From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8878B366541; Mon, 3 Aug 2026 16:09:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.156.1 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785773377; cv=none; b=O/KeUqoRCE7VvMDKwQ0y0Pud1hZt/rWU06LUK251CxCuDTPIb8Zz/PONszxSlPf4IU0xlI+SBNaU0nEsLXVTudjW8AkUfu0aPaOH3y1d6SmVP1VfVM3yOsttGVPfo/d3mO68U4O1928tTLiKfSLqEqI7wgt4ZrIpPTshNrptkvw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785773377; c=relaxed/simple; bh=MZLGhTpmCf0HmPw0E/FT+7gUpJf24jGlVzBJFBZ/1iE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=od+1nCUiyzLDlgDOV1UrKGkhPATXehJbHRT/PEVLlNpjwExRH+ctT5IJSgDvLTVPPG5l5aYrd4MovjJpVJNeoGk6f63v0lUHQ7jkTc0/6EFAwZqtCXC7Y7gLbcJbwWwcGGNq+x/gznWxHFXqG1NBQ7rQOIIW6PzRZ0CYyEigjqk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; spf=pass smtp.mailfrom=linux.ibm.com; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b=oHQE4FzB; arc=none smtp.client-ip=148.163.156.1 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="oHQE4FzB" Received: from pps.filterd (m0360083.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 673EHioK2262062; Mon, 3 Aug 2026 16:09:33 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:date:from:in-reply-to:message-id :mime-version:references:subject:to; s=pp1; bh=ljuyx8ykhxg0q5+xX aLbOHrr4rWkFsL0MFnEbCOYrGo=; b=oHQE4FzB0gltIakS66+Js0x3f4i715e/l p7EPFsWaWfXDwdTdQ30mk3hRloNpk4DhvmA5U6xfpNGSqY8+o6MdNTytk7z2zysb IzqVVtVaELLzHSuvW1Tpf02hRKrObpmi0jEcbUeXtor9TU2yNmsi4oXLUenQ0h4U FZ02rCoRtANWNsVpj6/eIYSVA4wl2AzBAL9KIGlWmv/JK3o3zHhYOVxnlZAG2WAk zzQTPF+D8FGVyvXpYNXvkt9jkdz5KTGzzgrFDUrMVUDoAVa8dY33qwXfJep+pyBA NM0RuYq3NSlF9sHEHsRayYLBezFc83sulvhlN0V2Gb4UrMm1wObbA== Received: from ppma23.wdc07v.mail.ibm.com (5d.69.3da9.ip4.static.sl-reverse.com [169.61.105.93]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4fs8a3sqtr-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 03 Aug 2026 16:09:33 +0000 (GMT) Received: from pps.filterd (ppma23.wdc07v.mail.ibm.com [127.0.0.1]) by ppma23.wdc07v.mail.ibm.com (8.18.1.7/8.18.1.7) with ESMTP id 673FuPdG007006; Mon, 3 Aug 2026 16:09:32 GMT Received: from smtprelay02.fra02v.mail.ibm.com ([9.218.2.226]) by ppma23.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4fsvmh63u0-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 03 Aug 2026 16:09:32 +0000 (GMT) Received: from smtpav07.fra02v.mail.ibm.com (smtpav07.fra02v.mail.ibm.com [10.20.54.106]) by smtprelay02.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 673G9Qqc42926476 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 3 Aug 2026 16:09:26 GMT Received: from smtpav07.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 11F532004E; Mon, 3 Aug 2026 16:09:26 +0000 (GMT) Received: from smtpav07.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id ECBD92004B; Mon, 3 Aug 2026 16:09:25 +0000 (GMT) Received: from p-imbrenda.ehn-de.ibm.com (unknown [9.224.75.30]) by smtpav07.fra02v.mail.ibm.com (Postfix) with ESMTP; Mon, 3 Aug 2026 16:09:25 +0000 (GMT) From: Claudio Imbrenda To: pbonzini@redhat.com Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, frankja@linux.ibm.com, borntraeger@de.ibm.com Subject: [GIT PULL v1 09/23] s390/vfio_ccw: Selectively expand io_mutex Date: Mon, 3 Aug 2026 18:09:10 +0200 Message-ID: <20260803160924.236807-10-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260803160924.236807-1-imbrenda@linux.ibm.com> References: <20260803160924.236807-1-imbrenda@linux.ibm.