[libvirt PATCH v2 4/5] qemu_migration: get migration blockers before hardcoded checks

[Eugenio Pérez]

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 blocking
migration, etc.

Enable qemuMigrationSrcIsAllowed to query it.

Signed-off-by: Eugenio Pérez <epere...@redhat.com>
---
 src/qemu/qemu_migration.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index b12cb518ee..4224339f39 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -1414,6 +1414,20 @@ qemuMigrationSrcIsAllowedHostdev(const virDomainDef *def)
     return true;
 }
 
+static int
+qemuDomainGetMigrationBlockers(virQEMUDriver *driver,
+                               virDomainObj *vm,
+                               char ***blockers)
+{
+    qemuDomainObjPrivate *priv = vm->privateData;
+    int rc;
+
+    qemuDomainObjEnterMonitor(driver, vm);
+    rc = qemuMonitorGetMigrationBlockers(priv->mon, blockers);
+    qemuDomainObjExitMonitor(vm);
+
+    return rc;
+}
 
 /**
  * qemuMigrationSrcIsAllowed:
@@ -1439,6 +1453,25 @@ qemuMigrationSrcIsAllowed(virQEMUDriver *driver,
     int nsnapshots;
     int pauseReason;
     size_t i;
+    int r;
+
+    /* Ask qemu if it have a migration blocker */
+    if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_MIGRATION_BLOCKED_REASONS)) {
+        g_auto(GStrv) blockers = NULL;
+        r = qemuDomainGetMigrationBlockers(driver, vm, &blockers);
+        if (r != 0) {
+            virReportError(VIR_ERR_OPERATION_INVALID,
+                           _("cannot migrate domain, %s"),
+                           _("error getting blockers"));
+            return false;
+        }
+
+        if (blockers[0]) {
+            virReportError(VIR_ERR_OPERATION_INVALID,
+                           _("cannot migrate domain, %s"), blockers[0]);
+            return false;
+        }
+    }
 
     /* perform these checks only when migrating to remote hosts */
     if (remote) {
-- 
2.31.1