qemu: wait for SPICE to migrate

Recently, there have been some improvements made to qemu so it
supports seamless migration or something very close to it.
However, it requires libvirt interaction. Once qemu is migrated,
the SPICE server needs to send its internal state to the destination.
Once it's done, it fires SPICE_MIGRATE_COMPLETED event and this
fact is advertised in 'query-spice' output as well.
We must not kill qemu until SPICE server finishes the transfer.

src/qemu/qemu_capabilities.c

@@ -183,6 +183,7 @@ VIR_ENUM_IMPL(qemuCaps, QEMU_CAPS_LAST,
 
               "reboot-timeout", /* 110 */
               "dump-guest-core",
+              "seamless-migration",
     );
 
 struct _qemuCaps {
@@ -1149,6 +1150,8 @@ qemuCapsComputeCmdFlags(const char *help,
     }
     if (strstr(help, "-spice"))
         qemuCapsSet(caps, QEMU_CAPS_SPICE);
+    if (strstr(help, "seamless-migration="))
+        qemuCapsSet(caps, QEMU_CAPS_SEAMLESS_MIGRATION);
     if (strstr(help, "boot=on"))
         qemuCapsSet(caps, QEMU_CAPS_DRIVE_BOOT);
     if (strstr(help, "serial=s"))

src/qemu/qemu_capabilities.h

@@ -147,6 +147,7 @@ enum qemuCapsFlags {
     QEMU_CAPS_SECCOMP_SANDBOX    = 109, /* -sandbox */
     QEMU_CAPS_REBOOT_TIMEOUT     = 110, /* -boot reboot-timeout */
     QEMU_CAPS_DUMP_GUEST_CORE    = 111, /* dump-guest-core-parameter */
+    QEMU_CAPS_SEAMLESS_MIGRATION = 112, /* seamless-migration for SPICE */
 
     QEMU_CAPS_LAST,                   /* this must always be the last item */
 };

src/qemu/qemu_command.c

@@ -6150,6 +6150,14 @@ qemuBuildCommandLine(virConnectPtr conn,
         if (def->graphics[0]->data.spice.copypaste == VIR_DOMAIN_GRAPHICS_SPICE_CLIPBOARD_COPYPASTE_NO)
             virBufferAddLit(&opt, ",disable-copy-paste");
 
+        if (qemuCapsGet(caps, QEMU_CAPS_SEAMLESS_MIGRATION)) {
+            /* If qemu supports seamless migration turn it
+             * unconditionally on. If migration destination
+             * doesn't support it, it fallbacks to previous
+             * migration algorithm silently. */
+            virBufferAddLit(&opt, ",seamless-migration=on");
+        }
+
         virCommandAddArg(cmd, "-spice");
         virCommandAddArgBuffer(cmd, &opt);
         if (def->graphics[0]->data.spice.keymap)

src/qemu/qemu_migration.c

@@ -896,10 +896,19 @@ qemuMigrationUpdateJobStatus(struct qemud_driver *driver,
     qemuDomainObjPrivatePtr priv = vm->privateData;
     int ret;
     int status;
+    bool wait_for_spice = false;
+    bool spice_migrated = false;
     unsigned long long memProcessed;
     unsigned long long memRemaining;
     unsigned long long memTotal;
 
+    /* If guest uses SPICE and supports seamles_migration we have to hold up
+     * migration finish until SPICE server transfers its data */
+    if (vm->def->ngraphics == 1 &&
+        vm->def->graphics[0]->type == VIR_DOMAIN_GRAPHICS_TYPE_SPICE &&
+        qemuCapsGet(priv->caps, QEMU_CAPS_SEAMLESS_MIGRATION))
+        wait_for_spice = true;
+
     ret = qemuDomainObjEnterMonitorAsync(driver, vm, asyncJob);
     if (ret < 0) {
         /* Guest already exited; nothing further to update.  */
@@ -910,6 +919,13 @@ qemuMigrationUpdateJobStatus(struct qemud_driver *driver,
                                         &memProcessed,
                                         &memRemaining,
                                         &memTotal);
+
+    /* If qemu says migrated, check spice */
+    if (wait_for_spice && (ret == 0) &&
+        (status == QEMU_MONITOR_MIGRATION_STATUS_COMPLETED))
+        ret = qemuMonitorGetSpiceMigrationStatus(priv->mon,
+                                                 &spice_migrated);
+
     qemuDomainObjExitMonitorWithDriver(driver, vm);
 
