From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Krowiak Subject: Re: [PATCH v5 11/13] KVM: s390: implement mediated device open callback Date: Mon, 11 Jun 2018 08:56:02 -0400 Message-ID: <5362ed8b-10bf-c5a1-3e8f-7f1a8f1bcccb@linux.ibm.com> References: <1525705912-12815-1-git-send-email-akrowiak@linux.vnet.ibm.com> <1525705912-12815-12-git-send-email-akrowiak@linux.vnet.ibm.com> <98ea7ce2-2539-e2ff-4bb4-297e784d87bd@linux.ibm.com> <7bb480ac-5723-83ff-c797-53c1ab0458c1@linux.vnet.ibm.com> <93cd0f46-a410-51c8-00b9-810c1b3d3ae2@linux.ibm.com> <0f37dc39-7355-19e5-40c9-a02a1ea58c2d@linux.vnet.ibm.com> <736a1346-f81a-7f71-7d13-38729ff78e4f@linux.ibm.com> <8f68183d-8385-8025-1898-23cad604ae94@linux.vnet.ibm.com> <9e30c9b0-a04c-0c4e-9d3d-37e7a53a7f72@linux.ibm.com> <5f9c3f97-34e2-bf68-b8ca-ac9288ea5efa@linux.vnet.ibm.com> <010679ed-bd80-42f8-3f6f-e4dee10e82f5@linux.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <010679ed-bd80-42f8-3f6f-e4dee10e82f5@linux.ibm.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: pmorel@linux.ibm.com, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: freude@de.ibm.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, borntraeger@de.ibm.com, cohuck@redhat.com, kwankhede@nvidia.com, bjsdjshi@linux.vnet.ibm.com, pbonzini@redhat.com, alex.williamson@redhat.com, pmorel@linux.vnet.ibm.com, alifm@linux.vnet.ibm.com, mjrosato@linux.vnet.ibm.com, jjherne@linux.vnet.ibm.com, thuth@redhat.com, pasic@linux.vnet.ibm.com, berrange@redhat.com, fiuczy@linux.vnet.ibm.com, buendgen@de.ibm.com List-ID: On 06/11/2018 05:23 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. > > > 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. Based on your, Halil's and Janosch's comments, I will make the changes. > > > > Regards, > > Pierre > > >> >>> >>> >>> >> >