On Tue, Sep 10, 2024 at 07:34:40AM -0400, Jason J. Herne wrote: > Advertise features of the driver for the benefit of automated tooling > like Libvirt and mdevctl. > > Signed-off-by: Jason J. Herne <jjherne@xxxxxxxxxxxxx> > Reviewed-by: Anthony Krowiak <akrowiak@xxxxxxxxxxxxx> > Reviewed-by: Boris Fiuczynski <fiuczy@xxxxxxxxxxxxx> > --- > Documentation/arch/s390/vfio-ap.rst | 34 +++++++++++++++++++++++++++++ > drivers/s390/crypto/vfio_ap_drv.c | 13 +++++++++++ > 2 files changed, 47 insertions(+) ... > +Driver Features > +=============== > +The vfio_ap driver exposes a sysfs file containing supported features. > +This exists so third party tools (like Libvirt and mdevctl) can query the > +availability of specific features. > + > +The features list can be found here: /sys/bus/matrix/devices/matrix/features > + > +Entries are \n delimited. Each entry contains a key value pair. The key is made > +up of a combination of alphanumeric and underscore characters. The separator > +consists of a space, a colon and then another space. The value consists of > +alphanumeric, space, and underscore characters. > + > +Example: > +cat /sys/bus/matrix/devices/matrix/features > +flags : guest_matrix dyn ap_config > + > +Presently only a single field named flags is defined. It is meant to advertise a > +list of features the driver provides. The flags fields advertises the following > +features: I stumbled across this only now: sysfs files are not supposed to have several key value pairs. Actually the file(name) itself is supposed to be the key and its contents are the value. So I would expect: cat /sys/bus/matrix/devices/matrix/flags guest_matrix dyn ap_config Which is also easier to parse. Is there a good reason why this does not follow the general approach for sysfs files?
