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GET /api/patches/2217835/?format=api
{ "id": 2217835, "url": "http://patchwork.ozlabs.org/api/patches/2217835/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-pci/patch/20260330174011.1161-2-alifm@linux.ibm.com/", "project": { "id": 28, "url": "http://patchwork.ozlabs.org/api/projects/28/?format=api", "name": "Linux PCI development", "link_name": "linux-pci", "list_id": "linux-pci.vger.kernel.org", "list_email": "linux-pci@vger.kernel.org", "web_url": null, "scm_url": null, "webscm_url": null, "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20260330174011.1161-2-alifm@linux.ibm.com>", "list_archive_url": null, "date": "2026-03-30T17:40:05", "name": "[v12,1/7] PCI: Allow per function PCI slots to fix slot reset on s390", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "8e7f2b0457c7e98f0c0436d5e4c94443ac3c933b", "submitter": { "id": 73785, "url": "http://patchwork.ozlabs.org/api/people/73785/?format=api", "name": "Farhan Ali", "email": "alifm@linux.ibm.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/linux-pci/patch/20260330174011.1161-2-alifm@linux.ibm.com/mbox/", "series": [ { "id": 498071, "url": "http://patchwork.ozlabs.org/api/series/498071/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-pci/list/?series=498071", "date": "2026-03-30T17:40:08", "name": "Error recovery for vfio-pci devices on s390x", "version": 12, "mbox": "http://patchwork.ozlabs.org/series/498071/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2217835/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2217835/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "\n <linux-pci+bounces-51481-incoming=patchwork.ozlabs.org@vger.kernel.org>", "X-Original-To": [ "incoming@patchwork.ozlabs.org", "linux-pci@vger.kernel.org" ], "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256\n header.s=pp1 header.b=SUEirvHq;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=172.234.253.10; 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c=relaxed/relaxed; d=ibm.com; h=cc\n\t:content-transfer-encoding:date:from:in-reply-to:message-id\n\t:mime-version:references:subject:to; s=pp1; bh=ko/PYRrBP1ZwZASqm\n\tmI5y0jvQ0bTno6kHMlVWd5SD+U=; b=SUEirvHq5e8vxhSb2lL5oXWAuR1zmAIww\n\t5lzK7wLugSxXOwzDqUXyQyY0P2bgfiF54Ot0xRi4hpQve3/iMdg4fTBAOtwGSvEH\n\tEnwd4Na68BHxDmQUUI7j4OV/26iOTPXZSYZ7q1GbAXfDk2iHB95KULoCMd04n8F8\n\t22F4Df8csh/c/DlE1/RswN0rtZR+MikhxdWp8JsJDYfTRKYpwZSd8vemkt6OQ/1j\n\t176xQfz07PSoWr5cwjvJ1IvWa4cA7eekD8ZxAW0hbskcjvpAlwj/15HpkbsLPnz7\n\tzVJtr5rKseW+nWTuWuwjATPT3JORMISMmAWBUY6L620dcNSuODYxw==", "From": "Farhan Ali <alifm@linux.ibm.com>", "To": "linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,\n linux-pci@vger.kernel.org", "Cc": "helgaas@kernel.org, lukas@wunner.de, alex@shazbot.org, clg@redhat.com,\n kbusch@kernel.org, alifm@linux.ibm.com, schnelle@linux.ibm.com,\n mjrosato@linux.ibm.com, stable@vger.kernel.org", "Subject": "[PATCH v12 1/7] PCI: Allow per function PCI slots to fix slot reset\n on s390", "Date": "Mon, 30 Mar 2026 