qemu: Implement virDomainMigrateGetMaxDowntime

Add code to support querying maximum allowable downtime during live migration.

src/qemu/qemu_driver.c

@@ -13150,6 +13150,61 @@ qemuDomainMigrateSetMaxDowntime(virDomainPtr dom,
     return ret;
 }
 
+
+static int
+qemuDomainMigrateGetMaxDowntime(virDomainPtr dom,
+                                unsigned long long *downtime,
+                                unsigned int flags)
+{
+    virQEMUDriverPtr driver = dom->conn->privateData;
+    virDomainObjPtr vm;
+    qemuDomainObjPrivatePtr priv;
+    qemuMonitorMigrationParams migparams = { 0 };
+    int ret = -1;
+
+    virCheckFlags(0, -1);
+
+    if (!(vm = qemuDomObjFromDomain(dom)))
+        return -1;
+
+    if (virDomainMigrateGetMaxDowntimeEnsureACL(dom->conn, vm->def) < 0)
+        goto cleanup;
+
+    if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_QUERY) < 0)
+        goto cleanup;
+
+    if (!virDomainObjIsActive(vm)) {
+        virReportError(VIR_ERR_OPERATION_INVALID,
+                       "%s", _("domain is not running"));
+        goto endjob;
+    }
+
+    priv = vm->privateData;
+    qemuDomainObjEnterMonitor(driver, vm);
+
+    if (qemuMonitorGetMigrationParams(priv->mon, &migparams) == 0) {
+        if (migparams.downtimeLimit_set) {
+            *downtime = migparams.downtimeLimit;
+            ret = 0;
+        } else {
+            virReportError(VIR_ERR_OPERATION_INVALID, "%s",
+                           _("Querying migration downtime is not supported by "
+                             "QEMU binary"));
+        }
+    }
+
+    if (qemuDomainObjExitMonitor(driver, vm) < 0)
+        ret = -1;
+
+ endjob:
+    qemuDomainObjEndJob(driver, vm);
+
+ cleanup:
+    virDomainObjEndAPI(&vm);
+    return ret;
+}
+
+
 static int
 qemuDomainMigrateGetCompressionCache(virDomainPtr dom,
                                      unsigned long long *cacheSize,
@@ -20829,6 +20884,7 @@ static virHypervisorDriver qemuHypervisorDriver = {
     .domainGetJobInfo = qemuDomainGetJobInfo, /* 0.7.7 */
     .domainGetJobStats = qemuDomainGetJobStats, /* 1.0.3 */
     .domainAbortJob = qemuDomainAbortJob, /* 0.7.7 */
+    .domainMigrateGetMaxDowntime = qemuDomainMigrateGetMaxDowntime, /* 3.7.0 */
     .domainMigrateSetMaxDowntime = qemuDomainMigrateSetMaxDowntime, /* 0.8.0 */
     .domainMigrateGetCompressionCache = qemuDomainMigrateGetCompressionCache, /* 1.0.3 */
     .domainMigrateSetCompressionCache = qemuDomainMigrateSetCompressionCache, /* 1.0.3 */

src/qemu/qemu_monitor.h

@@ -627,6 +627,9 @@ struct _qemuMonitorMigrationParams {
      * whereas, some string value indicates we can support setting/clearing */
     char *migrateTLSAlias;
     char *migrateTLSHostname;
+
+    bool downtimeLimit_set;
+    unsigned long long downtimeLimit;
 };
 
 int qemuMonitorGetMigrationParams(qemuMonitorPtr mon,

src/qemu/qemu_monitor_json.c

@@ -2705,6 +2705,10 @@ qemuMonitorJSONGetMigrationParams(qemuMonitorPtr mon,
 
 #undef PARSE
 
+    if (virJSONValueObjectGetNumberUlong(result, "downtime-limit",
+                                         &params->downtimeLimit) == 0)
+        params->downtimeLimit_set = true;
+
     if ((tlsStr = virJSONValueObjectGetString(result, "tls-creds"))) {
         if (VIR_STRDUP(params->migrateTLSAlias, tlsStr) < 0)
             goto cleanup;

src/remote/remote_driver.c

@@ -8400,6 +8400,7 @@ static virHypervisorDriver hypervisor_driver = {
     .domainGetJobInfo = remoteDomainGetJobInfo, /* 0.7.7 */
     .domainGetJobStats = remoteDomainGetJobStats, /* 1.0.3 */
     .domainAbortJob = remoteDomainAbortJob, /* 0.7.7 */
+    .domainMigrateGetMaxDowntime = remoteDomainMigrateGetMaxDowntime, /* 3.7.0 */
     .domainMigrateSetMaxDowntime = remoteDomainMigrateSetMaxDowntime, /* 0.8.0 */
     .domainMigrateGetCompressionCache = remoteDomainMigrateGetCompressionCache, /* 1.0.3 */
     .domainMigrateSetCompressionCache = remoteDomainMigrateSetCompressionCache, /* 1.0.3 */

src/remote/remote_protocol.x

@@ -2326,6 +2326,15 @@ struct remote_domain_abort_job_args {
 };
 
 
+struct remote_domain_migrate_get_max_downtime_args {
+    remote_nonnull_domain dom;
+    unsigned int flags;
+};
+
+struct remote_domain_migrate_get_max_downtime_ret {
+     unsigned hyper downtime; /* insert@1 */
+};
+
 struct remote_domain_migrate_set_max_downtime_args {
     remote_nonnull_domain dom;
     unsigned hyper downtime;
@@ -6064,7 +6073,12 @@ enum remote_procedure {
      * @generate: both
      * @acl: domain:write
      */
-    REMOTE_PROC_DOMAIN_SET_BLOCK_THRESHOLD = 386
+    REMOTE_PROC_DOMAIN_SET_BLOCK_THRESHOLD = 386,
 
+    /**
+     * @generate: both
+     * @acl: domain:migrate
+     */
+    REMOTE_PROC_DOMAIN_MIGRATE_GET_MAX_DOWNTIME = 387
 
 };

src/remote_protocol-structs

@@ -1773,6 +1773,13 @@ struct remote_domain_get_job_stats_ret {
 struct remote_domain_abort_job_args {
         remote_nonnull_domain      dom;
 };
+struct remote_domain_migrate_get_max_downtime_args {
+        remote_nonnull_domain      dom;
+        u_int                      flags;
+};
+struct remote_domain_migrate_get_max_downtime_ret {
+        uint64_t                   downtime;
+};
 struct remote_domain_migrate_set_max_downtime_args {
         remote_nonnull_domain      dom;
         uint64_t                   downtime;
@@ -3233,4 +3240,5 @@ enum remote_procedure {
         REMOTE_PROC_DOMAIN_SET_VCPU = 384,
         REMOTE_PROC_DOMAIN_EVENT_BLOCK_THRESHOLD = 385,
         REMOTE_PROC_DOMAIN_SET_BLOCK_THRESHOLD = 386,
+        REMOTE_PROC_DOMAIN_MIGRATE_GET_MAX_DOWNTIME = 387,
 };