vfio/iommufd: reconstruct hwpt

Skip allocation of, and attachment to, hwpt_id.  Recover it from CPR state.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Link: https://lore.kernel.org/qemu-devel/1751493538-202042-18-git-send-email-steven.sistare@oracle.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

Author: Steve Sistare

hw/vfio/iommufd.c

@@ -332,7 +332,14 @@ static bool iommufd_cdev_autodomains_get(VFIODevice *vbasedev,
 
     /* Try to find a domain */
     QLIST_FOREACH(hwpt, &container->hwpt_list, next) {
-        ret = iommufd_cdev_attach_ioas_hwpt(vbasedev, hwpt->hwpt_id, errp);
+        if (!cpr_is_incoming()) {
+            ret = iommufd_cdev_attach_ioas_hwpt(vbasedev, hwpt->hwpt_id, errp);
+        } else if (vbasedev->cpr.hwpt_id == hwpt->hwpt_id) {
+            ret = 0;
+        } else {
+            continue;
+        }
+
         if (ret) {
             /* -EINVAL means the domain is incompatible with the device. */
             if (ret == -EINVAL) {
@@ -349,6 +356,7 @@ static bool iommufd_cdev_autodomains_get(VFIODevice *vbasedev,
             return false;
         } else {
             vbasedev->hwpt = hwpt;
+            vbasedev->cpr.hwpt_id = hwpt->hwpt_id;
             QLIST_INSERT_HEAD(&hwpt->device_list, vbasedev, hwpt_next);
             vbasedev->iommu_dirty_tracking = iommufd_hwpt_dirty_tracking(hwpt);
             return true;
@@ -371,26 +379,32 @@ static bool iommufd_cdev_autodomains_get(VFIODevice *vbasedev,
         flags = IOMMU_HWPT_ALLOC_DIRTY_TRACKING;
     }
 
+    if (cpr_is_incoming()) {
+        hwpt_id = vbasedev->cpr.hwpt_id;
+        goto skip_alloc;
+    }
+
     if (!iommufd_backend_alloc_hwpt(iommufd, vbasedev->devid,
                                     container->ioas_id, flags,
                                     IOMMU_HWPT_DATA_NONE, 0, NULL,
                                     &hwpt_id, errp)) {
         return false;
     }
 
+    ret = iommufd_cdev_attach_ioas_hwpt(vbasedev, hwpt_id, errp);
+    if (ret) {
+        iommufd_backend_free_id(container->be, hwpt_id);
+        return false;
+    }
+
+skip_alloc:
     hwpt = g_malloc0(sizeof(*hwpt));
     hwpt->hwpt_id = hwpt_id;
     hwpt->hwpt_flags = flags;
     QLIST_INIT(&hwpt->device_list);
 
-    ret = iommufd_cdev_attach_ioas_hwpt(vbasedev, hwpt->hwpt_id, errp);
-    if (ret) {
-        iommufd_backend_free_id(container->be, hwpt->hwpt_id);
-        g_free(hwpt);
-        return false;
-    }
-
     vbasedev->hwpt = hwpt;
+    vbasedev->cpr.hwpt_id = hwpt->hwpt_id;
     vbasedev->iommu_dirty_tracking = iommufd_hwpt_dirty_tracking(hwpt);
     QLIST_INSERT_HEAD(&hwpt->device_list, vbasedev, hwpt_next);
     QLIST_INSERT_HEAD(&container->hwpt_list, hwpt, next);