On 11.06.2018 13:32, Halil Pasic wrote: > > > On 06/11/2018 11:23 AM, Pierre Morel wrote: >> On 08/06/2018 23:59, Tony Krowiak wrote: >>> On 06/07/2018 01:15 PM, Pierre Morel wrote: >>>> >> >> ...snip... >> >>>>>> >>>>>>> >>>>>>> Why maintain a list of kvm_ap_matrix structures if we don't have to; it is stored >>>>>>> with the mediated matrix device which is passed in to all of the vfio_ap driver >>>>>>> callbacks. >>>>>> >>>>>> Because using the vm_list which is a static in kvm makes you stick inside the kvm code. >>> >>> I understand your point here, but even if we did maintain a list of kvm_ap_matrix structures, >>> we still need the kvm code to configure the guest's CRYCB and eventually ECA.28. There is >>> also code in kvm-ap.c that is called from KVM. >> >> The only code from kvm-ap which is called from KVM is temporary code >> waiting for Harald to offer the clean interface to AP instructions. >> >>> The idea behind kvm-ap.c is that all code >>> related to configuration of AP structures in KVM is in this one spot. >> >> This I understand, but the code can be in one spot inside VFIO_AP instead >> of inside KVM. >> Putting the code inside KVM induce dependencies between KVM and AP >> while the kvm/vfio interface allows to avoid this dependency. >> >> The purpose of VFIO_AP is to handle the CRYCB, all get/clear/set crycb masks >> functions should be in VFIO AP. >> >> If we use wrappers in KVM, since the CRYCB is an a SIE extension, >> it is legitimate, the KVM interface to the CRYCB should only >> handle bitmaps and be unaware of the vfio_ap internal structures. Yes, please! >> >> Another concern, the kvm_ap_validate_queue_sharing() should not be >> inside KVM because it is a decision of current VFIO_AP driver >> to not share the queues between guest of level 2. >> >> The Z architecture does not allow to share AP queues between >> guests of level 1 but we could re-engineer the AP bus and the ' >> VFIO AP to offer queue sharing for guest level 2. >> >> This would be a new VFIO_AP driver (and an AP bus extension). >> We should not have to change KVM for this. >> > > > Pierre's proposal makes a lot of sense to me. We would not need to take > the kvm_lock (which we need to traverse the vm_list safely) for the > validation, and we could have immediate validation (which is in my opinion > better). Please do not use the kvm_lock if possible. > > Also your refcount (which is not a refcout) could go away. You simply > traverse your list and check for duplicates when hooking up the mdev > with KVM. > > And my opinion is if we don't have to add code to the kvm module we > better not. > > @Janosch: Does core KVM share my opinion? At least I do. KVM does not care about who has which crypto queue/card. I'd like to have a driver that does internal bookkeeping and then registers the crycb with KVM, so the VM can use it. > > Regards, > Halil >
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