Function validate_pci_for_passthrough

crates/openshell-vfio/src/pci.rs:282–311

Dry-run validation that [`prepare_pci_for_passthrough`] would accept this BDF right now. Performs every pre-bind check without touching `driver_override` or any other kernel state. Intended for `ValidateSandboxCreate` and similar pre-flight paths where the caller wants a typed error before committing to side effects. The IOMMU-peer check is inherently racy: a peer's driver state can change betwe

(sysfs: &SysfsRoot, bdf: &str)

/// Callers should treat a successful validation as best-effort and still be
/// prepared for the prepare call to fail.
pub fn validate_pci_for_passthrough(sysfs: &SysfsRoot, bdf: &str) -> Result<(), VfioError> {
    validate_bdf(bdf)?;

    let device = sysfs.pci_device_ref(bdf);
    if !device.exists() {
        return Err(VfioError::DeviceNotFound {
            bdf: bdf.to_string(),
        });
    }

    let iommu_group = device.iommu_group()?;
    let group_devices = sysfs.iommu_group_devices(iommu_group)?;
    let peers: Vec<String> = group_devices.into_iter().filter(|d| d != bdf).collect();

    // Refuse to silently auto-bind companions for non-GPU devices. The
    // operator must declare every BDF in the IOMMU group eligible and bind them
    // through separate calls (or use prepare_pci_group_for_passthrough).
    for peer in &peers {
        let peer_drv = crate::bind::current_driver_name(sysfs, peer);
        if peer_drv.as_deref() != Some("vfio-pci") {
            return Err(VfioError::IommuGroupConflict {
                bdf: bdf.to_string(),
                group: iommu_group,
                peers: peers.clone(),
            });
        }
    }

    Ok(())
}

/// Bind an arbitrary VFIO-capable `PCIe` device to `vfio-pci`, returning an RAII
/// guard that restores it to the host driver on drop.