[Qemu-devel] [PATCH v3 00/13] virtio: cleanup ioeventfd start/stop

[Paolo Bonzini <pbonzini@redhat.com>]

This series started as an attempt to always use the dataplane path
for virtio-blk and virtio-scsi when ioeventfd is active.  The aim
was three-fold:

1) to add more coverage for dataplane

2) to remove virtio_add_queue_aio

3) to simplify the dataplane start/stop code

It achieves the first two objectives, and while it doesn't quite
achieve the third it does cleanup the generic ioeventfd code in
virtio-bus more than I expected.  In particular, it reduces the set
of callbacks that transports must implement, and it removes the ugly
case where ioeventfd is started with generic callbacks and then moved
to the dataplane callbacks.  It also enables some simplification of the
functions that deal with host notifiers, and detects some configuration
errors better.

I've tested it with virtio-blk, virtio-scsi and vhost-net.

Patch 1 is a bugfix that I found while testing the TCG+dataplane combo.

Patches 2 and 3 are simplifications that are too nice to leave
them for later in the series.

Patch 4 moves some of the ioeventfd code from virtio-bus.c to
virtio.c.  At this point the transition is a bit half-assed, but
this changes as soon as we remove the generic->dataplane
handler transition.

Patches 5 to 7 do exactly that, and then the spring cleaning
begins, lasting for the whole second half of the series.

Thanks,

Paolo

        v2->v3: fix patch 4 to avoid virtio-mmio failures [Cornelia]
                fix patch 5 NULL-check-after-dereference [Cornelia]
                fix "before after" in comment [Cornelia]

Paolo Bonzini (13):
  virtio: disable ioeventfd as early as possible
  virtio: move ioeventfd_disabled flag to VirtioBusState
  virtio: move ioeventfd_started flag to VirtioBusState
  virtio: add start_ioeventfd and stop_ioeventfd to VirtioDeviceClass
  virtio: introduce virtio_device_ioeventfd_enabled
  virtio-blk: always use dataplane path if ioeventfd is active
  virtio-scsi: always use dataplane path if ioeventfd is active
  Revert "virtio: Introduce virtio_add_queue_aio"
  virtio: remove set_handler argument from set_host_notifier_internal
  virtio: remove ioeventfd_disabled altogether
  virtio: use virtio_bus_set_host_notifier to start/stop ioeventfd
  virtio: inline virtio_queue_set_host_notifier_fd_handler
  virtio: inline set_host_notifier_internal

 hw/block/dataplane/virtio-blk.c |  73 +++++++++++--------
 hw/block/dataplane/virtio-blk.h |   6 +-
 hw/block/virtio-blk.c           |  15 ++--
 hw/s390x/virtio-ccw.c           |  44 ++----------
 hw/s390x/virtio-ccw.h           |   2 -
 hw/scsi/virtio-scsi-dataplane.c |  56 +++++++++------
 hw/scsi/virtio-scsi.c           |  24 +++----
 hw/virtio/vhost.c               |   5 +-
 hw/virtio/virtio-bus.c          | 154 ++++++++++++++++------------------------
 hw/virtio/virtio-mmio.c         |  35 +--------
 hw/virtio/virtio-pci.c          |  40 ++---------
 hw/virtio/virtio-pci.h          |   2 -
 hw/virtio/virtio.c              | 139 +++++++++++++++++++++++-------------
 include/hw/virtio/virtio-bus.h  |  27 ++++---
 include/hw/virtio/virtio-scsi.h |   6 +-
 include/hw/virtio/virtio.h      |  11 +--
 16 files changed, 292 insertions(+), 347 deletions(-)

-- 
1.8.3.1