Hi, This Linux kernel patch series introduces support for error recovery for passthrough PCI devices on System Z (s390x). Background ---------- For PCI devices on s390x an operating system receives platform specific error events from firmware rather than through AER.Today for passthrough/userspace devices, we don't attempt any error recovery and ignore any error events for the devices. The passthrough/userspace devices are managed by the vfio-pci driver. The driver does register error handling callbacks (error_detected), and on an error trigger an eventfd to userspace. But we need a mechanism to notify userspace (QEMU/guest/userspace drivers) about the error event. Proposal -------- We can expose this error information (currently only the PCI Error Code) via a device feature. Userspace can then obtain the error information via VFIO_DEVICE_FEATURE ioctl and take appropriate actions such as driving a device reset. I would appreciate some feedback on this series. Thanks Farhan ChangeLog --------- v1 series https://lore.kernel.org/all/20250813170821.1115-1-alifm@xxxxxxxxxxxxx/ v1 - > v2 - Patches 1 and 2 adds some additional checks for FLR/PM reset to try other function reset method (suggested by Alex). - Patch 3 fixes a bug in s390 for resetting PCI devices with multiple functions. - Patch 7 adds a new device feature for zPCI devices for the VFIO_DEVICE_FEATURE ioctl. The ioctl is used by userspace to retriece any PCI error information for the device (suggested by Alex). - Patch 8 adds a reset_done() callback for the vfio-pci driver, to restore the state of the device after a reset. - Patch 9 removes the pcie check for triggering VFIO_PCI_ERR_IRQ_INDEX. Farhan Ali (9): PCI: Avoid restoring error values in config space PCI: Add additional checks for flr and pm reset PCI: Allow per function PCI slots for hypervisor isolated functions s390/pci: Restore airq unconditionally for the zPCI device s390/pci: Update the logic for detecting passthrough device s390/pci: Store PCI error information for passthrough devices vfio-pci/zdev: Add a device feature for error information vfio: Add a reset_done callback for vfio-pci driver vfio: Remove the pcie check for VFIO_PCI_ERR_IRQ_INDEX arch/s390/include/asm/pci.h | 30 ++++++++- arch/s390/pci/pci.c | 1 + arch/s390/pci/pci_event.c | 107 +++++++++++++++++------------- arch/s390/pci/pci_irq.c | 9 +-- drivers/pci/pci.c | 10 +++ drivers/pci/slot.c | 19 +++++- drivers/vfio/pci/vfio_pci_core.c | 20 ++++-- drivers/vfio/pci/vfio_pci_intrs.c | 3 +- drivers/vfio/pci/vfio_pci_priv.h | 8 +++ drivers/vfio/pci/vfio_pci_zdev.c | 45 ++++++++++++- include/uapi/linux/vfio.h | 14 ++++ 11 files changed, 200 insertions(+), 66 deletions(-) -- 2.43.0
