Re: [RFC PATCH 4/4] vfio/xe: Hide BAR ranges by default per device ID

[Alex Williamson <alex@shazbot.org>]

On Thu, 5 Nov 2026 16:37:38 +0100
"Piórkowski, Piotr" <piotr.piorkowski@intel.com> wrote:

> From: Piotr Piórkowski <piotr.piorkowski@intel.com>
> 
> xe-vfio-pci accesses the BARs only through vfio-pci-core, so opt in to
> hidden BAR ranges.
> 
> Let each entry of the PCI ID table describe the ranges to hide by
> default. The description is always looked up in the static table, so
> binding through new_id or driver_override can't skip them.
> 
> No device defines any ranges yet.

We don't merge dead code, so the whole series is to justify the
configfs mechanism to introduce excluded ranges without publishing them
to the community?  Hard no.  Thanks,

Alex

> 
> Cc: Michał Winiarski <michal.winiarski@intel.com>
> Cc: Alex Williamson <alex@shazbot.org>
> Cc: Jason Gunthorpe <jgg@ziepe.ca>
> Cc: Yishai Hadas <yishaih@nvidia.com>
> Cc: Shameer Kolothum <skolothumtho@nvidia.com>
> Cc: Kevin Tian <kevin.tian@intel.com>
> Signed-off-by: Piotr Piórkowski <piotr.piorkowski@intel.com>
> ---
>  drivers/vfio/pci/xe/main.c | 60 ++++++++++++++++++++++++++++----------
>  1 file changed, 45 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/vfio/pci/xe/main.c b/drivers/vfio/pci/xe/main.c
> index 7dab3e024aa8a..e63af6123f598 100644
> --- a/drivers/vfio/pci/xe/main.c
> +++ b/drivers/vfio/pci/xe/main.c
> @@ -24,6 +24,16 @@ struct xe_vfio_pci_migration_file {
>  	u8 disabled:1;
>  };
>  
> +/**
> + * struct xe_vfio_pci_desc - device specific description
> + * @hidden_ranges: BAR ranges hidden from the VFIO user by default
> + * @num_hidden_ranges: number of entries in @hidden_ranges
> + */
> +struct xe_vfio_pci_desc {
> +	const struct vfio_pci_bar_range *hidden_ranges;
> +	unsigned int num_hidden_ranges;
> +};
> +
>  struct xe_vfio_pci_core_device {
>  	struct vfio_pci_core_device core_device;
>  	struct xe_device *xe;
> @@ -543,8 +553,32 @@ static const struct vfio_device_ops xe_vfio_pci_ops = {
>  	.detach_ioas = vfio_iommufd_physical_detach_ioas,
>  };
>  
> +#define INTEL_PCI_VFIO_DEVICE(_id, _desc) { \
> +	PCI_DRIVER_OVERRIDE_DEVICE_VFIO(PCI_VENDOR_ID_INTEL, (_id)), \
> +	.driver_data = (kernel_ulong_t)(_desc), \
> +}
> +
> +static const struct pci_device_id xe_vfio_pci_table[] = {
> +	INTEL_BMG_IDS(INTEL_PCI_VFIO_DEVICE, NULL),
> +	INTEL_CRI_IDS(INTEL_PCI_VFIO_DEVICE, NULL),
> +	INTEL_NVLS_IDS(INTEL_PCI_VFIO_DEVICE, NULL),
> +	INTEL_NVLP_IDS(INTEL_PCI_VFIO_DEVICE, NULL),
> +	INTEL_PTL_IDS(INTEL_PCI_VFIO_DEVICE, NULL),
> +	INTEL_WCL_IDS(INTEL_PCI_VFIO_DEVICE, NULL),
> +	{}
> +};
> +MODULE_DEVICE_TABLE(pci, xe_vfio_pci_table);
> +
>  static int xe_vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  {
> +	/*
> +	 * Dynamic IDs added through new_id are matched before the static ones
> +	 * and carry no driver data, look the description up in the static
> +	 * table so that they can't bypass the default hidden ranges.
> +	 */
> +	const struct pci_device_id *match = pci_match_id(xe_vfio_pci_table, pdev);
> +	const struct xe_vfio_pci_desc *desc =
> +		match ? (const void *)match->driver_data : NULL;
>  	struct xe_vfio_pci_core_device *xe_vdev;
>  	int ret;
>  
> @@ -554,6 +588,17 @@ static int xe_vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *i
>  		return PTR_ERR(xe_vdev);
>  
>  	dev_set_drvdata(&pdev->dev, xe_vdev);
> +	xe_vdev->core_device.hidden_ranges_supported = true;
> +
> +	if (desc) {
> +		ret = vfio_pci_core_hide_bar_ranges(&xe_vdev->core_device,
> +						    desc->hidden_ranges,
> +						    desc->num_hidden_ranges);
> +		if (ret) {
> +			vfio_put_device(&xe_vdev->core_device.vdev);
> +			return ret;
> +		}
> +	}
>  
>  	ret = vfio_pci_core_register_device(&xe_vdev->core_device);
>  	if (ret) {
> @@ -572,21 +617,6 @@ static void xe_vfio_pci_remove(struct pci_dev *pdev)
>  	vfio_put_device(&xe_vdev->core_device.vdev);
>  }
>  
> -#define INTEL_PCI_VFIO_DEVICE(_id) { \
> -	PCI_DRIVER_OVERRIDE_DEVICE_VFIO(PCI_VENDOR_ID_INTEL, (_id)) \
> -}
> -
> -static const struct pci_device_id xe_vfio_pci_table[] = {
> -	INTEL_BMG_IDS(INTEL_PCI_VFIO_DEVICE),
> -	INTEL_CRI_IDS(INTEL_PCI_VFIO_DEVICE),
> -	INTEL_NVLS_IDS(INTEL_PCI_VFIO_DEVICE),
> -	INTEL_NVLP_IDS(INTEL_PCI_VFIO_DEVICE),
> -	INTEL_PTL_IDS(INTEL_PCI_VFIO_DEVICE),
> -	INTEL_WCL_IDS(INTEL_PCI_VFIO_DEVICE),
> -	{}
> -};
> -MODULE_DEVICE_TABLE(pci, xe_vfio_pci_table);
> -
>  static struct pci_driver xe_vfio_pci_driver = {
>  	.name = "xe-vfio-pci",
>  	.id_table = xe_vfio_pci_table,