Features/VirtioVsock: Difference between revisions

Latest revision as of 15:59, 11 January 2021

virtio-vsock is a host/guest communications device. It allows applications in the guest and host to communicate. This can be used to implement hypervisor services and guest agents (like qemu-guest-agent or SPICE vdagent).

POSIX Sockets API so existing networking applications require minimal modification (unlike virtio-serial char devices)
Listen sockets can accept connections from multiple clients (unlike virtio-serial char devices)
No address configuration required inside the guest
No Ethernet or TCP/IP for a reduced attack surface for hypervisor services
Can be used with VMs that have no network interfaces

Sockets are created with the AF_VSOCK address family. The SOCK_STREAM socket type is currently implemented for in-order, guaranteed stream semantics.

Code

Virtio specification: HTML or virtio.git
Linux kernel: Upstream since Linux 4.8, or see stefanha's linux.git
QEMU: Upstream since QEMU 2.8, or see stefanha's qemu.git

Packages

Fedora Copr repo

Quickstart

Host kernel requirements: CONFIG_VHOST_VSOCK=m
Guest kernel requirements: CONFIG_VIRTIO_VSOCKETS=m

Launch a guest and assign it CID 3:

 (host)# qemu-system-x86_64 -device vhost-vsock-pci,guest-cid=3 ...

Language bindings

C - use <linux/vm_sockets.h>
Python - starting from Python 3.7
Go - Matt Layher's vsock module
Rust
- libc crate (libc::sockaddr_vm, libc::VMADDR_*)
- nix crate (nix::sys::socket::VsockAddr)

Projects using vsock

nc-vsock - a netcat-like utility for AF_VSOCK
xpra - X11 persistent remote display server and client
cloonix_vsock - PTY over AF_VSOCK
iperf-vsock - iperf3 with AF_VSOCK support
socat - VSOCK-CONNECT and VSOCK-LISTEN addresses supported from socat 1.7.4 [2021-01-04]

Links

KVM Forum 2015 presentation: virtio-vsock: Zero-configuration host/guest communication (pdf)
Connectathon 2016 presentation: NFS over virtio-vsock: Host/guest file sharing for virtual machines (pdf)

@@ Line 24: / Line 24: @@
    (host)# qemu-system-x86_64 -device vhost-vsock-pci,guest-cid=3 ...
+==Language bindings==
+* C - use <linux/vm_sockets.h>
+* Python - starting from Python 3.7
+* Go - [https://github.com/mdlayher/vsock Matt Layher's vsock module]
+* Rust
+** [https://docs.rs/crate/libc libc crate] (libc::sockaddr_vm, libc::VMADDR_*)
+** [https://docs.rs/crate/nix nix crate] (nix::sys::socket::VsockAddr)
 ==Projects using vsock==
@@ Line 29: / Line 37: @@
 * [https://www.xpra.org/trac/wiki/Network xpra] - X11 persistent remote display server and client
 * [https://github.com/clownix/cloonix_vsock cloonix_vsock] - PTY over AF_VSOCK
+* [https://github.com/stefano-garzarella/iperf-vsock iperf-vsock] - iperf3 with AF_VSOCK support
-==Testing==
+* [http://www.dest-unreach.org/socat/ socat] - VSOCK-CONNECT and VSOCK-LISTEN addresses supported from socat 1.7.4 [2021-01-04]
-The vhost-vsock-test qtest replays packets from a JSON file and verifies that the expected reply is received.
-The JSON test file format is described in a [https://github.com/stefanha/qemu/blob/vsock/tests/vhost-vsock-test-data/README README].
-  $ cd qemu
-  $ make -j4
-  $ make tests/vhost-vsock-test
-  $ sudo QTEST_QEMU_BINARY=x86_64-softmmu/qemu-system-x86_64 QTEST_QEMU_IMG=qemu-img MALLOC_PERTURB_=${MALLOC_PERTURB_:-$((RANDOM % 255 + 1))} gtester -k --verbose -m=quick tests/vhost-vsock-test -o /dev/stderr
-Create and edit test cases in tests/vhost-vsock-test-data/*.json.
 ==Links==
 * KVM Forum 2015 presentation: [http://vmsplice.net/~stefan/stefanha-kvm-forum-2015.pdf virtio-vsock: Zero-configuration host/guest communication] (pdf)
 * Connectathon 2016 presentation: [http://vmsplice.net/~stefan/stefanha-connectathon-2016.pdf NFS over virtio-vsock: Host/guest file sharing for virtual machines] (pdf)