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Sat, 25 Jul 2026 15:27:09 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav06.fra02v.mail.ibm.com (Postfix) with SMTP; Sat, 25 Jul 2026 15:27:09 +0000 (GMT) Received: by tuxmaker.boeblingen.de.ibm.com (Postfix, from userid 4958) id 7707E162820; Sat, 25 Jul 2026 17:27:09 +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 v4 9/9] s390/vfio_ccw: implement a crw lock Date: Sat, 25 Jul 2026 17:27:05 +0200 Message-ID: <20260725152705.3958100-10-farman@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260725152705.3958100-1-farman@linux.ibm.com> References: <20260725152705.3958100-1-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-GUID: qBxJgc0yDB9mkazSg4M-51C7bCaushUb X-Proofpoint-ORIG-GUID: qBxJgc0yDB9mkazSg4M-51C7bCaushUb X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzI1MDE0NCBTYWx0ZWRfXyxVPmzlmgZM+ b3U4Gp/1TkyE2Kq70L4i9rj0wrTdkC5KvFr6x2y4TIrGwxPL1aR69fJsYtO4DK7ck/K/kMNdT7+ 75gWap1FVZIXb4Y/d//bBn3lE6I7Gwg+cO+8qHHcKvPvHpc1LdwWEdYYd1n2qfT9d/uKfxqPGOt 3gLGJ36223jR4nR4twHC7yQfWYL2CIuBGPqs521YB44wjnvMEzfmJ2i16xsZfRbK0N7oqyAmPmf KZYO6FVPA9U2wQqWyYEGBe2MnCAGsZuaMqfX+1sVs+lKu3uNiKiSv8u1+bh6KTF4nKoO61i5HOh WnbGZezmcFyKYEEY1qWDUhbja5N0xjLkUAsyQWj2XDqTGuvxTkodT5FNTolrIfIXdZcIM5RtdGA TYpuV/4mN+Qg3FrGvOv8ZXa4ncfBG0vfX9G7v2PWrdtXcGtrjkuxDMZty+FrUJ6vJ6uUA6kXX19 RSDaCFA5P7G4ghmRLGg== X-Authority-Analysis: v=2.4 cv=SKFykuvH c=1 sm=1 tr=0 ts=6a64d5d2 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=huIa1HNm52ewcn7HQvQA:9 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzI1MDE0NCBTYWx0ZWRfXxYDFKcPEOT8M fLKS28JktrMSuwVrK390OFylKud1NSsYl9PHoJdEOgqZ/jw/dDxMJjc5LBttz/pJ4som5Zj4nh6 P4IOJrHpibNlA+4Vq7xcAjaBZwg6vnI= 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=2026-07-25_04,2026-07-24_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 clxscore=1015 adultscore=0 lowpriorityscore=0 bulkscore=0 impostorscore=0 phishscore=0 spamscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607250144 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 | 25 +++++++++++++++---------- drivers/s390/cio/vfio_ccw_drv.c | 4 ++++ drivers/s390/cio/vfio_ccw_ops.c | 3 +++ drivers/s390/cio/vfio_ccw_private.h | 4 ++++ 4 files changed, 26 insertions(+), 10 deletions(-) diff --git a/drivers/s390/cio/vfio_ccw_chp.c b/drivers/s390/cio/vfio_ccw_= chp.c index f3015132d4b5..313c541e83eb 100644 --- a/drivers/s390/cio/vfio_ccw_chp.c +++ b/drivers/s390/cio/vfio_ccw_chp.c @@ -98,12 +98,6 @@ static ssize_t vfio_ccw_crw_region_read(struct vfio_cc= w_private *private, if (pos + count > sizeof(*region)) return -EINVAL; =20 - crw =3D list_first_entry_or_null(&private->crw, - struct vfio_ccw_crw, next); - - if (crw) - list_del(&crw->next); - mutex_lock(&private->io_mutex); if (i >=3D private->num_regions) { ret =3D -EINVAL; @@ -113,6 +107,16 @@ static ssize_t vfio_ccw_crw_region_read(struct vfio_= ccw_private *private, i =3D array_index_nospec(i, private->num_regions); region =3D private->region[i].data; =20 + spin_lock(&private->crw_lock); + crw =3D list_first_entry_or_null(&private->crw, + struct vfio_ccw_crw, next); + + if (crw) + list_del(&crw->next); + + /* Drop CRW lock while copying to userspace */ + spin_unlock(&private->crw_lock); + if (crw) memcpy(®ion->crw, &crw->crw, sizeof(region->crw)); =20 @@ -122,15 +126,16 @@ static ssize_t vfio_ccw_crw_region_read(struct vfio= _ccw_private *private, ret =3D count; =20 region->crw =3D 0; - -out: - 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); + +out: + 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 4830f0dd9c3a..32f631d08620 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 void vfio_ccw_notoper_todo(struct work_struct *work) @@ -307,7 +309,9 @@ 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 9242a37677a0..6735b5f4c07a 100644 --- a/drivers/s390/cio/vfio_ccw_ops.c +++ b/drivers/s390/cio/vfio_ccw_ops.c @@ -61,6 +61,7 @@ static int vfio_ccw_mdev_init_dev(struct vfio_device *v= dev) INIT_WORK(&private->io_work, vfio_ccw_sch_io_todo); INIT_WORK(&private->crw_work, vfio_ccw_crw_todo); INIT_WORK(&private->notoper_work, vfio_ccw_notoper_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) @@ -139,10 +140,12 @@ 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 b595fd81f370..ffa8be7547fe 100644 --- a/drivers/s390/cio/vfio_ccw_private.h +++ b/drivers/s390/cio/vfio_ccw_private.h @@ -98,6 +98,8 @@ struct vfio_ccw_parent { * @cp: channel program for the current I/O operation * @irb: irb info received from interrupt * @scsw: scsw info + * @crw_lock: serialization of CRW information + * @crw: list of Channel Report Word elements * @io_trigger: eventfd ctx for signaling userspace I/O results * @crw_trigger: eventfd ctx for signaling userspace CRW information * @req_trigger: eventfd ctx for signaling userspace to return device @@ -122,6 +124,8 @@ 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