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=E6P9Y6dl c=1 sm=1 tr=0 ts=6a70bd3d cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=VwQbUJbxAAAA:8 a=EkIAoCbfkmX2K6UF1qUA:9 X-Proofpoint-ORIG-GUID: KoRRfYZ2EOswn0WaUG925Ql96LgUtcG0 X-Proofpoint-GUID: KoRRfYZ2EOswn0WaUG925Ql96LgUtcG0 X-Proofpoint-Spam-Info: AW1haW4tMjYwODAzMDE0MSBTYWx0ZWRfX8AGEdk40dmw6 crx7xxX1r8CvmCW6cHFgSSi0ZwNmDwgK7E8rfdyUCARiyU5VoacHBXUW62LgU/Vb5QwN9c8UbLY 5t9sGpcjz7Ym8FhrbwdRQUBmV9iZv00= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODAzMDE0MSBTYWx0ZWRfXyMwfN924/Nbq FSPEZhed1nILaKQyQYiZ61IQhGj2PYLt5jYYnKO+XEVy5qd6z/xiGhJAhmPXOaZh639t2DKJRV1 c7z0C9+BxnglfQhH6VYg+8GUfqVAYqMIttkGJXOpQsvyqutsgE76cEYlU2ktouJr35fndVBNkSn BR6IT3QHpp7JyZnvyUqvCV7pdtyY+alpCgvK4f9ynzWmMb7p6YyMhJxdXL1ZekT/svxiTPK+iN3 C3gWX2hxI6MZp+ZNbsfpjEa95Qy9t54a9PMlmrfirqyz4Ay+Ucud4M9zxCoip+jp9IeKRzZrVtW Wo8gGWTCx5KZiMtG/p0jsWLK75SC9kPmc+bs033I3KfC1czvL25jI0zgnG1DaafEOGDSL8U9GwZ oMKFisu+O5Ei+T99B242GgAGZ15ZnSj9zLvIYHDDmd03sOU1NwCMz+Khi16iY5tjHeliMXFQC4R YOZmn7ALkF1WAugT8gQ== 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=2026-08-03_03,2026-08-03_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 clxscore=1015 lowpriorityscore=0 priorityscore=1501 suspectscore=0 adultscore=0 spamscore=0 malwarescore=0 impostorscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608030141 From: Eric Farman The io_mutex was defined to serialize the io_regions, but then has also sort of been associated with the I/O themselves because of the close relationship they share. With the handful of races that are possible, the choices are either to: A) expand the scope of io_mutex to close these remaining windows, or B) reduce the scope of io_mutex to just io_region, and introduce a new lock mechanism for the remaining I/O resources This patch implements A, since B brings with it a lot more interactions that would need to be tracked and kept in a correct hierarchy. It also takes advantage of the workqueue element for cp_free() that now gets called out of fsm_notoper(), which could be invoked out of an interrupt context and thus cannot acquire a mutex itself. Fixes: 4f76617378ee ("vfio-ccw: protect the I/O region") Cc: stable@vger.kernel.org Signed-off-by: Eric Farman Reviewed-by: Matthew Rosato Signed-off-by: Christian Borntraeger --- drivers/s390/cio/vfio_ccw_chp.c | 2 +- drivers/s390/cio/vfio_ccw_cp.c | 8 +++++++- drivers/s390/cio/vfio_ccw_drv.c | 6 ++++-- drivers/s390/cio/vfio_ccw_fsm.c | 5 +++++ drivers/s390/cio/vfio_ccw_private.h | 3 ++- 5 files changed, 19 insertions(+), 5 deletions(-) diff --git a/drivers/s390/cio/vfio_ccw_chp.c b/drivers/s390/cio/vfio_ccw_chp.c index f3015132d4b5..9269b54f5cfd 100644 --- a/drivers/s390/cio/vfio_ccw_chp.c +++ b/drivers/s390/cio/vfio_ccw_chp.c @@ -98,13 +98,13 @@ static ssize_t vfio_ccw_crw_region_read(struct vfio_ccw_private *private, if (pos + count > sizeof(*region)) return -EINVAL; + mutex_lock(&private->io_mutex); crw = 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 >= private->num_regions) { ret = -EINVAL; goto out; diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c index 5ef082b8289a..58722c4baa25 100644 --- a/drivers/s390/cio/vfio_ccw_cp.c +++ b/drivers/s390/cio/vfio_ccw_cp.c @@ -977,17 +977,23 @@ void cp_update_scsw(struct