Re: [PATCH v2 5/8] migration-test: Add COLO migration unit test

[Lukas Straub <lukasstraub2@web.de>]

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On Tue, 20 Jan 2026 12:23:08 -0500
Peter Xu <peterx@redhat.com> wrote:

> On Sat, Jan 17, 2026 at 03:09:12PM +0100, Lukas Straub wrote:
> > Add a COLO migration test for COLO migration and failover.
> > 
> > COLO does not support q35 machine at this time.
> > 
> > Signed-off-by: Lukas Straub <lukasstraub2@web.de>
> > ---
> >  MAINTAINERS                        |   1 +
> >  tests/qtest/meson.build            |   7 ++-
> >  tests/qtest/migration-test.c       |   1 +
> >  tests/qtest/migration/colo-tests.c | 113 +++++++++++++++++++++++++++++++++++++
> >  tests/qtest/migration/framework.c  |  87 +++++++++++++++++++++++++++-
> >  tests/qtest/migration/framework.h  |  10 ++++
> >  6 files changed, 217 insertions(+), 2 deletions(-)
> > 
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index dbb217255c2cf35dc0ce971c2021b130fac5469b..92ca20c9d4186a08519d15bfe8cbd583ab061a8b 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -3840,6 +3840,7 @@ F: migration/colo*
> >  F: migration/multifd-colo.*
> >  F: include/migration/colo.h
> >  F: include/migration/failover.h
> > +F: tests/qtest/migration/colo-tests.c
> >  F: docs/COLO-FT.txt
> >  
> >  COLO Proxy
> > diff --git a/tests/qtest/meson.build b/tests/qtest/meson.build
> > index 0f053fb56de5806d3c213e3a26c0b19998ae151a..d0129af4431bb08a94a918a1e40a8f657059d764 100644
> > --- a/tests/qtest/meson.build
> > +++ b/tests/qtest/meson.build
> > @@ -367,6 +367,11 @@ if gnutls.found()
> >    endif
> >  endif
> >  
> > +migration_colo_files = []
> > +if get_option('replication').allowed()
> > +  migration_colo_files = [files('migration/colo-tests.c')]
> > +endif
> > +
> >  qtests = {
> >    'aspeed_hace-test': files('aspeed-hace-utils.c', 'aspeed_hace-test.c'),
> >    'aspeed_smc-test': files('aspeed-smc-utils.c', 'aspeed_smc-test.c'),
> > @@ -378,7 +383,7 @@ qtests = {
> >                               'migration/migration-util.c') + dbus_vmstate1,
> >    'erst-test': files('erst-test.c'),
> >    'ivshmem-test': [rt, '../../contrib/ivshmem-server/ivshmem-server.c'],
> > -  'migration-test': test_migration_files + migration_tls_files,
> > +  'migration-test': test_migration_files + migration_tls_files + migration_colo_files,
> >    'pxe-test': files('boot-sector.c'),
> >    'pnv-xive2-test': files('pnv-xive2-common.c', 'pnv-xive2-flush-sync.c',
> >                            'pnv-xive2-nvpg_bar.c'),
> > diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
> > index 08936871741535c926eeac40a7d7c3f461c72fd0..e582f05c7dc2673dbd05a936df8feb6c964b5bbc 100644
> > --- a/tests/qtest/migration-test.c
> > +++ b/tests/qtest/migration-test.c
> > @@ -55,6 +55,7 @@ int main(int argc, char **argv)
> >      migration_test_add_precopy(env);
> >      migration_test_add_cpr(env);
> >      migration_test_add_misc(env);
> > +    migration_test_add_colo(env);
> >  
> >      ret = g_test_run();
> >  
> > diff --git a/tests/qtest/migration/colo-tests.c b/tests/qtest/migration/colo-tests.c
> > new file mode 100644
> > index 0000000000000000000000000000000000000000..5004f581e4d9e4e6f54eee6d70a9307b7fd123be
> > --- /dev/null
> > +++ b/tests/qtest/migration/colo-tests.c
> > @@ -0,0 +1,113 @@
> > +/*
> > + * SPDX-License-Identifier: GPL-2.0-or-later
> > + *
> > + * QTest testcases for COLO migration
> > + *
> > + * Copyright (c) 2025 Lukas Straub <lukasstraub2@web.de>
> > + *
> > + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> > + * See the COPYING file in the top-level directory.
> > + *
> > + */
> > +
> > +#include "qemu/osdep.h"
> > +#include "libqtest.h"
> > +#include "migration/framework.h"
> > +#include "migration/migration-qmp.h"
> > +#include "migration/migration-util.h"
> > +#include "qemu/module.h"
> > +
> > +static void test_colo_plain_common(MigrateCommon *args,
> > +                                   bool failover_during_checkpoint,
> > +                                   bool primary_failover)
> > +{
> > +    args->listen_uri = "tcp:127.0.0.1:0";
> > +    test_colo_common(args, failover_during_checkpoint, primary_failover);
> > +}
> > +
> > +static void *hook_start_multifd(QTestState *from, QTestState *to)
> > +{
