Re: [PATCH v5 10/13] s390: vfio-ap: sysfs interface to view matrix mdev matrix

[Pierre Morel]

On 30/05/2018 16:28, Tony Krowiak wrote:
> On 05/24/2018 05:10 AM, Pierre Morel wrote:
> > On 23/05/2018 16:38, Tony Krowiak wrote:
> > > On 05/16/2018 03:55 AM, Pierre Morel wrote:
> > > > On 07/05/2018 17:11, Tony Krowiak wrote:
> > > > > 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:
> > > >
> > > > This is the configured matrix, not the one used by the guest.
> > > > Nothing in the patches protect against binding a queue and assigning
> > > > a new AP when the guest runs.
> > > > The card and queue will be showed by this entry.
> > >
> > > Of course, as stated above, this is the matrix configured for the
> > > mediated matrix device. Are you suggesting here that the driver
> > > should prevent assigning a new adapter or domain while a guest is
> > > running? Couldn't this be a step in the process for hot (un)plugging
> > > AP queues?
> >
> > No, I mean what is the point to show this?
> > It is not what the guest sees.
> > Has it any use case?
>
> The point is to display the matrix so one can view the AP queues that
> have been assigned to the mediated matrix device. This is the only way
> to view the matrix. Do you not find value in being able to see what
> has been assigned to the mediated matrix device?

Two things:
1) I think it is better to retrieve the individual masks
2) As I said above, what you show is not the effective mask used by the 
guest




--
Pierre Morel
Linux/KVM/QEMU in BÃblingen - Germany