From: Peter Xu <peterx@redhat.com>
To: Fabiano Rosas <farosas@suse.de>
Cc: qemu-devel@nongnu.org
Subject: Re: [PATCH 13/18] migration: Use output visitor in info command
Date: Fri, 4 Sep 2026 08:04:02 -0400 [thread overview]
Message-ID: <apqzsh7pIkmKTYYg@x1.local> (raw)
In-Reply-To: <20260902221547.1812481-14-farosas@suse.de>
On Wed, Sep 02, 2026 at 07:15:41PM -0300, Fabiano Rosas wrote:
> The hmp_info_migrate_parameters function currently open-codes the
> mon_printf calls for each migration parameter. As with the set command
> in the last patch, this should not be necessary as the QAPI
> infrastructure already has generated code that takes type and struct
> member names into account, including converting _ from C into the '-'
> character as part of parameter names strings.
>
> The current code is also quite painful to rebase if a series has been
> carried for a long time while parameters have been added in master.
>
> Replace all of this with a conversion from MigrationParameters to
> QDict using an output visitor and a loop over the QDict that prints
> per-QAPI-type formatted strings.
>
> Modelled after block/qapi.c:dump_qobject, but with some changes to
> keep the migration command output formatting.
>
> Note that this was not a for-free improvement, the HMP command format
> output was changed incompatibly in a previous patch. It doesn't output
> units anymore.
IIUC both qlist and qdict are only used in BitmapMigrationNodeAlias only.
It would be nice to attach an example of HMP dump before/after the change
of these two patches, either in previous patch or here (assuming the layout
changed once). In case HMP has some suggestion in general, I suggest copy
Dave when repost in case he has something to say.
>
> Signed-off-by: Fabiano Rosas <farosas@suse.de>
> ---
> migration/migration-hmp-cmds.c | 243 ++++++++++++++-------------------
> 1 file changed, 100 insertions(+), 143 deletions(-)
>
> diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c
> index 089c6d4ff46..dff69650a0c 100644
> --- a/migration/migration-hmp-cmds.c
> +++ b/migration/migration-hmp-cmds.c
> @@ -25,7 +25,12 @@
> #include "qapi/qapi-commands-migration.h"
> #include "qapi/qapi-visit-migration.h"
> #include "qapi/qobject-input-visitor.h"
> +#include "qapi/qobject-output-visitor.h"
> +#include "qobject/qbool.h"
> #include "qobject/qdict.h"
> +#include "qobject/qjson.h"
> +#include "qobject/qlist.h"
> +#include "qobject/qnum.h"
> #include "qobject/qstring.h"
> #include "qapi/string-input-visitor.h"
> #include "qapi/string-output-visitor.h"
> @@ -316,170 +321,122 @@ void hmp_info_migrate_capabilities(Monitor *mon, const QDict *qdict)
> qapi_free_MigrationCapabilityStatusList(caps);
> }
>
> -static void monitor_print_cpr_exec_command(Monitor *mon, strList *args)
> +static QDict *migrate_params_to_dict(MigrationParameters *p, Error **errp)
> {
> - monitor_printf(mon, "%s:",
> - MigrationParameter_str(MIGRATION_PARAMETER_CPR_EXEC_COMMAND));
> + QObject *obj = NULL;
> + Visitor *v = qobject_output_visitor_new(&obj);
>
> - while (args) {
> - monitor_printf(mon, " %s", args->value);
> - args = args->next;
> + if (visit_type_MigrationParameters(v, NULL, &p, errp)) {
> + visit_complete(v, &obj);
> }
> - monitor_printf(mon, "\n");
> + visit_free(v);
> + return qobject_to(QDict, obj);
> }
This exact function also exists in options.c (with the same name and
impl). Can reuse.
