Re: [PATCH V3 1/7] mdev: class id support

Cornelia Huck
2019-10-15T10:26:07Z

On Fri, 11 Oct 2019 16:15:51 +0800
Jason Wang <jasowang@redhat.com> wrote:

> Mdev bus only supports vfio driver right now, so it doesn't implement
> match method. But in the future, we may add drivers other than vfio,
> the first driver could be virtio-mdev. This means we need to add
> device class id support in bus match method to pair the mdev device
> and mdev driver correctly.
>
> So this patch adds id_table to mdev_driver and class_id for mdev
> device with the match method for mdev bus.
>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
> Documentation/driver-api/vfio-mediated-device.rst | 7 ++++++-
> drivers/gpu/drm/i915/gvt/kvmgt.c | 1 +
> drivers/s390/cio/vfio_ccw_ops.c | 1 +
> drivers/s390/crypto/vfio_ap_ops.c | 1 +
> drivers/vfio/mdev/mdev_core.c | 11 +++++++++++
> drivers/vfio/mdev/mdev_driver.c | 14 ++++++++++++++
> drivers/vfio/mdev/mdev_private.h | 1 +
> drivers/vfio/mdev/vfio_mdev.c | 6 ++++++
> include/linux/mdev.h | 8 ++++++++
> include/linux/mod_devicetable.h | 8 ++++++++
> samples/vfio-mdev/mbochs.c | 1 +
> samples/vfio-mdev/mdpy.c | 1 +
> samples/vfio-mdev/mtty.c | 1 +
> 13 files changed, 60 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/driver-api/vfio-mediated-device.rst b/Documentation/driver-api/vfio-mediated-device.rst
> index 25eb7d5b834b..2035e48da7b2 100644
> --- a/Documentation/driver-api/vfio-mediated-device.rst
> +++ b/Documentation/driver-api/vfio-mediated-device.rst
> @@ -102,12 +102,14 @@ structure to represent a mediated device's driver::
> * @probe: called when new device created
> * @remove: called when device removed
> * @driver: device driver structure
> + * @id_table: the ids serviced by this driver
> */
> struct mdev_driver {
> const char *name;
> int (*probe) (struct device *dev);
> void (*remove) (struct device *dev);
> struct device_driver driver;
> + const struct mdev_class_id *id_table;
> };
>
> A mediated bus driver for mdev should use this structure in the function calls
> @@ -165,12 +167,15 @@ register itself with the mdev core driver::
> extern int mdev_register_device(struct device *dev,
> const struct mdev_parent_ops *ops);
>
> +It is also required to specify the class_id through::
> +
> + extern int mdev_set_class(struct device *dev, u16 id);

Should the document state explicitly that this should be done in the
->create() callback? Also, I think that the class_id might be different
for different mdevs (even if the parent is the same) -- should that be
mentioned explicitly?

> +
> However, the mdev_parent_ops structure is not required in the function call
> that a driver should use to unregister itself with the mdev core driver::
>
> extern void mdev_unregister_device(struct device *dev);
>
> -
> Mediated Device Management Interface Through sysfs
> ==================================================
>
(...)

Looks reasonable to me.