channel_program *cp, union scsw *scsw) */ bool cp_iova_pinned(struct channel_program *cp, u64 iova, u64 length) { + struct vfio_ccw_private *private = + container_of(cp, struct vfio_ccw_private, cp); struct ccwchain *chain; int i; if (!cp->initialized) return false; + mutex_lock(&private->io_mutex); list_for_each_entry(chain, &cp->ccwchain_list, next) { for (i = 0; i < chain->ch_len; i++) - if (page_array_iova_pinned(&chain->ch_pa[i], iova, length)) + if (page_array_iova_pinned(&chain->ch_pa[i], iova, length)) { + mutex_unlock(&private->io_mutex); return true; + } } + mutex_unlock(&private->io_mutex); return false; } diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c index c197ad5ab580..757ff5b2556e 100644 --- a/drivers/s390/cio/vfio_ccw_drv.c +++ b/drivers/s390/cio/vfio_ccw_drv.c @@ -91,6 +91,7 @@ void vfio_ccw_sch_io_todo(struct work_struct *work) is_final = !(scsw_actl(&irb->scsw) & (SCSW_ACTL_DEVACT | SCSW_ACTL_SCHACT)); + mutex_lock(&private->io_mutex); if (scsw_is_solicited(&irb->scsw)) { cp_update_scsw(&private->cp, &irb->scsw); if (is_final && private->state == VFIO_CCW_STATE_CP_PENDING) { @@ -98,9 +99,7 @@ void vfio_ccw_sch_io_todo(struct work_struct *work) cp_is_finished = true; } } - mutex_lock(&private->io_mutex); memcpy(private->io_region->irb_area, irb, sizeof(*irb)); - mutex_unlock(&private->io_mutex); /* * Reset to IDLE only if processing of a channel program @@ -110,6 +109,7 @@ void vfio_ccw_sch_io_todo(struct work_struct *work) */ if (cp_is_finished) private->state = VFIO_CCW_STATE_IDLE; + mutex_unlock(&private->io_mutex); if (private->io_trigger) eventfd_signal(private->io_trigger); @@ -131,7 +131,9 @@ void vfio_ccw_notoper_todo(struct work_struct *work) private = container_of(work, struct vfio_ccw_private, notoper_work); + mutex_lock(&private->io_mutex); cp_free(&private->cp); + mutex_unlock(&private->io_mutex); } /* diff --git a/drivers/s390/cio/vfio_ccw_fsm.c b/drivers/s390/cio/vfio_ccw_fsm.c index 4d47a3c7b9a0..5fd94e9d5c61 100644 --- a/drivers/s390/cio/vfio_ccw_fsm.c +++ b/drivers/s390/cio/vfio_ccw_fsm.c @@ -170,6 +170,7 @@ static void fsm_notoper(struct vfio_ccw_private *private, css_sched_sch_todo(sch, SCH_TODO_UNREG); private->state = VFIO_CCW_STATE_NOT_OPER; + /* This routine could be called from IRQ context, so defer */ queue_work(vfio_ccw_work_q, &private->notoper_work); } @@ -409,7 +410,11 @@ static void fsm_close(struct vfio_ccw_private *private, private->state = VFIO_CCW_STATE_STANDBY; spin_unlock_irq(&sch->lock); + + mutex_lock(&private->io_mutex); cp_free(&private->cp); + mutex_unlock(&private->io_mutex); + return; err_unlock: diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h index e2256402b089..739121116ab6 100644 --- a/drivers/s390/cio/vfio_ccw_private.h +++ b/drivers/s390/cio/vfio_ccw_private.h @@ -88,7 +88,8 @@ struct vfio_ccw_parent { * @state: internal state of the device * @completion: synchronization helper of the I/O completion * @io_region: MMIO region to input/output I/O arguments/results - * @io_mutex: protect against concurrent update of I/O regions + * @io_mutex: protect against concurrent update of I/O resources + * and @cp lifecycle * @region: additional regions for other subchannel operations * @cmd_region: MMIO region for asynchronous I/O commands other than START * @schib_region: MMIO region for SCHIB information -- 2.55.0