Subject: Re: [PATCH V10 0/6] mdev based hardware virtio offloading support

From: "Michael S. Tsirkin" <[email-masked]>
Date: Thu, 7 Nov 2019 04:09:35 -0500

On Wed, Nov 06, 2019 at 09:35:25PM +0800, Jason Wang wrote:
> Hi all:
> 
> There are hardwares 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.
> 
> Though the series only contains 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.
> 
> Also a real IFC VF driver was also posted here[2] which is a good
> reference for vendors who is interested in their own virtio datapath
> offloading product.
> 
> 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 ops out of the common ones for implementing class
> specific operations over mdev bus.
> 
> Pktgen test was done with virito-net + mvnet loop back device.

Patches 1-5:

Acked-by: Michael S. Tsirkin <[email-masked]>

Patch 6: I'd like the module to be renamed to make it more
obvious what it does. With that:

Acked-by: Michael S. Tsirkin <[email-masked]>

> Please review.
> 
> [1] https://lkml.org/lkml/2019/11/5/424
> [2] https://lkml.org/lkml/2019/11/5/227
> 
> Changes from V9:
> - Tweak the help text for virito-mdev kconfig
> 
> Changes from V8:
> - try silent checkpatch, some are still there becuase they were inherited
>   from virtio_config_ops which needs to be resolved in an independent series
> - tweak on the comment and doc
> - remove VIRTIO_MDEV_F_VERSION_1 completely
> - rename CONFIG_VIRTIO_MDEV_DEVICE to CONFIG_VIRTIO_MDEV
> 
> Changes from V7:
> - drop {set|get}_mdev_features for virtio
> - typo and comment style fixes
> 
> Changes from V6:
> - rename ops files and compile guard
> 
> Changes from V5:
> - use dev_warn() instead of WARN(1) when class id is not set
> - validate id_table before trying to do matching between device and
>   driver
> - add wildcard for modpost script
> - use unique name for id_table
> - move get_mdev_features() to be the first member of virtio_device_ops
>   and more comments for it
> - typo fixes for the comments above virtio_mdev_ops
> 
> Changes from V4:
> - keep mdev_set_class() for the device that doesn't use device ops
> - use union for device ops pointer in mdev_device
> - introduce class specific helper for getting is device ops
> - use WARN_ON instead of BUG_ON in mdev_set_virtio_ops
> - explain details of get_mdev_features() and get_vendor_id()
> - distinguish the optional virito device ops from mandatory ones and
>   make get_generation() optional
> - rename vfio_mdev.h to vfio_mdev_ops.h, rename virito_mdev.h to
>   virtio_mdev_ops.h
> - don't abuse version fileds in virtio_mdev structure, use features
>   instead
> - fix warning during device remove
> - style & docs tweaks and typo fixes
> 
> Changes from V3:
> - document that class id (device ops) must be specified in create()
> - add WARN() when trying to set class_id when it has already set
> - add WARN() when class_id is not specified in create() and correctly
>   return an error in this case
> - correct the prototype of mdev_set_class() in the doc
> - add documention of mdev_set_class()
> - remove the unnecessary "class_id_fail" label when class id is not
>   specified in create()
> - convert id_table in vfio_mdev to const
> - move mdev_set_class and its friends after mdev_uuid()
> - suqash the patch of bus uevent into patch of introducing class id
> - tweak the words in the docs per Cornelia suggestion
> - tie class_id and device ops through class specific initialization
>   routine like mdev_set_vfio_ops()
> - typos fixes in the docs of virtio-mdev callbacks
> - document the usage of virtqueues in struct virtio_mdev_device
> - remove the useless vqs array in struct virtio_mdev_device
> - rename MDEV_ID_XXX to MDEV_CLASS_ID_XXX
> 
> Changes from V2:
> - fail when class_id is not specified
> - drop the vringh patch
> - match the doc to the code
> - tweak the commit log
> - move device_ops from parent to mdev device
> - remove the unused MDEV_ID_VHOST
> 
> Changes from V1:
> - move virtio_mdev.c to drivers/virtio
> - store class_id in mdev_device instead of mdev_parent
> - store device_ops in mdev_device instead of mdev_parent
> - reorder the patch, vringh fix comes first
> - really silent compiling warnings
> - really switch to use u16 for class_id
> - uevent and modpost support for mdev class_id
> - vraious tweaks per comments from Parav
> 
> Changes from RFC-V2:
> - silent compile warnings on some specific configuration
> - use u16 instead u8 for class id
> - reseve MDEV_ID_VHOST for future vhost-mdev work
> - introduce "virtio" type for mvnet and make "vhost" type for future
>   work
> - add entries in MAINTAINER
> - tweak and typos fixes in commit log
> 
> Changes from RFC-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
>   modpost: add support for mdev class id
>   mdev: introduce device specific ops
>   mdev: introduce virtio device and its device ops
>   virtio: introduce a mdev based transport
>   docs: sample driver to demonstrate how to implement virtio-mdev
>     framework
> 
>  .../driver-api/vfio-mediated-device.rst       |  38 +-
>  MAINTAINERS                                   |   3 +
>  drivers/gpu/drm/i915/gvt/kvmgt.c              |  17 +-
>  drivers/s390/cio/vfio_ccw_ops.c               |  17 +-
>  drivers/s390/crypto/vfio_ap_ops.c             |  13 +-
>  drivers/vfio/mdev/mdev_core.c                 |  60 ++
>  drivers/vfio/mdev/mdev_driver.c               |  25 +
>  drivers/vfio/mdev/mdev_private.h              |   8 +
>  drivers/vfio/mdev/vfio_mdev.c                 |  45 +-
>  drivers/virtio/Kconfig                        |  13 +
>  drivers/virtio/Makefile                       |   1 +
>  drivers/virtio/virtio_mdev.c                  | 406 +++++++++++
>  include/linux/mdev.h                          |  57 +-
>  include/linux/mdev_vfio_ops.h                 |  52 ++
>  include/linux/mdev_virtio_ops.h               | 147 ++++
>  include/linux/mod_devicetable.h               |   8 +
>  samples/Kconfig                               |  10 +
>  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                     | 686 ++++++++++++++++++
>  scripts/mod/devicetable-offsets.c             |   3 +
>  scripts/mod/file2alias.c                      |  11 +
>  24 files changed, 1585 insertions(+), 91 deletions(-)
>  create mode 100644 drivers/virtio/virtio_mdev.c
>  create mode 100644 include/linux/mdev_vfio_ops.h
>  create mode 100644 include/linux/mdev_virtio_ops.h
>  create mode 100644 samples/vfio-mdev/mvnet.c
> 
> -- 
> 2.19.1