On Mon, 8 Jul 2019 10:27:11 -0400 Tony Krowiak <akrowiak@xxxxxxxxxxxxx> wrote: > On 7/1/19 3:26 PM, Cornelia Huck wrote: > > On Wed, 19 Jun 2019 09:04:18 -0400 > > Tony Krowiak <akrowiak@xxxxxxxxxxxxx> wrote: > >> Allow me to first address your fear that a bad actor can hog > >> resources that can't be removed by root. With this enhancement, > >> there is nothing preventing a root user from taking resources > >> from a matrix mdev, it simply forces him/her to follow the > >> proper procedure. The resources to be removed must first be > >> unassigned from the matrix mdev to which they are assigned. > >> The AP bus's /sys/bus/ap/apmask and /sys/bus/ap/aqmask > >> sysfs attributes can then be edited to transfer ownership > >> of the resources to zcrypt. > > > > What is the suggested procedure when root wants to unbind a queue > > device? Find the mdev using the queue (is that easy enough?), unassign > > it, then unbind? Failing to unbind is a bit unexpected; can we point > > the admin to the correct mdev from which the queue has to be removed > > first? > > The proper procedure is to first unassign the adapter, domain, or both > from the mdev to which the APQN is assigned. The difficulty in finding > the queue depends upon how many mdevs have been created. I would expect > that an admin would keep records of who owns what, but in the case he or > she doesn't, it would be a matter of printing out the matrix attribute > of each mdev until you find the mdev to which the APQN is assigned. Ok, so the information is basically available, if needed. > The only means I know of for informing the admin to which mdev a given > APQN is assigned is to log the error when it occurs. That might be helpful, if it's easy to do. > I think Matt is > also looking to provide query functions in the management tool on which > he is currently working. That also sounds helpful. (...) > >> * It forces the use of the proper procedure to change ownership of AP > >> queues. > > > > This needs to be properly documented, and the admin needs to have a > > chance to find out why unbinding didn't work and what needs to be done > > (see my comments above). > > I will create a section in the vfio-ap.txt document that comes with this > patch set describing the proper procedure for unbinding queues. Of > course, we'll make sure the official IBM doc also more thoroughly > describes this. +1 for good documentation. With that, I don't really object to this change.
