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

[Marcin Bernatowicz <marcin.bernatowicz@linux.intel.com>]

When the IOMMU is disabled VFs typically lack an iommu_group, and
xe-vfio-pci binding may fail. Skip load/bind in that case.

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);
-- 
2.43.0