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+// Copyright (C) 2019 Alibaba Cloud Computing. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0 or BSD-3-Clause
+//
+// Portions Copyright 2017 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE-BSD-Google file.
+
+//! Traits and structs to control Linux in-kernel vhost drivers.
+//!
+//! The initial vhost implementation is a part of the Linux kernel and uses ioctl interface to
+//! communicate with userspace applications. This sub module provides ioctl based interfaces to
+//! control the in-kernel net, scsi, vsock vhost drivers.
+
+use std::os::unix::io::{AsRawFd, RawFd};
+
+use sys_util::ioctl::{ioctl, ioctl_with_mut_ref, ioctl_with_ptr, ioctl_with_ref};
+use sys_util::EventFd;
+use vm_memory::{Address, GuestAddress, GuestAddressSpace, GuestMemory, GuestUsize};
+
+use super::{
+ Error, Result, VhostBackend, VhostUserMemoryRegionInfo, VringConfigData,
+ VHOST_MAX_MEMORY_REGIONS,
+};
+
+pub mod vhost_binding;
+use self::vhost_binding::*;
+
+#[cfg(feature = "vhost-vsock")]
+pub mod vsock;
+
+#[inline]
+fn ioctl_result<T>(rc: i32, res: T) -> Result<T> {
+ if rc < 0 {
+ Err(Error::IoctlError(std::io::Error::last_os_error()))
+ } else {
+ Ok(res)
+ }
+}
+
+/// Represent an in-kernel vhost device backend.
+pub trait VhostKernBackend: AsRawFd {
+ /// Associated type to access guest memory.
+ type AS: GuestAddressSpace;
+
+ /// Get the object to access the guest's memory.
+ fn mem(&self) -> &Self::AS;
+
+ /// Check whether the ring configuration is valid.
+ fn is_valid(&self, config_data: &VringConfigData) -> bool {
+ let queue_size = config_data.queue_size;
+ if queue_size > config_data.queue_max_size
+ || queue_size == 0
+ || (queue_size & (queue_size - 1)) != 0
+ {
+ return false;
+ }
+
+ let m = self.mem().memory();
+ let desc_table_size = 16 * u64::from(queue_size) as GuestUsize;
+ let avail_ring_size = 6 + 2 * u64::from(queue_size) as GuestUsize;
+ let used_ring_size = 6 + 8 * u64::from(queue_size) as GuestUsize;
+ if GuestAddress(config_data.desc_table_addr)
+ .checked_add(desc_table_size)
+ .map_or(true, |v| !m.address_in_range(v))
+ {
+ return false;
+ }
+ if GuestAddress(config_data.avail_ring_addr)
+ .checked_add(avail_ring_size)
+ .map_or(true, |v| !m.address_in_range(v))
+ {
+ return false;
+ }
+ if GuestAddress(config_data.used_ring_addr)
+ .checked_add(used_ring_size)
+ .map_or(true, |v| !m.address_in_range(v))
+ {
+ return false;
+ }
+
+ config_data.is_log_addr_valid()
+ }
+}
+
+impl<T: VhostKernBackend> VhostBackend for T {
+ /// Get a bitmask of supported virtio/vhost features.
+ fn get_features(&self) -> Result<u64> {
+ let mut avail_features: u64 = 0;
+ // This ioctl is called on a valid vhost fd and has its return value checked.
+ let ret = unsafe { ioctl_with_mut_ref(self, VHOST_GET_FEATURES(), &mut avail_features) };
+ ioctl_result(ret, avail_features)
+ }
+
+ /// Inform the vhost subsystem which features to enable. This should be a subset of
+ /// supported features from VHOST_GET_FEATURES.
+ ///
+ /// # Arguments
+ /// * `features` - Bitmask of features to set.
+ fn set_features(&self, features: u64) -> Result<()> {
+ // This ioctl is called on a valid vhost fd and has its return value checked.
