From patchwork Tue Apr 6 15:31:10 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anthony Krowiak X-Patchwork-Id: 12185479 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BF2AEC43460 for ; Tue, 6 Apr 2021 15:31:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 95A226139C for ; Tue, 6 Apr 2021 15:31:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345715AbhDFPb4 (ORCPT ); Tue, 6 Apr 2021 11:31:56 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:56512 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1345688AbhDFPbu (ORCPT ); Tue, 6 Apr 2021 11:31:50 -0400 Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 136F8kZQ110125; Tue, 6 Apr 2021 11:31:40 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding; s=pp1; bh=eddZYayLgbK9LT7a0g2otyK+KzhpC5hr6wrwydXZlus=; b=O2YDa2BvMEAxVsU63EhvskycOfHtSYqbBMU1uAOjDZb0fGTot5TsSC2EY8eo7bOz4NAo 4GA4I3jAsPW2rA/aiz1z7rs5kqqqSfEJAQAFpiVehwEDBxAjFtq/cqEXh5wkqlFJzewL NRFU6vE8ktICDOqGdqGZv3ILEl0yxGJevnRfCpZIX5yQKW2EU1WR19mM5ojISKt0lpvF clyZSj+hvwm3fdqNYRCPnUqmQ2zkH7750FMmHKE+MfWTSuqyN50IfSY60MQdCUFCBP0C Y+mR7NHAn2yiWjP1DQbZ8kQthxRo4p4WR/Ng+QChpOTLchI4Zh5ydP0d5WYNM4QJvNTa Zg== Received: from pps.reinject (localhost [127.0.0.1]) by mx0b-001b2d01.pphosted.com with ESMTP id 37q5eb6dax-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 06 Apr 2021 11:31:40 -0400 Received: from m0098413.ppops.net (m0098413.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 136FFYxY129710; Tue, 6 Apr 2021 11:31:39 -0400 Received: from ppma01wdc.us.ibm.com (fd.55.37a9.ip4.static.sl-reverse.com [169.55.85.253]) by mx0b-001b2d01.pphosted.com with ESMTP id 37q5eb6da9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 06 Apr 2021 11:31:39 -0400 Received: from pps.filterd (ppma01wdc.us.ibm.com [127.0.0.1]) by ppma01wdc.us.ibm.com (8.16.0.43/8.16.0.43) with SMTP id 136FM3x5002596; Tue, 6 Apr 2021 15:31:39 GMT Received: from b03cxnp07029.gho.boulder.ibm.com (b03cxnp07029.gho.boulder.ibm.com [9.17.130.16]) by ppma01wdc.us.ibm.com with ESMTP id 37q2q90r3q-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 06 Apr 2021 15:31:37 +0000 Received: from b03ledav005.gho.boulder.ibm.com (b03ledav005.gho.boulder.ibm.com [9.17.130.236]) by b03cxnp07029.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 136FVYGP31982060 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 6 Apr 2021 15:31:34 GMT Received: from b03ledav005.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5CB22BE053; Tue, 6 Apr 2021 15:31:34 +0000 (GMT) Received: from b03ledav005.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id AF922BE051; Tue, 6 Apr 2021 15:31:32 +0000 (GMT) Received: from cpe-172-100-182-241.stny.res.rr.com.com (unknown [9.85.175.110]) by b03ledav005.gho.boulder.ibm.com (Postfix) with ESMTP; Tue, 6 Apr 2021 15:31:32 +0000 (GMT) From: Tony Krowiak To: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: jjherne@linux.ibm.com, 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, frankja@linux.ibm.com, david@redhat.com, hca@linux.ibm.com, gor@linux.ibm.com, Tony Krowiak , stable@vger.kernel.org Subject: [PATCH v15 01/13] s390/vfio-ap: fix circular lockdep when setting/clearing crypto masks Date: Tue, 6 Apr 2021 11:31:10 -0400 Message-Id: <20210406153122.22874-2-akrowiak@linux.ibm.com> X-Mailer: git-send-email 2.21.3 In-Reply-To: <20210406153122.22874-1-akrowiak@linux.ibm.com> References: <20210406153122.22874-1-akrowiak@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: Sol9zDNYMd2TtVmicGXzBOJytPz6ZBx8 X-Proofpoint-ORIG-GUID: G2er4JRwIL5Bu0R5W34c0tY6B-g_EtYP X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369,18.0.761 definitions=2021-04-06_04:2021-04-01,2021-04-06 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 priorityscore=1501 mlxscore=0 suspectscore=0 adultscore=0 phishscore=0 bulkscore=0 mlxlogscore=999 clxscore=1015 spamscore=0 lowpriorityscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104030000 definitions=main-2104060102 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org This patch fixes a lockdep splat introduced by commit f21916ec4826 ("s390/vfio-ap: clean up vfio_ap resources when KVM pointer invalidated"). The lockdep splat only occurs when starting a Secure Execution guest. Crypto virtualization (vfio_ap) is not yet supported for SE guests; however, in order to avoid this problem when support becomes available, this fix is being provided. The circular locking dependency was introduced when the setting of the masks in the guest's APCB was executed while holding the matrix_dev->lock. While the lock is definitely needed to protect the setting/unsetting of the matrix_mdev->kvm pointer, it is not necessarily critical for setting the masks; so, the matrix_dev->lock will be released while the masks are being set or cleared. Keep in mind, however, that another process that takes the matrix_dev->lock can get control while the masks in the guest's APCB are being set or cleared as a result of the driver being notified that the KVM pointer has been set or unset. This could result in invalid access to the matrix_mdev->kvm pointer by the intervening process. To avoid this scenario, two new fields are being added to the ap_matrix_mdev struct: struct ap_matrix_mdev { ... bool kvm_busy; wait_queue_head_t wait_for_kvm; ... }; The functions that handle notification that the KVM pointer value has been set or cleared will set the kvm_busy flag to true until they are done processing at which time they will set it to false and wake up the tasks on the matrix_mdev->wait_for_kvm wait queue. Functions that require access to matrix_mdev->kvm will sleep on the wait queue until they are awakened at which time they can safely access the matrix_mdev->kvm field. Fixes: f21916ec4826 ("s390/vfio-ap: clean up vfio_ap resources when KVM pointer invalidated") Cc: stable@vger.kernel.org Signed-off-by: Tony Krowiak --- drivers/s390/crypto/vfio_ap_ops.c | 308 ++++++++++++++++++-------- drivers/s390/crypto/vfio_ap_private.h | 2 + 2 files changed, 215 insertions(+), 95 deletions(-) diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c index 1ffdd411201c..6946a7e26eff 100644 --- a/drivers/s390/crypto/vfio_ap_ops.c +++ b/drivers/s390/crypto/vfio_ap_ops.c @@ -294,6 +294,19 @@ static int handle_pqap(struct kvm_vcpu *vcpu) matrix_mdev = container_of(vcpu->kvm->arch.crypto.pqap_hook, struct ap_matrix_mdev, pqap_hook); + /* + * If the KVM pointer is in the process of being set, wait until the + * process has completed. + */ + wait_event_cmd(matrix_mdev->wait_for_kvm, + !matrix_mdev->kvm_busy, + mutex_unlock(&matrix_dev->lock), + mutex_lock(&matrix_dev->lock)); + + /* If the there is no guest using the mdev, there