Re: [PATCH] vfio/iommufd: Add comment emphasizing no movement of hiod->realize() call

[Cédric Le Goater]

On 5/21/25 13:03, Zhenzhong Duan wrote:

The nested IOMMU support needs device and hwpt id which are generated
only after attachment. Hiod encapsulates these information in realize()
and passes to vIOMMU.

Suggested-by: Cédric Le Goater <c...@redhat.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>

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

Thanks,

C.

---
  hw/vfio/iommufd.c | 4 ++++
  1 file changed, 4 insertions(+)

diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
index af1c7ab10a..6b2696793f 100644
--- a/hw/vfio/iommufd.c
+++ b/hw/vfio/iommufd.c
@@ -592,6 +592,10 @@ found_container:
          goto err_listener_register;
      }

+ /*

+     * Do not move this code before attachment! The nested IOMMU support
+     * needs device and hwpt id which are generated only after attachment.
+     */
      if (!vfio_device_hiod_create_and_realize(vbasedev,
                       TYPE_HOST_IOMMU_DEVICE_IOMMUFD_VFIO, errp)) {
          goto err_listener_register;