Re: [PATCH] vfio/pci: Restore standard PCI config space in .slot_reset()

[Lukas Wunner <lukas@wunner.de>]

On Mon, Aug 17, 2026 at 08:04:04PM +0000, sashiko-bot@kernel.org wrote:
> [Severity: High]
> Is this callback reachable under normal single-device circumstances?
> 
> In pcie_do_recovery(), the report_slot_reset broadcast is gated behind
> checking if the combined error status is PCI_ERS_RESULT_NEED_RESET.
> 
> However, vfio_pci_core_aer_err_detected() unconditionally returns
> PCI_ERS_RESULT_CAN_RECOVER. The PCI recovery state machine promotes
> CAN_RECOVER to RECOVERED during the mmio_enabled phase, so the
> condition to call slot_reset evaluates to false unless another driver
> on the same PCIe bridge votes for NEED_RESET.

I have a patch on my development branch so that ->reset_slot() is
also invoked if (state == pci_channel_io_frozen), i.e. on Fatal Errors.

I have another patch pending to allow error recovery for unbound devices.

Both patches are available for testing on this branch and I hope to
submit them in the upcoming cycle:

https://github.com/l1k/linux/commits/aer_unbound/

> [Severity: High]
> Can pci_restore_state() clobber userspace runtime configurations with
> an outdated probe-time snapshot?
> 
> For a VFIO device, pdev->saved_config_space contains the host kernel's
> baseline state captured during vfio_pci_core_enable(). Subsequent
> userspace modifications (like enabling bus master or setting up MSI)
> are recorded in VFIO's virtual cache (vdev->vconfig) but do not update
> pdev->saved_config_space.

I guess the right thing to do is to write vdev->vconfig to config space
after pci_restore_state()?

Thanks,

Lukas