+ /* if we've signalled device presence to the guest, or if the guest
+ * has gone ahead and configured the device (via manually-executed
+ * device add via drmgr in guest, namely), we need to wait
+ * for the guest to quiesce the device before completing detach.
+ * Otherwise, we can assume the guest hasn't seen it and complete the
+ * detach immediately. Note that there is a small race window
+ * just before, or during, configuration, which is this context
+ * refers mainly to fetching the device tree via RTAS.
+ * During this window the device access will be arbitrated by
+ * associated DRC, which will simply fail the RTAS calls as invalid.
+ * This is recoverable within guest and current implementations of
+ * drmgr should be able to cope.
+ */
+ if (!drc->signalled && !drc->configured) {
+ /* if the guest hasn't seen the device we can't rely on it to
+ * set it back to an isolated state via RTAS, so do it here manually
+ */
+ drc->isolation_state = SPAPR_DR_ISOLATION_STATE_ISOLATED;
+ }
+