Re: [patch net-next v2 1/6] virtio: add debugfs infrastructure to allow to debug virtio features

[Jiri Pirko <jiri@resnulli.us>]

Tue, Apr 16, 2024 at 05:52:41AM CEST, jasowang@redhat.com wrote:
>On Tue, Apr 16, 2024 at 12:25 AM Jiri Pirko <jiri@resnulli.us> wrote:
>>
>> From: Jiri Pirko <jiri@nvidia.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" know already exists, this patch does not
>> touch it.
>>
>> Signed-off-by: Jiri Pirko <jiri@nvidia.com>
>> ---
>
>Note that this can be done already with vp_vdpa feature provisioning:
>
>commit c1ca352d371f724f7fb40f016abdb563aa85fe55
>Author: Jason Wang <jasowang@redhat.com>
>Date:   Tue Sep 27 15:48:10 2022 +0800
>
>    vp_vdpa: support feature provisioning
>
>For example:
>
>vdpa dev add name dev1 mgmtdev pci/0000:02:00.0 device_features 0x300020000

Sure. My intension was to make the testing possible on any virtio
device. Narrowing the testing for vpda would be limitting.


>
>Thanks
>