From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (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 B310E28DC4; Wed, 20 May 2026 17:11:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.158.5 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779297083; cv=none; b=EeRv+gMwyjOV6T2tPUkiF4w+jwvqQzVxwCwO532D9S4eI29ncAkytHgo/hU914KfLQ4t1txfyIzRxIOEWDS0s7wPvqtgny/ByYxHX3d83n99akkuyJQ1vG4tQrJIDpCKV/o4o21etGew7Z9Uvx01L/vcZmAZazSfYylOVY017iY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779297083; c=relaxed/simple; bh=+ANx1Fg2CXSc4kvWW7/srV3haQCn9ZU6yeMizd6WObY=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=sxOsKTpRMApVxuSvdicZHeY4e4vdQaSvAF6Sq3FEj07Z1poqpKe0EhwjsFzXkY/c4KJsIIAKlDaOqQvy1VfnfYrEHigES0KHa9fi8tFvl1CGrviJmY/KB4VnY9z1JUDFOyNshtSbR3NQ+fUs9Dsp0mqWjwkWvyo/U6E6Eh6WgvQ= 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=N59oJtCL; arc=none smtp.client-ip=148.163.158.5 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="N59oJtCL" Received: from pps.filterd (m0353725.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 64KCGqnV223129; Wed, 20 May 2026 17:11:17 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:date:from:message-id:mime-version :subject:to; s=pp1; bh=kmcB/qs4A3VRgHLFn/GGJi/agcECc5rJf3+ETSPpx Mc=; b=N59oJtCLjprf/c6zMEg2FdZz6GZvrunrXCAosVRYaDM5waVo6GB0LCv+A njKAp6ICBAOtot9mlvb4l4BUP2rxrB5a2VztKVP4td0CElQDRxDGxi1zdzrOxkbZ sM2dFN+1RLhAW2pEDm0Uf0gN93zeADPoUeoJcQyi/5MRWSWUs6Heu0YuB0B5GyPu 6oVwyvubPRYI9RyskgKBSxcSz3sI0pQiOqxk0T9zIOajWffbjRnvqJ4QU+AIb0fq 7v5eLDKbDmWBJsMRQkoG/zKPyV1VZq0wY4dB4PWl3FQG0wBWM3Jr9E/+GTX1R326 BnJecsZ9bazHMs70NgJFcjWto80Pw== Received: from ppma13.dal12v.mail.ibm.com (dd.9e.1632.ip4.static.sl-reverse.com [50.22.158.221]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4e6h88j51b-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 20 May 2026 17:11:17 +0000 (GMT) Received: from pps.filterd (ppma13.dal12v.mail.ibm.com [127.0.0.1]) by ppma13.dal12v.mail.ibm.com (8.18.1.7/8.18.1.7) with ESMTP id 64KH9ApM014280; Wed, 20 May 2026 17:11:16 GMT Received: from smtprelay05.wdc07v.mail.ibm.com ([172.16.1.72]) by ppma13.dal12v.mail.ibm.com (PPS) with ESMTPS id 4e754gg308-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 20 May 2026 17:11:16 +0000 (GMT) Received: from smtpav01.wdc07v.mail.ibm.com (smtpav01.wdc07v.mail.ibm.com [10.39.53.228]) by smtprelay05.wdc07v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 64KHBF3V21234388 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 20 May 2026 17:11:15 GMT Received: from smtpav01.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 37DA458059; Wed, 20 May 2026 17:11:15 +0000 (GMT) Received: from smtpav01.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4ABA858055; Wed, 20 May 2026 17:11:14 +0000 (GMT) Received: from IBM-D32RQW3.ibm.com (unknown [9.61.255.46]) by smtpav01.wdc07v.mail.ibm.com (Postfix) with ESMTP; Wed, 20 May 2026 17:11:14 +0000 (GMT) From: Farhan Ali To: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org Cc: helgaas@kernel.org, alex@shazbot.org, alifm@linux.ibm.com, schnelle@linux.ibm.com, mjrosato@linux.ibm.com Subject: [PATCH v17 0/7] Error recovery for vfio-pci devices on s390x Date: Wed, 20 May 2026 10:11:06 -0700 Message-ID: <20260520171113.1111-1-alifm@linux.ibm.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: oGYD8o1q0JdiEU-adNN7Krk8GdqEvHek X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE2NiBTYWx0ZWRfXxkXaLoE+IUPS g/TNXeIW+LQj/5irCTkugghme3C31xyhxyVwxoeXNy3ScpNHUVyp+KuDHszl5x7nuhKEtlb6HH/ 5aOVQ+aZ9Xu1va6G7plY4sxLY+s+heeHjr7oZHAoH7UYBBpd4tZcWjOPbjswOC5max5gWIuOO9a t2wYbAVDXFoLBthyHviG4aeQO8vCe9WuViCfmiu8ddcgfvfmSEJJXhiUSgQvBFqc4yjeOaECZTC y4lzPFF9DY5JTPgAyUszu7vtQnssE/UD7BwavCUiPBTks8NknKrFXN1sij2qsjXJd3EZPCgqO+p 7Q7PdSOgbla1NFFMnVEa71Dupk8d6RbSmROtJq/xHKtPWI5ioujJm7NryEJ+fJEeEzZNyAis/6u K3zQAl4dDhqWLJHviifhsEwRbBQwX9g+FZOw+6n7FoAuYQaMTfmzLPq3iKTeP39UxGrLn/oJlMx 4g5GaiyxFA22tMls0ZQ== X-Proofpoint-GUID: oGYD8o1q0JdiEU-adNN7Krk8GdqEvHek X-Authority-Analysis: v=2.4 cv=apyCzyZV c=1 sm=1 tr=0 ts=6a0deb35 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=4zu8aI-QVnT60ftJUTQA:9 a=O8hF6Hzn-FEA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 lowpriorityscore=0 priorityscore=1501 impostorscore=0 bulkscore=0 suspectscore=0 adultscore=0 spamscore=0 phishscore=0 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200166 Hi, This Linux kernel patch series introduces support for error recovery for passthrough PCI devices on System Z (s390x). Background ---------- For PCI devices on s390x an operating system receives platform specific error events from