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 1: / Line 1: @@
 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).
-Unlike virtio-serial, virtio-vsock supports the POSIX Sockets API so existing networking applications require minimal modification.  The Sockets API allows N:1 connections so multiple clients can connect to a server simultaneously.
+* 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
-The device has an address assigned automatically so no configuration is required inside the guest.
+Sockets are created with the AF_VSOCK address family.  The SOCK_STREAM socket type is currently implemented for in-order, guaranteed stream semantics.
-Sockets are created with the AF_VSOCK address family.  The SOCK_STREAM socket type is currently implemented.
+==Code==
+* Virtio specification: [https://stefanha.github.com/virtio HTML] or [https://github.com/stefanha/virtio virtio.git]
+* Linux kernel: Upstream since Linux 4.8, or see [https://github.com/stefanha/linux/tree/vsock stefanha's linux.git]
+* QEMU: Upstream since QEMU 2.8, or see [https://github.com/stefanha/qemu/tree/vsock stefanha's qemu.git]
-==Code==
+==Packages==
-* Virtio specification: [http://comments.gmane.org/gmane.comp.emulators.virtio.devel/855 RFC]
+* [https://copr.fedorainfracloud.org/coprs/stefanha/vsock/ Fedora Copr repo]
-* Linux kernel: [https://github.com/stefanha/linux/tree/vsock stefanha's linux.git]
-* QEMU: [https://github.com/stefanha/qemu/tree/vsock stefanha's qemu.git]
-* netcat-like utility: [https://github.com/stefanha/linux/blob/vsock-extras/nc-vsock.c nc-vsock]
 ==Quickstart==
-QEMU:
+* Host kernel requirements: CONFIG_VHOST_VSOCK=m
-  $ git clone -b vsock https://github.com/stefanha/qemu
+* Guest kernel requirements: CONFIG_VIRTIO_VSOCKETS=m
-  $ cd qemu
-  $ ./configure --target-list=x86_64-softmmu
-  $ make
-Linux:
+Launch a guest and assign it CID 3:
-  $ git clone -b vsock https://github.com/stefanha/linux
-  $ cd linux
-  $ cp /boot/config-$(uname -r) .config
-  $ make menuconfig # select CONFIG_VHOST_VSOCK=m and CONFIG_VIRTIO_VSOCKETS=m
-  $ make install modules_install
-To use vhost_vsock.ko you must boot into the new host kernel and modprobe vhost_vsock.
+  (host)# qemu-system-x86_64 -device vhost-vsock-pci,guest-cid=3 ...
-The guest should also use the kernel so that modprobe virtio_transport can load the vsock guest driver.
+==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)
-For details on host and guest boot, see [https://github.com/stefanha/linux/blob/vsock-extras/go.sh go.sh].  Use nc-vsock 2 1234 inside the guest to connect to vsock port 1234 on the host.  Use nc-vsock -l 1234 on the host to listen on that port.
+==Projects using vsock==
+* [https://github.com/stefanha/nc-vsock nc-vsock] - a netcat-like utility for AF_VSOCK
+* [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
+* [http://www.dest-unreach.org/socat/ socat] - VSOCK-CONNECT and VSOCK-LISTEN addresses supported from socat 1.7.4 [2021-01-04]
 ==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)