is nothing to do */ + if (!matrix_mdev->kvm) + goto out_unlock; + q = vfio_ap_get_queue(matrix_mdev, apqn); if (!q) goto out_unlock; @@ -337,6 +350,7 @@ static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev) matrix_mdev->mdev = mdev; vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->matrix); + init_waitqueue_head(&matrix_mdev->wait_for_kvm); mdev_set_drvdata(mdev, matrix_mdev); matrix_mdev->pqap_hook.hook = handle_pqap; matrix_mdev->pqap_hook.owner = THIS_MODULE; @@ -351,17 +365,23 @@ static int vfio_ap_mdev_remove(struct mdev_device *mdev) { struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev); - if (matrix_mdev->kvm) + mutex_lock(&matrix_dev->lock); + + /* + * If the KVM pointer is in flux or the guest is running, disallow + * un-assignment of control domain. + */ + if (matrix_mdev->kvm_busy || matrix_mdev->kvm) { + mutex_unlock(&matrix_dev->lock); return -EBUSY; + } - mutex_lock(&matrix_dev->lock); vfio_ap_mdev_reset_queues(mdev); list_del(&matrix_mdev->node); - mutex_unlock(&matrix_dev->lock); - kfree(matrix_mdev); mdev_set_drvdata(mdev, NULL); atomic_inc(&matrix_dev->available_instances); + mutex_unlock(&matrix_dev->lock); return 0; } @@ -606,24 +626,31 @@ static ssize_t assign_adapter_store(struct device *dev, struct mdev_device *mdev = mdev_from_dev(dev); struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev); - /* If the guest is running, disallow assignment of adapter */ - if (matrix_mdev->kvm) - return -EBUSY; + mutex_lock(&matrix_dev->lock); + + /* + * If the KVM pointer is in flux or the guest is running, disallow + * un-assignment of adapter + */ + if (matrix_mdev->kvm_busy || matrix_mdev->kvm) { + ret = -EBUSY; + goto done; + } ret = kstrtoul(buf, 0, &apid); if (ret) - return ret; + goto done; - if (apid > matrix_mdev->matrix.apm_max) - return -ENODEV; + if (apid > matrix_mdev->matrix.apm_max) { + ret = -ENODEV; + goto done; + } /* * Set the bit in the AP mask (APM) corresponding to the AP adapter * number (APID). The bits in the mask, from most significant to least * significant bit, correspond to APIDs 0-255. */ - mutex_lock(&matrix_dev->lock); - ret = vfio_ap_mdev_verify_queues_reserved_for_apid(matrix_mdev, apid); if (ret) goto done; @@ -672,22 +699,31 @@ static ssize_t unassign_adapter_store(struct device *dev, struct mdev_device *mdev = mdev_from_dev(dev); struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev); - /* If the guest is running, disallow un-assignment of adapter */ - if (matrix_mdev->kvm) - return -EBUSY; + mutex_lock(&matrix_dev->lock); + + /* + * If the KVM pointer is in flux or the guest is running, disallow + * un-assignment of adapter + */ + if (matrix_mdev->kvm_busy || matrix_mdev->kvm) { + ret = -EBUSY; + goto done; + } ret = kstrtoul(buf, 0, &apid); if (ret) - return ret; + goto done; - if (apid > matrix_mdev->matrix.apm_max) - return -ENODEV; + if (apid > matrix_mdev->matrix.apm_max) { + ret = -ENODEV; + goto done; + } - mutex_lock(&matrix_dev->lock); clear_bit_inv((unsigned long)apid, matrix_mdev->matrix.apm); + ret = count; +done: mutex_unlock(&matrix_dev->lock); - - return count; + return ret; } static DEVICE_ATTR_WO(unassign_adapter); @@ -753,17 +789,24 @@ static ssize_t assign_domain_store(struct device *dev, struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev); unsigned long