vfio: Cleanup host IOMMU device creation

realize() is now moved after attachment, do the same for hiod creation.
Introduce a new function vfio_device_hiod_create_and_realize() to do
them all in one go.

Suggested-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20250423072824.3647952-5-zhenzhong.duan@intel.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

hw/vfio/container.c

@@ -898,7 +898,9 @@ static bool vfio_legacy_attach_device(const char *name, VFIODevice *vbasedev,
         goto group_put_exit;
     }
 
-    if (!vfio_device_hiod_realize(vbasedev, errp)) {
+    if (!vfio_device_hiod_create_and_realize(vbasedev,
+                                             TYPE_HOST_IOMMU_DEVICE_LEGACY_VFIO,
+                                             errp)) {
         goto device_put_exit;
     }
 
@@ -924,6 +926,7 @@ static void vfio_legacy_detach_device(VFIODevice *vbasedev)
     QLIST_REMOVE(vbasedev, container_next);
     vbasedev->bcontainer = NULL;
     trace_vfio_device_detach(vbasedev->name, group->groupid);
+    object_unref(vbasedev->hiod);
     vfio_device_put(vbasedev);
     vfio_group_put(group);
 }

hw/vfio/device.c

@@ -347,15 +347,24 @@ bool vfio_device_is_mdev(VFIODevice *vbasedev)
     return subsys && (strcmp(subsys, "/sys/bus/mdev") == 0);
 }
 
-bool vfio_device_hiod_realize(VFIODevice *vbasedev, Error **errp)
+bool vfio_device_hiod_create_and_realize(VFIODevice *vbasedev,
+                                         const char *typename, Error **errp)
 {
-    HostIOMMUDevice *hiod = vbasedev->hiod;
+    HostIOMMUDevice *hiod;
 
-    if (!hiod) {
+    if (vbasedev->mdev) {
         return true;
     }
 
-    return HOST_IOMMU_DEVICE_GET_CLASS(hiod)->realize(hiod, vbasedev, errp);
+    hiod = HOST_IOMMU_DEVICE(object_new(typename));
+
+    if (!HOST_IOMMU_DEVICE_GET_CLASS(hiod)->realize(hiod, vbasedev, errp)) {
+        object_unref(hiod);
+        return false;
+    }
+
+    vbasedev->hiod = hiod;
+    return true;
 }
 
 VFIODevice *vfio_get_vfio_device(Object *obj)
@@ -372,7 +381,6 @@ bool vfio_device_attach(char *name, VFIODevice *vbasedev,
 {
     const VFIOIOMMUClass *ops =
         VFIO_IOMMU_CLASS(object_class_by_name(TYPE_VFIO_IOMMU_LEGACY));
-    HostIOMMUDevice *hiod = NULL;
 
     if (vbasedev->iommufd) {
         ops = VFIO_IOMMU_CLASS(object_class_by_name(TYPE_VFIO_IOMMU_IOMMUFD));
@@ -380,19 +388,7 @@ bool vfio_device_attach(char *name, VFIODevice *vbasedev,
 
     assert(ops);
 
-
+    return ops->attach_device(name, vbasedev, as, errp);
-    if (!vbasedev->mdev) {
-        hiod = HOST_IOMMU_DEVICE(object_new(ops->hiod_typename));
-        vbasedev->hiod = hiod;
-    }
-
-    if (!ops->attach_device(name, vbasedev, as, errp)) {
-        object_unref(hiod);
-        vbasedev->hiod = NULL;
-        return false;
-    }
-
-    return true;
 }
 
 void vfio_device_detach(VFIODevice *vbasedev)
@@ -400,6 +396,5 @@ void vfio_device_detach(VFIODevice *vbasedev)
     if (!vbasedev->bcontainer) {
         return;
     }
-    object_unref(vbasedev->hiod);
     VFIO_IOMMU_GET_CLASS(vbasedev->bcontainer)->detach_device(vbasedev);
 }

hw/vfio/iommufd.c

@@ -574,7 +574,8 @@ found_container:
         goto err_listener_register;
     }
 
-    if (!vfio_device_hiod_realize(vbasedev, errp)) {
+    if (!vfio_device_hiod_create_and_realize(vbasedev,
+                     TYPE_HOST_IOMMU_DEVICE_IOMMUFD_VFIO, errp)) {
         goto err_hiod_realize;
     }
 
@@ -630,6 +631,7 @@ static void iommufd_cdev_detach(VFIODevice *vbasedev)
         iommufd_cdev_ram_block_discard_disable(false);
     }
 
+    object_unref(vbasedev->hiod);
     vfio_cpr_unregister_container(bcontainer);
     iommufd_cdev_detach_container(vbasedev, container);
     iommufd_cdev_container_destroy(container);

include/hw/vfio/vfio-device.h

@@ -123,7 +123,8 @@ bool vfio_device_irq_set_signaling(VFIODevice *vbasedev, int index, int subindex
 
 void vfio_device_reset_handler(void *opaque);
 bool vfio_device_is_mdev(VFIODevice *vbasedev);
-bool vfio_device_hiod_realize(VFIODevice *vbasedev, Error **errp);
+bool vfio_device_hiod_create_and_realize(VFIODevice *vbasedev,
+                                         const char *typename, Error **errp);
 bool vfio_device_attach(char *name, VFIODevice *vbasedev,
                         AddressSpace *as, Error **errp);
 void vfio_device_detach(VFIODevice *vbasedev);