Re: [PATCH] vfio: Register/unregister container for CPR only once for each container

[Cédric Le Goater]

On 4/24/25 08:33, Zhenzhong Duan wrote:

vfio_cpr_register_container and vfio_cpr_unregister_container are container
scoped function. Calling them for each device attaching/detaching would
corrupt CPR reboot notifier list, i.e., when two VFIO devices are attached
to same container and have same notifier registered twice.

Fixes: d9fa4223b30a ("vfio: register container for cpr")
Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>

Looks OK to me, so

Reviewed-by: Cédric Le Goater <c...@redhat.com>

Some feedback from Steve would be good to have.

---
btw: untested as I have no env with two migration capable devices,
      appreciate if someone have env to help test, thanks

I did.

Thanks,

C.

  hw/vfio/iommufd.c | 14 ++++++--------
  1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
index f24054a6a5..b2f72dc8c3 100644
--- a/hw/vfio/iommufd.c
+++ b/hw/vfio/iommufd.c
@@ -416,6 +416,7 @@ static void 
iommufd_cdev_container_destroy(VFIOIOMMUFDContainer *container)
      if (!QLIST_EMPTY(&bcontainer->device_list)) {
          return;
      }
+    vfio_cpr_unregister_container(bcontainer);
      vfio_listener_unregister(bcontainer);
      iommufd_backend_free_id(container->be, container->ioas_id);
      object_unref(container);
@@ -561,6 +562,10 @@ static bool iommufd_cdev_attach(const char *name, 
VFIODevice *vbasedev,
          goto err_listener_register;
      }

+ if (!vfio_cpr_register_container(bcontainer, errp)) {

+        goto err_listener_register;
+    }
+
      bcontainer->initialized = true;

found_container:

@@ -570,13 +575,9 @@ found_container:
          goto err_listener_register;
      }

- if (!vfio_cpr_register_container(bcontainer, errp)) {

-        goto err_listener_register;
-    }
-
      if (!vfio_device_hiod_create_and_realize(vbasedev,
                       TYPE_HOST_IOMMU_DEVICE_IOMMUFD_VFIO, errp)) {
-        goto err_hiod_realize;
+        goto err_listener_register;
      }

/*

@@ -600,8 +601,6 @@ found_container:
                                     vbasedev->num_regions, vbasedev->flags);
      return true;

-err_hiod_realize:

-    vfio_cpr_unregister_container(bcontainer);
  err_listener_register:
      iommufd_cdev_ram_block_discard_disable(false);
  err_discard_disable:
@@ -632,7 +631,6 @@ static void iommufd_cdev_detach(VFIODevice *vbasedev)
      }

object_unref(vbasedev->hiod);

-    vfio_cpr_unregister_container(bcontainer);
      iommufd_cdev_detach_container(vbasedev, container);
      iommufd_cdev_container_destroy(container);
      vfio_address_space_put(space);