From: Cornelia Huck <cohuck@redhat.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>,
kvm@vger.kernel.org, linux-s390@vger.kernel.org,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
intel-gfx@lists.freedesktop.org,
intel-gvt-dev@lists.freedesktop.org, kwankhede@nvidia.com,
mst@redhat.com, tiwei.bie@intel.com,
virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, maxime.coquelin@redhat.com,
cunming.liang@intel.com, zhihong.wang@intel.com,
rob.miller@broadcom.com, xiao.w.wang@intel.com,
haotian.wang@sifive.com, zhenyuw@linux.intel.com,
zhi.a.wang@intel.com, jani.nikula@linux.intel.com,
joonas.lahtinen@linux.intel.com, rodrigo.vivi@intel.com,
airlied@linux.ie, daniel@ffwll.ch, farman@linux.ibm.com,
pasic@linux.ibm.com, sebott@linux.ibm.com, oberpar@linux.ibm.com,
heiko.carstens@de.ibm.com, gor@linux.ibm.com,
borntraeger@de.ibm.com, akrowiak@linux.ibm.com,
freude@linux.ibm.com, lingshan.zhu@intel.com, idos@mellanox.com,
eperezma@redhat.com, lulu@redhat.com, parav@mellanox.com,
christophe.de.dinechin@gmail.com, kevin.tian@intel.com,
stefanha@redhat.com
Subject: Re: [PATCH V8 3/6] mdev: introduce device specific ops
Date: Tue, 5 Nov 2019 19:28:51 +0100 [thread overview]
Message-ID: <20191105192851.40548978.cohuck@redhat.com> (raw)
In-Reply-To: <20191105104418.1735d800@x1.home>
On Tue, 5 Nov 2019 10:44:18 -0700
Alex Williamson <alex.williamson@redhat.com> wrote:
> On Tue, 5 Nov 2019 17:50:25 +0100
> Cornelia Huck <cohuck@redhat.com> wrote:
>
> > On Tue, 5 Nov 2019 17:32:37 +0800
> > Jason Wang <jasowang@redhat.com> wrote:
> >
> > > Currently, except for the create and remove, the rest of
> > > mdev_parent_ops is designed for vfio-mdev driver only and may not help
> > > for kernel mdev driver. With the help of class id, this patch
> > > introduces device specific callbacks inside mdev_device
> > > structure. This allows different set of callback to be used by
> > > vfio-mdev and virtio-mdev.
> > >
> > > Reviewed-by: Parav Pandit <parav@mellanox.com>
> > > Signed-off-by: Jason Wang <jasowang@redhat.com>
> > > ---
> > > .../driver-api/vfio-mediated-device.rst | 35 +++++++++----
> > > MAINTAINERS | 1 +
> > > drivers/gpu/drm/i915/gvt/kvmgt.c | 18 ++++---
> > > drivers/s390/cio/vfio_ccw_ops.c | 18 ++++---
> > > drivers/s390/crypto/vfio_ap_ops.c | 14 +++--
> > > drivers/vfio/mdev/mdev_core.c | 24 ++++++++-
> > > drivers/vfio/mdev/mdev_private.h | 5 ++
> > > drivers/vfio/mdev/vfio_mdev.c | 37 ++++++-------
> > > include/linux/mdev.h | 43 ++++-----------
> > > include/linux/mdev_vfio_ops.h | 52 +++++++++++++++++++
> > > samples/vfio-mdev/mbochs.c | 20 ++++---
> > > samples/vfio-mdev/mdpy.c | 20 ++++---
> > > samples/vfio-mdev/mtty.c | 18 ++++---
> > > 13 files changed, 206 insertions(+), 99 deletions(-)
> > > create mode 100644 include/linux/mdev_vfio_ops.h
> > >
> >
> > (...)
> >
> > > @@ -172,10 +163,34 @@ that a driver should use to unregister itself with the mdev core driver::
> > >
> > > extern void mdev_unregister_device(struct device *dev);
> > >
> > > -It is also required to specify the class_id in create() callback through::
> > > +As multiple types of mediated devices may be supported, class id needs
> > > +to be specified in the create callback(). This could be done
> >
> > The brackets should probably go behind 'create'?
