Re: [PATCH v3 i-g-t 7/7] tests/intel/xe_sriov_flr: Skip xe-vfio-pci load/bind when IOMMU is off

["Laguna, Lukasz" <lukasz.laguna@intel.com>]

On 2/4/2026 17:32, Marcin Bernatowicz wrote:
> When the IOMMU is disabled VFs typically lack an iommu_group, and
> xe-vfio-pci binding may fail. Skip load/bind in that case.

I'm not sure if checking for IOMMU groups is enough.
I think it's possible that the device has the IOMMU group and vfio-pci 
still fail to bind if e.g. CONFIG_VFIO_IOMMU_TYPE1 is disabled.

We have a control on the environment where test is executed, so I'm not 
sure if this patch is needed. We prefer to use the approach with 
xe-vfio-pci, so if it fails because of the system configuration than I 
think it would be better to fix the configuration.

> Signed-off-by: Marcin Bernatowicz <marcin.bernatowicz@linux.intel.com>
> Cc: Jakub Kolakowski <jakub1.kolakowski@intel.com>
> Cc: Lukasz Laguna <lukasz.laguna@intel.com>
> Cc: Michał Winiarski <michal.winiarski@intel.com>
> Cc: Piotr Piórkowski <piotr.piorkowski@intel.com>
> ---
>   tests/intel/xe_sriov_flr.c | 43 +++++++++++++++++++++++++++++++++++---
>   1 file changed, 40 insertions(+), 3 deletions(-)
>
> diff --git a/tests/intel/xe_sriov_flr.c b/tests/intel/xe_sriov_flr.c
> index b73727787..3fc84bbf9 100644
> --- a/tests/intel/xe_sriov_flr.c
> +++ b/tests/intel/xe_sriov_flr.c
> @@ -13,6 +13,7 @@
>   #include "igt_kmod.h"
>   #include "igt_pci.h"
>   #include "igt_sriov_device.h"
> +#include "igt_sysfs.h"
>   #include "intel_chipset.h"
>   #include "intel_vram.h"
>   #include "linux_scaffold.h"
> @@ -325,6 +326,44 @@ static void vf_unbind_driver_override(int pf_fd, unsigned int vf_id)
>   	free(slot);
>   }
>   
> +static bool vf_has_iommu_group(int pf_fd, unsigned int vf_id)
> +{
> +	int sysfs;
> +	bool present;
> +
> +	sysfs = igt_sriov_device_sysfs_open(pf_fd, vf_id);
> +	if (sysfs < 0)
> +		return false;
> +
> +	present = igt_sysfs_has_attr(sysfs, "iommu_group");
> +	close(sysfs);
> +
> +	return present;
> +}
> +
> +static bool vfs_have_iommu_groups(int pf_fd, int num_vfs)
> +{
> +	for (int vf_id = 1; vf_id <= num_vfs; vf_id++)
> +		if (!vf_has_iommu_group(pf_fd, vf_id))
> +			return false;
> +
> +	return true;
> +}
> +
> +static bool try_load_xe_vfio_pci(int pf_fd, int num_vfs)
> +{
> +	if (!g_use_xe_vfio_pci)
> +		return false;
> +
> +	if (!vfs_have_iommu_groups(pf_fd, num_vfs)) {
> +		igt_info("Disabling xe-vfio-pci binding: missing VF IOMMU group(s) (IOMMU off?)\n");
> +		g_use_xe_vfio_pci = false;
> +		return false;
> +	}
> +
> +	return igt_kmod_load("xe_vfio_pci", NULL) >= 0;
> +}
> +
>   /**
>    * flr_exec_strategy - Function pointer for FLR execution strategy
>    * @pf_fd: File descriptor for the Physical Function (PF).
> @@ -386,9 +425,7 @@ static void verify_flr(int pf_fd, int num_vfs, struct subcheck *checks,
>   	if (igt_warn_on(igt_pci_system_reinit()))
>   		goto disable_vfs;
>   
> -	xe_vfio_loaded = false;
> -	if (g_use_xe_vfio_pci)
> -		xe_vfio_loaded = igt_kmod_load("xe_vfio_pci", NULL) >= 0;
> +	xe_vfio_loaded = try_load_xe_vfio_pci(pf_fd, num_vfs);
>   	if (xe_vfio_loaded) {
>   		vf_bound = calloc(num_vfs + 1, sizeof(*vf_bound));
>   		igt_assert(vf_bound);