From: Eugenio Pérez <eperezma@redhat.com>
Date: Wed, 20 Jul 2022 16:05:47 +0000 (+0200)
Subject: qemu: new function to retrieve migration blocker reasons from QEMU
X-Git-Tag: v8.6.0-rc1~51
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=7e52c4839fabac2d19c6f22c99142e992e3d898e;p=thirdparty%2Flibvirt.git

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 109107eaae..9687746703 100644
--- 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 cc1a0bc8c9..b82f198285 100644
--- 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 5e4a86e5ad..941596563a 100644
--- 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 2759566892..e4c65e250e 100644
--- 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);