max_apqi = matrix_mdev->matrix.aqm_max; - /* If the guest is running, disallow assignment of domain */ - if (matrix_mdev->kvm) - return -EBUSY; + mutex_lock(&matrix_dev->lock); + + /* + * If the KVM pointer is in flux or the guest is running, disallow + * assignment of domain + */ + if (matrix_mdev->kvm_busy || matrix_mdev->kvm) { + ret = -EBUSY; + goto done; + } ret = kstrtoul(buf, 0, &apqi); if (ret) - return ret; - if (apqi > max_apqi) - return -ENODEV; - - mutex_lock(&matrix_dev->lock); + goto done; + if (apqi > max_apqi) { + ret = -ENODEV; + goto done; + } ret = vfio_ap_mdev_verify_queues_reserved_for_apqi(matrix_mdev, apqi); if (ret) @@ -814,22 +857,32 @@ static ssize_t unassign_domain_store(struct device *dev, struct mdev_device *mdev = mdev_from_dev(dev); struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev); - /* If the guest is running, disallow un-assignment of domain */ - if (matrix_mdev->kvm) - return -EBUSY; + mutex_lock(&matrix_dev->lock); + + /* + * If the KVM pointer is in flux or the guest is running, disallow + * un-assignment of domain + */ + if (matrix_mdev->kvm_busy || matrix_mdev->kvm) { + ret = -EBUSY; + goto done; + } ret = kstrtoul(buf, 0, &apqi); if (ret) - return ret; + goto done; - if (apqi > matrix_mdev->matrix.aqm_max) - return -ENODEV; + if (apqi > matrix_mdev->matrix.aqm_max) { + ret = -ENODEV; + goto done; + } - mutex_lock(&matrix_dev->lock); clear_bit_inv((unsigned long)apqi, matrix_mdev->matrix.aqm); - mutex_unlock(&matrix_dev->lock); + ret = count; - return count; +done: + mutex_unlock(&matrix_dev->lock); + return ret; } static DEVICE_ATTR_WO(unassign_domain); @@ -858,27 +911,36 @@ static ssize_t assign_control_domain_store(struct device *dev, struct mdev_device *mdev = mdev_from_dev(dev); struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev); - /* If the guest is running, disallow assignment of control domain */ - if (matrix_mdev->kvm) - return -EBUSY; + mutex_lock(&matrix_dev->lock); + + /* + * If the KVM pointer is in flux or the guest is running, disallow + * assignment of control domain. + */ + if (matrix_mdev->kvm_busy || matrix_mdev->kvm) { + ret = -EBUSY; + goto done; + } ret = kstrtoul(buf, 0, &id); if (ret) - return ret; + goto done; - if (id > matrix_mdev->matrix.adm_max) - return -ENODEV; + if (id > matrix_mdev->matrix.adm_max) { + ret = -ENODEV; + goto done; + } /* Set the bit in the ADM (bitmask) corresponding to the AP control * domain number (id). The bits in the mask, from most significant to * least significant, correspond to IDs 0 up to the one less than the * number of control domains that can be assigned. */ - mutex_lock(&matrix_dev->lock); set_bit_inv(id, matrix_mdev->matrix.adm); + ret = count; +done: mutex_unlock(&matrix_dev->lock); - - return count; + return ret; } static DEVICE_ATTR_WO(assign_control_domain); @@ -908,21 +970,30 @@ static ssize_t unassign_control_domain_store(struct device *dev, struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev); unsigned long max_domid = matrix_mdev->matrix.adm_max; - /* If the guest is running, disallow un-assignment of control domain */ - if (matrix_mdev->kvm) - return -EBUSY; + mutex_lock(&matrix_dev->lock); + + /* + * If the KVM pointer is in flux or the guest is running, disallow + * un-assignment of control domain. + */ + if (matrix_mdev->kvm_busy || matrix_mdev->kvm) { + ret = -EBUSY; + goto done; + } ret = kstrtoul(buf, 0, &domid); if (ret) - return ret; - if (domid > max_domid) - return -ENODEV; + goto done; + if (domid > max_domid) { + ret = -ENODEV; + goto done; + } - mutex_lock(&matrix_dev->lock); clear_bit_inv(domid, matrix_mdev->matrix.adm); + ret = count; +done: mutex_unlock(&matrix_dev->lock); - - return count; + return ret; } static DEVICE_ATTR_WO(unassign_control_domain); @@ -1027,8 +1098,15 @@ static const struct attribute_group *vfio_ap_mdev_attr_groups[] = { * @matrix_mdev: a mediated matrix device * @kvm: reference to KVM instance * - * Verifies no other mediated matrix device has @kvm and sets a reference to - * it in @matrix_mdev->kvm. + * Sets all data for @matrix_mdev that are needed to manage AP resources + * for the guest whose state is represented by @kvm. + * + * Note: The matrix_dev->lock must be taken prior to calling + * this function; however, the lock will be temporarily released while the + * guest's AP configuration is set to avoid a potential lockdep splat. + * The kvm->lock is taken to set the guest's AP configuration which, under + * certain circumstances, will result in a circular lock dependency if this is + * done under the @matrix_mdev->lock. * * Return 0 if no other mediated matrix device has a reference to @kvm; * otherwise, returns an -EPERM. @@ -1038,14 +1116,25 @@ static int vfio_ap_mdev_set_kvm(struct ap_matrix_mdev *matrix_mdev, { struct ap_matrix_mdev *m; - list_for_each_entry(m, &matrix_dev->mdev_list, node) { - if ((m != matrix_mdev) && (m->kvm == kvm)) - return -EPERM; - } + if (kvm->arch.crypto.crycbd) { + list_for_each_entry(m, &matrix_dev->mdev_list, node) { + if (m != matrix_mdev && m->kvm == kvm) + return -EPERM; + } - matrix_mdev->kvm = kvm; - kvm_get_kvm(kvm); - kvm->arch.crypto.pqap_hook = &matrix_mdev->pqap_hook; + kvm_get_kvm(kvm); + matrix_mdev->kvm_busy = true; + mutex_unlock(&matrix_dev->lock); + kvm_arch_crypto_set_masks(kvm, + matrix_mdev->matrix.apm, + matrix_mdev->matrix.aqm, + matrix_mdev->matrix.adm); + mutex_lock(&matrix_dev->lock); + kvm->arch.crypto.pqap_hook = &matrix_mdev->pqap_hook; + matrix_mdev->kvm = kvm; + matrix_mdev->kvm_busy = false; + wake_up_all(&matrix_mdev->wait_for_kvm); + } return 0; } @@ -1079,51 +1168,65 @@ static int vfio_ap_mdev_iommu_notifier(struct notifier_block *nb, return NOTIFY_DONE; } +/** + * vfio_ap_mdev_unset_kvm + * + * @matrix_mdev: a matrix mediated device + * + * Performs clean-up of resources no longer needed by @matrix_mdev. + * + * Note: The matrix_dev->lock must be taken prior to calling + * this function; however, the lock will be temporarily released while the + * guest's AP configuration is cleared to avoid a potential lockdep splat. + * The kvm->lock is taken to clear the guest's AP configuration which, under + * certain circumstances, will result in a circular lock dependency if this is + * done under the @matrix_mdev->lock. + * + */ static void vfio_ap_mdev_unset_kvm(struct ap_matrix_mdev *matrix_mdev) { - kvm_arch_crypto_clear_masks(matrix_mdev->kvm); - matrix_mdev->kvm->arch.crypto.pqap_hook = NULL; - vfio_ap_mdev_reset_queues(matrix_mdev->mdev); - kvm_put_kvm(matrix_mdev->kvm); - matrix_mdev->kvm = NULL; + /* + * If the KVM pointer is in the process of being set, wait until the + * process