From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pierre Morel Subject: Re: [PATCH v3 6/9] vfio: ap: register IOMMU VFIO notifier Date: Tue, 19 Feb 2019 20:04:22 +0100 Message-ID: References: <1550152269-6317-1-git-send-email-pmorel@linux.ibm.com> <1550152269-6317-7-git-send-email-pmorel@linux.ibm.com> <3ce0a3a0-22fb-c418-321d-7e6e3af5b66c@linux.ibm.com> <20190219105946.29e510a6@oc2783563651> Reply-To: pmorel@linux.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format="flowed" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20190219105946.29e510a6@oc2783563651> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: Halil Pasic , Tony Krowiak Cc: borntraeger@de.ibm.com, alex.williamson@redhat.com, cohuck@redhat.com, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, frankja@linux.ibm.com, david@redhat.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, freude@linux.ibm.com, mimu@linux.ibm.com List-ID: On 19/02/2019 10:59, Halil Pasic wrote: > On Fri, 15 Feb 2019 17:55:35 -0500 > Tony Krowiak wrote: > >> On 2/14/19 8:51 AM, Pierre Morel wrote: >>> To be able to use the VFIO interface to facilitate the >>> mediated device memory pining/unpining we need to register >>> a notifier for IOMMU. >>> >>> Signed-off-by: Pierre Morel >>> --- >>> drivers/s390/crypto/vfio_ap_ops.c | 64 +++++++++++++++++++++++++++++++---- >>> drivers/s390/crypto/vfio_ap_private.h | 2 ++ >>> 2 files changed, 60 insertions(+), 6 deletions(-) >>> >>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c >>> index 1851b24..6eddc2c 100644 >>> --- a/drivers/s390/crypto/vfio_ap_ops.c >>> +++ b/drivers/s390/crypto/vfio_ap_ops.c > > [..] > struct vfio_ap_queue *q; >>> @@ -967,12 +996,32 @@ static int vfio_ap_mdev_open(struct mdev_device *mdev) >>> >>> ret = vfio_register_notifier(mdev_dev(mdev), VFIO_GROUP_NOTIFY, >>> &events, &matrix_mdev->group_notifier); >>> - if (ret) { >>> - module_put(THIS_MODULE); >>> - return ret; >>> - } >>> + if (ret) >>> + goto err_group; >>> + >>> + matrix_mdev->iommu_notifier.notifier_call = vfio_ap_mdev_iommu_notifier; >>> + events = VFIO_IOMMU_NOTIFY_DMA_UNMAP; >>> + >>> + ret = vfio_register_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY, >>> + &events, &matrix_mdev->iommu_notifier); >>> + if (ret) >>> + goto err_iommu; >>> + >>> + ret = vfio_ap_associate_queues(matrix_mdev); >>> + if (ret) >>> + goto err_associate; >> >> I think the matrix_mdev should be associated with queues when an >> assignment of an adapter or domain is made to the mdev device via its >> sysfs interfaces. I say this because assigning an adapter or domain to >> an mdev device effectively grants ownership of any additional AP queues >> added to the mdev device's AP matrix as a result of the assignment. It >> only makes sense to assign ownership to the vfio_ap_queue objects >> representing the queues at that time. If an adapter or domain is >> dynamically assigned while a guest is using the affected queues, then >> the associations will have to be made at that time and this code will >> likely go bye bye. >> > > > Actually, we need the stuff in vfio_ap_queues only if the guest is > offered to decides to use AP adaper interrupts. I would prefer to have > it around only when needed: as long as we have the nib pinned for any > given queue. Is there a reason why not to do so? > > Regards, > Halil > > [..] > Since I will rework the vfio_ap_queue life cycle, I will study this. But I find the creation / deletion in probe/remove and the link/unlimk to the matrix device in assign/un_assign as suggested by Tony more logical. Regards, Pierre -- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany