[libvirt] [PATCH] qemu: Don't use query-migrate on destination

[Jiri Denemark]

When migration fails, we need to poke QEMU monitor to check for a reason
of the failure. We did this using query-migrate QMP command, which is
not supposed to return any meaningful result on the destination side.
Thus if the monitor was still functional when we detected the migration
failure, parsing the answer from query-migrate always failed with the
following error message:

    "info migration reply was missing return status"

This irrelevant message was then used as the reason for the migration
failure replacing any message we might have had.

Let's use harmless query-status for poking the monitor to make sure we
only get an error if the monitor connection is broken.

https://bugzilla.redhat.com/show_bug.cgi?id=1374613

Signed-off-by: Jiri Denemark <jdenemar at redhat.com>
---
 src/qemu/qemu_domain.c    | 20 ++++++++++++++++++++
 src/qemu/qemu_domain.h    |  4 ++++
 src/qemu/qemu_migration.c |  6 +-----
 src/qemu/qemu_monitor.c   |  8 ++++++++
 src/qemu/qemu_monitor.h   |  1 +
 5 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index fd79390..fb766d0 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -6127,3 +6127,23 @@ qemuDomainVcpuPersistOrder(virDomainDefPtr def)
         }
     }
 }
+
+
+int
+qemuDomainCheckMonitor(virQEMUDriverPtr driver,
+                       virDomainObjPtr vm,
+                       qemuDomainAsyncJob asyncJob)
+{
+    qemuDomainObjPrivatePtr priv = vm->privateData;
+    int ret;
+
+    if (qemuDomainObjEnterMonitorAsync(driver, vm, asyncJob) < 0)
+        return -1;
+
+    ret = qemuMonitorCheck(priv->mon);
+
+    if (qemuDomainObjExitMonitor(driver, vm) < 0)
+        return -1;
+
+    return ret;
+}
diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h
index 13c0372..a1404d0 100644
--- a/src/qemu/qemu_domain.h
+++ b/src/qemu/qemu_domain.h
@@ -728,4 +728,8 @@ bool qemuDomainVcpuHotplugIsInOrder(virDomainDefPtr def)
 void qemuDomainVcpuPersistOrder(virDomainDefPtr def)
     ATTRIBUTE_NONNULL(1);
 
+int qemuDomainCheckMonitor(virQEMUDriverPtr driver,
+                           virDomainObjPtr vm,
+                           qemuDomainAsyncJob asyncJob);
+
 #endif /* __QEMU_DOMAIN_H__ */
diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index 07f18db..e734816 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -6208,14 +6208,10 @@ qemuMigrationFinish(virQEMUDriverPtr driver,
     }
 
     if (retcode != 0) {
-        qemuDomainJobInfo info;
-
         /* Check for a possible error on the monitor in case Finish was called
          * earlier than monitor EOF handler got a chance to process the error
          */
-        qemuMigrationFetchJobStatus(driver, vm,
-                                    QEMU_ASYNC_JOB_MIGRATION_IN,
-                                    &info);
+        qemuDomainCheckMonitor(driver, vm, QEMU_ASYNC_JOB_MIGRATION_IN);
         goto endjob;
     }
 
diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
index 4171914..1fdee3a 100644
--- a/src/qemu/qemu_monitor.c
+++ b/src/qemu/qemu_monitor.c
@@ -1617,6 +1617,14 @@ qemuMonitorStopCPUs(qemuMonitorPtr mon)
 
 
 int
+qemuMonitorCheck(qemuMonitorPtr mon)
+{
+    bool running;
+    return qemuMonitorGetStatus(mon, &running, NULL);
+}
+
+
+int
 qemuMonitorGetStatus(qemuMonitorPtr mon,
                      bool *running,
                      virDomainPausedReason *reason)
diff --git a/src/qemu/qemu_monitor.h b/src/qemu/qemu_monitor.h
index b838725..255fff2 100644
--- a/src/qemu/qemu_monitor.h
+++ b/src/qemu/qemu_monitor.h
@@ -382,6 +382,7 @@ typedef enum {
 VIR_ENUM_DECL(qemuMonitorVMStatus)
 int qemuMonitorVMStatusToPausedReason(const char *status);
 
+int qemuMonitorCheck(qemuMonitorPtr mon);
 int qemuMonitorGetStatus(qemuMonitorPtr mon,
                          bool *running,
                          virDomainPausedReason *reason)
-- 
2.10.0