qemu: new function to retrieve migration blocker reasons from QEMU

Since QEMU 6.0, if migration is blocked for some reason,
'query-migrate' will return an array of error strings describing the
migration blockers.  This can be used to check whether there are any
devices, or other conditions, that would cause migration to fail.

This patch adds a function that sends this query via a QMP command and
returns the resulting array of reasons. qemuMigrationSrcIsAllowed()
will be able to use the new function to ask QEMU for migration
blockers, instead of the hardcoded guesses that libvirt currently has.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Laine Stump <laine@redhat.com>

diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
index 109107eaaedff33290f4a6a98e5619c4895fb07e..96877467034c43ce173b911800800fa0be0770c3 100644 (file)
--- a/src/qemu/qemu_monitor.c
+++ b/src/qemu/qemu_monitor.c
@@ -4486,3 +4486,15 @@ qemuMonitorMigrateRecover(qemuMonitor *mon,
 
     return qemuMonitorJSONMigrateRecover(mon, uri);
 }
+
+
+int
+qemuMonitorGetMigrationBlockers(qemuMonitor *mon,
+                                char ***blockers)
+{
+    VIR_DEBUG("blockers=%p", blockers);
+
+    QEMU_CHECK_MONITOR(mon);
+
+    return qemuMonitorJSONGetMigrationBlockers(mon, blockers);
+}

diff --git a/src/qemu/qemu_monitor.h b/src/qemu/qemu_monitor.h
index cc1a0bc8c9958acaf1fcf0aaee3ce04813761ea0..b82f198285cc6c57679c7d5a41f88fa944d5107e 100644 (file)
--- a/src/qemu/qemu_monitor.h
+++ b/src/qemu/qemu_monitor.h
@@ -1543,3 +1543,7 @@ qemuMonitorChangeMemoryRequestedSize(qemuMonitor *mon,
 int
 qemuMonitorMigrateRecover(qemuMonitor *mon,
                           const char *uri);
+
+int
+qemuMonitorGetMigrationBlockers(qemuMonitor *mon,
+                                char ***blockers);

diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
index 5e4a86e5ad90ce40cf78ac54270ee9d40b1e6ea2..941596563a0582e25dffdf66e33f591a07395f28 100644 (file)
--- a/src/qemu/qemu_monitor_json.c
+++ b/src/qemu/qemu_monitor_json.c
@@ -3338,6 +3338,52 @@ int qemuMonitorJSONMigrate(qemuMonitor *mon,
     return 0;
 }
 
+
+/*
+ * Get the exposed migration blockers.
+ *
+ * This function assume qemu has the capability of request them.
+ *
+ * It returns a NULL terminated array on blockers if there are any, or it set
+ * it to NULL otherwise.
+ */
+int
+qemuMonitorJSONGetMigrationBlockers(qemuMonitor *mon,
+                                    char ***blockers)
+{
+    g_autoptr(virJSONValue) cmd = NULL;
+    g_autoptr(virJSONValue) reply = NULL;
+    virJSONValue *data;
+    virJSONValue *jblockers;
+    size_t i;
+
+    *blockers = NULL;
+    if (!(cmd = qemuMonitorJSONMakeCommand("query-migrate", NULL)))
+        return -1;
+
+    if (qemuMonitorJSONCommand(mon, cmd, &reply) < 0)
+        return -1;
+
+    if (qemuMonitorJSONCheckReply(cmd, reply, VIR_JSON_TYPE_OBJECT) < 0)
+        return -1;
+
+    data = virJSONValueObjectGetObject(reply, "return");
+
+    if (!(jblockers = virJSONValueObjectGetArray(data, "blocked-reasons")))
+        return 0;
+
+    *blockers = g_new0(char *, virJSONValueArraySize(jblockers) + 1);
+    for (i = 0; i < virJSONValueArraySize(jblockers); i++) {
+        virJSONValue *jblocker = virJSONValueArrayGet(jblockers, i);
+        const char *blocker = virJSONValueGetString(jblocker);
+
+        (*blockers)[i] = g_strdup(blocker);
+    }
+
+    return 0;
+}
+
+
 int qemuMonitorJSONMigrateCancel(qemuMonitor *mon)
 {
     g_autoptr(virJSONValue) cmd = qemuMonitorJSONMakeCommand("migrate_cancel", NULL);

diff --git a/src/qemu/qemu_monitor_json.h b/src/qemu/qemu_monitor_json.h
index 2759566892dccb38a6f6e953e5eee7d0358cfc7c..e4c65e250ea8dd806c7995fd05e1ad230721356f 100644 (file)
--- a/src/qemu/qemu_monitor_json.h
+++ b/src/qemu/qemu_monitor_json.h
@@ -184,6 +184,9 @@ qemuMonitorJSONMigrate(qemuMonitor *mon,
                        unsigned int flags,
                        const char *uri);
 int
+qemuMonitorJSONGetMigrationBlockers(qemuMonitor *mon,
+                                    char ***blockers);
+int
 qemuMonitorJSONGetSpiceMigrationStatus(qemuMonitor *mon,
                                        bool *spice_migrated);