[PATCH rfcv2 03/20] HostIOMMUDevice: Introduce realize_late callback

[Zhenzhong Duan]

Currently we have realize() callback which is called before attachment.
But there are still some elements e.g., hwpt_id is not ready before
attachment. So we need a realize_late() callback to further initialize
them.

Currently, this callback is only useful for iommufd backend. For legacy
backend nothing needs to be initialized after attachment.

Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
---
 include/system/host_iommu_device.h | 17 +++++++++++++++++
 hw/vfio/common.c                   | 17 ++++++++++++++---
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/include/system/host_iommu_device.h 
b/include/system/host_iommu_device.h
index 809cced4ba..df782598f2 100644
--- a/include/system/host_iommu_device.h
+++ b/include/system/host_iommu_device.h
@@ -66,6 +66,23 @@ struct HostIOMMUDeviceClass {
      * Returns: true on success, false on failure.
      */
     bool (*realize)(HostIOMMUDevice *hiod, void *opaque, Error **errp);
+    /**
+     * @realize_late: initialize host IOMMU device instance after attachment,
+     *                some elements e.g., ioas are ready only after attachment.
+     *                This callback initialize them.
+     *
+     * Optional callback.
+     *
+     * @hiod: pointer to a host IOMMU device instance.
+     *
+     * @opaque: pointer to agent device of this host IOMMU device,
+     *          e.g., VFIO base device or VDPA device.
+     *
+     * @errp: pass an Error out when realize fails.
+     *
+     * Returns: true on success, false on failure.
+     */
+    bool (*realize_late)(HostIOMMUDevice *hiod, void *opaque, Error **errp);
     /**
      * @get_cap: check if a host IOMMU device capability is supported.
      *
diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index abbdc56b6d..e198b1e5a2 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -1550,6 +1550,7 @@ bool vfio_attach_device(char *name, VFIODevice *vbasedev,
     const VFIOIOMMUClass *ops =
         VFIO_IOMMU_CLASS(object_class_by_name(TYPE_VFIO_IOMMU_LEGACY));
     HostIOMMUDevice *hiod = NULL;
+    HostIOMMUDeviceClass *hiod_ops = NULL;
 
     if (vbasedev->iommufd) {
         ops = VFIO_IOMMU_CLASS(object_class_by_name(TYPE_VFIO_IOMMU_IOMMUFD));
@@ -1560,16 +1561,26 @@ bool vfio_attach_device(char *name, VFIODevice 
*vbasedev,
 
     if (!vbasedev->mdev) {
         hiod = HOST_IOMMU_DEVICE(object_new(ops->hiod_typename));
+        hiod_ops = HOST_IOMMU_DEVICE_GET_CLASS(hiod);
         vbasedev->hiod = hiod;
     }
 
     if (!ops->attach_device(name, vbasedev, as, errp)) {
-        object_unref(hiod);
-        vbasedev->hiod = NULL;
-        return false;
+        goto err_attach;
+    }
+
+    if (hiod_ops && hiod_ops->realize_late &&
+        !hiod_ops->realize_late(hiod, vbasedev, errp)) {
+        ops->detach_device(vbasedev);
+        goto err_attach;
     }
 
     return true;
+
+err_attach:
+    object_unref(hiod);
+    vbasedev->hiod = NULL;
+    return false;
 }
 
 void vfio_detach_device(VFIODevice *vbasedev)
-- 
2.34.1