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Wed, 12 May 2021 16:49:24 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id EB68842373; Wed, 12 May 2021 16:49:23 +0000 (GMT) Received: from oc7455500831.ibm.com (unknown [9.171.73.206]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 12 May 2021 16:49:23 +0000 (GMT) Subject: Re: [PATCH v2] s390/vfio-ap: fix memory leak in mdev remove callback To: Tony Krowiak , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org Cc: cohuck@redhat.com, pasic@linux.vnet.ibm.com, jjherne@linux.ibm.com, jgg@nvidia.com, alex.williamson@redhat.com, kwankhede@nvidia.com, stable@vger.kernel.org, Vasily Gorbik References: <20210510214837.359717-1-akrowiak@linux.ibm.com> From: Christian Borntraeger Message-ID: <834f95f8-c1ca-17da-b709-69d5c55e8fcd@de.ibm.com> Date: Wed, 12 May 2021 18:49:23 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.0 MIME-Version: 1.0 In-Reply-To: <20210510214837.359717-1-akrowiak@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: XmYRU7UqZaQFb980xrp-qzfwD8aYDKXH X-Proofpoint-ORIG-GUID: bort9dkKKEBHY1AtuudoK0dv5_liwnku X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.761 definitions=2021-05-12_09:2021-05-12,2021-05-12 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 mlxlogscore=999 priorityscore=1501 impostorscore=0 suspectscore=0 mlxscore=0 malwarescore=0 bulkscore=0 lowpriorityscore=0 spamscore=0 adultscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2105120105 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10.05.21 23:48, Tony Krowiak wrote: > The mdev remove callback for the vfio_ap device driver bails out with > -EBUSY if the mdev is in use by a KVM guest. The intended purpose was > to prevent the mdev from being removed while in use; however, returning a > non-zero rc does not prevent removal. This could result in a memory leak > of the resources allocated when the mdev was created. In addition, the > KVM guest will still have access to the AP devices assigned to the mdev > even though the mdev no longer exists. > > To prevent this scenario, cleanup will be done - including unplugging the > AP adapters, domains and control domains - regardless of whether the mdev > is in use by a KVM guest or not. > > Fixes: 258287c994de ("s390: vfio-ap: implement mediated device open callback") > Cc: stable@vger.kernel.org > Signed-off-by: Tony Krowiak applied to the internal s390 tree. Lets give it some days of testing coverage of CI and others. Vasily, can you add this for the s390/fixes branch early next week if nothing goes wrong? > --- > drivers/s390/crypto/vfio_ap_ops.c | 13 ++----------- > 1 file changed, 2 insertions(+), 11 deletions(-) > > diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c > index b2c7e10dfdcd..f90c9103dac2 100644 > --- a/drivers/s390/crypto/vfio_ap_ops.c > +++ b/drivers/s390/crypto/vfio_ap_ops.c > @@ -26,6 +26,7 @@ > > static int vfio_ap_mdev_reset_queues(struct mdev_device *mdev); > static struct vfio_ap_queue *vfio_ap_find_queue(int apqn); > +static void vfio_ap_mdev_unset_kvm(struct ap_matrix_mdev *matrix_mdev); > > static int match_apqn(struct device *dev, const void *data) > { > @@ -366,17 +367,7 @@ static int vfio_ap_mdev_remove(struct mdev_device *mdev) > struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev); > > 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; > - } > - > - vfio_ap_mdev_reset_queues(mdev); > + vfio_ap_mdev_unset_kvm(matrix_mdev); > list_del(&matrix_mdev->node); > kfree(matrix_mdev); > mdev_set_drvdata(mdev, NULL); >