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Fri, 22 Jan 2021 08:26:06 +0000 (GMT) Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 585A9A405F; Fri, 22 Jan 2021 08:26:06 +0000 (GMT) Received: from oc7455500831.ibm.com (unknown [9.171.82.42]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 22 Jan 2021 08:26:06 +0000 (GMT) Subject: Re: [PATCH v5] s390/vfio-ap: clean up vfio_ap resources when KVM pointer invalidated To: Tony Krowiak , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: stable@vger.kernel.org, cohuck@redhat.com, kwankhede@nvidia.com, pbonzini@redhat.com, alex.williamson@redhat.com, pasic@linux.vnet.ibm.com, Halil Pasic References: <20201223012013.5418-1-akrowiak@linux.ibm.com> From: Christian Borntraeger Message-ID: <0649ba1e-ecd3-890a-72b5-a8ff54417faf@de.ibm.com> Date: Fri, 22 Jan 2021 09:26:06 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20201223012013.5418-1-akrowiak@linux.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.343,18.0.737 definitions=2021-01-22_03:2021-01-21,2021-01-22 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 bulkscore=0 mlxlogscore=999 spamscore=0 priorityscore=1501 impostorscore=0 phishscore=0 lowpriorityscore=0 adultscore=0 mlxscore=0 clxscore=1015 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2101220038 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 23.12.20 02:20, 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") > Cc: stable@vger.kernel.org > Signed-off-by: Tony Krowiak > Reviewed-by: Halil Pasic > Reviewed-by: Cornelia Huck Just to keep you up2date why this patch is still waiting in our queue. This triggered a lockdep splat in the CI which we want to fix first.