firmware rather than through AER.Today for passthrough/userspace devices, we don't attempt any error recovery and ignore any error events for the devices. The passthrough/userspace devices are managed by the vfio-pci driver. The driver does register error handling callbacks (error_detected), and on an error trigger an eventfd to userspace. But we need a mechanism to notify userspace (QEMU/guest/userspace drivers) about the error event. Proposal -------- We can expose this error information (currently only the PCI Error Code) via a device feature. Userspace can then obtain the error information via VFIO_DEVICE_FEATURE ioctl and take appropriate actions such as driving a device reset. This is how a typical flow for passthrough devices to a VM would work: For passthrough devices to a VM, the driver bound to the device on the host is vfio-pci. vfio-pci driver does support the error_detected() callback (vfio_pci_core_aer_err_detected()), and on an PCI error s390x recovery code on the host will call the vfio-pci error_detected() callback. The vfio-pci error_detected() callback will notify userspace/QEMU via an eventfd, and return PCI_ERS_RESULT_CAN_RECOVER. At this point the s390x error recovery on the host will skip any further action(see patch 4) and let userspace drive the error recovery. Once userspace/QEMU is notified, it then injects this error into the VM so device drivers in the VM can take recovery actions. For example for a passthrough NVMe device, the VM's OS NVMe driver will access the device. At this point the VM's NVMe driver's error_detected() will drive the recovery by returning PCI_ERS_RESULT_NEED_RESET, and the s390x error recovery in the VM's OS will try to do a reset. Resets are privileged operations and so the VM will need intervention from QEMU to perform the reset. QEMU will invoke the VFIO_DEVICE_RESET ioctl to now notify the host that the VM is requesting a reset of the device. The vfio-pci driver on the host will then perform the reset on the device to recover it. Thanks Farhan ChangeLog --------- This only includes change log from last 5 revision. Older change log is available in previous version cover letter. v16 https://lore.kernel.org/all/20260514180059.1553-1-alifm@linux.ibm.com/ v16 -> v17 - Handle ENOMEM case and remove unnecessary mutex_unlock (patch 4). - Rebase on 7.1-rc4 v15 https://lore.kernel.org/all/20260505200510.2954-1-alifm@linux.ibm.com/ v15 -> v16 - Implement error recovery to be handled in user space mode or host mode based on checking mediated_recovery only once (suggested by Niklas). - Rebase on 7.1-rc3 v14 https://lore.kernel.org/all/20260421163031.704-1-alifm@linux.ibm.com/ v14 -> v15 - Fix issues identified by Sashiko (patch 4). - Address Niklas feedback (patch 4 and patch 5). - Rebase on 7.1-rc2. v13 series https://lore.kernel.org/all/20260413210608.2912-1-alifm@linux.ibm.com/ v13 -> v14 - Remove version from vfio uAPI struct. Instead reserve additional space and add a flags field. The flags will be used to indicate any usage of the reserved space (patch 5). - Remove pending_errors from vfio uAPI struct and instead return an error to indicate no more pending error for userspace to handle (patch 5). - Rebase on recent linux master v12 series https://lore.kernel.org/all/20260330174011.1161-1-alifm@linux.ibm.com/ v12 -> v13 - Add the mediated_recovery flag as part of struct zpci_ccdf_pending and protect the struct with pending_errs_lock (patch 4). - Move dequeing pending error logic to a helper function (patch 5). - Update device feature number for VFIO_DEVICE_FEATURE_ZPCI_ERROR (patch 5). - Rebase on linux-next with tag next-20260410 Farhan Ali (7): PCI: Allow per function PCI slots to fix slot reset on s390 PCI: Avoid saving config space state if inaccessible PCI: Fail FLR when config space is inaccessible s390/pci: Store PCI error information for passthrough devices vfio-pci/zdev: Add a device feature for error information vfio/pci: Add a reset_done callback for vfio-pci driver vfio/pci: Remove the pcie check for VFIO_PCI_ERR_IRQ_INDEX arch/s390/include/asm/pci.h | 32 +++++++ arch/s390/pci/pci.c | 1 + arch/s390/pci/pci_event.c | 135 +++++++++++++++++++----------- drivers/pci/hotplug/rpaphp_slot.c | 2 +- drivers/pci/pci.c | 32 ++++++- drivers/pci/slot.c | 33 ++++++-- drivers/vfio/pci/vfio_pci_core.c | 22 +++-- drivers/vfio/pci/vfio_pci_intrs.c | 3 +- drivers/vfio/pci/vfio_pci_priv.h | 9 ++ drivers/vfio/pci/vfio_pci_zdev.c | 57 ++++++++++++- include/linux/pci.h | 8 +- include/uapi/linux/vfio.h | 30 +++++++ 12 files changed, 289 insertions(+), 75 deletions(-) -- 2.43.0