kernel/linux.git/drivers/pci/hotplug, branch v6.1.168

PCI: pnv_php: Fix surprise plug detection and recovery

2025-08-15T10:05:08+00:00

[ Upstream commit a2a2a6fc2469524caa713036297c542746d148dc ] 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 Signed-off-by: Sasha Levin

PCI: pnv_php: Work around switches with broken presence detection

2025-08-15T10:05:08+00:00

[ Upstream commit 80f9fc2362797538ebd4fd70a1dfa838cc2c2cdb ] 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 Signed-off-by: Sasha Levin

PCI: pnv_php: Clean up allocated IRQs on unplug

2025-08-15T10:05:08+00:00

[ Upstream commit 4668619092554e1b95c9a5ac2941ca47ba6d548a ] 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 Signed-off-by: Sasha Levin

PCI: pciehp: Don't enable HPIE when resuming in poll mode

2025-04-10T12:33:33+00:00

[ Upstream commit 527664f738afb6f2c58022cd35e63801e5dc7aec ] PCIe hotplug can operate in poll mode without interrupt handlers using a polling kthread only. eb34da60edee ("PCI: pciehp: Disable hotplug interrupt during suspend") failed to consider that and enables HPIE (Hot-Plug Interrupt Enable) unconditionally when resuming the Port. Only set HPIE if non-poll mode is in use. This makes pcie_enable_interrupt() match how pcie_enable_notification() already handles HPIE. Link: https://lore.kernel.org/r/20250321162114.3939-1-ilpo.jarvinen@linux.intel.com Fixes: eb34da60edee ("PCI: pciehp: Disable hotplug interrupt during suspend") Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Reviewed-by: Lukas Wunner Signed-off-by: Sasha Levin

PCI: cpqphp: Fix PCIBIOS_* return value confusion

2024-12-14T18:53:44+00:00

[ Upstream commit e2226dbc4a4919d9c8bd9293299b532090bdf020 ] Code in and related to PCI_RefinedAccessConfig() has three types of return type confusion: - PCI_RefinedAccessConfig() tests pci_bus_read_config_dword() return value against -1. - PCI_RefinedAccessConfig() returns both -1 and PCIBIOS_* return codes. - Callers of PCI_RefinedAccessConfig() only test for -1. Make PCI_RefinedAccessConfig() return PCIBIOS_* codes consistently and adapt callers accordingly. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Link: https://lore.kernel.org/r/20241022091140.3504-2-ilpo.jarvinen@linux.intel.com Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Signed-off-by: Sasha Levin

PCI: cpqphp: Use PCI_POSSIBLE_ERROR() to check config reads

2024-12-14T18:53:44+00:00

[ Upstream commit 87d5403378cccc557af9e02a8a2c8587ad8b7e9a ] Use PCI_POSSIBLE_ERROR() to check the response we get when we read data from hardware. This unifies PCI error response checking and makes error checks consistent and easier to find. Link: https://lore.kernel.org/r/20240806065050.28725-1-412574090@163.com Signed-off-by: weiyufeng Signed-off-by: Bjorn Helgaas Stable-dep-of: e2226dbc4a49 ("PCI: cpqphp: Fix PCIBIOS_* return value confusion") Signed-off-by: Sasha Levin

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

2024-09-12T09:10:23+00:00

[ Upstream commit 335e35b748527f0c06ded9eebb65387f60647fda ] 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 Signed-off-by: Sasha Levin

Revert "PCI: acpiphp: Reassign resources on bridge if necessary"

2023-12-20T16:00:20+00:00

commit 5df12742b7e3aae2594a30a9d14d5d6e9e7699f4 upstream. This reverts commit 40613da52b13fb21c5566f10b287e0ca8c12c4e9 and the subsequent fix to it: cc22522fd55e ("PCI: acpiphp: Use pci_assign_unassigned_bridge_resources() only for non-root bus") 40613da52b13 fixed a problem where hot-adding a device with large BARs failed if the bridge windows programmed by firmware were not large enough. cc22522fd55e ("PCI: acpiphp: Use pci_assign_unassigned_bridge_resources() only for non-root bus") fixed a problem with 40613da52b13: an ACPI hot-add of a device on a PCI root bus (common in the virt world) or firmware sending ACPI Bus Check to non-existent Root Ports (e.g., on Dell Inspiron 7352/0W6WV0) caused a NULL pointer dereference and suspend/resume hangs. Unfortunately the combination of 40613da52b13 and cc22522fd55e caused other problems: - Fiona reported that hot-add of SCSI disks in QEMU virtual machine fails sometimes. - Dongli reported a similar problem with hot-add of SCSI disks. - Jonathan reported a console freeze during boot on bare metal due to an error in radeon GPU initialization. Revert both patches to avoid adding these problems. This means we will again see the problems with hot-adding devices with large BARs and the NULL pointer dereferences and suspend/resume issues that 40613da52b13 and cc22522fd55e were intended to fix. Fixes: 40613da52b13 ("PCI: acpiphp: Reassign resources on bridge if necessary") Fixes: cc22522fd55e ("PCI: acpiphp: Use pci_assign_unassigned_bridge_resources() only for non-root bus") Reported-by: Fiona Ebner Closes: https://lore.kernel.org/r/9eb669c0-d8f2-431d-a700-6da13053ae54@proxmox.com Reported-by: Dongli Zhang Closes: https://lore.kernel.org/r/3c4a446a-b167-11b8-f36f-d3c1b49b42e9@oracle.com Reported-by: Jonathan Woithe Closes: https://lore.kernel.org/r/ZXpaNCLiDM+Kv38H@marvin.atrad.com.au Signed-off-by: Bjorn Helgaas Acked-by: Michael S. Tsirkin Acked-by: Igor Mammedov Cc: Signed-off-by: Greg Kroah-Hartman