> > +    return migrate_hook_start_precopy_tcp_multifd_common(from, to, "none");
> > +}
> > +
> > +static void test_colo_multifd_common(MigrateCommon *args,
> > +                                     bool failover_during_checkpoint,
> > +                                     bool primary_failover)
> > +{
> > +    args->listen_uri = "defer";
> > +    args->start_hook = hook_start_multifd;
> > +    args->start.caps[MIGRATION_CAPABILITY_MULTIFD] = true;
> > +    test_colo_common(args, failover_during_checkpoint, primary_failover);
> > +}
> > +
> > +static void test_colo_plain_primary_failover(char *name, MigrateCommon *args)
> > +{
> > +    test_colo_plain_common(args, false, true);
> > +}
> > +
> > +static void test_colo_plain_secondary_failover(char *name, MigrateCommon *args)
> > +{
> > +    test_colo_plain_common(args, false, false);
> > +}
> > +
> > +static void test_colo_multifd_primary_failover(char *name, MigrateCommon *args)
> > +{
> > +    test_colo_multifd_common(args, false, true);
> > +}
> > +
> > +static void test_colo_multifd_secondary_failover(char *name,
> > +                                                 MigrateCommon *args)
> > +{
> > +    test_colo_multifd_common(args, false, false);
> > +}
> > +
> > +static void test_colo_plain_primary_failover_checkpoint(char *name,
> > +                                                        MigrateCommon *args)
> > +{
> > +    test_colo_plain_common(args, true, true);
> > +}
> > +
> > +static void test_colo_plain_secondary_failover_checkpoint(char *name,
> > +                                                          MigrateCommon *args)
> > +{
> > +    test_colo_plain_common(args, true, false);
> > +}
> > +
> > +static void test_colo_multifd_primary_failover_checkpoint(char *name,
> > +                                                          MigrateCommon *args)
> > +{
> > +    test_colo_multifd_common(args, true, true);
> > +}
> > +
> > +static void test_colo_multifd_secondary_failover_checkpoint(char *name,
> > +                                                            MigrateCommon *args)
> > +{
> > +    test_colo_multifd_common(args, true, false);
> > +}
> > +
> > +void migration_test_add_colo(MigrationTestEnv *env)
> > +{
> > +    if (!env->full_set) {
> > +        return;
> > +    }
> > +
> > +    migration_test_add("/migration/colo/plain/primary_failover",
> > +                       test_colo_plain_primary_failover);
> > +    migration_test_add("/migration/colo/plain/secondary_failover",
> > +                       test_colo_plain_secondary_failover);
> > +
> > +    migration_test_add("/migration/colo/multifd/primary_failover",
> > +                       test_colo_multifd_primary_failover);
> > +    migration_test_add("/migration/colo/multifd/secondary_failover",
> > +                       test_colo_multifd_secondary_failover);
> > +
> > +    migration_test_add("/migration/colo/plain/primary_failover_checkpoint",
> > +                       test_colo_plain_primary_failover_checkpoint);
> > +    migration_test_add("/migration/colo/plain/secondary_failover_checkpoint",
> > +                       test_colo_plain_secondary_failover_checkpoint);
> > +
> > +    migration_test_add("/migration/colo/multifd/primary_failover_checkpoint",
> > +                       test_colo_multifd_primary_failover_checkpoint);
> > +    migration_test_add("/migration/colo/multifd/secondary_failover_checkpoint",
> > +                       test_colo_multifd_secondary_failover_checkpoint);
> > +}
> > diff --git a/tests/qtest/migration/framework.c b/tests/qtest/migration/framework.c
> > index 57d3b9b7c5a269d31659971e308367bd916d28f6..fe34e7cc7a1a4eeb8d5219f54733bbd8446b0e4e 100644
> > --- a/tests/qtest/migration/framework.c
> > +++ b/tests/qtest/migration/framework.c
> > @@ -315,7 +315,7 @@ int migrate_args(char **from, char **to, const char *uri, MigrateStart *args)
> >      if (strcmp(arch, "i386") == 0 || strcmp(arch, "x86_64") == 0) {
> >          memory_size = "150M";
> >  
> > -        if (g_str_equal(arch, "i386")) {
> > +        if (g_str_equal(arch, "i386") || args->force_pc_machine) {  
> 
> The naming is better, thanks.  Said that, force_pc_machine is unwanted
> either.. if we can drop it.  I asked this in v1:
> 
> https://lore.kernel.org/qemu-devel/aWltRH6Nra-Tji7w@x1.local/
> 
> Can we explore that possibility?

Never mind. I found the issue and will remove this in the next version.

> 
> >              machine_alias = "pc";
> >          } else {
> >              machine_alias = "q35";
> > @@ -1066,6 +1066,91 @@ void *migrate_hook_start_precopy_tcp_multifd_common(QTestState *from,
> >      return NULL;
> >  }
> >  
> > +int test_colo_common(MigrateCommon *args, bool failover_during_checkpoint,
> > +                     bool primary_failover)
> > +{
> > +    QTestState *from, *to;
> > +    void *data_hook = NULL;
> > +
> > +    /*
> > +     * For the COLO test, both VMs will run in parallel. Thus both VMs want to
> > +     * open the image read/write at the same time. Using read-only=on is not
> > +     * possible here, because ide-hd does not support read-only backing image.
> > +     *
> > +     * So use -snapshot, where each qemu instance creates its own writable
> > +     * snapshot internally while leaving the real image read-only.
> > +     */
> > +    args->start.opts_source = "-snapshot";
> > +    args->start.opts_target = "-snapshot";
> > +
> > +    /*
> > +     * COLO migration code logs many errors when the migration socket
> > +     * is shut down, these are expected so we hide them here.
> > +     */
> > +    args->start.hide_stderr = true;
> > +
> > +    /*
> > +     * COLO currently does not work with Q35 machine
> > +     */
> > +    args->start.force_pc_machine = true;
> > +
> > +    args->start.oob = true;  
> 
> Just curious: is OOB required in COLO for some reason?  I understand yank
> you used below uses OOB, so the question is behind that, on what can be
> blocked in main thread, and special in COLO.
> 
> > +    args->start.caps[MIGRATION_CAPABILITY_X_COLO] = true;
> > +
> > +    if (migrate_start(&from, &to, args->listen_uri, &args->start)) {
> > +        return -1;
> > +    }
> > +
> > +    migrate_set_parameter_int(from, "x-checkpoint-delay", 300);
> > +
> > +    if (args->start_hook) {
> > +        data_hook = args->start_hook(from, to);
> > +    }
> > +
> > +    migrate_ensure_converge(from);
> > +    wait_for_serial("src_serial");
> > +
> > +    migrate_qmp(from, to, args->connect_uri, NULL, "{}");
> > +
> > +    wait_for_migration_status(from, "colo", NULL);
> > +    wait_for_resume(to, &dst_state);  
> 
> We can move this whole function into colo-tests.c.  Here you may want to
> use get_dst() instead.

