Hello,
On Tue, Jan 14, 2014 at 12:14 PM, Michael S. Tsirkin <m...@redhat.com> wrote: > On Mon, Jan 13, 2014 at 03:25:11PM +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. > > > > We change -mem-path to QemuOpts and add prealloc, share and unlink as > properties > > to it. HugeTLBFS requirements of -mem-path are relaxed, so any valid > path can > > be used now. > > Wait a second. This does not actually work well: if you mmap > a random file outside HugeTLBFS, kernel won't create huge pages > from this memory so performance of the system as a whole will suffer. > > You'll have fix the kernel MM before this scheme can fly. > I'm not sure I completely understand this point. It is up to the user to choose not to use HugeTLBFS. Is there a particular problem with the kernel when not using it? > > > > The new properties allow more fine grained control over the guest > > RAM backing store. > > > > 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. > > > > Example usage: > > > > qemu -m 1024 -mem-path /hugetlbfs,prealloc=on,share=on \ > > -netdev type=vhost-user,id=net0,path=/path/to/sock,poll_time=2500 \ > > -device virtio-net-pci,netdev=net0 > > > > 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 (8): > > Convert -mem-path to QemuOpts and add prealloc and share properties > > New -mem-path option - unlink. > > Decouple vhost from kernel interface > > Add vhost-user skeleton > > Add domain socket communication for vhost-user backend > > Add vhost-user calls implementation > > Add new vhost-user netdev backend > > Add vhost-user reconnection > > > > exec.c | 57 +++- > > hmp-commands.hx | 4 +- > > hw/net/vhost_net.c | 144 +++++++--- > > hw/net/virtio-net.c | 42 ++- > > hw/scsi/vhost-scsi.c | 13 +- > > hw/virtio/Makefile.objs | 2 +- > > hw/virtio/vhost-backend.c | 556 > ++++++++++++++++++++++++++++++++++++++ > > hw/virtio/vhost.c | 46 ++-- > > include/exec/cpu-all.h | 3 - > > include/hw/virtio/vhost-backend.h | 40 +++ > > include/hw/virtio/vhost.h | 4 +- > > include/net/vhost-user.h | 17 ++ > > include/net/vhost_net.h | 15 +- > > net/Makefile.objs | 2 +- > > net/clients.h | 3 + > > net/hub.c | 1 + > > net/net.c | 2 + > > net/tap.c | 16 +- > > net/vhost-user.c | 177 ++++++++++++ > > qapi-schema.json | 21 +- > > qemu-options.hx | 24 +- > > vl.c | 41 ++- > > 22 files changed, 1106 insertions(+), 124 deletions(-) > > create mode 100644 hw/virtio/vhost-backend.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 > > >