PCI: pciehp: Use RMW accessors for changing LNKCTL

2023-09-13T07:42:46+00:00

[ Upstream commit 5f75f96c61039151c193775d776fde42477eace1 ] As hotplug is not the only driver touching LNKCTL, use the RMW capability accessor which handles concurrent changes correctly. Suggested-by: Lukas Wunner Fixes: 7f822999e12a ("PCI: pciehp: Add Disable/enable link functions") Link: https://lore.kernel.org/r/20230717120503.15276-4-ilpo.jarvinen@linux.intel.com Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Acked-by: "Rafael J. Wysocki" Signed-off-by: Sasha Levin

PCI: acpiphp: Use pci_assign_unassigned_bridge_resources() only for non-root bus

2023-08-30T14:11:09+00:00

commit cc22522fd55e257c86d340ae9aedc122e705a435 upstream. 40613da52b13 ("PCI: acpiphp: Reassign resources on bridge if necessary") changed acpiphp hotplug to use pci_assign_unassigned_bridge_resources() which depends on bridge being available, however enable_slot() can be called without bridge associated: 1. Legitimate case of hotplug on root bus (widely used in virt world) 2. A (misbehaving) firmware, that sends ACPI Bus Check notifications to non existing root ports (Dell Inspiron 7352/0W6WV0), which end up at enable_slot(..., bridge = 0) where bus has no bridge assigned to it. acpihp doesn't know that it's a bridge, and bus specific 'PCI subsystem' can't augment ACPI context with bridge information since the PCI device to get this data from is/was not available. Issue is easy to reproduce with QEMU's 'pc' machine, which supports PCI hotplug on hostbridge slots. To reproduce, boot kernel at commit 40613da52b13 in VM started with following CLI (assuming guest root fs is installed on sda1 partition): # qemu-system-x86_64 -M pc -m 1G -enable-kvm -cpu host \ -monitor stdio -serial file:serial.log \ -kernel arch/x86/boot/bzImage \ -append "root=/dev/sda1 console=ttyS0" \ guest_disk.img Once guest OS is fully booted at qemu prompt: (qemu) device_add e1000 (check serial.log) it will cause NULL pointer dereference at: void pci_assign_unassigned_bridge_resources(struct pci_dev *bridge) { struct pci_bus *parent = bridge->subordinate; BUG: kernel NULL pointer dereference, address: 0000000000000018 ? pci_assign_unassigned_bridge_resources+0x1f/0x260 enable_slot+0x21f/0x3e0 acpiphp_hotplug_notify+0x13d/0x260 acpi_device_hotplug+0xbc/0x540 acpi_hotplug_work_fn+0x15/0x20 process_one_work+0x1f7/0x370 worker_thread+0x45/0x3b0 The issue was discovered on Dell Inspiron 7352/0W6WV0 laptop with following sequence: 1. Suspend to RAM 2. Wake up with the same backtrace being observed: 3. 2nd suspend to RAM attempt makes laptop freeze Fix it by using __pci_bus_assign_resources() instead of pci_assign_unassigned_bridge_resources() as we used to do, but only in case when bus doesn't have a bridge associated (to cover for the case of ACPI event on hostbridge or non existing root port). That lets us keep hotplug on root bus working like it used to and at the same time keeps resource reassignment usable on root ports (and other 1st level bridges) that was fixed by 40613da52b13. Fixes: 40613da52b13 ("PCI: acpiphp: Reassign resources on bridge if necessary") Link: https://lore.kernel.org/r/20230726123518.2361181-2-imammedo@redhat.com Reported-by: Woody Suwalski Tested-by: Woody Suwalski Tested-by: Michal Koutný Link: https://lore.kernel.org/r/11fc981c-af49-ce64-6b43-3e282728bd1a@gmail.com Signed-off-by: Igor Mammedov Signed-off-by: Bjorn Helgaas Acked-by: Rafael J. Wysocki Acked-by: Michael S. Tsirkin Signed-off-by: Greg Kroah-Hartman