From 1cc65fe9d09b28a0bec636d581d1f684ff373d43 Mon Sep 17 00:00:00 2001
From: Frederic Crozat <fcrozat@suse.com>
Date: Tue, 17 Mar 2026 14:40:05 +0100
Subject: [PATCH] mount /lib/modules from host when using precompiled driver

Signed-off-by: Frederic Crozat <fcrozat@suse.com>
---
 controllers/object_controls.go      | 22 +++++++++++++++
 controllers/object_controls_test.go | 43 +++++++++++++++++++++++++++++
 internal/state/driver_volumes.go    | 22 +++++++++++++++
 3 files changed, 87 insertions(+)

diff --git a/controllers/object_controls.go b/controllers/object_controls.go
index b436bcab1..843309583 100644
--- a/controllers/object_controls.go
+++ b/controllers/object_controls.go
@@ -3553,6 +3553,28 @@ func transformDriverContainer(obj *appsv1.DaemonSet, config *gpuv1.ClusterPolicy
 		}
 	}
 
+	// Mount /lib/modules for precompiled drivers
+	if config.Driver.UsePrecompiledDrivers() {
+		n.logger.Info("Mounting /lib/modules into the driver container")
+		libModulesVolMount := corev1.VolumeMount{
+			Name:      "lib-modules",
+			MountPath: "/run/host/lib/modules",
+			ReadOnly:  true,
+		}
+		driverContainer.VolumeMounts = append(driverContainer.VolumeMounts, libModulesVolMount)
+
+		libModulesVol := corev1.Volume{
+			Name: "lib-modules",
+			VolumeSource: corev1.VolumeSource{
+				HostPath: &corev1.HostPathVolumeSource{
+					Path: "/lib/modules",
+					Type: ptr.To(corev1.HostPathDirectory),
+				},
+			},
+		}
+		podSpec.Volumes = append(podSpec.Volumes, libModulesVol)
+	}
+
 	// no further repo configuration required when using pre-compiled drivers, return here.
 	if config.Driver.UsePrecompiledDrivers() {
 		return nil
diff --git a/controllers/object_controls_test.go b/controllers/object_controls_test.go
index f6df7340d..80db14d04 100644
--- a/controllers/object_controls_test.go
+++ b/controllers/object_controls_test.go
@@ -1883,3 +1883,46 @@ func TestMIGManager(t *testing.T) {
 		})
 	}
 }
+
+// TestDriverPrecompiledLibModules tests that /lib/modules is mounted when precompiled drivers are used
+func TestDriverPrecompiledLibModules(t *testing.T) {
+	cp := getDriverTestInput("precompiled")
+	output := getDriverTestOutput("precompiled")
+
+	ds, err := testDaemonsetCommon(t, cp, "Driver", output["numDaemonsets"].(int))
+	if err != nil {
+		t.Fatalf("error in testDaemonsetCommon(): %v", err)
+	}
+	require.NotNil(t, ds)
+
+	// Check for /lib/modules volume and mount
+	foundVolume := false
+	for _, vol := range ds.Spec.Template.Spec.Volumes {
+		if vol.Name == "lib-modules" {
+			foundVolume = true
+			require.NotNil(t, vol.HostPath)
+			require.Equal(t, "/lib/modules", vol.HostPath.Path)
+		}
+	}
+	require.True(t, foundVolume, "lib-modules volume not found for precompiled drivers")
+
+	foundMount := false
+	driverContainer := findContainerByName(ds.Spec.Template.Spec.Containers, "nvidia-driver-ctr")
+	require.NotNil(t, driverContainer)
+
+	for _, mount := range driverContainer.VolumeMounts {
+		if mount.Name == "lib-modules" {
+			foundMount = true
+			require.Equal(t, "/run/host/lib/modules", mount.MountPath)
+			require.True(t, mount.ReadOnly)
+		}
+	}
+	require.True(t, foundMount, "lib-modules volume mount not found for precompiled drivers")
+
+	// Cleanup
+	err = removeState(&clusterPolicyController, clusterPolicyController.idx-1)
+	if err != nil {
+		t.Fatalf("error removing state %v:", err)
+	}
+	clusterPolicyController.idx--
+}
diff --git a/internal/state/driver_volumes.go b/internal/state/driver_volumes.go
index c9e13b998..2ed1c7074 100644
--- a/internal/state/driver_volumes.go
+++ b/internal/state/driver_volumes.go
@@ -209,6 +209,28 @@ func (s *stateDriver) getDriverAdditionalConfigs(ctx context.Context, cr *v1alph
 				additionalCfgs.Volumes = append(additionalCfgs.Volumes, subscriptionVol)
 			}
 		}
+
+		// Mount /lib/modules for precompiled drivers
+		if cr.Spec.UsePrecompiledDrivers() {
+			logger.Info("Mounting /lib/modules into the driver container")
+			libModulesVolMount := corev1.VolumeMount{
+				Name:      "lib-modules",
+				MountPath: "/run/host/lib/modules",
+				ReadOnly:  true,
+			}
+			additionalCfgs.VolumeMounts = append(additionalCfgs.VolumeMounts, libModulesVolMount)
+
+			libModulesVol := corev1.Volume{
+				Name: "lib-modules",
+				VolumeSource: corev1.VolumeSource{
+					HostPath: &corev1.HostPathVolumeSource{
+						Path: "/lib/modules",
+						Type: ptr.To(corev1.HostPathDirectory),
+					},
+				},
+			}
+			additionalCfgs.Volumes = append(additionalCfgs.Volumes, libModulesVol)
+		}
 	}
 
 	// mount any custom kernel module configuration parameters at /drivers