From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:30370 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727123AbgLQAj6 (ORCPT ); Wed, 16 Dec 2020 19:39:58 -0500 Subject: Re: [PATCH v3] s390/vfio-ap: clean up vfio_ap resources when KVM pointer invalidated References: <20201214165617.28685-1-akrowiak@linux.ibm.com> From: Tony Krowiak Message-ID: <7732abbb-ded8-e17e-858b-e79737bba8a6@linux.ibm.com> Date: Wed, 16 Dec 2020 19:39:09 -0500 MIME-Version: 1.0 In-Reply-To: <20201214165617.28685-1-akrowiak@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US List-ID: To: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: stable@vger.kernel.org, gregkh@linuxfoundation.org, sashal@kernel.org, borntraeger@de.ibm.com, cohuck@redhat.com, kwankhede@nvidia.com, pbonzini@redhat.com, alex.williamson@redhat.com, pasic@linux.vnet.ibm.com On 12/14/20 11:56 AM, Tony Krowiak wrote: > The vfio_ap device driver registers a group notifier with VFIO when the > file descriptor for a VFIO mediated device for a KVM guest is opened to > receive notification that the KVM pointer is set (VFIO_GROUP_NOTIFY_SET_KVM > event). When the KVM pointer is set, the vfio_ap driver takes the > following actions: > 1. Stashes the KVM pointer in the vfio_ap_mdev struct that holds the state > of the mediated device. > 2. Calls the kvm_get_kvm() function to increment its reference counter. > 3. Sets the function pointer to the function that handles interception of > the instruction that enables/disables interrupt processing. > 4. Sets the masks in the KVM guest's CRYCB to pass AP resources through to > the guest. > > In order to avoid memory leaks, when the notifier is called to receive > notification that the KVM pointer has been set to NULL, the vfio_ap device > driver should reverse the actions taken when the KVM pointer was set. > > Fixes: 258287c994de ("s390: vfio-ap: implement mediated device open callback") > Signed-off-by: Tony Krowiak > --- > drivers/s390/crypto/vfio_ap_ops.c | 29 ++++++++++++++++++++--------- > 1 file changed, 20 insertions(+), 9 deletions(-) > > diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c > index e0bde8518745..cd22e85588e1 100644 > --- a/drivers/s390/crypto/vfio_ap_ops.c > +++ b/drivers/s390/crypto/vfio_ap_ops.c > @@ -1037,8 +1037,6 @@ static int vfio_ap_mdev_set_kvm(struct ap_matrix_mdev *matrix_mdev, > { > struct ap_matrix_mdev *m; > > - mutex_lock(&matrix_dev->lock); > - > list_for_each_entry(m, &matrix_dev->mdev_list, node) { > if ((m != matrix_mdev) && (m->kvm == kvm)) { > mutex_unlock(&matrix_dev->lock); This unlock needs to be removed. > @@ -1049,7 +1047,6 @@ static int vfio_ap_mdev_set_kvm(struct ap_matrix_mdev *matrix_mdev, > matrix_mdev->kvm = kvm; > kvm_get_kvm(kvm); > kvm->arch.crypto.pqap_hook = &matrix_mdev->pqap_hook; > - mutex_unlock(&matrix_dev->lock); > > return 0; > } > @@ -1083,35 +1080,49 @@ static int vfio_ap_mdev_iommu_notifier(struct notifier_block *nb, > return NOTIFY_DONE; > } > > +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; > +} > + > static int vfio_ap_mdev_group_notifier(struct notifier_block *nb, > unsigned long action, void *data) > { > - int ret; > + int ret, notify_rc = NOTIFY_DONE; > 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); > > if (!data) { > - matrix_mdev->kvm = NULL; > - return NOTIFY_OK; > + if (matrix_mdev->kvm) > + vfio_ap_mdev_unset_kvm(matrix_mdev); > + notify_rc = NOTIFY_OK; > + goto notify_done; > } > > ret = vfio_ap_mdev_set_kvm(matrix_mdev, data); > if (ret) > - return 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) > - return 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); > > - return NOTIFY_OK; > +notify_done: > + mutex_unlock(&matrix_dev->lock); > + return notify_rc; > } > > static void vfio_ap_irq_disable_apqn(int apqn)