>
> -void hmp_info_migrate_parameters(Monitor *mon, const QDict *qdict)
> +static void hmp_migrate_print_qobject(Monitor *mon, const char *label,
> + QObject *obj)
> {
> - MigrationParameters *params;
> - MigrationState *s = migrate_get_current();
> + const char *sep;
>
> - params = qmp_query_migrate_parameters(NULL);
> + if (!obj) {
> + return;
> + }
>
> - if (params) {
> - monitor_printf(mon, "%s: %" PRIu64 "\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_ANNOUNCE_INITIAL),
> - params->announce_initial);
> - monitor_printf(mon, "%s: %" PRIu64 "\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_ANNOUNCE_MAX),
> - params->announce_max);
> - monitor_printf(mon, "%s: %" PRIu64 "\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_ANNOUNCE_ROUNDS),
> - params->announce_rounds);
> - monitor_printf(mon, "%s: %" PRIu64 "\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_ANNOUNCE_STEP),
> - params->announce_step);
> - assert(params->has_throttle_trigger_threshold);
> - monitor_printf(mon, "%s: %u\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_THROTTLE_TRIGGER_THRESHOLD),
> - params->throttle_trigger_threshold);
> - assert(params->has_cpu_throttle_initial);
> - monitor_printf(mon, "%s: %u\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_CPU_THROTTLE_INITIAL),
> - params->cpu_throttle_initial);
> - assert(params->has_cpu_throttle_increment);
> - monitor_printf(mon, "%s: %u\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_CPU_THROTTLE_INCREMENT),
> - params->cpu_throttle_increment);
> - assert(params->has_cpu_throttle_tailslow);
> - monitor_printf(mon, "%s: %s\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_CPU_THROTTLE_TAILSLOW),
> - params->cpu_throttle_tailslow ? "on" : "off");
> - assert(params->has_max_cpu_throttle);
> - monitor_printf(mon, "%s: %u\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_MAX_CPU_THROTTLE),
> - params->max_cpu_throttle);
> - assert(params->tls_creds);
> - monitor_printf(mon, "%s: %s\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_TLS_CREDS),
> - params->tls_creds->u.s);
> - assert(params->tls_hostname);
> - monitor_printf(mon, "%s: %s\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_TLS_HOSTNAME),
> - params->tls_hostname->u.s);
> - assert(params->tls_authz);
> - monitor_printf(mon, "%s: %s\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_TLS_AUTHZ),
> - params->tls_authz->u.s);
> - assert(params->has_max_bandwidth);
> - monitor_printf(mon, "%s: %" PRIu64 "\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_MAX_BANDWIDTH),
> - params->max_bandwidth);
> - assert(params->has_avail_switchover_bandwidth);
> - monitor_printf(mon, "%s: %" PRIu64 "\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_AVAIL_SWITCHOVER_BANDWIDTH),
> - params->avail_switchover_bandwidth);
> - assert(params->has_max_postcopy_bandwidth);
> - monitor_printf(mon, "%s: %" PRIu64 "\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_MAX_POSTCOPY_BANDWIDTH),
> - params->max_postcopy_bandwidth);
> - assert(params->has_downtime_limit);
> - monitor_printf(mon, "%s: %" PRIu64 "\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_DOWNTIME_LIMIT),
> - params->downtime_limit);
> - assert(params->has_x_checkpoint_delay);
> - monitor_printf(mon, "%s: %u\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_X_CHECKPOINT_DELAY),
> - params->x_checkpoint_delay);
> - monitor_printf(mon, "%s: %u\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_MULTIFD_CHANNELS),
> - params->multifd_channels);
> - monitor_printf(mon, "%s: %s\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_MULTIFD_COMPRESSION),
> - MultiFDCompression_str(params->multifd_compression));
> - assert(params->has_zero_page_detection);
> - monitor_printf(mon, "%s: %s\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_ZERO_PAGE_DETECTION),
> - qapi_enum_lookup(&ZeroPageDetection_lookup,
> - params->zero_page_detection));
> - monitor_printf(mon, "%s: %" PRIu64 "\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_XBZRLE_CACHE_SIZE),
> - params->xbzrle_cache_size);
> + /*
> + * Put a space after labels
> + * foo: bar
> + * ^
> + */
> + if (label && label[0] && label[strlen(label) - 1] == ':') {
> + sep = " ";
> + } else {
> + sep = "";
> + }
>
> - if (s->has_block_bitmap_mapping) {
> - BitmapMigrationNodeAliasList *nal;
> - BitmapMigrationNodeAlias *na;
> - BitmapMigrationBitmapAliasList *bal;
> - BitmapMigrationBitmapAlias *ba;
> - BitmapMigrationBitmapAliasTransform *bat;
> + switch (qobject_type(obj)) {
> + case QTYPE_NONE:
> + g_assert_not_reached();
> + case QTYPE_QNULL:
> + break;
Shall we assert too if we don't expect it?
