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Sun, 26 Jul 2026 17:21:56 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav02.fra02v.mail.ibm.com (Postfix) with SMTP; Sun, 26 Jul 2026 17:21:56 +0000 (GMT) Received: by tuxmaker.boeblingen.de.ibm.com (Postfix, from userid 4958) id 92C081612A3; Sun, 26 Jul 2026 19:21:56 +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 v6 10/10] s390/vfio_ccw: implement a crw lock Date: Sun, 26 Jul 2026 19:21:53 +0200 Message-ID: <20260726172153.1818056-11-farman@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260726172153.1818056-1-farman@linux.ibm.com> References: <20260726172153.1818056-1-farman@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@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-Spam-Info: AW1haW4tMjYwNzI2MDE3NSBTYWx0ZWRfXwi+Mll8gbseR S4LNOl4aCSoXLjTgJvsmjfCc1tXl8lJ3Mvy0chUIYfhG3QXapzQDOCniXP2oA4xFNcVRd6QjPrs 2k8CdIrhBtsKy+dsczhsJwPgAYZcnjs= X-Proofpoint-GUID: esA2I2yhvpkcc4YGFJGF6szGWX3qbMHy X-Proofpoint-ORIG-GUID: esA2I2yhvpkcc4YGFJGF6szGWX3qbMHy X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzI2MDE3NSBTYWx0ZWRfX7BdvDGTDkle/ gLQ3J0/3K0J+VGIPmSCwmf333hHT1HY8Y4Rr5kDZ/MDgN6S5iFQsCBRQTVcaOV1lIB4Ncy/ooOW rBd2IUxyE+cNSJmZIZfKZGUPrD3xdioXFw+CNBKdcjTK38GU8SP/uZDPL4545dD9jcmkzdpysKs fLqKyuvWVpJ9Eh0l3pL5dlo49+QNUpxViFFG9kSJ7na5HbxCgrmQhONFi02kqKUbjZ5eBsJ2bB6 Wq94WsFuoj+zoxN5EYOl5nlQUNwTNX+yik6ne70gH/9BRNXOk3bUyvCBmx+3sDAJ0rYFjodllAy /ZvbgDiAVr5qS4WrY9h4EEIr2SWDLU8Si/rrGhk3HYE+4+xd1yu/bTq+jKrPvbJiJkyEXIGYGYC gmSuARD6H70cVXYpV3oyEa3vAO85H5VXFKz33qZlTMf0p2jw/2ovbiO90kUImKIW7yDCt9YmDdB 0t7AGAFEoTs8d24UrmA== X-Authority-Analysis: v=2.4 cv=X5Vi7mTe c=1 sm=1 tr=0 ts=6a664239 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=huIa1HNm52ewcn7HQvQA: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=2026-07-26_05,2026-07-24_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 impostorscore=0 lowpriorityscore=0 phishscore=0 priorityscore=1501 malwarescore=0 spamscore=0 suspectscore=0 bulkscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607260175 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 Reviewed-by: Matthew Rosato Signed-off-by: Eric Farman --- drivers/s390/cio/vfio_ccw_chp.c | 26 ++++++++++++++++---------- drivers/s390/cio/vfio_ccw_drv.c | 6 ++++++ drivers/s390/cio/vfio_ccw_ops.c | 4 ++++ drivers/s390/cio/vfio_ccw_private.h | 4 ++++ 4 files changed, 30 insertions(+), 10 deletions(-) diff --git a/drivers/s390/cio/vfio_ccw_chp.c b/drivers/s390/cio/vfio_ccw_= chp.c index f3015132d4b5..7708eb4d6de0 100644 --- a/drivers/s390/cio/vfio_ccw_chp.c +++ b/drivers/s390/cio/vfio_ccw_chp.c @@ -93,17 +93,12 @@ static ssize_t vfio_ccw_crw_region_read(struct vfio_c= cw_private *private, loff_t pos =3D *ppos & VFIO_CCW_OFFSET_MASK; struct ccw_crw_region *region; struct vfio_ccw_crw *crw; + unsigned long flags; int ret; =20 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 +108,16 @@ 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_irqsave(&private->crw_lock, flags); + 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_irqrestore(&private->crw_lock, flags); + if (crw) memcpy(®ion->crw, &crw->crw, sizeof(region->crw)); =20 @@ -122,15 +127,16 @@ 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_irqsave(&private->crw_lock, flags); if (!list_empty(&private->crw) && private->crw_trigger) eventfd_signal(private->crw_trigger); + spin_unlock_irqrestore(&private->crw_lock, flags); + +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 faf2de074a10..d7e93b9d491c 100644 --- a/drivers/s390/cio/vfio_ccw_drv.c +++ b/drivers/s390/cio/vfio_ccw_drv.c @@ -122,11 +122,14 @@ void vfio_ccw_sch_io_todo(struct work_struct *work) void vfio_ccw_crw_todo(struct work_struct *work) { struct vfio_ccw_private *private; + unsigned long flags; =20 private =3D container_of(work, struct vfio_ccw_private, crw_work); =20 + spin_lock_irqsave(&private->crw_lock, flags); if (!list_empty(&private->crw) && private->crw_trigger) eventfd_signal(private->crw_trigger); + spin_unlock_irqrestore(&private->crw_lock, flags); } =20 /* @@ -279,6 +282,7 @@ static void vfio_ccw_queue_crw(struct vfio_ccw_privat= e *private, unsigned int rsid) { struct vfio_ccw_crw *crw; + unsigned long flags; =20 /* * If unable to allocate a CRW, just drop the event and @@ -296,7 +300,9 @@ 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_irqsave(&private->crw_lock, flags); list_add_tail(&crw->next, &private->crw); + spin_unlock_irqrestore(&private->crw_lock, flags); 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 ddfcd2b4296f..2f28846fdf72 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) @@ -137,11 +138,14 @@ static void vfio_ccw_mdev_release_dev(struct vfio_d= evice *vdev) struct vfio_ccw_private *private =3D container_of(vdev, struct vfio_ccw_private, vdev); struct vfio_ccw_crw *crw, *temp; + unsigned long flags; =20 + spin_lock_irqsave(&private->crw_lock, flags); list_for_each_entry_safe(crw, temp, &private->crw, next) { list_del(&crw->next); kfree(crw); } + spin_unlock_irqrestore(&private->crw_lock, flags); =20 /* Should be empty, but just in case */ cancel_work_sync(&private->io_work); diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_= ccw_private.h index ac5aaa78a74b..c23430e1a78e 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 list 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 @@ -121,6 +123,8 @@ 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