Also posted a QEMU series utilizing these kernel patches
https://lore.kernel.org/qemu-devel/20250813174152.1238-1-alifm@linux.ibm.com/
Thanks
Farhan
On 8/13/2025 10:08 AM, Farhan Ali wrote:
> 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 specific memory region for s390 vfio pci devices. Userspace can then read
> the memory region to obtain the error information and take appropriate actions
> such as driving a device reset. The memory region provides some flexibility in
> providing more information in the future if required.
>
> I would appreciate some feedback on this approach.
>
> Thanks
> Farhan
>
> Farhan Ali (6):
> 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: Setup a zpci memory region for error information
> vfio-pci/zdev: Perform platform specific function reset for zPCI
> vfio: Allow error notification and recovery for ISM device
>
> arch/s390/include/asm/pci.h | 29 +++++++
> arch/s390/pci/pci.c | 2 +
> arch/s390/pci/pci_event.c | 107 ++++++++++++++-----------
> arch/s390/pci/pci_irq.c | 3 +-
> drivers/vfio/pci/vfio_pci_core.c | 22 +++++-
> drivers/vfio/pci/vfio_pci_intrs.c | 2 +-
> drivers/vfio/pci/vfio_pci_priv.h | 8 ++
> drivers/vfio/pci/vfio_pci_zdev.c | 126 +++++++++++++++++++++++++++++-
> include/uapi/linux/vfio.h | 2 +
> include/uapi/linux/vfio_zdev.h | 5 ++
> 10 files changed, 253 insertions(+), 53 deletions(-)
>