Features/VirtioVsock: Difference between revisions

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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).
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==
==Code==

Revision as of 10:58, 27 July 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

Packages

Quickstart

QEMU:

 $ git clone git://git.qemu-project.org/qemu.git
 $ cd qemu
 $ ./configure --target-list=x86_64-softmmu
 $ make

Linux:

 $ 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.

The guest should also use the kernel so that modprobe virtio_transport can load the vsock guest driver.

For details on host and guest boot, see 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.

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