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

[Jiri Pirko <jiri@resnulli.us>]

Thu, Apr 18, 2024 at 02:59:41AM CEST, jasowang@redhat.com wrote:
>On Wed, Apr 17, 2024 at 3:23 PM Jiri Pirko <jiri@resnulli.us> wrote:
>>
>> Wed, Apr 17, 2024 at 06:37:30AM CEST, jasowang@redhat.com wrote:
>> >On Tue, Apr 16, 2024 at 5:37 PM Jiri Pirko <jiri@resnulli.us> wrote:
>> >>
>> >> 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.
>> >
>> >It did that actually, vp_vdpa bridge virtio-pci device into vDPA bus
>> >with mediation layer (like feature filtering etc). So it can only run
>> >on top of standard virtio-pci device.
>> >
>> >> Narrowing the testing for vpda would be limitting.
>> >
>> >Unless you want to use other transport like virtio-mmio.
>>
>> Also, the goal is to test virtio_net emulated devices.
>> There are couple
>> of implementation. Non-vdpa.
>
>So what I want to say is, vp_vdpa works for all types of virtio-pci
>devices no matter if it is emulated or hardware.

Sure, but I wanted to have a simple generic way, working on all virtio
devices, even the ones backed by a different transport, and without need
of extra vdpa layer.


>
>Thanks
>
>>
>>
>> >
>> >Thanks
>> >
>> >>
>> >>
>> >> >
>> >> >Thanks
>> >> >
>> >>
>> >
>>
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