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Fri, 18 Mar 2022 17:54:28 +0000 (GMT) Message-ID: Date: Fri, 18 Mar 2022 13:54:27 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.3.0 Subject: Re: [PATCH v18 12/18] s390/vfio-ap: reset queues after adapter/domain unassignment Content-Language: en-US To: jjherne@linux.ibm.com, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: freude@linux.ibm.com, borntraeger@de.ibm.com, cohuck@redhat.com, mjrosato@linux.ibm.com, pasic@linux.ibm.com, alex.williamson@redhat.com, kwankhede@nvidia.com, fiuczy@linux.ibm.com References: <20220215005040.52697-1-akrowiak@linux.ibm.com> <20220215005040.52697-13-akrowiak@linux.ibm.com> <6083d83b-6867-2525-fdd8-baccde1a599f@linux.ibm.com> From: Tony Krowiak In-Reply-To: <6083d83b-6867-2525-fdd8-baccde1a599f@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: eEZulnVsfM1xWhGozvJAuy0cIMndvhM4 X-Proofpoint-GUID: ufxfhyos-Nq7-pR9TvVOg0rCRMv2ik_J X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.850,Hydra:6.0.425,FMLib:17.11.64.514 definitions=2022-03-18_13,2022-03-15_01,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 spamscore=0 lowpriorityscore=0 adultscore=0 priorityscore=1501 impostorscore=0 clxscore=1015 mlxlogscore=999 phishscore=0 mlxscore=0 malwarescore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2202240000 definitions=main-2203180093 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 3/15/22 10:13, Jason J. Herne wrote: > On 2/14/22 19:50, Tony Krowiak wrote: >> When an adapter or domain is unassigned from an mdev providing the AP >> configuration to a running KVM guest, one or more of the guest's >> queues may >> get dynamically removed. Since the removed queues could get >> re-assigned to >> another mdev, they need to be reset. So, when an adapter or domain is >> unassigned from the mdev, the queues that are removed from the guest's >> AP configuration will be reset. >> >> Signed-off-by: Tony Krowiak >> --- > ... >>   +static void vfio_ap_unlink_apqn_fr_mdev(struct ap_matrix_mdev >> *matrix_mdev, >> +                    unsigned long apid, unsigned long apqi, >> +                    struct ap_queue_table *qtable) >> +{ >> +    struct vfio_ap_queue *q; >> + >> +    q = vfio_ap_mdev_get_queue(matrix_mdev, AP_MKQID(apid, apqi)); >> +    /* If the queue is assigned to the matrix mdev, unlink it. */ >> +    if (q) >> +        vfio_ap_unlink_queue_fr_mdev(q); >> + >> +    /* If the queue is assigned to the APCB, store it in @qtable. */ >> +    if (test_bit_inv(apid, matrix_mdev->shadow_apcb.apm) && >> +        test_bit_inv(apqi, matrix_mdev->shadow_apcb.aqm)) >> +        hash_add(qtable->queues, &q->mdev_qnode, q->apqn); >> +} >> + >> +/** >> + * vfio_ap_mdev_unlink_adapter - unlink all queues associated with >> unassigned >> + *                 adapter from the matrix mdev to which the >> + *                 adapter was assigned. >> + * @matrix_mdev: the matrix mediated device to which the adapter was >> assigned. >> + * @apid: the APID of the unassigned adapter. >> + * @qtable: table for storing queues associated with unassigned >> adapter. >> + */ >>   static void vfio_ap_mdev_unlink_adapter(struct ap_matrix_mdev >> *matrix_mdev, >> -                    unsigned long apid) >> +                    unsigned long apid, >> +                    struct ap_queue_table *qtable) >>   { >>       unsigned long apqi; >> + >> +    for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, AP_DOMAINS) >> +        vfio_ap_unlink_apqn_fr_mdev(matrix_mdev, apid, apqi, qtable); >> +} > > Here is an alternate version of the above two functions that stops the > profileration of the qtables variable into vfio_ap_unlink_apqn_fr_mdev. > It may seem like a change with no benefit, but it simplifies things a > bit and avoids the reader from having to sink three functions deep to > find out where qtables is used. This is 100% untested. > > > static bool vfio_ap_unlink_apqn_fr_mdev(struct ap_matrix_mdev > *matrix_mdev, >                     unsigned long apid, unsigned long apqi) > { >     struct vfio_ap_queue *q; > >     q = vfio_ap_mdev_get_queue(matrix_mdev, AP_MKQID(apid, apqi)); >     /* If the queue is assigned to the matrix mdev, unlink it. */ >     if (q) { >         vfio_ap_unlink_queue_fr_mdev(q); >         return true; >     } >     return false; > } > > static void vfio_ap_mdev_unlink_adapter(struct ap_matrix_mdev > *matrix_mdev, >                     unsigned long apid, >                     struct ap_queue_table *qtable) > { >     unsigned long apqi; >     bool unlinked; > >     for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, AP_DOMAINS) { >         unlinked = vfio_ap_unlink_apqn_fr_mdev(matrix_mdev, apid, > apqi, qtable); > >         if (unlinked && qtable) { >             if (test_bit_inv(apid, matrix_mdev->shadow_apcb.apm) && >                 