{"id":2222856,"url":"http://patchwork.ozlabs.org/api/patches/2222856/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-pci/patch/20260413210608.2912-2-alifm@linux.ibm.com/","project":{"id":28,"url":"http://patchwork.ozlabs.org/api/projects/28/?format=json","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":"<20260413210608.2912-2-alifm@linux.ibm.com>","list_archive_url":null,"date":"2026-04-13T21:06:02","name":"[v13,1/7] 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=json","name":"Farhan Ali","email":"alifm@linux.ibm.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/linux-pci/patch/20260413210608.2912-2-alifm@linux.ibm.com/mbox/","series":[{"id":499754,"url":"http://patchwork.ozlabs.org/api/series/499754/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-pci/list/?series=499754","date":"2026-04-13T21:06:01","name":"Error recovery for vfio-pci devices on s390x","version":13,"mbox":"http://patchwork.ozlabs.org/series/499754/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2222856/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2222856/checks/","tags":{},"related":[],"headers":{"Return-Path":"\n ","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=Vm1Mt5aE;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c0a:e001:db::12fc:5321; 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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=jQfPUqqA91bdGrgU+\n\tyThItyVt6xMwgVJ/HtFOXJWzEo=; b=Vm1Mt5aEV99EmoNsYfZX1RePbp+Kh2nKR\n\tq3VaEsz7iHz9vBlZ2Mefn+oep6xxCiNA+d+3tho+rYUEQMswhpTPs5AchXsXyUAR\n\toh9zWZ2ZaKsm7+2sBqpHfdjSIBT4ZLIQ2GWPH+xTV5DV3CnW4xUs/vn8b4RyOMnw\n\txfL+xz4UgZfeBCbWdNpppdfyVGNfnaq5Hs8/ELkZHQJ2TGge928mulWIvvJ5c50R\n\ty1NtRlMlLYBlcjYku59SyfHMdz/V4w8iHWDU+mWHBkczjF7VxsxO2adFfUORVrJ9\n\tyW4tSBvAE+ffDuHvOHWoaULbfVHxezjw3gMYqJ1IXaFK1ptBLrdMg==","From":"Farhan Ali ","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 v13 1/7] PCI: Allow per function PCI slots to fix slot reset\n on s390","Date":"Mon, 13 Apr 2026 14:06:02 -0700","Message-ID":"<20260413210608.2912-2-alifm@linux.ibm.com>","X-Mailer":"git-send-email 2.43.0","In-Reply-To":"<20260413210608.2912-1-alifm@linux.ibm.com>","References":"<20260413210608.2912-1-alifm@linux.ibm.com>","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-Spam-Details-Enc":"AW1haW4tMjYwNDEzMDIwNSBTYWx0ZWRfX/clYHEhBVv08\n pgCMhIUu0apayFOu/BPf09Cu4NongGxiRSBH9a4TPzCN13uZ+PKwFHG1jLQyWjY/tBQ9ADXpQ0K\n f4cbkVntcrZfFIMeD9RPDcPTdOoOITuHG6g9TgN9oUXyMEWA1JTKLw/SOAAnC/slUP8vw7xTyTR\n rguDXzaFw5iuuIL9bbNSpvHeJoxwZ2zbwSwGewGLsHNDDPLoUngJ+N8XqqZdpzp+sC6JYdVqU63\n IQqtwMITGqT8UC3Jgg4iUNxlnJ6tJatLGwJClohevVc9+bpbV1EJ940u586ItS/oSHkwQ7neAii\n 7rKU8Sx9OrXtafMfrTRTf79+KxC/XuW8wPnszw7pLOnMvR/wxIGQ+X/p62zTghW7ShIU4rktTY5\n bqzcxzmf/5jxH+aIHm9p9WZ6hXiPyatC8HdNiD6TESdle0JhdVznN9Z9xLm5d5e9k8ctun8tt2q\n 0cvEFUuJbO9GIcpZhjQ==","X-Proofpoint-GUID":"jcbr_TyHDvi1KHh1u12mGMgPiRWeszf5","X-Proofpoint-ORIG-GUID":"jcbr_TyHDvi1KHh1u12mGMgPiRWeszf5","X-Authority-Analysis":"v=2.4 cv=YemNIQRf c=1 sm=1 tr=0 ts=69dd5ac6 cx=c_pps\n a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17\n a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22\n a=V8glGbnc2Ofi9Qvn3v5h:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8\n a=9_SSeoq7eJPDN4OswFYA:9 a=O8hF6Hzn-FEA:10","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=2026-04-13_03,2026-04-13_04,2025-10-01_01","X-Proofpoint-Spam-Details":"rule=outbound_notspam policy=outbound score=0\n spamscore=0 adultscore=0 priorityscore=1501 lowpriorityscore=0 clxscore=1015\n impostorscore=0 bulkscore=0 malwarescore=0 suspectscore=0 phishscore=0\n classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0\n reason=mlx scancount=1 engine=8.22.0-2604010000 definitions=main-2604130205"},"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 \nReviewed-by: Niklas Schnelle \nSigned-off-by: Farhan Ali \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 8f7cfcc00090..d0c9f0166af5 100644\n--- a/drivers/pci/pci.c\n+++ b/drivers/pci/pci.c\n@@ -4865,8 +4865,9 @@ 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 2c4454583c11..d58982aa8730 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":["v13","1/7"]}