has completed. + */ + wait_event_cmd(matrix_mdev->wait_for_kvm, + !matrix_mdev->kvm_busy, + mutex_unlock(&matrix_dev->lock), + mutex_lock(&matrix_dev->lock)); + + if (matrix_mdev->kvm) { + matrix_mdev->kvm_busy = true; + mutex_unlock(&matrix_dev->lock); + kvm_arch_crypto_clear_masks(matrix_mdev->kvm); + mutex_lock(&matrix_dev->lock); + vfio_ap_mdev_reset_queues(matrix_mdev->mdev); + matrix_mdev->kvm->arch.crypto.pqap_hook = NULL; + kvm_put_kvm(matrix_mdev->kvm); + matrix_mdev->kvm = NULL; + matrix_mdev->kvm_busy = false; + wake_up_all(&matrix_mdev->wait_for_kvm); + } } static int vfio_ap_mdev_group_notifier(struct notifier_block *nb, unsigned long action, void *data) { - int ret, notify_rc = NOTIFY_OK; + int notify_rc = NOTIFY_OK; struct ap_matrix_mdev *matrix_mdev; if (action != VFIO_GROUP_NOTIFY_SET_KVM) return NOTIFY_OK; - matrix_mdev = container_of(nb, struct ap_matrix_mdev, group_notifier); mutex_lock(&matrix_dev->lock); + matrix_mdev = container_of(nb, struct ap_matrix_mdev, group_notifier); - if (!data) { - if (matrix_mdev->kvm) - vfio_ap_mdev_unset_kvm(matrix_mdev); - goto notify_done; - } - - ret = vfio_ap_mdev_set_kvm(matrix_mdev, data); - if (ret) { - notify_rc = NOTIFY_DONE; - goto notify_done; - } - - /* If there is no CRYCB pointer, then we can't copy the masks */ - if (!matrix_mdev->kvm->arch.crypto.crycbd) { + if (!data) + vfio_ap_mdev_unset_kvm(matrix_mdev); + else if (vfio_ap_mdev_set_kvm(matrix_mdev, data)) notify_rc = NOTIFY_DONE; - goto notify_done; - } - - kvm_arch_crypto_set_masks(matrix_mdev->kvm, matrix_mdev->matrix.apm, - matrix_mdev->matrix.aqm, - matrix_mdev->matrix.adm); -notify_done: mutex_unlock(&matrix_dev->lock); + return notify_rc; } @@ -1258,8 +1361,7 @@ static void vfio_ap_mdev_release(struct mdev_device *mdev) struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev); mutex_lock(&matrix_dev->lock); - if (matrix_mdev->kvm) - vfio_ap_mdev_unset_kvm(matrix_mdev); + vfio_ap_mdev_unset_kvm(matrix_mdev); mutex_unlock(&matrix_dev->lock); vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY, @@ -1293,6 +1395,7 @@ static ssize_t vfio_ap_mdev_ioctl(struct mdev_device *mdev, unsigned int cmd, unsigned long arg) { int ret; + struct ap_matrix_mdev *matrix_mdev; mutex_lock(&matrix_dev->lock); switch (cmd) { @@ -1300,6 +1403,21 @@ static ssize_t vfio_ap_mdev_ioctl(struct mdev_device *mdev, ret = vfio_ap_mdev_get_device_info(arg); break; case VFIO_DEVICE_RESET: + matrix_mdev = mdev_get_drvdata(mdev); + if (WARN(!matrix_mdev, "Driver data missing from mdev!!")) { + ret = -EINVAL; + break; + } + + /* + * If the KVM pointer is in the process of being set, wait until + * the process has completed. + */ + wait_event_cmd(matrix_mdev->wait_for_kvm, + !matrix_mdev->kvm_busy, + mutex_unlock(&matrix_dev->lock), + mutex_lock(&matrix_dev->lock)); + ret = vfio_ap_mdev_reset_queues(mdev); break; default: diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h index 28e9d9989768..f82a6396acae 100644 --- a/drivers/s390/crypto/vfio_ap_private.h +++ b/drivers/s390/crypto/vfio_ap_private.h @@ -83,6 +83,8 @@ struct ap_matrix_mdev { struct ap_matrix matrix; struct notifier_block group_notifier; struct notifier_block iommu_notifier; + bool kvm_busy; + wait_queue_head_t wait_for_kvm; struct kvm *kvm; struct kvm_s390_module_hook pqap_hook; struct mdev_device *mdev;