From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pierre Morel Subject: Re: [PATCH v4 6/7] s390: ap: Cleanup on removing the AP device Date: Wed, 13 Mar 2019 11:15:20 +0100 Message-ID: <85f772b4-0b62-701d-c3e5-e55e88c3fb4e@linux.ibm.com> References: <1550849400-27152-1-git-send-email-pmorel@linux.ibm.com> <1550849400-27152-7-git-send-email-pmorel@linux.ibm.com> <3956ad4c-55c9-e42c-4ab2-00ddae05b317@linux.ibm.com> <94904df0-42b6-51f8-6440-68722ef5419d@linux.ibm.com> Reply-To: pmorel@linux.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Cc: 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, pasic@linux.ibm.com, david@redhat.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, freude@linux.ibm.com, mimu@linux.ibm.com To: Tony Krowiak , borntraeger@de.ibm.com Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 12/03/2019 22:53, Tony Krowiak wrote: > On 3/11/19 4:31 AM, Pierre Morel wrote: >> On 08/03/2019 23:43, Tony Krowiak wrote: >>> On 2/22/19 10:29 AM, Pierre Morel wrote: >>>> When the device is remove, we must make sure to >>>> clear the interruption and reset the AP device. >>>> >>>> We also need to clear the CRYCB of the guest. >>>> >>>> Signed-off-by: Pierre Morel >>>> --- >>>>   drivers/s390/crypto/vfio_ap_drv.c     | 35 >>>> +++++++++++++++++++++++++++++++++++ >>>>   drivers/s390/crypto/vfio_ap_ops.c     |  3 ++- >>>>   drivers/s390/crypto/vfio_ap_private.h |  3 +++ >>>>   3 files changed, 40 insertions(+), 1 deletion(-) >>>> ...snip... >>>> + * vfio_ap_update_crycb >>>> + * @q: A pointer to the queue being removed >>>> + * >>>> + * We clear the APID of the queue, making this queue unusable for >>>> the guest. >>>> + * After this function we can reset the queue without to fear a >>>> race with >>>> + * the guest to access the queue again. >>>> + * We do not fear race with the host as we still get the devic >>>> + */ >>>> +static void vfio_ap_update_crycb(struct vfio_ap_queue *q) >>>> +{ >>>> +    struct ap_matrix_mdev *matrix_mdev = q->matrix_mdev; >>>> + >>>> +    if (!matrix_mdev) >>>> +        return; >>>> + > > You should probably check whether the APID has been cleared before > proceeding. Take the case where an AP with multiple queues is removed > from the configuration via the SE or SCLP. The AP bus is going to invoke > the vfio_ap_queue_dev_remove() function for each of the queues. The APID > will get cleared on the first remove, so it is not only unnecessary to > clear it on subsequent removes, it is kind of nasty to keep resetting > the masks in the guest's CRYCB (below) each time the remove callback is > invoked. This can not happen. The only way to clear the APM is when the matrix is not associated with KVM. This case is tested and the masks are not changed. > >>>> +    clear_bit_inv(AP_QID_CARD(q->apqn), matrix_mdev->matrix.apm); >>>> + >>>> +    if (!matrix_mdev->kvm) >>>> +        return; >>>> + >>>> +    kvm_arch_crypto_set_masks(matrix_mdev->kvm, >>>> +                  matrix_mdev->matrix.apm, >>>> +                  matrix_mdev->matrix.aqm, >>>> +                  matrix_mdev->matrix.adm); >>>> +} -- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany