On Mon, 13 Aug 2018 17:48:10 -0400
Tony Krowiak <akrow...@linux.vnet.ibm.com> wrote:

> From: Tony Krowiak <akrow...@linux.ibm.com>
> 
> Provides a sysfs interface to view the AP matrix configured for the
> mediated matrix device.
> 
> The relevant sysfs structures are:
> 
> /sys/devices/vfio_ap/matrix/
> ...... [mdev_supported_types]
> ......... [vfio_ap-passthrough]
> ............ [devices]
> ...............[$uuid]
> .................. matrix
> 
> To view the matrix configured for the mediated matrix device,
> print the matrix file:
> 
>       cat matrix
> 
> Below are examples of the output from the above command:
> 
> Example 1: Adapters and domains assigned
>       Assignments:
>               Adapters 5 and 6
>               Domains 4 and 71 (0x47)
> 
>       Output
>               05.0004
>               05.0047
>               06.0004
>       06.0047
> 
> Examples 2: Only adapters assigned
>       Assignments:
>               Adapters 5 and 6
> 
>       Output:
>               05.
>               06.
> 
> Examples 3: Only domains assigned
>       Assignments:
>               Domains 4 and 71 (0x47)
> 
>       Output:
>               .0004
>               .0047

I find this output to be a bit confusing; but OTOH, I'm probably not
the person to parse it :) Still, some comments.

>From previous discussions, ISTR that this is mainly supposed to be a
debugging/administration aid. Of course, this generates some questions:
- Should this be in sysfs (sysfs attributes are supposed to follow the
  "one value per file" rule, at least for the most part), or would
  debugfs be a better fit?
- Should userspace code be able to introspect the current
  configuration? If yes, it might be better to have some
  not-so-nice-but-easily-parsable output, possibly one attribute for
  the assigned adapters and one for the assigned domains, and a tool
  which distills that into a nice "matrix" with labeled rows and
  columns for human consumption.

That said, I don't really have major objections to that interface.

> 
> Signed-off-by: Tony Krowiak <akrow...@linux.ibm.com>
> Reviewed-by: Halil Pasic <pa...@linux.ibm.com>
> Tested-by: Michael Mueller <m...@linux.ibm.com>
> Tested-by: Farhan Ali <al...@linux.ibm.com>
> Tested-by: Pierre Morel <pmo...@linux.ibm.com>
> Signed-off-by: Christian Borntraeger <borntrae...@de.ibm.com>
> ---
>  drivers/s390/crypto/vfio_ap_ops.c |   52 
> +++++++++++++++++++++++++++++++++++++
>  1 files changed, 52 insertions(+), 0 deletions(-)

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