diff --git a/drivers/gpu/drm/i915/selftests/mock_gem_device.c b/drivers/gpu/drm/i915/selftests/mock_gem_device.c
index f127e633f7ca..397c313a8b69 100644
--- a/drivers/gpu/drm/i915/selftests/mock_gem_device.c
+++ b/drivers/gpu/drm/i915/selftests/mock_gem_device.c
@@ -118,11 +118,11 @@ static struct dev_pm_domain pm_domain = {
 
 struct drm_i915_private *mock_gem_device(void)
 {
+#if IS_ENABLED(CONFIG_IOMMU_API) && defined(CONFIG_INTEL_IOMMU)
+	static struct dev_iommu fake_iommu = { .priv = (void *)-1 };
+#endif
 	struct drm_i915_private *i915;
 	struct pci_dev *pdev;
-#if IS_ENABLED(CONFIG_IOMMU_API) && defined(CONFIG_INTEL_IOMMU)
-	struct dev_iommu iommu;
-#endif
 	int err;
 
 	pdev = kzalloc(sizeof(*pdev), GFP_KERNEL);
@@ -141,10 +141,8 @@ struct drm_i915_private *mock_gem_device(void)
 	dma_coerce_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
 
 #if IS_ENABLED(CONFIG_IOMMU_API) && defined(CONFIG_INTEL_IOMMU)
-	/* HACK HACK HACK to disable iommu for the fake device; force identity mapping */
-	memset(&iommu, 0, sizeof(iommu));
-	iommu.priv = (void *)-1;
-	pdev->dev.iommu = &iommu;
+	/* HACK to disable iommu for the fake device; force identity mapping */
+	pdev->dev.iommu = &fake_iommu;
 #endif
 
 	pci_set_drvdata(pdev, i915);