number of MQ pairs out of range: {}", queue_pairs);
                            false
                        } else {
                            info!("Number of MQ pairs requested: {}", queue_pairs);
                            true
                        }
                    }
                    VIRTIO_NET_CTRL_GUEST_OFFLOADS => {
                        let features = desc_chain
                            .memory()
                            .read_obj::<u64>(data_desc_addr)
                            .map_err(Error::GuestMemory)?;
                        if u32::from(ctrl_hdr.cmd) != VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET {
                            warn!("Unsupported command: {}", ctrl_hdr.cmd);
                            false
                        } else {
                            let mut ok = true;
                            for tap in self.taps.iter_mut() {
                                info!("Reprogramming tap offload with features: {}", features);
                                tap.set_offload(virtio_features_to_tap_offload(features))
                                    .map_err(|e| {
                                        error!("Error programming tap offload: {:?}", e);
                                        ok = false
                                    })
                                    .ok();
                            }
                            ok
                        }
                    }
                    _ => {
                        warn!("Unsupported command {:?}", ctrl_hdr);
                        false
                    }
                };

                desc_chain
                    .memory()
                    .write_obj(
                        if ok { VIRTIO_NET_OK } else { VIRTIO_NET_ERR } as u8,
                        status_desc
                            .addr()
                            .translate_gva(access_platform, status_desc.len() as usize),
                    )
                    .map_err(Error::GuestMemory)?;
                let len = ctrl_desc.len() + data_desc.len() + status_desc.len();
                used_desc_heads.push((desc_chain.head_index(), len));
            }

            for (desc_index, len) in used_desc_heads.iter() {
                queue
                    .add_used(mem, *desc_index, *len)
                    .map_err(Error::QueueAddUsed)?;
            }

            if !queue
                .enable_notification(mem)
                .map_err(Error::QueueEnableNotification)?
            {
                break;
            }
        }

        Ok(())
    }
}

pub fn virtio_features_to_tap_offload(features: u64) -> c_uint {
    let mut tap_offloads: c_uint = 0;
    if features & (1 << VIRTIO_NET_F_GUEST_CSUM) != 0 {
        tap_offloads |= net_gen::TUN_F_CSUM;
    }
    if features & (1 << VIRTIO_NET_F_GUEST_TSO4) != 0 {
        tap_offloads |= net_gen::TUN_F_TSO4;
    }
    if features & (1 << VIRTIO_NET_F_GUEST_TSO6) != 0 {
        tap_offloads |= net_gen::TUN_F_TSO6;
    }
    if features & (1 << VIRTIO_NET_F_GUEST_ECN) != 0 {
        tap_offloads |= net_gen::TUN_F_TSO_ECN;
    }
    if features & (1 << VIRTIO_NET_F_GUEST_UFO) != 0 {
        tap_offloads |= net_gen::TUN_F_UFO;
    }

    tap_offloads
}