kernel/linux.git/drivers/pci/hotplug/pnv_php.c, branch v6.19.11

PCI: Add WQ_PERCPU to alloc_workqueue() users

2026-02-26T23:01:04+00:00

[ Upstream commit 78f5d0d5a23dd81106cbe999d9dcd522964a8f1a ] Currently work items enqueued by schedule_delayed_work() use "system_wq" (a per-CPU wq), while queue_delayed_work() uses WORK_CPU_UNBOUND (used when a CPU is not specified). The same applies to schedule_work() that is using system_wq and queue_work(), that makes use again of WORK_CPU_UNBOUND. This lack of consistency cannot be addressed without refactoring the API. alloc_workqueue() treats all queues as per-CPU by default, while unbound workqueues must opt-in via WQ_UNBOUND. This default is suboptimal: most workloads benefit from unbound queues, allowing the scheduler to place worker threads where they're needed and reducing noise when CPUs are isolated. This continues the effort to refactor workqueue APIs, which began with the introduction of new workqueues and a new alloc_workqueue() flag in: 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq") 930c2ea566af ("workqueue: Add new WQ_PERCPU flag") Add WQ_PERCPU to explicitly request alloc_workqueue() to be per-CPU when WQ_UNBOUND has not been specified. With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND), any alloc_workqueue() caller that doesn't explicitly specify WQ_UNBOUND must now use WQ_PERCPU. Once migration is complete, WQ_UNBOUND can be removed and unbound will become the implicit default. Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari [bhelgaas: squash similar commits] Signed-off-by: Bjorn Helgaas Link: https://patch.msgid.link/20251107142526.234685-1-marco.crivellari@suse.com Link: https://patch.msgid.link/20251107142835.237636-1-marco.crivellari@suse.com Link: https://patch.msgid.link/20251107143108.240025-1-marco.crivellari@suse.com Link: https://patch.msgid.link/20251107143335.242342-1-marco.crivellari@suse.com Link: https://patch.msgid.link/20251107143624.244978-1-marco.crivellari@suse.com Stable-dep-of: 03f336a869b3 ("PCI: endpoint: Add missing NULL check for alloc_workqueue()") Signed-off-by: Sasha Levin

PCI: pnv_php: Enable third attention indicator state

2025-07-26T07:39:20+00:00

The PCIe specification allows three attention indicator states, on, off, and blink. Enable all three states instead of basic on / off control. This changes the userspace API (writes to the sysfs "attention" file) to match the behavior of pciehp. Here's the comparison of previous and new indicator behavior: Value Previous New Behavior ----- -------- ------------------------ 0 off (reserved, so undefined) 1 on on 2 on blink 3 on off Signed-off-by: Timothy Pearson [bhelgaas: add specifics of behavior change] Signed-off-by: Bjorn Helgaas Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/1210309411.1359866.1752615582001.JavaMail.zimbra@raptorengineeringinc.com

PCI: pnv_php: Fix surprise plug detection and recovery

2025-07-26T07:39:15+00:00

The existing PowerNV hotplug code did not handle surprise plug events correctly, leading to a complete failure of the hotplug system after device removal and a required reboot to detect new devices. This comes down to two issues: 1) When a device is surprise removed, often the bridge upstream port will cause a PE freeze on the PHB. If this freeze is not cleared, the MSI interrupts from the bridge hotplug notification logic will not be received by the kernel, stalling all plug events on all slots associated with the PE. 2) When a device is removed from a slot, regardless of surprise or programmatic removal, the associated PHB/PE ls left frozen. If this freeze is not cleared via a fundamental reset, skiboot is unable to clear the freeze and cannot retrain / rescan the slot. This also requires a reboot to clear the freeze and redetect the device in the slot. Issue the appropriate unfreeze and rescan commands on hotplug events, and don't oops on hotplug if pci_bus_to_OF_node() returns NULL. Signed-off-by: Timothy Pearson [bhelgaas: tidy comments] Signed-off-by: Bjorn Helgaas Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/171044224.1359864.1752615546988.JavaMail.zimbra@raptorengineeringinc.com

PCI: pnv_php: Work around switches with broken presence detection

2025-07-26T07:37:42+00:00

The Microsemi Switchtec PM8533 PFX 48xG3 [11f8:8533] PCIe switch system was observed to incorrectly assert the Presence Detect Set bit in its capabilities when tested on a Raptor Computing Systems Blackbird system, resulting in the hot insert path never attempting a rescan of the bus and any downstream devices not being re-detected. Work around this by additionally checking whether the PCIe data link is active or not when performing presence detection on downstream switches' ports, similar to the pciehp_hpc.c driver. Signed-off-by: Shawn Anastasio Signed-off-by: Timothy Pearson Signed-off-by: Bjorn Helgaas Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/505981576.1359853.1752615415117.JavaMail.zimbra@raptorengineeringinc.com