     if (ret < 0 || virTimeMillisNow(&priv->job.info.timeElapsed) < 0) {
@@ -939,7 +955,8 @@ qemuMigrationUpdateJobStatus(struct qemud_driver *driver,
         break;
 
     case QEMU_MONITOR_MIGRATION_STATUS_COMPLETED:
-        priv->job.info.type = VIR_DOMAIN_JOB_COMPLETED;
+        if ((wait_for_spice && spice_migrated) || (!wait_for_spice))
+            priv->job.info.type = VIR_DOMAIN_JOB_COMPLETED;
         ret = 0;
         break;
 

src/qemu/qemu_monitor.c

@@ -1828,6 +1828,30 @@ int qemuMonitorGetMigrationStatus(qemuMonitorPtr mon,
 }
 
 
+int qemuMonitorGetSpiceMigrationStatus(qemuMonitorPtr mon,
+                                       bool *spice_migrated)
+{
+    int ret;
+    VIR_DEBUG("mon=%p", mon);
+
+    if (!mon) {
+        virReportError(VIR_ERR_INVALID_ARG, "%s",
+                       _("monitor must not be NULL"));
+        return -1;
+    }
+
+    if (mon->json) {
+        ret = qemuMonitorJSONGetSpiceMigrationStatus(mon, spice_migrated);
+    } else {
+        virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
+                       _("JSON monitor is required"));
+        return -1;
+    }
+
+    return ret;
+}
+
+
 int qemuMonitorMigrateToFd(qemuMonitorPtr mon,
                            unsigned int flags,
                            int fd)

src/qemu/qemu_monitor.h

@@ -343,6 +343,8 @@ int qemuMonitorGetMigrationStatus(qemuMonitorPtr mon,
                                   unsigned long long *transferred,
                                   unsigned long long *remaining,
                                   unsigned long long *total);
+int qemuMonitorGetSpiceMigrationStatus(qemuMonitorPtr mon,
+                                       bool *spice_migrated);
 
 typedef enum {
   QEMU_MONITOR_MIGRATE_BACKGROUND	= 1 << 0,

src/qemu/qemu_monitor_json.c

@@ -2490,6 +2490,58 @@ int qemuMonitorJSONGetMigrationStatus(qemuMonitorPtr mon,
 }
 
 
+static int
+qemuMonitorJSONSpiceGetMigrationStatusReply(virJSONValuePtr reply,
+                                            bool *spice_migrated)
+{
+    virJSONValuePtr ret;
+    const char *migrated_str;
+
+    if (!(ret = virJSONValueObjectGet(reply, "return"))) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("query-spice reply was missing return data"));
+        return -1;
+    }
+
+    if (!(migrated_str = virJSONValueObjectGetString(ret, "migrated"))) {
+        /* Deliberately don't report error here as we are
+         * probably dealing with older qemu which doesn't
+         * report this yet. Pretend spice is migrated. */
+        *spice_migrated = true;
+    } else {
+        *spice_migrated = STREQ(migrated_str, "true");
+    }
+
+    return 0;
+}
+
+
+int qemuMonitorJSONGetSpiceMigrationStatus(qemuMonitorPtr mon,
+                                           bool *spice_migrated)
+{
+    int ret;
+    virJSONValuePtr cmd = qemuMonitorJSONMakeCommand("query-spice",
+                                                     NULL);
+    virJSONValuePtr reply = NULL;
+
+    if (!cmd)
+        return -1;
+
+    ret = qemuMonitorJSONCommand(mon, cmd, &reply);
+
+    if (ret == 0)
+        ret = qemuMonitorJSONCheckError(cmd, reply);
+
+    if (ret == 0)
+        ret = qemuMonitorJSONSpiceGetMigrationStatusReply(reply,
+                                                          spice_migrated);
+
+    virJSONValueFree(cmd);
+    virJSONValueFree(reply);
+    return ret;
+}
+
+
 int qemuMonitorJSONMigrate(qemuMonitorPtr mon,
                            unsigned int flags,
                            const char *uri)

src/qemu/qemu_monitor_json.h

@@ -134,6 +134,9 @@ int qemuMonitorJSONGetMigrationStatus(qemuMonitorPtr mon,
 int qemuMonitorJSONMigrate(qemuMonitorPtr mon,
                            unsigned int flags,
                            const char *uri);
+int qemuMonitorJSONGetSpiceMigrationStatus(qemuMonitorPtr mon,
+                                           bool *spice_migrated);
+
 
 int qemuMonitorJSONMigrateCancel(qemuMonitorPtr mon);