10:40:05 -0700", "Message-ID": "<20260330174011.1161-2-alifm@linux.ibm.com>", "X-Mailer": "git-send-email 2.43.0", "In-Reply-To": "<20260330174011.1161-1-alifm@linux.ibm.com>", "References": "<20260330174011.1161-1-alifm@linux.ibm.com>", "Precedence": "bulk", "X-Mailing-List": "linux-pci@vger.kernel.org", "List-Id": "<linux-pci.vger.kernel.org>", "List-Subscribe": "<mailto:linux-pci+subscribe@vger.kernel.org>", "List-Unsubscribe": "<mailto:linux-pci+unsubscribe@vger.kernel.org>", "MIME-Version": "1.0", "Content-Transfer-Encoding": "8bit", "X-TM-AS-GCONF": "00", "X-Authority-Analysis": "v=2.4 cv=Fdo6BZ+6 c=1 sm=1 tr=0 ts=69cab581 cx=c_pps\n a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17\n a=Yq5XynenixoA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22\n a=iQ6ETzBq9ecOQQE5vZCe:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8\n a=9_SSeoq7eJPDN4OswFYA:9 a=O8hF6Hzn-FEA:10", "X-Proofpoint-ORIG-GUID": "xghHOGXHJ9l2VuVo-LHV-Uha4e3hn4WT", "X-Proofpoint-Spam-Details-Enc": "AW1haW4tMjYwMzMwMDE0MSBTYWx0ZWRfX3lL/S9qx6GCQ\n wB5PXo7ImWWXutYIPJXmaPwj5u6C0jPbzhIVLi0tCGTPVjW0HIopAoxkkhzwvSIICiZiMVJBrn4\n s3oDht6sHLMUvmYRJhi8lqaW2Jx3EORuQzBH4gBjU4VCb7jul7X1CfjmNI2E75p36VmYjnP5MAe\n krYw8fzpIm7/aezDcfVnVrqRY5IrQZiniVBeC2h+gSR8oPBBuLdpUR1Uy2k70GJuztbm7BLfVCe\n WMvo3TOLNz06LxBMqCbc3+8pqmSQj/2R/+E4vTe3a0ZhVpS2KTZue17H9Ld+MP8Ee1ngHOT9dbU\n T+8c3RDDRChVEZqG4ufQ5NK6PAvP3BXKiGeqjPQX8gnSUjh5RcsaSfc2hVjJfhhirZ6JQHzY1An\n 9zkVHzP5zPY+dLtP+G+glK2oDMl0BTKsaZfLL+UwDEwcwsJgmXZ5C7S/AUCqk1cIVx4FbdRGnd1\n yZ4Jed+btq/evKwgUxg==", "X-Proofpoint-GUID": "xghHOGXHJ9l2VuVo-LHV-Uha4e3hn4WT", "X-Proofpoint-Virus-Version": "vendor=baseguard\n engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49\n definitions=2026-03-29_05,2026-03-28_01,2025-10-01_01", "X-Proofpoint-Spam-Details": "rule=outbound_notspam policy=outbound score=0\n impostorscore=0 clxscore=1015 bulkscore=0 suspectscore=0 priorityscore=1501\n adultscore=0 malwarescore=0 phishscore=0 spamscore=0 lowpriorityscore=0\n classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0\n reason=mlx scancount=1 engine=8.22.0-2603050001 definitions=main-2603300141" }, "content": "On s390 systems, which use a machine level hypervisor, PCI devices are\nalways accessed through a form of PCI pass-through which fundamentally\noperates on a per PCI function granularity. This is also reflected in the\ns390 PCI hotplug driver which creates hotplug slots for individual PCI\nfunctions. Its reset_slot() function, which is a wrapper for\nzpci_hot_reset_device(), thus also resets individual functions.\n\nCurrently, the kernel's PCI_SLOT() macro assigns the same pci_slot object\nto multifunction devices. This approach worked fine on s390 systems that\nonly exposed virtual functions as individual PCI domains to the operating\nsystem. Since commit 44510d6fa0c0 (\"s390/pci: Handling multifunctions\")\ns390 supports exposing the topology of multifunction PCI devices by\ngrouping them in a shared PCI domain. This creates a problem when resetting\na function through the hotplug driver's slot_reset() interface.