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Thu, 23 Jul 2026 17:47:54 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav03.fra02v.mail.ibm.com (Postfix) with SMTP; Thu, 23 Jul 2026 17:47:54 +0000 (GMT) Received: by tuxmaker.boeblingen.de.ibm.com (Postfix, from userid 4958) id AE4F7162803; Thu, 23 Jul 2026 19:47:54 +0200 (CEST) From: Eric Farman To: linux-s390@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Matthew Rosato , Halil Pasic , Christian Borntraeger , Eric Farman , stable@vger.kernel.org, Farhan Ali Subject: [PATCH v3 8/8] s390/vfio_ccw: implement a crw lock Date: Thu, 23 Jul 2026 19:47:51 +0200 Message-ID: <20260723174751.1180334-9-farman@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260723174751.1180334-1-farman@linux.ibm.com> References: <20260723174751.1180334-1-farman@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: bgtAFuClzCIx4xB1kz-Rtd-FR0vDqFZD X-Proofpoint-Spam-Info: AW1haW4tMjYwNzIzMDE3MyBTYWx0ZWRfX1jYqx8JkMBk2 mnUYKqO0HRDT+e1h+vGX+aKzTY3Oke3Rhv/pSeUdCyVKVBXdl2bcrSKLNuhMFAiFoTMsxC+E6Sl l7Zi4y/AZYglMFHdjPRM5kMgjlN8fUk= X-Proofpoint-GUID: bgtAFuClzCIx4xB1kz-Rtd-FR0vDqFZD X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzIzMDE3MyBTYWx0ZWRfX2QGs2z+kanpQ nku7+8W0kgkwzBSXOehsAnNsQDvfvb1+LzFt/0a0iogap2y4hqmrllO3jY8AVOSh1sbia2Cd+XO uzH1ti2JsnXDfZP6fyz4e5TzqoqFTZM1eLeX/Ns8XPxJWFh8Bvu9PeILH3awOZAEwGzqG/Ee4oT YEkDTOGyxS3G0xchZBmscd8AfDKeBsaHDMGlyPGjb/5OSlB7Z31Bjqf216YKskt0PhmLFV1NZdS 6n8ihQ80yBuOEwzEy3Fz2WZ29sq7NrocB6/iNgjsejKxd0Cx/PpoRRfxX8wPel4AixV2agNeHe1 d6E6x+h1l6WAVVuhCUOkt046Ox5G9Bw/MQitBsiXiQaXbCUGjIdxuTmiyC/gU8KDsilXXQlBSLy N81WeB/A6mUoAv6vOO2qoewI+kBf8hIyBnOp3mrKi8IchJk3NlD3aiTHZ9zQX7ZeYSZI3tub2jO qw290ZkvcJOpMuMjGqw== X-Authority-Analysis: v=2.4 cv=K7AS2SWI c=1 sm=1 tr=0 ts=6a6253d0 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=0_ASXfQLkdswD2wDWUsA:9 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-23_05,2026-07-22_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 suspectscore=0 bulkscore=0 clxscore=1015 priorityscore=1501 spamscore=0 phishscore=0 malwarescore=0 adultscore=0 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607230173 Unlike the channel_program struct, which covers synchronous I/O submissions and asynchronous interrupts, the CRW region relies exclusively on asynchronous events coming from hardware. Implement a lock to manage the list of those payloads, to ensure they are read cohesively. Fixes: 3f02cb2fd9d2 ("vfio-ccw: Wire up the CRW irq and CRW region") Cc: stable@vger.kernel.org Cc: Farhan Ali Signed-off-by: Eric Farman --- drivers/s390/cio/vfio_ccw_chp.c | 17 +++++++++++------ drivers/s390/cio/vfio_ccw_drv.c | 4 ++++ drivers/s390/cio/vfio_ccw_ops.c | 3 +++ drivers/s390/cio/vfio_ccw_private.h | 2 ++ 4 files changed, 20 insertions(+), 6 deletions(-) diff --git a/drivers/s390/cio/vfio_ccw_chp.c b/drivers/s390/cio/vfio_ccw_= chp.c index bf678270c457..3d05aaf790fa 100644 --- a/drivers/s390/cio/vfio_ccw_chp.c +++ b/drivers/s390/cio/vfio_ccw_chp.c @@ -93,15 +93,19 @@ static ssize_t vfio_ccw_crw_region_read(struct vfio_c= cw_private *private, if (pos + count > sizeof(*region)) return -EINVAL; =20 + mutex_lock(&private->io_mutex); + i =3D array_index_nospec(i, private->num_regions); + region =3D private->region[i].data; + + spin_lock(&private->crw_lock); crw =3D list_first_entry_or_null(&private->crw, struct vfio_ccw_crw, next); =20 if (crw) list_del(&crw->next); =20 - mutex_lock(&private->io_mutex); - i =3D array_index_nospec(i, private->num_regions); - region =3D private->region[i].data; + /* Drop CRW lock while copying to userspace */ + spin_unlock(&private->crw_lock); =20 if (crw) memcpy(®ion->crw, &crw->crw, sizeof(region->crw)); @@ -112,14 +116,15 @@ static ssize_t vfio_ccw_crw_region_read(struct vfio= _ccw_private *private, ret =3D count; =20 region->crw =3D 0; - - mutex_unlock(&private->io_mutex); - kfree(crw); =20 /* Notify the guest if more CRWs are on our queue */ + spin_lock(&private->crw_lock); if (!list_empty(&private->crw) && private->crw_trigger) eventfd_signal(private->crw_trigger); + spin_unlock(&private->crw_lock); + + mutex_unlock(&private->io_mutex); =20 return ret; } diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_= drv.c index 1d8c2ed9da50..2c0a27851342 100644 --- a/drivers/s390/cio/vfio_ccw_drv.c +++ b/drivers/s390/cio/vfio_ccw_drv.c @@ -125,8 +125,10 @@ void vfio_ccw_crw_todo(struct work_struct *work) =20 private =3D container_of(work, struct vfio_ccw_private, crw_work); =20 + spin_lock(&private->crw_lock); if (!list_empty(&private->crw) && private->crw_trigger) eventfd_signal(private->crw_trigger); + spin_unlock(&private->crw_lock); } =20 /* @@ -300,7 +302,9 @@ static void vfio_ccw_queue_crw(struct vfio_ccw_privat= e *private, crw->crw.erc =3D erc; crw->crw.rsid =3D rsid; =20 + spin_lock(&private->crw_lock); list_add_tail(&crw->next, &private->crw); + spin_unlock(&private->crw_lock); queue_work(vfio_ccw_work_q, &private->crw_work); } =20 diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_= ops.c index 04800cfa779b..277138f14b25 100644 --- a/drivers/s390/cio/vfio_ccw_ops.c +++ b/drivers/s390/cio/vfio_ccw_ops.c @@ -60,6 +60,7 @@ static int vfio_ccw_mdev_init_dev(struct vfio_device *v= dev) INIT_LIST_HEAD(&private->crw); INIT_WORK(&private->io_work, vfio_ccw_sch_io_todo); INIT_WORK(&private->crw_work, vfio_ccw_crw_todo); + spin_lock_init(&private->crw_lock); =20 private->cp.guest_cp =3D kzalloc_objs(struct ccw1, CCWCHAIN_LEN_MAX); if (!private->cp.guest_cp) @@ -138,10 +139,12 @@ static void vfio_ccw_mdev_release_dev(struct vfio_d= evice *vdev) container_of(vdev, struct vfio_ccw_private, vdev); struct vfio_ccw_crw *crw, *temp; =20 + spin_lock(&private->crw_lock); list_for_each_entry_safe(crw, temp, &private->crw, next) { list_del(&crw->next); kfree(crw); } + spin_unlock(&private->crw_lock); =20 kmem_cache_free(vfio_ccw_crw_region, private->crw_region); kmem_cache_free(vfio_ccw_schib_region, private->schib_region); diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_= ccw_private.h index ac5aaa78a74b..2562679b5ef5 100644 --- a/drivers/s390/cio/vfio_ccw_private.h +++ b/drivers/s390/cio/vfio_ccw_private.h @@ -121,6 +121,8 @@ struct vfio_ccw_private { =20 struct irb irb; union scsw scsw; + + spinlock_t crw_lock; struct list_head crw; =20 struct eventfd_ctx *io_trigger; --=20 2.53.0