Created attachment 307958 [details] lspci Device: Asus Zephyrus GA402RJ dGPU: RX 6700S Kernel: 6.14.2 03:00.0: dGPU (IOMMU Group 16) 03:00.1: GPU Audio Controller (IOMMU Group 17) qemu-system-x86_64: vfio: Cannot reset device 0000:03:00.1, no available reset mechanism. qemu-system-x86_64: vfio: Cannot reset device 0000:03:00.0, no available reset mechanism. BISECTED: 792bd08a41bdc309e08ff4d429f670cbb30f2b63 03:00.0 does have `bus` in `03:00.0/reset_method`, and `03:00.1` does not have `03:00.1/reset` file. Removing `03:00.1` from PCI passthrough still shows error: qemu-system-x86_64: vfio: Cannot reset device 0000:03:00.0, no available reset mechanism. Attached lspci -vv output
792bd08a41bdc309e08ff4d429f670cbb30f2b63 is stable tree commit-id commit 792bd08a41bdc309e08ff4d429f670cbb30f2b63 Author: Nishanth Aravamudan <naravamudan@nvidia.com> Date: Fri Feb 7 14:56:00 2025 -0600 PCI: Avoid reset when disabled via sysfs [ 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> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 23609dd123f9..3e78cf86ef03 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -5413,6 +5413,8 @@ 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; @@ -5489,6 +5491,8 @@ 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;
Created attachment 307959 [details] dmesg_1.log dmesg_1.log: 03:00.0 and 03:00.1
Created attachment 307960 [details] dmesg_2.log dmesg_2.log: 03:00.0 only
Created attachment 307961 [details] dmesg_3.log dmesg_3.log: 792bd08a41bdc309e08ff4d429f670cbb30f2b63 reverted
Thanks for the report and sorry for the trouble. Fix queued for v6.16: https://git.kernel.org/cgit/linux/kernel/git/pci/pci.git/commit/?id=bc0b828ef6e5 I added you as another reporter and included a link to this bugzilla.
Thanks for the support. I shall mark this as resolved.