> >
> > > +explicitly for the device that does not use on mdev bus for its
> >
> > "for devices that do not use the mdev bus" ?
> >
> > But why wouldn't they? I feel like I've missed some discussion here :/
>
> The device ops provide a route through mdev-core for known callbacks,
> which is primarily useful when we have 1:N relation between mdev bus
> driver and vendor drivers. The obvious example here is vfio-mdev,
> where we have GVT-g, vfio-ap, vfio-ccw, NVIDIA GRID, and various sample
> drivers all advertising vfio-mdev support via their class id. However,
> if we have a tightly coupled vendor driver and mdev bus driver, as the
> mlx5 support that Parav is developing, the claim is that they prefer
> not to expose any device ops and intend to interact directly with the
> mdev device. At least that's my understanding. Thanks,
>
> Alex
Ah, ok.
So maybe use the phrasing "devices that interact with the mdev device
directly" vs "devices that use device-specific ops" instead?
Not a strong critique, though.
>
> > > +operation through:
> > >
> > > int mdev_set_class(struct mdev_device *mdev, u16 id);
> > >
> > > +For the device that uses on the mdev bus for its operation, the
> > > class
> >
> > "For devices that use the mdev bus..."
> >
> > But same comment as above.
> >
> > > +should provide helper function to set class id and device
> > > specific +ops. E.g for vfio-mdev devices, the function to be
> > > called is:: +
> > > + int mdev_set_vfio_ops(struct mdev_device *mdev,
> > > + const struct mdev_vfio_device_ops
> > > *vfio_ops); +
> > > +The class id (set by this function to MDEV_CLASS_ID_VFIO) is
> > > used to +match a device with an mdev driver via its id table. The
> > > device +specific callbacks (specified in *vfio_ops) are
> > > obtainable via +mdev_get_vfio_ops() (for use by the mdev bus
> > > driver). A vfio-mdev +device (class id MDEV_CLASS_ID_VFIO) uses
> > > the following +device-specific ops:
> > > +
> > > +* open: open callback of vfio mediated device
> > > +* close: close callback of vfio mediated device
> > > +* ioctl: ioctl callback of vfio mediated device
> > > +* read : read emulation callback
> > > +* write: write emulation callback
> > > +* mmap: mmap emulation callback
> > > +
> > > Mediated Device Management Interface Through sysfs
> > > ==================================================
> >
> > Otherwise, looks good.
>
next prev parent reply other threads:[~2019-11-05 18:29 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-05 9:32 [PATCH V8 0/6] mdev based hardware virtio offloading support Jason Wang
2019-11-05 9:32 ` [PATCH V8 1/6] mdev: class id support Jason Wang
2019-11-05 16:03 ` Cornelia Huck
2019-11-05 9:32 ` [PATCH V8 2/6] modpost: add support for mdev class id Jason Wang
2019-11-05 16:06 ` Cornelia Huck
2019-11-05 9:32 ` [PATCH V8 3/6] mdev: introduce device specific ops Jason Wang
2019-11-05 16:50 ` Cornelia Huck
2019-11-05 17:44 ` Alex Williamson
2019-11-05 18:28 ` Cornelia Huck [this message]
2019-11-06 3:48 ` Jason Wang
2019-11-05 9:32 ` [PATCH V8 4/6] mdev: introduce virtio device and its device ops Jason Wang
2019-11-05 16:57 ` Cornelia Huck
2019-11-05 17:47 ` Alex Williamson
2019-11-06 3:51 ` Jason Wang
2019-11-05 9:32 ` [PATCH V8 5/6] virtio: introduce a mdev based transport Jason Wang
2019-11-05 18:33 ` Cornelia Huck
2019-11-05 9:32 ` [PATCH V8 6/6] docs: sample driver to demonstrate how to implement virtio-mdev framework Jason Wang
2019-11-05 18:35 ` Cornelia Huck
2019-11-05 17:58 ` [PATCH V8 0/6] mdev based hardware virtio offloading support Alex Williamson
2019-11-06 3:56 ` Jason Wang
2019-11-06 19:03 ` Alex Williamson
2019-11-06 19:25 ` Michael S. Tsirkin
2019-11-06 21:13 ` Alex Williamson
2019-11-07 4:11 ` Jason Wang
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