+ let ret = unsafe { ioctl_with_ref(self, VHOST_SET_FEATURES(), &features) };
+ ioctl_result(ret, ())
+ }
+
+ /// Set the current process as the owner of this file descriptor.
+ /// This must be run before any other vhost ioctls.
+ fn set_owner(&self) -> Result<()> {
+ // This ioctl is called on a valid vhost fd and has its return value checked.
+ let ret = unsafe { ioctl(self, VHOST_SET_OWNER()) };
+ ioctl_result(ret, ())
+ }
+
+ fn reset_owner(&self) -> Result<()> {
+ // This ioctl is called on a valid vhost fd and has its return value checked.
+ let ret = unsafe { ioctl(self, VHOST_RESET_OWNER()) };
+ ioctl_result(ret, ())
+ }
+
+ /// Set the guest memory mappings for vhost to use.
+ fn set_mem_table(&self, regions: &[VhostUserMemoryRegionInfo]) -> Result<()> {
+ if regions.is_empty() || regions.len() > VHOST_MAX_MEMORY_REGIONS {
+ return Err(Error::InvalidGuestMemory);
+ }
+
+ let mut vhost_memory = VhostMemory::new(regions.len() as u16);
+ for (index, region) in regions.iter().enumerate() {
+ vhost_memory.set_region(
+ index as u32,
+ &vhost_memory_region {
+ guest_phys_addr: region.guest_phys_addr,
+ memory_size: region.memory_size,
+ userspace_addr: region.userspace_addr,
+ flags_padding: 0u64,
+ },
+ )?;
+ }
+
+ // This ioctl is called with a pointer that is valid for the lifetime
+ // of this function. The kernel will make its own copy of the memory
+ // tables. As always, check the return value.
+ let ret = unsafe { ioctl_with_ptr(self, VHOST_SET_MEM_TABLE(), vhost_memory.as_ptr()) };
+ ioctl_result(ret, ())
+ }
+
+ /// Set base address for page modification logging.
+ ///
+ /// # Arguments
+ /// * `base` - Base address for page modification logging.
+ fn set_log_base(&self, base: u64, fd: Option<RawFd>) -> Result<()> {
+ if fd.is_some() {
+ return Err(Error::LogAddress);
+ }
+
+ // This ioctl is called on a valid vhost fd and has its return value checked.
+ let ret = unsafe { ioctl_with_ref(self, VHOST_SET_LOG_BASE(), &base) };
+ ioctl_result(ret, ())
+ }
+
+ /// Specify an eventfd file descriptor to signal on log write.
+ fn set_log_fd(&self, fd: RawFd) -> Result<()> {
+ // This ioctl is called on a valid vhost fd and has its return value checked.
+ let val: i32 = fd;
+ let ret = unsafe { ioctl_with_ref(self, VHOST_SET_LOG_FD(), &val) };
+ ioctl_result(ret, ())
+ }
+
+ /// Set the number of descriptors in the vring.
+ ///
+ /// # Arguments
+ /// * `queue_index` - Index of the queue to set descriptor count for.
+ /// * `num` - Number of descriptors in the queue.
+ fn set_vring_num(&self, queue_index: usize, num: u16) -> Result<()> {
+ let vring_state = vhost_vring_state {
+ index: queue_index as u32,
+ num: u32::from(num),
+ };
+
+ // This ioctl is called on a valid vhost fd and has its return value checked.
+ let ret = unsafe { ioctl_with_ref(self, VHOST_SET_VRING_NUM(), &vring_state) };
+ ioctl_result(ret, ())
+ }
+
+ /// Set the addresses for a given vring.
+ ///
+ /// # Arguments
+ /// * `queue_index` - Index of the queue to set addresses for.
+ /// * `config_data` - Vring config data.
