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Mon, 20 Oct 2025 18:58:42 +0000 (GMT) Received: from IBM-D32RQW3.ibm.com (unknown [9.61.240.93]) by smtpav01.wdc07v.mail.ibm.com (Postfix) with ESMTP; Mon, 20 Oct 2025 18:58:42 +0000 (GMT) From: Farhan Ali To: alifm@linux.ibm.com Cc: stable@vger.kernel.org Subject: [PATCH v1 1/3] PCI: Allow per function PCI slots Date: Mon, 20 Oct 2025 11:58:38 -0700 Message-ID: <20251020185840.1346-2-alifm@linux.ibm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251020185840.1346-1-alifm@linux.ibm.com> References: <20251020185840.1346-1-alifm@linux.ibm.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: ALeC-u0jy_JyG4-JaiO2mJxO8EWrZaeq X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMDE4MDAyMiBTYWx0ZWRfX6AXH15n6dDdV Qax70LjOxm/Ebd3jiJ173AEV6Jftv1rA5015JBppj44wy7Kbc2Ourkyg1fRiMw559J56S60HVA+ dD1tfkUlONI17LF/IAXvBV3/gf/7oQqCSdyTJca1YB6sOfK8y0SfGGUcCoMBtsGUtboVeccTwB0 bEqzWXcHL1Ow6ADslheYguHXorowdrkxuOFyRSUJTpC+75kRisPgNxRi/SPmZAHyGTh4zZ5ULWo ZdTSHCRtrcCwJx/a7Epl1vq0Nm2bBrkrxnZ/rkc3Z5PzrggkdZfTUiZxe/CBx7tpnOBAAVSq7+l c0VVQWzqY/ZgxGn03YGCBoaXmmaZrk7K7q8CwNAx4Qn27oLUejyg5akWBrQYw6449DelmJEJGBU lcN3IMIxs6wuKPFyOMRVqerdcSsZnw== X-Authority-Analysis: v=2.4 cv=MIJtWcZl c=1 sm=1 tr=0 ts=68f68664 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=x6icFKpwvdMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=K-1LnuYzVcpd1HOvht4A:9 X-Proofpoint-ORIG-GUID: ALeC-u0jy_JyG4-JaiO2mJxO8EWrZaeq X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-10-20_05,2025-10-13_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 spamscore=0 phishscore=0 lowpriorityscore=0 adultscore=0 clxscore=1015 impostorscore=0 bulkscore=0 priorityscore=1501 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510020000 definitions=main-2510180022 On s390 systems, which use a machine level hypervisor, PCI devices are always accessed through a form of PCI pass-through which fundamentally operates on a per PCI function granularity. This is also reflected in the s390 PCI hotplug driver which creates hotplug slots for individual PCI functions. Its reset_slot() function, which is a wrapper for zpci_hot_reset_device(), thus also resets individual functions. Currently, the kernel's PCI_SLOT() macro assigns the same pci_slot object to multifunction devices. This approach worked fine on s390 systems that only exposed virtual functions as individual PCI domains to the operating system. Since commit 44510d6fa0c0 ("s390/pci: Handling multifunctions") s390 supports exposing the topology of multifunction PCI devices by grouping them in a shared PCI domain. When attempting to reset a function through the hotplug driver, the shared slot assignment causes the wrong function to be reset instead of the intended one. It also leaks memory as we do create a pci_slot object for the function, but don't correctly free it in pci_slot_release(). Add a flag for struct pci_slot to allow per function PCI slots for functions managed through a hypervisor, which exposes individual PCI functions while retaining the topology. Fixes: 44510d6fa0c0 ("s390/pci: Handling multifunctions") Cc: stable@vger.kernel.org Suggested-by: Niklas Schnelle Reviewed-by: Benjamin Block Signed-off-by: Farhan Ali --- drivers/pci/hotplug/s390_pci_hpc.c | 10 ++++++++-- drivers/pci/pci.c | 5 +++-- drivers/pci/slot.c | 14 +++++++++++--- include/linux/pci.h | 1 + 4 files changed, 23 insertions(+), 7 deletions(-) diff --git a/drivers/pci/hotplug/s390_pci_hpc.c b/drivers/pci/hotplug/s390_pci_hpc.c index d9996516f49e..8b547de464bf 100644 --- a/drivers/pci/hotplug/s390_pci_hpc.c +++ b/drivers/pci/hotplug/s390_pci_hpc.c @@ -126,14 +126,20 @@ static const struct hotplug_slot_ops s390_hotplug_slot_ops = { int zpci_init_slot(struct zpci_dev *zdev) { + int ret; char name[SLOT_NAME_SIZE]; struct zpci_bus *zbus = zdev->zbus; zdev->hotplug_slot.ops = &s390_hotplug_slot_ops; snprintf(name, SLOT_NAME_SIZE, "%08x", zdev->fid); - return pci_hp_register(&zdev->hotplug_slot, zbus->bus, - zdev->devfn, name); + ret = pci_hp_register(&zdev->hotplug_slot, zbus->bus, + zdev->devfn, name); + if (ret) + return ret; + + zdev->hotplug_slot.pci_slot->per_func_slot = 1; + return 0; } void zpci_exit_slot(struct zpci_dev *zdev) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index b14dd064006c..36ee38e0d817 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -4980,8 +4980,9 @@ static int pci_reset_hotplug_slot(struct hotplug_slot *hotplug, bool probe) static int pci_dev_reset_slot_function(struct pci_dev *dev, bool probe) { - if (dev->multifunction || dev->subordinate || !dev->slot || - dev->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET) + if (dev->subordinate || !dev->slot || + dev->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET || + (dev->multifunction && !dev->slot->per_func_slot)) return -ENOTTY; return pci_reset_hotplug_slot(dev->slot->hotplug, probe); diff --git a/drivers/pci/slot.c b/drivers/pci/slot.c index 50fb3eb595fe..51ee59e14393 100644 --- a/drivers/pci/slot.c +++ b/drivers/pci/slot.c @@ -63,6 +63,14 @@ static ssize_t cur_speed_read_file(struct pci_slot *slot, char *buf) return bus_speed_read(slot->bus->cur_bus_speed, buf); } +static bool pci_dev_matches_slot(struct pci_dev *dev, struct pci_slot *slot) +{ + if (slot->per_func_slot) + return dev->devfn == slot->number; + + return PCI_SLOT(dev->devfn) == slot->number; +} + static void pci_slot_release(struct kobject *kobj) { struct pci_dev *dev; @@ -73,7 +81,7 @@ static void pci_slot_release(struct kobject *kobj) down_read(&pci_bus_sem); list_for_each_entry(dev, &slot->bus->devices, bus_list) - if (PCI_SLOT(dev->devfn) == slot->number) + if (pci_dev_matches_slot(dev, slot)) dev->slot = NULL; up_read(&pci_bus_sem); @@ -166,7 +174,7 @@ void pci_dev_assign_slot(struct pci_dev *dev) mutex_lock(&pci_slot_mutex); list_for_each_entry(slot, &dev->bus->slots, list) - if (PCI_SLOT(dev->devfn) == slot->number) + if (pci_dev_matches_slot(dev, slot)) dev->slot = slot; mutex_unlock(&pci_slot_mutex); } @@ -285,7 +293,7 @@ struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr, down_read(&pci_bus_sem); list_for_each_entry(dev, &parent->devices, bus_list) - if (PCI_SLOT(dev->devfn) == slot_nr) + if (pci_dev_matches_slot(dev, slot)) dev->slot = slot; up_read(&pci_bus_sem); diff --git a/include/linux/pci.h b/include/linux/pci.h index d1fdf81fbe1e..6ad194597ab5 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -78,6 +78,7 @@ struct pci_slot { struct list_head list; /* Node in list of slots */ struct hotplug_slot *hotplug; /* Hotplug info (move here) */ unsigned char number; /* PCI_SLOT(pci_dev->devfn) */ + unsigned int per_func_slot:1; /* Allow per function slot */ struct kobject kobj; }; -- 2.43.0