6.6-stable review patch. If anyone has any objections, please let me know.
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From: Nishanth Aravamudan naravamudan@nvidia.com
[ Upstream commit 479380efe1625e251008d24b2810283db60d6fcd ]
After d88f521da3ef ("PCI: Allow userspace to query and set device reset mechanism"), userspace can disable reset of specific PCI devices by writing an empty string to the sysfs reset_method file.
However, pci_slot_resettable() does not check pci_reset_supported(), which means that pci_reset_function() will still reset the device even if userspace has disabled all the reset methods.
I was able to reproduce this issue with a vfio device passed to a qemu guest, where I had disabled PCI reset via sysfs.
Add an explicit check of pci_reset_supported() in both pci_slot_resettable() and pci_bus_resettable() to ensure both the reset status and reset execution are bypassed if an administrator disables it for a device.
Link: https://lore.kernel.org/r/20250207205600.1846178-1-naravamudan@nvidia.com Fixes: d88f521da3ef ("PCI: Allow userspace to query and set device reset mechanism") Signed-off-by: Nishanth Aravamudan naravamudan@nvidia.com [bhelgaas: commit log] Signed-off-by: Bjorn Helgaas bhelgaas@google.com Cc: Alex Williamson alex.williamson@redhat.com Cc: Raphael Norwitz raphael.norwitz@nutanix.com Cc: Amey Narkhede ameynarkhede03@gmail.com Cc: Jason Gunthorpe jgg@nvidia.com Cc: Yishai Hadas yishaih@nvidia.com Cc: Shameer Kolothum shameerali.kolothum.thodi@huawei.com Cc: Kevin Tian kevin.tian@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pci/pci.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 095fa1910d36d..bcce569a83395 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -5714,6 +5714,8 @@ static bool pci_bus_resettable(struct pci_bus *bus) return false;
list_for_each_entry(dev, &bus->devices, bus_list) { + if (!pci_reset_supported(dev)) + return false; if (dev->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET || (dev->subordinate && !pci_bus_resettable(dev->subordinate))) return false; @@ -5790,6 +5792,8 @@ static bool pci_slot_resettable(struct pci_slot *slot) list_for_each_entry(dev, &slot->bus->devices, bus_list) { if (!dev->slot || dev->slot != slot) continue; + if (!pci_reset_supported(dev)) + return false; if (dev->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET || (dev->subordinate && !pci_bus_resettable(dev->subordinate))) return false;