test_bit_inv(apqi, matrix_mdev->shadow_apcb.aqm)) >                 hash_add(qtable->queues, &q->mdev_qnode, >                      q->apqn); >         } >     } > } This code didn't compile because in the function immediately above, the variable q is not defined nor is it initialized with a value. What I did to fix that is return  the vfio_ap_queue pointer from the vfio_ap_unlink_apqn_fr_mdev function and checked the return value for NULL instead of the boolean: vfio_ap_queue *q; ... q = vfio_ap_unlink_apqn_fr_mdev(matrix_mdev, apid, apqi, qtable); ... if (q && qtable) ... > > >> +static void vfio_ap_mdev_hot_unplug_adapter(struct ap_matrix_mdev >> *matrix_mdev, >> +                        unsigned long apid) >> +{ >> +    int bkt; >>       struct vfio_ap_queue *q; >> +    struct ap_queue_table qtable; >> +    hash_init(qtable.queues); >> +    vfio_ap_mdev_unlink_adapter(matrix_mdev, apid, &qtable); >> + >> +    if (test_bit_inv(apid, matrix_mdev->shadow_apcb.apm)) { >> +        clear_bit_inv(apid, matrix_mdev->shadow_apcb.apm); >> +        vfio_ap_mdev_hotplug_apcb(matrix_mdev); >> +    } >>   -    for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, AP_DOMAINS) { >> -        q = vfio_ap_mdev_get_queue(matrix_mdev, AP_MKQID(apid, apqi)); >> +    vfio_ap_mdev_reset_queues(&qtable); >>   -        if (q) >> -            vfio_ap_mdev_unlink_queue(q); >> +    hash_for_each(qtable.queues, bkt, q, mdev_qnode) { > > This comment applies to all instances of btk: What is btk? Can we come > up with a more descriptive name? If you look at the hash_for_each macro, you will see that I used the exact same variable name as the macro does to indicate it is a bucket loop cursor. Since that is a long name I'll go with loop_cursor. > > >> +        vfio_ap_unlink_mdev_fr_queue(q); >> +        hash_del(&q->mdev_qnode); >>       } >>   } > ... >> @@ -1273,9 +1320,9 @@ static void vfio_ap_mdev_unset_kvm(struct >> ap_matrix_mdev *matrix_mdev, >>           mutex_lock(&kvm->lock); >>           mutex_lock(&matrix_dev->mdevs_lock); >>   -        kvm_arch_crypto_clear_masks(kvm); >> -        vfio_ap_mdev_reset_queues(matrix_mdev); >> -        kvm_put_kvm(kvm); >> +        kvm_arch_crypto_clear_masks(matrix_mdev->kvm); >> +        vfio_ap_mdev_reset_queues(&matrix_mdev->qtable); >> +        kvm_put_kvm(matrix_mdev->kvm); >>           matrix_mdev->kvm = NULL; > > I understand changing the call to vfio_ap_mdev_reset_queues, but why > are we changing the > kvm pointer on the surrounding lines? In reality, both pointers are one in the same given the two callers pass matrix_mdev->kvm into the function. I'm not sure why that is the case, it is probably a remnant from the commits that fixed the lockdep splat; however, there is no reason other than I've gotten used to retrieving the KVM pointer from the ap_matrix_mdev structure. In reality, there is no reason to pass a 'struct kvm *kvm' into this function, so I'm going to look into that and adjust accordingly. > > >> mutex_unlock(&matrix_dev->mdevs_lock); >> @@ -1328,14 +1375,17 @@ static int vfio_ap_mdev_reset_queue(struct >> vfio_ap_queue *q, unsigned int retry) >>         if (!q) >>           return 0; >> +    q->reset_rc = 0; > > This line seems unnecessary. You set q->reset_rc in every single case > below, so this 0 > will always get overwritten. Right you are. It is also unnecessary to set q->reset_rc every case when it can be set once right after the call to ap_zapq. > > >>   retry_zapq: >>       status = ap_zapq(q->apqn); >>       switch (status.response_code) { >>       case AP_RESPONSE_NORMAL: >>           ret = 0; >> +        q->reset_rc = status.response_code; >>           break; >>       case AP_RESPONSE_RESET_IN_PROGRESS: >> +        q->reset_rc = status.response_code; >>           if (retry--) { >>               msleep(20); >>               goto retry_zapq; >> @@ -1345,13 +1395,20 @@ static int vfio_ap_mdev_reset_queue(struct >> vfio_ap_queue *q, unsigned int retry) >>       case AP_RESPONSE_Q_NOT_AVAIL: >>       case AP_RESPONSE_DECONFIGURED: >>       case AP_RESPONSE_CHECKSTOPPED: >> -        WARN_ON_ONCE(status.irq_enabled); >> +        WARN_ONCE(status.irq_enabled, >> +              "PQAP/ZAPQ for %02x.%04x failed with rc=%u while IRQ >> enabled", >> +              AP_QID_CARD(q->apqn), AP_QID_QUEUE(q->apqn), >> +              status.response_code); >> +        q->reset_rc = status.response_code; >>           ret = -EBUSY; >>           goto free_resources; >>       default: >>           /* things are really broken, give up */ >> -        WARN(true, "PQAP/ZAPQ completed with invalid rc (%x)\n", >> +        WARN(true, >> +             "PQAP/ZAPQ for %02x.%04x failed with invalid rc=%u\n", >> +             AP_QID_CARD(q->apqn), AP_QID_QUEUE(q->apqn), >>                status.response_code); >> +        q->reset_rc = status.response_code; >>           return -EIO; >>       } > ... >