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Tue, 18 Aug 2026 11:58:20 +0000 (GMT) Received: from li-4c4c4544-004d-4810-8043-b7c04f423534.ibm.com.com (unknown [9.61.26.94]) by smtpav06.wdc07v.mail.ibm.com (Postfix) with ESMTP; Tue, 18 Aug 2026 11:58:20 +0000 (GMT) From: Anthony Krowiak To: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: jjherne@linux.ibm.com, borntraeger@de.ibm.com, mjrosato@linux.ibm.com, pasic@linux.ibm.com, alex@shazbot.org, kwankhede@nvidia.com, fiuczy@linux.ibm.com, pbonzini@redhat.com, frankja@linux.ibm.com, imbrenda@linux.ibm.com, agordeev@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, stable@vger.kernel.org Subject: [PATCH] s390/vfio-ap: Fix leak of KVM GISC resources Date: Tue, 18 Aug 2026 07:58:19 -0400 Message-ID: <20260818115819.1656595-1-akrowiak@linux.ibm.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODE4MDA4NSBTYWx0ZWRfX2EzqcBrKuhvS XpHh5i72HwdU1BJ/mqpMmO+qB9NkzB0hqN8aBEFqSEv9sjzGGRMzDna7i1rhY58+PnZb7B1jWig 9j+UqPV1TAsqkqC161ZtRdq+/ZiGggYDbVpp9DLXyLz2++4KnBnbNNboXFd4701eQkXiHAoA7EC feMbsvNl1MrzEVy1+P7lHpMm4NoCXaJVLKkKLp7I4Ke7nSehkPmV+z3TXMss2OQ3kd9uKsM2+CK BhzopblItr2TEgBBu7bUCQKMWgD5VMyVjsK50KdeRKDB/H0a/efRtRC3vTZy8CNcrhVSQ5H239N XZ52HSGio594Uq/AcpubIpfYDDfpwO3P3l/y3tKhI6o8IzonM/AWm9nCycOf3ymVAJtw2o9PRwo xIT7+Q9mV/3PVHARpQ2fFNLjFR5P30sywVUFCNEukfiidbqWpQoT1OIDq3B1cP5tHclQweAA8Yy CKJhPX/UJfwacZasr5A== X-Authority-Analysis: v=2.4 cv=DY8nbPtW c=1 sm=1 tr=0 ts=6a8448e0 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=dWikMghobCptM3iWzFMA:9 X-Proofpoint-ORIG-GUID: uQ8iEsBcJzv9tCGQe9NG0AzK7yKKN-KG X-Proofpoint-GUID: uQ8iEsBcJzv9tCGQe9NG0AzK7yKKN-KG X-Proofpoint-Spam-Info: AW1haW4tMjYwODE4MDA4NSBTYWx0ZWRfX/XtY6tquMdhO 9TjbThnfm2mEizqO31HblDLwXX9jTYaUXU9kDEPNtjjcLgRUd2L4HSuULve8zVN938ZPMrH5sJ5 zw6t7MTh3klDb1GKuIuCLaoxHKSv0H8= 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=2026-08-18_01,2026-08-12_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 clxscore=1015 spamscore=0 malwarescore=0 priorityscore=1501 impostorscore=0 lowpriorityscore=0 phishscore=0 suspectscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608180085 s390/vfio-ap: fix KVM GISC and page leak when queue removed from host config Two related problems exist in the handling of KVM interrupt and page resources when a queue is removed from the host's AP configuration while assigned to a mediated device (mdev). Problem 1: AP_RESPONSE_Q_NOT_AVAIL not handled in vfio_ap_mdev_reset_queue() When the AP bus removes a queue device whose adapter or domain has been removed from the host's AP configuration, vfio_ap_mdev_remove_queue() is called. If the queue is still in the host's AP configuration at that point, it calls vfio_ap_mdev_reset_queue(), which issues a PQAP(ZAPQ). Since the adapter is already gone from the host configuration, ap_zapq() returns AP_RESPONSE_Q_NOT_AVAIL (0x01). This response code is not handled in vfio_ap_mdev_reset_queue()'s switch statement and falls through to the default case, which issues a WARN but does not call vfio_ap_free_aqic_resources(). As a result, if IRQ handling was enabled for the queue by the guest, the KVM GISC registration and the pinned guest page holding the notification indicator byte (NIB) are both leaked. This is fixed by adding AP_RESPONSE_Q_NOT_AVAIL to the same case as AP_RESPONSE_DECONFIGURED and AP_RESPONSE_CHECKSTOPPED in vfio_ap_mdev_reset_queue(). Like those response codes, Q_NOT_AVAIL indicates the queue is not operational and no further reset attempts are possible; the correct action is to free the IRQ resources immediately. Problem 2: vfio_ap_free_aqic_resources() leaks saved_isc when kvm is NULL vfio_ap_free_aqic_resources() guards the call to kvm_s390_gisc_unregister() with: if (q->saved_isc != VFIO_AP_ISC_INVALID && !WARN_ON(!