\n\nWhen attempting to reset a function through the hotplug driver, the shared\nslot assignment causes the wrong function to be reset instead of the\nintended one. It also leaks memory as we do create a pci_slot object for\nthe function, but don't correctly free it in pci_slot_release().\n\nAdd a flag for struct pci_slot to allow per function PCI slots for\nfunctions managed through a hypervisor, which exposes individual PCI\nfunctions while retaining the topology. Since we can use all 8 bits\nfor slot 'number' (for ARI devices), change slot 'number' u16 to\naccount for special values -1 and PCI_SLOT_ALL_DEVICES.\n\nFixes: 44510d6fa0c0 (\"s390/pci: Handling multifunctions\")\nCc: stable@vger.kernel.org\nSuggested-by: Niklas Schnelle <schnelle@linux.ibm.com>\nReviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>\nSigned-off-by: Farhan Ali <alifm@linux.ibm.com>\n---\n drivers/pci/hotplug/rpaphp_slot.c | 2 +-\n drivers/pci/pci.c | 5 +++--\n drivers/pci/slot.c | 33 +++++++++++++++++++++++--------\n include/linux/pci.h | 8 ++++++--\n 4 files changed, 35 insertions(+), 13 deletions(-)", "diff": "diff --git a/drivers/pci/hotplug/rpaphp_slot.c b/drivers/pci/hotplug/rpaphp_slot.c\nindex 67362e5b9971..92eabf5f61b9 100644\n--- a/drivers/pci/hotplug/rpaphp_slot.c\n+++ b/drivers/pci/hotplug/rpaphp_slot.c\n@@ -84,7 +84,7 @@ int rpaphp_register_slot(struct slot *slot)\n \tstruct hotplug_slot *php_slot = &slot->hotplug_slot;\n \tu32 my_index;\n \tint retval;\n-\tint slotno = -1;\n+\tint slotno = PCI_SLOT_PLACEHOLDER;\n \n \tdbg(\"%s registering slot:path[%pOF] index[%x], name[%s] pdomain[%x] type[%d]\\n\",\n \t\t__func__, slot->dn, slot->index, slot->name,\ndiff --git a/drivers/pci/pci.c b/drivers/pci/pci.c\nindex b4b99fb32731..70162f15a72c 100644\n--- a/drivers/pci/pci.c\n+++ b/drivers/pci/pci.c\n@@ -4867,8 +4867,9 @@ static int pci_reset_hotplug_slot(struct hotplug_slot *hotplug, bool probe)\n \n static int pci_dev_reset_slot_function(struct pci_dev *dev, bool probe)\n {\n-\tif (dev->multifunction || dev->subordinate || !dev->slot ||\n-\t dev->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET)\n+\tif (dev->subordinate || !dev->slot ||\n+\t dev->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET ||\n+\t (dev->multifunction && !dev->slot->per_func_slot))\n \t\treturn -ENOTTY;\n \n \treturn pci_reset_hotplug_slot(dev->slot->hotplug, probe);\ndiff --git a/drivers/pci/slot.c b/drivers/pci/slot.c\nindex e0b7fb43423c..3f6e5dce27a0 100644\n--- a/drivers/pci/slot.c\n+++ b/drivers/pci/slot.c\n@@ -37,7 +37,7 @@ static const struct sysfs_ops pci_slot_sysfs_ops = {\n \n static ssize_t address_read_file(struct pci_slot *slot, char *buf)\n {\n-\tif (slot->number == 0xff)\n+\tif (slot->number == (u16)PCI_SLOT_PLACEHOLDER)\n \t\treturn sysfs_emit(buf, \"%04x:%02x\\n\",\n \t\t\t\t pci_domain_nr(slot->bus),\n \t\t\t\t slot->bus->number);\n@@ -72,6 +72,23 @@ static ssize_t cur_speed_read_file(struct pci_slot *slot, char *buf)\n \treturn bus_speed_read(slot->bus->cur_bus_speed, buf);\n }\n \n+static bool pci_dev_matches_slot(struct pci_dev *dev, struct pci_slot *slot)\n+{\n+\tif (slot->per_func_slot)\n+\t\treturn dev->devfn == slot->number;\n+\n+\treturn slot->number == PCI_SLOT_ALL_DEVICES ||\n+\t\tPCI_SLOT(dev->devfn) == slot->number;\n+}\n+\n+static bool pci_slot_enabled_per_func(void)\n+{\n+\tif (IS_ENABLED(CONFIG_S390))\n+\t\treturn true;\n+\n+\treturn false;\n+}\n+\n static void pci_slot_release(struct kobject *kobj)\n {\n \tstruct pci_dev *dev;\n@@ -82,8 +99,7 @@ static void pci_slot_release(struct kobject *kobj)\n \n \tdown_read(&pci_bus_sem);\n \tlist_for_each_entry(dev, &slot->bus->devices, bus_list)\n-\t\tif (slot->number == PCI_SLOT_ALL_DEVICES ||\n-\t\t PCI_SLOT(dev->devfn) == slot->number)\n+\t\tif (pci_dev_matches_slot(dev, slot))\n \t\t\tdev->slot = NULL;\n \tup_read(&pci_bus_sem);\n \n@@ -176,8 +192,7 @@ void pci_dev_assign_slot(struct pci_dev *dev)\n \n \tmutex_lock(&pci_slot_mutex);\n \tlist_for_each_entry(slot, &dev->bus->slots, list)\n-\t\tif (slot->number == PCI_SLOT_ALL_DEVICES ||\n-\t\t PCI_SLOT(dev->devfn) == slot->number)\n+\t\tif (pci_dev_matches_slot(dev, slot))\n \t\t\tdev->slot = slot;\n \tmutex_unlock(&pci_slot_mutex);\n }\n@@ -256,7 +271,7 @@ struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr,\n \n \tmutex_lock(&pci_slot_mutex);\n \n-\tif (slot_nr == -1)\n+\tif (slot_nr == PCI_SLOT_PLACEHOLDER)\n \t\tgoto placeholder;\n \n \t/*\n@@ -287,6 +302,9 @@ struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr,\n \tslot->bus = pci_bus_get(parent);\n \tslot->number = slot_nr;\n \n+\tif (pci_slot_enabled_per_func())\n+\t\tslot->per_func_slot = 1;\n+\n \tslot->kobj.kset = pci_slots_kset;\n \n \tslot_name = make_slot_name(name);\n@@ -307,8 +325,7 @@ struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr,\n \n \tdown_read(&pci_bus_sem);\n \tlist_for_each_entry(dev, &parent->devices, bus_list)\n-\t\tif (slot_nr == PCI_SLOT_ALL_DEVICES ||\n-\t\t PCI_SLOT(dev->devfn) == slot_nr)\n+\t\tif (pci_dev_matches_slot(dev, slot))\n \t\t\tdev->slot = slot;\n \tup_read(&pci_bus_sem);\n \ndiff --git a/include/linux/pci.h b/include/linux/pci.h\nindex 8861eeb4381d..ce0f7bff080a 100644\n--- a/include/linux/pci.h\n+++ b/include/linux/pci.h\n@@ -78,14 +78,18 @@\n * and, if ARI Forwarding is enabled, functions may appear to be on multiple\n * devices.\n */\n-#define PCI_SLOT_ALL_DEVICES\t0xfe\n+#define PCI_SLOT_ALL_DEVICES\t0xfeff\n+\n+/* Used to identify a slot as a placeholder */\n+#define PCI_SLOT_PLACEHOLDER\t-1\n \n /* pci_slot represents a physical slot */\n struct pci_slot {\n \tstruct pci_bus\t\t*bus;\t\t/* Bus this slot is on */\n \tstruct list_head\tlist;\t\t/* Node in list of slots */\n \tstruct hotplug_slot\t*hotplug;\t/* Hotplug info (move here) */\n-\tunsigned char\t\tnumber;\t\t/* Device nr, or PCI_SLOT_ALL_DEVICES */\n+\tu16\t\t\tnumber;\t\t/* Device nr, or PCI_SLOT_ALL_DEVICES */\n+\tunsigned int\t\tper_func_slot:1; /* Allow per function slot */\n \tstruct kobject\t\tkobj;\n };\n \n", "prefixes": [ "v12", "1/7" ] }