From c043762bfe04d7b10030b76fae12473b031c3c0a Mon Sep 17 00:00:00 2001
Message-Id: <c043762bfe04d7b10030b76fae12473b031c3c0a@dist-git>
From: Peter Krempa <pkrempa@redhat.com>
Date: Fri, 2 Feb 2018 11:05:00 +0100
Subject: [PATCH] qemu: migration: Refresh device information after
 transferring state

In my first approach in 4b480d10768c I overlooked the comment in
qemuMigrationRunIncoming stating that during actual migration the
qemuMigrationRunIncoming does not wait until the migration is complete
but rather offloads that to the Finish phase of migration.

This means that during actual migration qemuProcessRefreshState was
called prior to qemu actually transferring the full state and thus the
queries did not get the correct information. The approach worked only
for restore, where we wait for the migration to finish during qemu
startup.

Fix the issue by calling qemuProcessRefreshState both from
qemuProcessStart if there's no incomming migration and from
qemuMigrationFinish so that the code actually works as expected.

(cherry picked from commit 93db7eea1b86408e02852a8c886d473f4f5007e3)

 https://bugzilla.redhat.com/show_bug.cgi?id=1463168
---
 src/qemu/qemu_migration.c |  9 +++++++++
 src/qemu/qemu_process.c   | 17 ++++++++++-------
 src/qemu/qemu_process.h   |  4 ++++
 3 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index a50bb7206c..0968dd62a4 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -5351,6 +5351,15 @@ qemuMigrationFinish(virQEMUDriverPtr driver,
             goto endjob;
     }
 
+    /* Now that the state data was transferred we can refresh the actual state
+     * of the devices */
+    if (qemuProcessRefreshState(driver, vm, QEMU_ASYNC_JOB_MIGRATION_IN) < 0) {
+        /* Similarly to the case above v2 protocol will not be able to recover
+         * from this. Let's ignore this and perhaps stuff will not break. */
+        if (v3proto)
+            goto endjob;
+    }
+
     if (priv->job.current->status == QEMU_DOMAIN_JOB_STATUS_POSTCOPY)
         inPostCopy = true;
 
diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index 3bb4b14948..caf967dac5 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -6080,7 +6080,7 @@ qemuProcessLaunch(virConnectPtr conn,
  * function is called after a deferred migration finishes so that we can update
  * state influenced by the migration stream.
  */
-static int
+int
 qemuProcessRefreshState(virQEMUDriverPtr driver,
                         virDomainObjPtr vm,
                         qemuDomainAsyncJob asyncJob)
@@ -6121,9 +6121,6 @@ qemuProcessFinishStartup(virConnectPtr conn,
     virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
     int ret = -1;
 
-    if (qemuProcessRefreshState(driver, vm, asyncJob) < 0)
-        goto cleanup;
-
     if (startCPUs) {
         VIR_DEBUG("Starting domain CPUs");
         if (qemuProcessStartCPUs(driver, vm, conn,
@@ -6227,11 +6224,17 @@ qemuProcessStart(virConnectPtr conn,
                                  VIR_DOMAIN_PAUSED_USER) < 0)
         goto stop;
 
-    /* Keep watching qemu log for errors during incoming migration, otherwise
-     * unset reporting errors from qemu log. */
-    if (!incoming)
+    if (!incoming) {
+        /* Keep watching qemu log for errors during incoming migration, otherwise
+         * unset reporting errors from qemu log. */
         qemuMonitorSetDomainLog(priv->mon, NULL, NULL, NULL);
 
+        /* Refresh state of devices from qemu. During migration this needs to
+         * happen after the state information is fully transferred. */
+        if (qemuProcessRefreshState(driver, vm, asyncJob) < 0)
+            goto stop;
+    }
+
     ret = 0;
 
  cleanup:
diff --git a/src/qemu/qemu_process.h b/src/qemu/qemu_process.h
index cd9a720313..b383ff309b 100644
--- a/src/qemu/qemu_process.h
+++ b/src/qemu/qemu_process.h
@@ -129,6 +129,10 @@ int qemuProcessFinishStartup(virConnectPtr conn,
                              bool startCPUs,
                              virDomainPausedReason pausedReason);
 
+int qemuProcessRefreshState(virQEMUDriverPtr driver,
+                            virDomainObjPtr vm,
+                            qemuDomainAsyncJob asyncJob);
+
 typedef enum {
     VIR_QEMU_PROCESS_STOP_MIGRATED      = 1 << 0,
     VIR_QEMU_PROCESS_STOP_NO_RELABEL    = 1 << 1,
-- 
2.16.1