(q->matrix_mdev && q->matrix_mdev->kvm))) If matrix_mdev->kvm is NULL -- which can happen when vfio_ap_mdev_unset_kvm() has already run and cleared kvm before a subsequent cleanup path reaches this function -- the WARN_ON fires and the entire block is skipped. This leaves q->saved_isc set to a non-invalid value, creating a potential double-free on any subsequent call to this function. When kvm is NULL the KVM guest is already torn down, so kvm_s390_gisc_unregister() need not and cannot be called; however, q->saved_isc must always be cleared. Fix this by separating the kvm_s390_gisc_unregister() call from the q->saved_isc reset. The WARN_ON now guards only the genuinely impossible case of matrix_mdev being NULL. A NULL kvm is handled gracefully by skipping only the unregister call, and q->saved_isc = VFIO_AP_ISC_INVALID is set unconditionally whenever saved_isc was not already invalid. Additionally, add an else clause to the host-config check in vfio_ap_mdev_remove_queue() to call vfio_ap_free_aqic_resources() directly when the queue is not in the host's AP configuration. This serves as a backstop: when the AP bus fires the driver .remove callback after an adapter is removed from the host config, the queue is by definition no longer addressable, so vfio_ap_mdev_reset_queue() would always return Q_NOT_AVAIL. The else clause handles this case directly without the unnecessary ap_zapq() call, and ensures cleanup occurs even if kvm has already been set to NULL by a prior call to vfio_ap_mdev_unset_kvm(). Fixes: b9bd10c43456d ("s390/vfio-ap: do not reset queue removed from host config") Cc: stable@vger.kernel.org Signed-off-by: Anthony Krowiak --- drivers/s390/crypto/vfio_ap_ops.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c index 44b3a1dcc1b3..e277062e92be 100644 --- a/drivers/s390/crypto/vfio_ap_ops.c +++ b/drivers/s390/crypto/vfio_ap_ops.c @@ -270,9 +270,9 @@ static void vfio_ap_free_aqic_resources(struct vfio_ap_queue *q) { if (!q) return; - if (q->saved_isc != VFIO_AP_ISC_INVALID && - !WARN_ON(!(q->matrix_mdev && q->matrix_mdev->kvm))) { - kvm_s390_gisc_unregister(q->matrix_mdev->kvm, q->saved_isc); + if (q->saved_isc != VFIO_AP_ISC_INVALID) { + if (!WARN_ON(!q->matrix_mdev) && q->matrix_mdev->kvm) + kvm_s390_gisc_unregister(q->matrix_mdev->kvm, q->saved_isc); q->saved_isc = VFIO_AP_ISC_INVALID; } if (q->saved_iova && !WARN_ON(!q->matrix_mdev)) { @@ -2004,6 +2004,7 @@ static void vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q) break; case AP_RESPONSE_DECONFIGURED: case AP_RESPONSE_CHECKSTOPPED: + case AP_RESPONSE_Q_NOT_AVAIL: vfio_ap_free_aqic_resources(q); break; default: @@ -2499,12 +2500,15 @@ void vfio_ap_mdev_remove_queue(struct ap_device *apdev) /* * If the queue is not in the host's AP configuration, then resetting * it will fail with response code 01, (APQN not valid); so, let's make - * sure it is in the host's config. + * sure it is in the host's config. If it is not, free the KVM GISC + * resources. */ if (test_bit_inv(apid, (unsigned long *)matrix_dev->info.apm) && test_bit_inv(apqi, (unsigned long *)matrix_dev->info.aqm)) { vfio_ap_mdev_reset_queue(q); flush_work(&q->reset_work); + } else { + vfio_ap_free_aqic_resources(q); } done: -- 2.53.0