+ fn set_vring_addr(&self, queue_index: usize, config_data: &VringConfigData) -> Result<()> {
+ if !self.is_valid(config_data) {
+ return Err(Error::InvalidQueue);
+ }
+
+ let vring_addr = vhost_vring_addr {
+ index: queue_index as u32,
+ flags: config_data.flags,
+ desc_user_addr: config_data.desc_table_addr,
+ used_user_addr: config_data.used_ring_addr,
+ avail_user_addr: config_data.avail_ring_addr,
+ log_guest_addr: config_data.get_log_addr(),
+ };
+
+ // This ioctl is called on a valid vhost fd and has its
+ // return value checked.
+ let ret = unsafe { ioctl_with_ref(self, VHOST_SET_VRING_ADDR(), &vring_addr) };
+ ioctl_result(ret, ())
+ }
+
+ /// Set the first index to look for available descriptors.
+ ///
+ /// # Arguments
+ /// * `queue_index` - Index of the queue to modify.
+ /// * `num` - Index where available descriptors start.
+ fn set_vring_base(&self, queue_index: usize, base: u16) -> Result<()> {
+ let vring_state = vhost_vring_state {
+ index: queue_index as u32,
+ num: u32::from(base),
+ };
+
+ // This ioctl is called on a valid vhost fd and has its return value checked.
+ let ret = unsafe { ioctl_with_ref(self, VHOST_SET_VRING_BASE(), &vring_state) };
+ ioctl_result(ret, ())
+ }
+
+ /// Get a bitmask of supported virtio/vhost features.
+ fn get_vring_base(&self, queue_index: usize) -> Result<u32> {
+ let vring_state = vhost_vring_state {
+ index: queue_index as u32,
+ num: 0,
+ };
+ // This ioctl is called on a valid vhost fd and has its return value checked.
+ let ret = unsafe { ioctl_with_ref(self, VHOST_GET_VRING_BASE(), &vring_state) };
+ ioctl_result(ret, vring_state.num)
+ }
+
+ /// Set the eventfd to trigger when buffers have been used by the host.
+ ///
+ /// # Arguments
+ /// * `queue_index` - Index of the queue to modify.
+ /// * `fd` - EventFd to trigger.
+ fn set_vring_call(&self, queue_index: usize, fd: &EventFd) -> Result<()> {
+ let vring_file = vhost_vring_file {
+ index: queue_index as u32,
+ fd: fd.as_raw_fd(),
+ };
+
+ // This ioctl is called on a valid vhost fd and has its return value checked.
+ let ret = unsafe { ioctl_with_ref(self, VHOST_SET_VRING_CALL(), &vring_file) };
+ ioctl_result(ret, ())
+ }
+
+ /// Set the eventfd that will be signaled by the guest when buffers are
+ /// available for the host to process.
+ ///
+ /// # Arguments
+ /// * `queue_index` - Index of the queue to modify.
+ /// * `fd` - EventFd that will be signaled from guest.
+ fn set_vring_kick(&self, queue_index: usize, fd: &EventFd) -> Result<()> {
+ let vring_file = vhost_vring_file {
+ index: queue_index as u32,
+ fd: fd.as_raw_fd(),
+ };
+
+ // This ioctl is called on a valid vhost fd and has its return value checked.
+ let ret = unsafe { ioctl_with_ref(self, VHOST_SET_VRING_KICK(), &vring_file) };
+ ioctl_result(ret, ())
+ }
+
+ /// Set the eventfd to signal an error from the vhost backend.
+ ///
+ /// # Arguments
+ /// * `queue_index` - Index of the queue to modify.
+ /// * `fd` - EventFd that will be signaled from the backend.
+ fn set_vring_err(&self, queue_index: usize, fd: &EventFd) -> Result<()> {
+ let vring_file = vhost_vring_file {
+ index: queue_index as u32,
+ fd: fd.as_raw_fd(),
+ };
+
+ // This ioctl is called on a valid vhost fd and has its return value checked.
+ let ret = unsafe { ioctl_with_ref(self, VHOST_SET_VRING_ERR(), &vring_file) };
+ ioctl_result(ret, ())
+ }
+}