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Mon, 20 Jul 2026 20:19:33 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav06.fra02v.mail.ibm.com (Postfix) with SMTP; Mon, 20 Jul 2026 20:19:32 +0000 (GMT) Received: by tuxmaker.boeblingen.de.ibm.com (Postfix, from userid 4958) id C25821627A5; Mon, 20 Jul 2026 22:19:32 +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 Subject: [PATCH v2 6/7] s390/vfio_ccw: implement a channel program lock Date: Mon, 20 Jul 2026 22:19:30 +0200 Message-ID: <20260720201931.976660-7-farman@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260720201931.976660-1-farman@linux.ibm.com> References: <20260720201931.976660-1-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-ORIG-GUID: oKQiAWJkwtVUlFu2iQc-eTnxDsTyKDWl X-Proofpoint-Spam-Info: AW1haW4tMjYwNzIwMDIyMCBTYWx0ZWRfXzaT7+s4YclG8 dXz4QwxNZSgvpNqnpV4h2VKPBVO4gP3KzEkqPrq5KQNtb22p1AK8oyqoP1hwswxLPD6KqgsHR9O 7os0M5wGoLwEOEwjJsOGX93PGAdKJdo= X-Proofpoint-GUID: oKQiAWJkwtVUlFu2iQc-eTnxDsTyKDWl X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzIwMDIyMCBTYWx0ZWRfX+uIRxKZVqbZA L9QKJT6GXck2cVKRccWFUAbQmEZw2QduUpSwEEPneqTq819Gf7RKQoqNOBBxhZI5MLiltdag+hL +ejmTOWUs2G6lkF4i6TWZYNtFcevfJMTUjh46425hdRB6vw0E4Fg7IZi/YnwrSMkJqoRzbvgjfc UIV05K7AJ4a8s+jjj2/5PoJQ7G0eT/Ro2pd1K/qU/l3hL3VRMJAFwKTw5b21+feBafQmT5odrwz VFWstPa6SCweXHckRkJGZ97ZrFaM9bdfZuOlrMW8PMycYPIzwH5l1rBWyssu+6WvG2fYuPCx0yC X2XiIIMgL0Aq9bgFXuNNqsNbA8ATPXv+IAvBFkTQkwRrZw5JIO8FVUhJuoGGDpAiY9hGAuh23RY wraFepmM9DWZTp3jP3Y7CxLpHj7YhFB7cv1DlTTwW8ZdhfhIm4YZvOeZhGnPp9oWM71V4BosFEk S/7POXKnz5r/6afVJYQ== X-Authority-Analysis: v=2.4 cv=K7AS2SWI c=1 sm=1 tr=0 ts=6a5e82da 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=VnNF1IyMAAAA:8 a=nvEYHYHUJT7TizB4bHYA: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=2026-07-20_05,2026-07-20_03,2025-10-01_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-2607200220 The channel_program struct is manipulated without a serialization mechanism to ensure consistent behavior. Take a broad stroke of putting the entire structure behind a spin lock, which can be acquired with or without the mutex guarding the I/O regions that feed into the population of the channel program. Signed-off-by: Eric Farman --- drivers/s390/cio/vfio_ccw_cp.c | 13 ++++++++++++- drivers/s390/cio/vfio_ccw_cp.h | 1 + drivers/s390/cio/vfio_ccw_drv.c | 6 +++++- drivers/s390/cio/vfio_ccw_ops.c | 8 +++++++- drivers/s390/cio/vfio_ccw_private.h | 2 ++ 5 files changed, 27 insertions(+), 3 deletions(-) diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_c= p.c index c6f0264fb5d3..7bfb3a952817 100644 --- a/drivers/s390/cio/vfio_ccw_cp.c +++ b/drivers/s390/cio/vfio_ccw_cp.c @@ -790,7 +790,7 @@ int cp_init(struct channel_program *cp, union orb *or= b) * @cp, which must have been returned by a previous call to cp_init(). * Otherwise, undefined behavior occurs. */ -void cp_free(struct channel_program *cp) +void cp_free_locked(struct channel_program *cp) { struct vfio_device *vdev =3D &container_of(cp, struct vfio_ccw_private, cp)->vdev; @@ -810,6 +810,17 @@ void cp_free(struct channel_program *cp) } } =20 +void cp_free(struct channel_program *cp) +{ + struct vfio_ccw_private *private =3D + container_of(cp, struct vfio_ccw_private, cp); + unsigned long flags; + + spin_lock_irqsave(&private->cp_lock, flags); + cp_free_locked(cp); + spin_unlock_irqrestore(&private->cp_lock, flags); +} + /** * cp_prefetch() - translate a guest physical address channel program to * a real-device runnable channel program. diff --git a/drivers/s390/cio/vfio_ccw_cp.h b/drivers/s390/cio/vfio_ccw_c= p.h index d547dbc969cc..edfb47a292ca 100644 --- a/drivers/s390/cio/vfio_ccw_cp.h +++ b/drivers/s390/cio/vfio_ccw_cp.h @@ -48,6 +48,7 @@ struct channel_program { }; =20 int cp_init(struct channel_program *cp, union orb *orb); +void cp_free_locked(struct channel_program *cp); void cp_free(struct channel_program *cp); int cp_prefetch(struct channel_program *cp); union orb *cp_get_orb(struct channel_program *cp, struct subchannel *sch= ); diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_= drv.c index 1a095085bc72..bfb68de6e52c 100644 --- a/drivers/s390/cio/vfio_ccw_drv.c +++ b/drivers/s390/cio/vfio_ccw_drv.c @@ -83,6 +83,7 @@ void vfio_ccw_sch_io_todo(struct work_struct *work) { struct vfio_ccw_private *private; struct irb *irb; + unsigned long flags; bool is_final; bool cp_is_finished =3D false; =20 @@ -91,13 +92,16 @@ void vfio_ccw_sch_io_todo(struct work_struct *work) =20 is_final =3D !(scsw_actl(&irb->scsw) & (SCSW_ACTL_DEVACT | SCSW_ACTL_SCHACT)); + spin_lock_irqsave(&private->cp_lock, flags); if (scsw_is_solicited(&irb->scsw)) { cp_update_scsw(&private->cp, &irb->scsw); if (is_final && private->state =3D=3D VFIO_CCW_STATE_CP_PENDING) { - cp_free(&private->cp); + cp_free_locked(&private->cp); cp_is_finished =3D true; } } + spin_unlock_irqrestore(&private->cp_lock, flags); + mutex_lock(&private->io_mutex); memcpy(private->io_region->irb_area, irb, sizeof(*irb)); mutex_unlock(&private->io_mutex); diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_= ops.c index e695cd985369..d2475b3158cf 100644 --- a/drivers/s390/cio/vfio_ccw_ops.c +++ b/drivers/s390/cio/vfio_ccw_ops.c @@ -36,10 +36,15 @@ static void vfio_ccw_dma_unmap(struct vfio_device *vd= ev, u64 iova, u64 length) { struct vfio_ccw_private *private =3D container_of(vdev, struct vfio_ccw_private, vdev); + unsigned long flags; =20 /* Drivers MUST unpin pages in response to an invalidation. */ - if (!cp_iova_pinned(&private->cp, iova, length)) + spin_lock_irqsave(&private->cp_lock, flags); + if (!cp_iova_pinned(&private->cp, iova, length)) { + spin_unlock_irqrestore(&private->cp_lock, flags); return; + } + spin_unlock_irqrestore(&private->cp_lock, flags); =20 vfio_ccw_mdev_reset(private); } @@ -54,6 +59,7 @@ 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->cp_lock); =20 private->cp.guest_cp =3D kzalloc_objs(struct ccw1, CCWCHAIN_LEN_MAX); if (!private->cp.guest_cp) diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_= ccw_private.h index 0501d4bbcdbd..061b594fde36 100644 --- a/drivers/s390/cio/vfio_ccw_private.h +++ b/drivers/s390/cio/vfio_ccw_private.h @@ -115,7 +115,9 @@ struct vfio_ccw_private { struct ccw_crw_region *crw_region; int num_regions; =20 + spinlock_t cp_lock; struct channel_program cp; + struct irb irb; union scsw scsw; struct list_head crw; --=20 2.53.0