PCI: pnv_php: Clean up allocated IRQs on unplug

2025-07-26T07:37:10+00:00

When the root of a nested PCIe bridge configuration is unplugged, the pnv_php driver leaked the allocated IRQ resources for the child bridges' hotplug event notifications, resulting in a panic. Fix this by walking all child buses and deallocating all its IRQ resources before calling pci_hp_remove_devices(). Also modify the lifetime of the workqueue at struct pnv_php_slot::wq so that it is only destroyed in pnv_php_free_slot(), instead of pnv_php_disable_irq(). This is required since pnv_php_disable_irq() will now be called by workers triggered by hot unplug interrupts, so the workqueue needs to stay allocated. The abridged kernel panic that occurs without this patch is as follows: WARNING: CPU: 0 PID: 687 at kernel/irq/msi.c:292 msi_device_data_release+0x6c/0x9c CPU: 0 UID: 0 PID: 687 Comm: bash Not tainted 6.14.0-rc5+ #2 Call Trace: msi_device_data_release+0x34/0x9c (unreliable) release_nodes+0x64/0x13c devres_release_all+0xc0/0x140 device_del+0x2d4/0x46c pci_destroy_dev+0x5c/0x194 pci_hp_remove_devices+0x90/0x128 pci_hp_remove_devices+0x44/0x128 pnv_php_disable_slot+0x54/0xd4 power_write_file+0xf8/0x18c pci_slot_attr_store+0x40/0x5c sysfs_kf_write+0x64/0x78 kernfs_fop_write_iter+0x1b0/0x290 vfs_write+0x3bc/0x50c ksys_write+0x84/0x140 system_call_exception+0x124/0x230 system_call_vectored_common+0x15c/0x2ec Signed-off-by: Shawn Anastasio Signed-off-by: Timothy Pearson [bhelgaas: tidy comments] Signed-off-by: Bjorn Helgaas Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/2013845045.1359852.1752615367790.JavaMail.zimbra@raptorengineeringinc.com

pci/hotplug/pnv_php: Fix hotplug driver crash on Powernv

2024-07-04T13:10:40+00:00

The hotplug driver for powerpc (pci/hotplug/pnv_php.c) causes a kernel crash when we try to hot-unplug/disable the PCIe switch/bridge from the PHB. The crash occurs because although the MSI data structure has been released during disable/hot-unplug path and it has been assigned with NULL, still during unregistration the code was again trying to explicitly disable the MSI which causes the NULL pointer dereference and kernel crash. The patch fixes the check during unregistration path to prevent invoking pci_disable_msi/msix() since its data structure is already freed. Reported-by: Timothy Pearson Closes: https://lore.kernel.org/all/1981605666.2142272.1703742465927.JavaMail.zimbra@raptorengineeringinc.com/ Acked-by: Bjorn Helgaas Tested-by: Shawn Anastasio Signed-off-by: Krishna Kumar Signed-off-by: Michael Ellerman Link: https://msgid.link/20240701074513.94873-2-krishnak@linux.ibm.com

PCI: hotplug: Use FIELD_GET/PREP()

2023-10-24T15:54:04+00:00

Instead of handcrafted shifts to handle register fields, use FIELD_GET/FIELD_PREP(). Link: https://lore.kernel.org/r/20231018113254.17616-4-ilpo.jarvinen@linux.intel.com Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas

PCI: hotplug: Clean up include files

2022-04-05T16:13:33+00:00

arch/powerpc/include/asm/prom.h includes some headers that it doesn't need itself. Add the missing headers to files that include prom.h so we can remove them from prom.h. Link: https://lore.kernel.org/r/79201f5fae8d003164ac36ed3be7789db1bc5ab4.1648833421.git.christophe.leroy@csgroup.eu Signed-off-by: Christophe Leroy Signed-off-by: Bjorn Helgaas

PCI: Change the type of probe argument in reset functions

2021-08-18T22:32:42+00:00

Change the type of probe argument in functions which implement reset methods from int to bool to make the context and intent clear. Suggested-by: Alex Williamson Link: https://lore.kernel.org/r/20210817180500.1253-10-ameynarkhede03@gmail.com Signed-off-by: Amey Narkhede Signed-off-by: Bjorn Helgaas

pci/hotplug/pnv-php: Wrap warnings in macro

2020-01-23T10:31:17+00:00

An opencapi slot doesn't have an associated bridge device. It's not needed for operation, but any warning is displayed through pci_warn() which uses the pci_dev struct of the assocated bridge device. So wrap those warning so that a different trace mechanism can be used if it's an opencapi slot. Reviewed-by: Alastair D'Silva Reviewed-by: Andrew Donnellan Signed-off-by: Frederic Barrat Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20191121134918.7155-11-fbarrat@linux.ibm.com