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Wed, 14 Oct 2026 15:51:44 +0000 (GMT) Received: from [9.61.158.18] (unknown [9.61.158.18]) by smtpav03.wdc07v.mail.ibm.com (Postfix) with ESMTP; Wed, 14 Oct 2026 15:51:44 +0000 (GMT) Message-ID: <21a7ab10-2e9d-4167-afba-a0bb37e5cbc4@linux.ibm.com> Date: Wed, 14 Oct 2026 11:51:44 -0400 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v9 03/15] s390/vfio-ap: Functions to initialize/release vfio device migration data To: sashiko-reviews@lists.linux.dev, linux-s390@vger.kernel.org, kvm@vger.kernel.org Cc: Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Jason Herne , Matthew Rosato References: <20261013153219.3534306-1-akrowiak@linux.ibm.com> <20261013153219.3534306-4-akrowiak@linux.ibm.com> Content-Language: en-US From: Anthony Krowiak In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Info: AW1haW4tMjYxMDE0MDA2MiBTYWx0ZWRfXw78LbncbW8BA UyXK1Aa/8tiFWhJVqxPd93Cx5VaHrF2ie77gMSaLUZrSFkLI2mYToTITkHP+5rdeIowyxu5tSnJ RAXU6UmxBr9mCoA+EKOx51lDraqJMEY= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDE0MDA2MiBTYWx0ZWRfX5XqPobD4mYmo JBZKWTqCEhPGqV72PCboUL2v2TFSSnrPi0cxLdGn2HaAY74xb9ze77sDIhhFbfyjOEoW8D+6geH qqFWtObr1BUvykP7Cba85Q30nXoTvA1fqJX39lOV3ZhlBwyUCLdP6D48sgKkAJPr/5GBN45r2fU CTd80MTfb7n9hGJC+hK68o/GtvVp8cfj1H/J5qf6DXdtYwHt45jeJgSf19FisJx8JoVH19J6zks WOuHgnSJFjNb0G+Cz1hAUba6vyClH8fEqCtyZDaWXFV9SweJHleWu5hwl6446YGATMlf9ttg7M2 by0MgSsoX0tara8kzH4HRn4Bp7ZVu+7dDTXdpR8iPEizdvrGO9BzBKCxlMt2m8YSQr+A/JSs0gk 7QgHsMwpMXnB+ck4MuxdOO5XVL1lmRWO6Yzp7leVkUZmPm9uO5RYeM/N3oRUPgeeindFhp3NWHW b98CsFh0PkDyOFNKxow== X-Proofpoint-GUID: IBM1AcXIR_EI00VWXvAJWgTiBUIQnugb X-Authority-Analysis: v=2.4 cv=RoFQvymK c=1 sm=1 tr=0 ts=6acfa514 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=660iZSQnnn4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=Y5rATk9AAFfwMYsNrMYA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: IBM1AcXIR_EI00VWXvAJWgTiBUIQnugb X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-10-13_01,2026-10-14_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 spamscore=0 phishscore=0 adultscore=0 bulkscore=0 impostorscore=0 suspectscore=0 malwarescore=0 clxscore=1015 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610080000 definitions=main-2610140062 On 10/13/26 11:47 AM, sashiko-bot@kernel.org wrote: > Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: > - [Medium] s390/vfio-ap: Data race on matrix_dev->info during mdev init > -- > > commit 61bb5cee71d03ac3e82343abe74a853a264da523 > Author: Anthony Krowiak > > s390/vfio-ap: Functions to initialize/release vfio device migration data > > Provides the functions that initialize and release the data structures > used during live guest migration. > >> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c >> index 01439f0ca42ab..6829e423b5a46 100644 >> --- a/drivers/s390/crypto/vfio_ap_ops.c >> +++ b/drivers/s390/crypto/vfio_ap_ops.c >> @@ -782,18 +782,30 @@ static bool vfio_ap_mdev_filter_matrix(struct ap_matrix_mdev *matrix_mdev, >> >> static int vfio_ap_mdev_init_dev(struct vfio_device *vdev) >> { >> - struct ap_matrix_mdev *matrix_mdev = >> - container_of(vdev, struct ap_matrix_mdev, vdev); >> + struct ap_matrix_mdev *matrix_mdev; >> >> + mutex_lock(&matrix_dev->mdevs_lock); >> + matrix_mdev = container_of(vdev, struct ap_matrix_mdev, vdev); >> matrix_mdev->mdev = to_mdev_device(vdev->dev); >> vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->matrix); > [Severity: Medium] > Could this result in a data race on matrix_dev->info? > > The modified vfio_ap_mdev_init_dev() reads matrix_dev->info via > vfio_ap_matrix_init() while holding only matrix_dev->mdevs_lock. > > However, vfio_ap_on_cfg_changed() updates matrix_dev->info via memcpy() > while holding only matrix_dev->guests_lock: > > drivers/s390/crypto/vfio_ap_ops.c:vfio_ap_on_cfg_changed() { > ... > memcpy(&matrix_dev->info, cur_cfg_info, sizeof(*cur_cfg_info)); > ... > } > > Since memcpy() is not atomic and the two functions acquire different locks, > can a concurrent AP configuration change cause vfio_ap_mdev_init_dev() > to read a torn or partially updated ap_config_info struct, potentially > leading to incorrect apm_max, aqm_max, or adm_max values? > > Note that follow-up patches in the series do not resolve this lock mismatch. This is actually a pre-existing bug. Also, the chunk above is unrelated to this patch series. This will be fixed in a separate patch. > >> matrix_mdev->pqap_hook = handle_pqap; >> vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->shadow_apcb); >> hash_init(matrix_mdev->qtable.queues); >> + mutex_unlock(&matrix_dev->mdevs_lock); >> >> return 0; >> }