This patch set introduces support for selective datapath in DPDK vhost-user
lib. vDPA stands for vhost Data Path Acceleration. The idea is to enable
various types of virtio-compatible devices to do data transfer with virtio
driver directly to enable acceleration.

The default datapath is the existing software implementation, more options
will be available when new engines are added.

Design details

An engine is a group of virtio-compatible devices. The definition of engine
is as follows:

struct rte_vdpa_eng_addr {
        union {
                uint8_t __dummy[64];

                struct {
                        struct rte_pci_addr pci_addr;

struct rte_vdpa_eng_info {
        char name[MAX_VDPA_NAME_LEN];
        struct rte_vdpa_eng_addr *addr;

struct rte_vdpa_dev_ops {
        vdpa_dev_conf_t        dev_conf;
        vdpa_dev_close_t       dev_close;
        vdpa_vring_state_set_t vring_state_set;
        vdpa_feature_set_t     feature_set;
        vdpa_migration_done_t  migration_done;

struct rte_vdpa_eng_ops {
        vdpa_eng_init_t   eng_init;
        vdpa_eng_uninit_t eng_uninit;
        vdpa_info_query_t info_query;

struct rte_vdpa_eng_driver {
        const char *name;
        struct rte_vdpa_eng_ops eng_ops;
        struct rte_vdpa_dev_ops dev_ops;
} __rte_cache_aligned;

struct rte_vdpa_engine {
        struct rte_vdpa_eng_info    eng_info;
        struct rte_vdpa_eng_driver *eng_drv;
} __rte_cache_aligned;

A set of engine ops is defined in rte_vdpa_eng_ops for engine init, uninit,
and attributes reporting. The attributes are defined as follows:

struct rte_vdpa_eng_attr {
        uint64_t features;
        uint64_t protocol_features;
        uint32_t queue_num;
        uint32_t dev_num;

A set of device ops is defined in rte_vdpa_dev_ops for each virtio device
in the engine to do device specific operations.

Changes to the current vhost-user lib are:

 1. Make vhost device capabilities configurable to adopt various engines.
    Such capabilities include supported features, protocol features, queue
    number. APIs are introduced to let app configure these capabilities.

 2. In addition to the existing vhost framework, a set of callbacks is
    added for vhost to call the driver for device operations at the right

     a. dev_conf: Called to configure the actual device when the virtio
        device becomes ready.

     b. dev_close: Called to close the actual device when the virtio device
        is stopped.

     c. vring_state_set: Called to change the state of the vring in the
        actual device when vring state changes.

     d. feature_set: Called to set the negotiated features to device.

     e. migration_done: Called to allow the device to response to RARP

 3. To make vhost aware of its own type, an engine id (eid) and a device
    id (did) are added into the vhost data structure to identify the actual
    device. APIs are introduced to let app configure them. When the default
    software datapath is used, eid and did are set to -1. When alternative
    datapath is used, eid and did are set by app to specify which device to
    use. Each vhost-user socket can have only 1 connection in this case.

Working process:

 1. Register driver during DPDK initialization.

 2. Register engine with driver name and address.

 3. Get engine attributes.

 4. For vhost device creation:

      a. Register vhost-user socket.

      b. Set eid and did of the vhost-user socket.

      c. Set attributes of the vhost-user socket.

      d. Register vhost-user callbacks.

      e. Start to wait for connection.

 4. When connection comes and virtio device data structure is negotiated,
    configure the device with all needed info.

Zhihong Wang (7):
  vhost: make capabilities configurable
  vhost: expose vhost feature definitions
  vhost: support selective datapath
  vhost: add apis for datapath configuration
  vhost: adapt vhost lib for selective datapath
  vhost: get callfd before device setup
  vhost: expose new apis

 lib/librte_vhost/Makefile              |   4 +-
 lib/librte_vhost/rte_vdpa.h            | 119 +++++++++++++++++++++++++++
 lib/librte_vhost/rte_vhost.h           | 136 +++++++++++++++++++++++++++++++
 lib/librte_vhost/ |  18 ++++
 lib/librte_vhost/socket.c              | 145 +++++++++++++++++++++++++++++++++
 lib/librte_vhost/vdpa.c                | 125 ++++++++++++++++++++++++++++
 lib/librte_vhost/vhost.c               |  49 +++++++++++
 lib/librte_vhost/vhost.h               |  14 +++-
 lib/librte_vhost/vhost_user.c          | 108 +++++++++++++++++++-----
 lib/librte_vhost/vhost_user.h          |  20 ++---
 10 files changed, 700 insertions(+), 38 deletions(-)
 create mode 100644 lib/librte_vhost/rte_vdpa.h
 create mode 100644 lib/librte_vhost/vdpa.c


Reply via email to