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Fri, 30 Oct 2020 17:27:58 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 74C694C058; Fri, 30 Oct 2020 17:27:57 +0000 (GMT) Received: from oc2783563651 (unknown [9.145.172.93]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 30 Oct 2020 17:27:57 +0000 (GMT) Date: Fri, 30 Oct 2020 18:27:55 +0100 From: Halil Pasic To: Tony Krowiak Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, freude@linux.ibm.com, borntraeger@de.ibm.com, cohuck@redhat.com, mjrosato@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 Subject: Re: [PATCH v11 01/14] s390/vfio-ap: No need to disable IRQ after queue reset Message-ID: <20201030182755.433e3e2d.pasic@linux.ibm.com> In-Reply-To: <7a2c5930-9c37-8763-7e5d-c08a3638e6a1@linux.ibm.com> References: <20201022171209.19494-1-akrowiak@linux.ibm.com> <20201022171209.19494-2-akrowiak@linux.ibm.com> <20201027074846.30ee0ddc.pasic@linux.ibm.com> <7a2c5930-9c37-8763-7e5d-c08a3638e6a1@linux.ibm.com> Organization: IBM X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.31; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.312,18.0.737 definitions=2020-10-30_07:2020-10-30,2020-10-30 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 bulkscore=0 clxscore=1015 suspectscore=0 adultscore=0 malwarescore=0 mlxscore=0 mlxlogscore=999 lowpriorityscore=0 spamscore=0 impostorscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2010300122 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, 29 Oct 2020 19:29:35 -0400 Tony Krowiak wrote: > On 10/27/20 2:48 AM, Halil Pasic wrote: > > On Thu, 22 Oct 2020 13:11:56 -0400 > > Tony Krowiak wrote: > > > >> The queues assigned to a matrix mediated device are currently reset when: > >> > >> * The VFIO_DEVICE_RESET ioctl is invoked > >> * The mdev fd is closed by userspace (QEMU) > >> * The mdev is removed from sysfs. > > What about the situation when vfio_ap_mdev_group_notifier() is called to > > tell us that our pointer to KVM is about to become invalid? Do we need to > > clean up the IRQ stuff there? > > After reading this question, I decided to do some tracing using > printk's and learned that the vfio_ap_mdev_group_notifier() > function does not get called when the guest is shutdown. The reason > for this is because the vfio_ap_mdev_release() function, which is called > before the KVM pointer is invalidated, unregisters the group notifier. > > I took a look at some of the other drivers that register a group > notifier in the mdev_parent_ops.open callback and each unregistered > the notifier in the mdev_parent_ops.release callback. > > So, to answer your question, there is no need to cleanup the IRQ > stuff in the vfio_ap_mdev_group_notifier() function since it will > not get called when the KVM pointer is invalidated. The cleanup > should be done in the vfio_ap_mdev_release() function that gets > called when the mdev fd is closed. You say if vfio_ap_mdev_group_notifier() is called to tell us that KVM going away, then it is a bug? If that is the case, I would like that reflected in the code! By that I mean at logging an error at least (if not BUG_ON). Regards, Halil