Re: [PATCH v8 15/16] s390x/pci: Implement migration for emulated devices

[Farhan Ali]

On 9/11/2026 8:21 AM, Konstantin Shkolnyy wrote:
@@ -1303,11 +1380,22 @@ static void s390_pcihost_unplug(HotplugHandler 
*hotplug_dev, DeviceState *dev,
          pbdev = S390_PCI_DEVICE(dev);
          pbdev->fid = 0;
          QTAILQ_REMOVE(&s->zpci_devs, pbdev, link);
-        g_hash_table_remove(s->zpci_table, &pbdev->idx);
+        /*
+         * If this QEMU is running a migrated guest, and was configured with
+         * more zpci devices than the source QEMU, extra zpci devices could be
+         * excluded from zpci_table and invisible to the guest and have
+         * pbdev->idx values duplicating those of active devices. If the
+         * pbdev being unplugged is such, the zpci_table entry for pbdev->idx
+         * can find a different pbdev which we must not remove.
+         */
+        if (g_hash_table_lookup(s->zpci_table, &pbdev->idx) == pbdev) {
+            g_hash_table_remove(s->zpci_table, &pbdev->idx);
+        }

If we are migrating, won't we re-create the exact same state and devices 
on the target host? Is it possible that the target QEMU can have more 
devices than source?


          if (pbdev->dma_limit) {
              s390_pci_end_dma_count(s, pbdev->dma_limit);
          }
          g_hash_table_destroy(pbdev->iotlb);
+        s390_clear_zpci_migration_blocker(pbdev);
          qdev_unrealize(dev);
      }