Function restore_to_host_driver_ex

crates/openshell-vfio/src/bind.rs:213–254

Inner restore implementation. When `skip_deregister` is `true` the caller has already removed the device's vendor:device ID from vfio-pci's match table (e.g. via a cached value), so we skip the sysfs-based deregistration.

(
    sysfs: &SysfsRoot,
    bdf: &str,
    skip_deregister: bool,
)

/// device's vendor:device ID from vfio-pci's match table (e.g. via a cached
/// value), so we skip the sysfs-based deregistration.
pub(crate) fn restore_to_host_driver_ex(
    sysfs: &SysfsRoot,
    bdf: &str,
    skip_deregister: bool,
) -> Result<(), VfioError> {
    let device = sysfs.pci_device_ref(bdf);

    if !skip_deregister {
        // Deregister the device ID from vfio-pci's match table before
        // unbind+reprobe. Without this, drivers_probe re-binds to vfio-pci
        // via the still-registered new_id entry.
        deregister_vfio_new_id(sysfs, bdf);
    }

    let unbind_path = device.driver_unbind_path();
    if unbind_path.exists() {
        write_sysfs(&unbind_path, bdf).map_err(|e| VfioError::UnbindFailed {
            bdf: bdf.to_string(),
            reason: format!("unbind: {e}"),
        })?;
    }

    if device.driver_override_path().exists() {
        device
            .clear_driver_override()
            .map_err(|e| VfioError::UnbindFailed {
                bdf: bdf.to_string(),
                reason: format!("clear driver_override: {e}"),
            })?;
    }

    let probe = sysfs.drivers_probe();
    if probe.exists() {
        write_sysfs(&probe, bdf).map_err(|e| VfioError::UnbindFailed {
            bdf: bdf.to_string(),
            reason: format!("drivers_probe: {e}"),
        })?;
    }

    tracing::info!(bdf, "PCI device restored to host driver");
    Ok(())
}

/// Process-local reference counter for vendor:device ID registrations in the
/// vfio-pci match table. Multiple devices may share the same vendor:device