> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Huawei Xie > Sent: Wednesday, March 11, 2015 4:22 PM > To: dev at dpdk.org > Subject: [dpdk-dev] [PATCH] vhost library doc update > > add vhost user documentation > > Signed-off-by: Huawei Xie <huawei.xie at intel.com> > --- > doc/guides/prog_guide/vhost_lib.rst | 52 > ++++++++++++++++++++++++++++++------- > 1 file changed, 42 insertions(+), 10 deletions(-) > > diff --git a/doc/guides/prog_guide/vhost_lib.rst > b/doc/guides/prog_guide/vhost_lib.rst > index 0b6eda7..ab35b74 100644 > --- a/doc/guides/prog_guide/vhost_lib.rst > +++ b/doc/guides/prog_guide/vhost_lib.rst > @@ -31,25 +31,28 @@ > Vhost Library > ============= > > -The vhost cuse (cuse: user space character device driver) library implements > a -vhost cuse driver. It also creates, manages and destroys vhost devices for > - > corresponding virtio devices in the guest. Vhost supported vSwitch could > register -callbacks to this library, which will be called when a vhost device > is > activated -or deactivated by guest virtual machine. > +The vhost library implements a user space vhost driver. It supports > +both vhost-cuse > +(cuse: user space character device) and vhost-user(user space socket > server). > +It also creates, manages and destroys vhost devices for corresponding > +virtio devices in the guest. Vhost supported vSwitch could register > +callbacks to this library, which will be called when a vhost device is > +activated or deactivated by guest virtual machine. > > Vhost API Overview > ------------------ > > * Vhost driver registration > > - rte_vhost_driver_register registers the vhost cuse driver into the > system. > - Character device file will be created in the /dev directory. > + rte_vhost_driver_register registers the vhost driver into the system. > + For vhost-cuse, character device file will be created under the /dev > directory. > Character device name is specified as the parameter. > + For vhost-user, a unix domain socket server will be created with the > parameter as > + the local socket path. > > * Vhost session start > > rte_vhost_driver_session_start starts the vhost session loop. > - Vhost cuse session is an infinite blocking loop. > + Vhost session is an infinite blocking loop. > Put the session in a dedicate DPDK thread. > > * Callback register > @@ -73,6 +76,8 @@ Vhost API Overview > Vhost Implementation > -------------------- > > +Vhost cuse implementation > +~~~~~~~~~~~~~~~~~~~~~~~~~ > When vSwitch registers the vhost driver, it will register a cuse device > driver > into the system and creates a character device file. This cuse driver will > receive vhost open/release/IOCTL message from QEMU simulator. > @@ -89,13 +94,40 @@ which means vhost could access the shared virtio ring > and the guest physical address specified in the entry of the ring. > > The guest virtual machine tells the vhost whether the virtio device is ready > - > for processing or is de-activated through VHOST_SET_BACKEND message. > +for processing or is de-activated through VHOST_NET_SET_BACKEND > message. > The registered callback from vSwitch will be called. > > When the release call is released, vhost will destroy the device. > > +Vhost user implementation > +~~~~~~~~~~~~~~~~~~~~~~~~~ > +When vSwitch registers a vhost driver, it will create a unix domain > +socket server into the system. This server will listen for a connection > +and process the vhost message from QEMU simulator. > + > +When there is a new socket connection, it means a new virtio device has > +been created in the guest virtual machine, and the vhost driver will create a > vhost device for this virtio device. > + > +For messages with a file descriptor, the file descriptor could be > +directly used in the vhost process as it is already installed by unix domain > socket. > + * VHOST_SET_MEM_TABLE > + * VHOST_SET_VRING_KICK > + * VHOST_SET_VRING_CALL > + * VHOST_SET_LOG_FD > + * VHOST_SET_VRING_ERR > + > +For VHOST_SET_MEM_TABLE message, QEMU will send us information for > each > +memory region and its file descriptor in the ancillary data of the message. > The fd is used to map that region. > + > +There is no VHOST_NET_SET_BACKEND message as in vhost cuse to signal > us > +whether virtio device is ready or should be stopped. > +VHOST_SET_VRING_KICK is used as the signal to put the vhost device onto > data plane. > +VHOST_GET_VRING_BASE is used as the signal to remove vhost device > from data plane. > + > +When the socket connection is closed, vhost will destroy the device. > + > Vhost supported vSwitch reference > --------------------------------- > > -For how to support vhost in vSwitch, please refer to vhost example in the > +For more vhost details and how to support vhost in vSwitch, please > +refer to vhost example in the > DPDK Sample Applications Guide. > -- > 1.8.1.4
Acked-by Siobhan Butler <siobhan.a.butler at intel.com>
