Features/VirtioVsock: Difference between revisions

Revision as of 11:00, 6 November 2017

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 ...

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

Testing

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

@@ Line 11: / Line 11: @@
 ==Code==
 * Virtio specification: [https://stefanha.github.com/virtio HTML] or [https://github.com/stefanha/virtio virtio.git]
-* Linux kernel: Available since Linux 4.8, or see [https://github.com/stefanha/linux/tree/vsock stefanha's linux.git]
+* Linux kernel: Upstream since Linux 4.8, or see [https://github.com/stefanha/linux/tree/vsock stefanha's linux.git]
-* QEMU: Available in QEMU 2.8, or see [https://github.com/stefanha/qemu/tree/vsock stefanha's qemu.git]
+* QEMU: Upstream since QEMU 2.8, or see [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]
 ==Packages==
-* [https://copr.fedorainfracloud.org/coprs/stefanha/vsock/ Fedora 24 copr repo]
+* [https://copr.fedorainfracloud.org/coprs/stefanha/vsock/ Fedora Copr repo]
 ==Quickstart==
-QEMU:
+* Host kernel requirements: CONFIG_VHOST_VSOCK=m
-  $ git clone git://git.qemu-project.org/qemu.git
+* 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 https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
-  $ 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.
+==Projects using vsock==
+* [https://github.com/stefanha/nc-vsock nc-vsock] - a netcat-like utility for AF_VSOCK
-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.
+* [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
 ==Testing==