vhost-device/vsock

vhost-user-vsock

Design

The crate introduces a vhost-user-vsock device that enables communication between an application running in the guest i.e inside a VM and an application running on the host i.e outside the VM. The application running in the guest communicates over VM sockets i.e over AF_VSOCK sockets. The application running on the host connects to a unix socket on the host i.e communicates over AF_UNIX sockets. The main components of the crate are split into various files as described below:

• packet.rs
  • Introduces the VsockPacket structure that represents a single vsock packet processing methods.
• rxops.rs
  • Introduces various vsock operations that are enqueued into the rxqueue to be sent to the guest. Exposes a RxOps structure.
• rxqueue.rs
  • rxqueue contains the pending rx operations corresponding to that connection. The queue is represented as a bitmap as we handle connection-oriented connections. The module contains various queue manipulation methods. Exposes a RxQueue structure.
• thread_backend.rs
  • Multiplexes connections between host and guest and calls into per connection methods that are responsible for processing data and packets corresponding to the connection. Exposes a VsockThreadBackend structure.
• txbuf.rs
  • Module to buffer data that is sent from the guest to the host. The module exposes a LocalTxBuf structure.
• vhost_user_vsock_thread.rs
  • Module exposes a VhostUserVsockThread structure. It also handles new host initiated connections and provides interfaces for registering host connections with the epoll fd. Also provides interfaces for iterating through the rx and tx queues.
• vsock_conn.rs
  • Module introduces a VsockConnection structure that represents a single vsock connection between the guest and the host. It also processes packets according to their type.
• vhu_vsock.rs
  • exposes the main vhost user vsock backend interface.

Usage

Run the vhost-user-vsock device:

vhost-user-vsock --guest-cid=4 --uds-path=/tmp/vm4.vsock --socket=/tmp/vhost4.socket

Run qemu:

qemu-system-x86_64 -drive file=/path/to/disk.qcow2 -enable-kvm -m 512M \
  -smp 2 -vga virtio -chardev socket,id=char0,reconnect=0,path=/tmp/vhost4.socket \
  -device vhost-user-vsock-pci,chardev=char0 \
  -object memory-backend-file,share=on,id=mem,size="512M",mem-path="/dev/hugepages" \
  -numa node,memdev=mem -mem-prealloc

Guest listening

iperf

# https://github.com/stefano-garzarella/iperf-vsock
guest$ iperf3 --vsock -s
host$  iperf3 --vsock -c /tmp/vm4.vsock

netcat

guest$ nc --vsock -l 1234

host$  nc -U /tmp/vm4.vsock
CONNECT 1234

Host listening

iperf

# https://github.com/stefano-garzarella/iperf-vsock
host$  iperf3 --vsock -s -B /tmp/vm4.vsock
guest$ iperf3 --vsock -c 2

netcat

host$ nc -l -U /tmp/vm4.vsock_1234

guest$ nc --vsock 2 1234

use my_crate;

...

License

!!!NOTICE: The BSD-3-Clause license is not included in this template. The license needs to be manually added because the text of the license file also includes the copyright. The copyright can be different for different crates. If the crate contains code from CrosVM, the crate must add the CrosVM copyright which can be found here. For crates developed from scratch, the copyright is different and depends on the contributors.