Okey, will do that.

> 
> > +
> > +    wait_for_serial("src_serial");
> > +    wait_for_serial("dest_serial");
> > +
> > +    /* wait for 3 checkpoints */
> > +    for (int i = 0; i < 3; i++) {
> > +        qtest_qmp_eventwait(to, "RESUME");
> > +        wait_for_serial("src_serial");
> > +        wait_for_serial("dest_serial");
> > +    }
> > +
> > +    if (failover_during_checkpoint) {
> > +        qtest_qmp_eventwait(to, "STOP");
> > +    }
> > +    if (primary_failover) {
> > +        qtest_qmp_assert_success(from, "{'exec-oob': 'yank', 'id': 'yank-cmd', "
> > +                                            "'arguments': {'instances':"
> > +                                                "[{'type': 'migration'}]}}");
> > +        qtest_qmp_assert_success(from, "{'execute': 'x-colo-lost-heartbeat'}");
> > +        wait_for_serial("src_serial");
> > +    } else {
> > +        qtest_qmp_assert_success(to, "{'exec-oob': 'yank', 'id': 'yank-cmd', "
> > +                                        "'arguments': {'instances':"
> > +                                            "[{'type': 'migration'}]}}");
> > +        qtest_qmp_assert_success(to, "{'execute': 'x-colo-lost-heartbeat'}");
> > +        wait_for_serial("dest_serial");
> > +    }
> > +
> > +    if (args->end_hook) {
> > +        args->end_hook(from, to, data_hook);
> > +    }
> > +
> > +    migrate_end(from, to, !primary_failover);
> > +
> > +    return 0;
> > +}
> > +
> >  QTestMigrationState *get_src(void)
> >  {
> >      return &src_state;
> > diff --git a/tests/qtest/migration/framework.h b/tests/qtest/migration/framework.h
> > index 2ef0f57962605c9e3bc7b7de48e52351e5389138..75088c5fb098a0f95acb1e23585d3b6e8307451e 100644
> > --- a/tests/qtest/migration/framework.h
> > +++ b/tests/qtest/migration/framework.h
> > @@ -139,6 +139,9 @@ typedef struct {
> >      /* Do not connect to target monitor and qtest sockets in qtest_init */
> >      bool defer_target_connect;
> >  
> > +    /* Use pc machine for x86_64 */
> > +    bool force_pc_machine;
> > +
> >      /*
> >       * Migration capabilities to be set in both source and
> >       * destination. For unilateral capabilities, use
> > @@ -248,6 +251,8 @@ void test_postcopy_common(MigrateCommon *args);
> >  void test_postcopy_recovery_common(MigrateCommon *args);
> >  int test_precopy_common(MigrateCommon *args);
> >  void test_file_common(MigrateCommon *args, bool stop_src);
> > +int test_colo_common(MigrateCommon *args, bool failover_during_checkpoint,
> > +                     bool colo_primary_failover);
> >  void *migrate_hook_start_precopy_tcp_multifd_common(QTestState *from,
> >                                                      QTestState *to,
> >                                                      const char *method);
> > @@ -267,5 +272,10 @@ void migration_test_add_file(MigrationTestEnv *env);
> >  void migration_test_add_precopy(MigrationTestEnv *env);
> >  void migration_test_add_cpr(MigrationTestEnv *env);
> >  void migration_test_add_misc(MigrationTestEnv *env);
> > +#ifdef CONFIG_REPLICATION
> > +void migration_test_add_colo(MigrationTestEnv *env);
> > +#else
> > +static inline void migration_test_add_colo(MigrationTestEnv *env) {};
> > +#endif
> >  
> >  #endif /* TEST_FRAMEWORK_H */
> > 
> > -- 
> > 2.39.5
> >   
> 


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