Hello,
On Mon, Feb 10, 2014 at 9:57 AM, Michael S. Tsirkin <m...@redhat.com> wrote: > > On Fri, Jan 31, 2014 at 06:34:29PM +0100, Antonios Motakis wrote: > > In this patch series we would like to introduce our approach for putting a > > virtio-net backend in an external userspace process. Our eventual target is > > to > > run the network backend in the Snabbswitch ethernet switch, while receiving > > traffic from a guest inside QEMU/KVM which runs an unmodified virtio-net > > implementation. > > > > For this, we are working into extending vhost to allow equivalent > > functionality > > for userspace. Vhost already passes control of the data plane of virtio-net > > to > > the host kernel; we want to realize a similar model, but for userspace. > > > > In this patch series the concept of a vhost-backend is introduced. > > > > We define two vhost backend types - vhost-kernel and vhost-user. The former > > is > > the interface to the current kernel module implementation. Its control > > plane is > > ioctl based. The data plane is the kernel directly accessing the QEMU > > allocated, > > guest memory. > > > > In the new vhost-user backend, the control plane is based on communication > > between QEMU and another userspace process using a unix domain socket. This > > allows to implement a virtio backend for a guest running in QEMU, inside the > > other userspace process. For this communication we use a chardev with a > > unix socket > > backend. Vhost-user is client/server agnostic regarding the chardev, however > > it does not support the 'nowait' and 'telnet' options. > > > > We change -mem-path to QemuOpts and add prealloc and share as properties > > to it. HugeTLBFS is required for this option to work. > > > > The data path is realized by directly accessing the vrings and the buffer > > data > > off the guest's memory. > > > > The current user of vhost-user is only vhost-net. We add new netdev backend > > that is intended to initialize vhost-net with vhost-user backend. > > > You mentioned that there will be an in-tree utility that can > communicate over this channel from the other side. > Did I miss it in this patchset or is it not included yet? You haven't missed it; we just wanted to push our intermediate changes for review, while we were still implementing the in-tree test. The next version (v8), which we will post quite soon, will include it. > > > > Example usage: > > > > qemu -m 1024 -mem-path /hugetlbfs,share=on \ > > -chardev socket,id=chr0,path=/path/to/socket \ > > -netdev type=vhost-user,id=net0,chardev=chr0 \ > > -device virtio-net-pci,netdev=net0 > > > > This code can be pulled from g...@github.com:virtualopensystems/qemu.git > > vhost-user-v7 > > > > A reference vhost-user slave for testing is available from > > g...@github.com:virtualopensystems/vapp.git > > > > TODOs include: > > - Include a test in QEMU to avoid regressions > > - Slave reconnection and nowait support > > > > Changes from v6: > > - Remove the 'unlink' property of '-mem-path' > > - Extend qemu-char: blocking read, send fds, monitor for connection close > > - Vhost-user uses chardev as a backend > > - Poll and reconnect removed (no VHOST_USER_ECHO). > > - Disconnect is deteced by the chardev (G_IO_HUP event) > > - vhost-backend.c split to vhost-user.c > > > > Changes from v5: > > - Split -mem-path unlink option to a separate patch > > - Fds are passed only in the ancillary data > > - Stricter message size checks on receive/send > > - Netdev vhost-user now includes path and poll_time options > > - The connection probing interval is configurable > > > > Changes from v4: > > - Use error_report for errors > > - VhostUserMsg has new field `size` indicating the following payload > > length. > > Field `flags` now has version and reply bits. The structure is packed. > > - Send data is of variable length (`size` field in message) > > - Receive in 2 steps, header and payload > > - Add new message type VHOST_USER_ECHO, to check connection status > > > > Changes from v3: > > - Convert -mem-path to QemuOpts with prealloc, share and unlink properties > > - Set 1 sec timeout when read/write to the unix domain socket > > - Fix file descriptor leak > > > > Changes from v2: > > - Reconnect when the backend disappears > > > > Changes from v1: > > - Implementation of vhost-user netdev backend > > - Code improvements > > > > Antonios Motakis (13): > > Convert -mem-path to QemuOpts and add prealloc and share properties > > Add chardev API qemu_chr_fe_read_all > > Add chardev API qemu_chr_fe_set_msgfds > > Add G_IO_HUP handler for socket chardev > > vhost_net should call the poll callback only when it is set > > Refactor virtio-net to use a generic get_vhost_net > > vhost_net_init will use VhostNetOptions to get all its arguments > > Add vhost_ops to the vhost_dev struct and replace all relevant ioctls > > Add vhost-backend and VhostBackendType > > Add vhost-user as a vhost backend. > > Add new vhost-user netdev backend > > Add the vhost-user netdev backend to command line > > Add vhost-user protocol documentation > > > > docs/specs/vhost-user.txt | 249 ++++++++++++++++++++++++++++ > > exec.c | 30 +++- > > hmp-commands.hx | 4 +- > > hw/net/vhost_net.c | 142 +++++++++++----- > > hw/net/virtio-net.c | 42 ++--- > > hw/scsi/vhost-scsi.c | 20 ++- > > hw/virtio/Makefile.objs | 2 +- > > hw/virtio/vhost-backend.c | 71 ++++++++ > > hw/virtio/vhost-user.c | 331 > > ++++++++++++++++++++++++++++++++++++++ > > hw/virtio/vhost.c | 55 ++++--- > > include/exec/cpu-all.h | 3 - > > include/hw/virtio/vhost-backend.h | 38 +++++ > > include/hw/virtio/vhost.h | 8 +- > > include/net/vhost-user.h | 17 ++ > > include/net/vhost_net.h | 11 +- > > include/sysemu/char.h | 28 ++++ > > net/Makefile.objs | 2 +- > > net/clients.h | 3 + > > net/hub.c | 1 + > > net/net.c | 2 + > > net/tap.c | 18 ++- > > net/vhost-user.c | 217 +++++++++++++++++++++++++ > > qapi-schema.json | 18 ++- > > qemu-char.c | 185 ++++++++++++++++++++- > > qemu-options.hx | 25 ++- > > vl.c | 37 ++++- > > 26 files changed, 1425 insertions(+), 134 deletions(-) > > create mode 100644 docs/specs/vhost-user.txt > > create mode 100644 hw/virtio/vhost-backend.c > > create mode 100644 hw/virtio/vhost-user.c > > create mode 100644 include/hw/virtio/vhost-backend.h > > create mode 100644 include/net/vhost-user.h > > create mode 100644 net/vhost-user.c > > > > -- > > 1.8.3.2 > > -- Antonios Motakis Virtual Open Systems
