Re: [RFC PATCH V2 0/6] mdev based hardware virtio offloading support

[Michael S. Tsirkin]

On Fri, Sep 20, 2019 at 04:20:44PM +0800, Jason Wang wrote:
> Hi all:
> 
> There are hardware that can do virtio datapath offloading while having
> its own control path. This path tries to implement a mdev based
> unified API to support using kernel virtio driver to drive those
> devices. This is done by introducing a new mdev transport for virtio
> (virtio_mdev) and register itself as a new kind of mdev driver. Then
> it provides a unified way for kernel virtio driver to talk with mdev
> device implementation.

This is actually simple enough that I'm inclined to just
put this into linux-next.
This mixes virtio and vfio so the code can thinkably
be merged through either tree.
Alex, any strong opinions on any of this?

> Though the series only contain kernel driver support, the goal is to
> make the transport generic enough to support userspace drivers. This
> means vhost-mdev[1] could be built on top as well by resuing the
> transport.
> 
> A sample driver is also implemented which simulate a virito-net
> loopback ethernet device on top of vringh + workqueue. This could be
> used as a reference implementation for real hardware driver.
> 
> Consider mdev framework only support VFIO device and driver right now,
> this series also extend it to support other types. This is done
> through introducing class id to the device and pairing it with
> id_talbe claimed by the driver. On top, this seris also decouple
> device specific parents ops out of the common ones.
> 
> Pktgen test was done with virito-net + mvnet loop back device.
> 
> Please review.
> 
> Changes from V1:
> 
> - rename device id to class id
> - add docs for class id and device specific ops (device_ops)
> - split device_ops into seperate headers
> - drop the mdev_set_dma_ops()
> - use device_ops to implement the transport API, then it's not a part
>   of UAPI any more
> - use GFP_ATOMIC in mvnet sample device and other tweaks
> - set_vring_base/get_vring_base support for mvnet device
> 
> Jason Wang (6):
>   mdev: class id support
>   mdev: introduce device specific ops
>   mdev: introduce virtio device and its device ops
>   virtio: introudce a mdev based transport
>   vringh: fix copy direction of vringh_iov_push_kern()
>   docs: Sample driver to demonstrate how to implement virtio-mdev
>     framework
> 
>  .../driver-api/vfio-mediated-device.rst       |  11 +-
>  drivers/gpu/drm/i915/gvt/kvmgt.c              |  17 +-
>  drivers/s390/cio/vfio_ccw_ops.c               |  17 +-
>  drivers/s390/crypto/vfio_ap_ops.c             |  14 +-
>  drivers/vfio/mdev/Kconfig                     |   7 +
>  drivers/vfio/mdev/Makefile                    |   1 +
>  drivers/vfio/mdev/mdev_core.c                 |  21 +-
>  drivers/vfio/mdev/mdev_driver.c               |  14 +
>  drivers/vfio/mdev/mdev_private.h              |   1 +
>  drivers/vfio/mdev/vfio_mdev.c                 |  37 +-
>  drivers/vfio/mdev/virtio_mdev.c               | 418 +++++++++++
>  drivers/vhost/vringh.c                        |   8 +-
>  include/linux/mdev.h                          |  46 +-
>  include/linux/mod_devicetable.h               |   8 +
>  include/linux/vfio_mdev.h                     |  50 ++
>  include/linux/virtio_mdev.h                   | 141 ++++
>  samples/Kconfig                               |   7 +
>  samples/vfio-mdev/Makefile                    |   1 +
>  samples/vfio-mdev/mbochs.c                    |  19 +-
>  samples/vfio-mdev/mdpy.c                      |  19 +-
>  samples/vfio-mdev/mtty.c                      |  17 +-
>  samples/vfio-mdev/mvnet.c                     | 688 ++++++++++++++++++
>  22 files changed, 1473 insertions(+), 89 deletions(-)
>  create mode 100644 drivers/vfio/mdev/virtio_mdev.c
>  create mode 100644 include/linux/vfio_mdev.h
>  create mode 100644 include/linux/virtio_mdev.h
>  create mode 100644 samples/vfio-mdev/mvnet.c
> 
> -- 
> 2.19.1