[PATCH v2 0/3] vhost: add device op to offload the interrupt kick

[Eelco Chaudron <echaudro@redhat.com>]

This series adds an operation callback which gets called every time the
library wants to call eventfd_write(). This eventfd_write() call could
result in a system call, which could potentially block the PMD thread.

The callback function can decide whether it's ok to handle the
eventfd_write() now or have the newly introduced function,
rte_vhost_notify_guest(), called at a later time.

This can be used by 3rd party applications, like OVS, to avoid system
calls being called as part of the PMD threads.

v2: - Used vhost_virtqueue->index to find index for operation.
    - Aligned function name to VDUSE RFC patchset.
    - Added error and offload statistics counter.
    - Mark new API as experimental.
    - Change the virtual queue spin lock to read/write spin lock.
    - Made shared counters atomic.
    - Add versioned rte_vhost_driver_callback_register() for
      ABI compliance.

Eelco Chaudron (3):
      vhost: Change vhost_virtqueue access lock to a read/write one.
      vhost: make the guest_notifications statistic counter atomic.
      vhost: add device op to offload the interrupt kick


 lib/eal/include/generic/rte_rwlock.h | 17 +++++
 lib/vhost/meson.build                |  2 +
 lib/vhost/rte_vhost.h                | 23 ++++++-
 lib/vhost/socket.c                   | 72 ++++++++++++++++++++--
 lib/vhost/version.map                |  9 +++
 lib/vhost/vhost.c                    | 92 +++++++++++++++++++++-------
 lib/vhost/vhost.h                    | 70 ++++++++++++++-------
 lib/vhost/vhost_user.c               | 14 ++---
 lib/vhost/virtio_net.c               | 90 +++++++++++++--------------
 9 files changed, 288 insertions(+), 101 deletions(-)