The virtio specifications allows for up to 128 bits for the
device features. Soon we are going to use some of the 'extended'
bits features (above 64) for the virtio_net driver.
Introduce extended features as a fixed size array of u64. To minimize
the diffstat allows legacy driver to access the low 64 bits via a
transparent union.
Introduce an extended get_extended_features configuration callback
that devices supporting the extended features range must implement in
place of the traditional one.
Note that legacy and transport features don't need any change, as
they are always in the low 64 bit range.
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Currently there is no way for user to set what features the driver
should obey or not, it is hard wired in the code.
In order to be able to debug the device behavior in case some feature is
disabled, introduce a debugfs infrastructure with couple of files
allowing user to see what features the device advertises and
to set filter for features used by driver.
Example:
$cat /sys/bus/virtio/devices/virtio0/features
1110010111111111111101010000110010000000100000000000000000000000
$ echo "5" >/sys/kernel/debug/virtio/virtio0/filter_feature_add
$ cat /sys/kernel/debug/virtio/virtio0/filter_features
5
$ echo "virtio0" > /sys/bus/virtio/drivers/virtio_net/unbind
$ echo "virtio0" > /sys/bus/virtio/drivers/virtio_net/bind
$ cat /sys/bus/virtio/devices/virtio0/features
1110000111111111111101010000110010000000100000000000000000000000
Note that sysfs "features" now already exists, this patch does not
touch it.
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