> + case QTYPE_QNUM: {
> + int64_t i64;
>
> - monitor_printf(mon, "%s:",
> - MigrationParameter_str(
> - MIGRATION_PARAMETER_BLOCK_BITMAP_MAPPING));
> + if (qnum_get_try_int(qobject_to(QNum, obj), &i64)) {
> + monitor_printf(mon, "%s%s%" PRId64, label, sep, i64);
Should we use qnum_to_string() like what dump_qobject() does?
Logically any size/u64 parameter (which may not be a normal use case..) can
be set larger than INT64_MAX, so qnum_get_try_int() may return false? Here
skipping to print anything is benign if it only happens with a malicious
monitor client, but I think we should try to capture all cases.
> + }
> + break;
> + }
> + case QTYPE_QSTRING: {
> + QString *str = qobject_to(QString, obj);
>
> - for (nal = params->block_bitmap_mapping; nal; nal = nal->next)
> - {
> - na = nal->value;
> - monitor_printf(mon, " bitmaps:");
> - for (bal = na->bitmaps; bal; bal = bal->next) {
> - ba = bal->value;
> - bat = ba->transform;
> + if (str) {
Any chance str==NULL here?
> + monitor_printf(mon, "%s%s%s", label, sep, qstring_get_str(str));
> + }
> + break;
> + }
> + case QTYPE_QDICT: {
> + QDict *d = qobject_to(QDict, obj);
> + const QDictEntry *e;
> + int i = 0;
>
> - monitor_printf(mon, " name: %s", ba->name);
> - if (bat && bat->has_persistent) {
> - if (bat->persistent) {
> - monitor_printf(mon, " persistent: on");
> - } else {
> - monitor_printf(mon, " persistent: off");
> - }
> - }
> - monitor_printf(mon, " alias: %s", ba->alias);
> + if (d) {
> + for (e = qdict_first(d); e; e = qdict_next(d, e), i++) {
> + g_autofree char *l = g_strdup_printf("%s:", qdict_entry_key(e));
> + if (i) {
> + monitor_printf(mon, " ");
> }
> - monitor_printf(mon, " node-name: %s alias: %s",
> - na->node_name, na->alias);
> + hmp_migrate_print_qobject(mon, l, qdict_entry_value(e));
> }
> -
> - monitor_printf(mon, "\n");
> }
> + break;
> + }
> + case QTYPE_QLIST: {
> + QList *l = qobject_to(QList, obj);
> + const QListEntry *e;
>
> - monitor_printf(mon, "%s: %" PRIu64 "\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_X_VCPU_DIRTY_LIMIT_PERIOD),
> - params->x_vcpu_dirty_limit_period);
> + if (l) {
> + monitor_printf(mon, "%s", label);
>
> - monitor_printf(mon, "%s: %" PRIu64 "\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_VCPU_DIRTY_LIMIT),
> - params->vcpu_dirty_limit);
> + for (e = qlist_first(l); e; e = qlist_next(e)) {
> + /*
> + * In the first iteration, this is the space after the
> + * colon, otherwise it's the space between list
> + * elements.
> + */
> + monitor_printf(mon, " ");
> + hmp_migrate_print_qobject(mon, "", e->value);
> + }
> + }
> + break;
> + }
> + case QTYPE_QBOOL: {
> + QBool *b = qobject_to(QBool, obj);
> + if (b) {
Similarly, I'd drop "if" if it will always happen, making qbool_get_bool()
assert itself by deref.
> + monitor_printf(mon, "%s%s%s", label, sep,
> + qbool_get_bool(b) ? "on" : "off");
> + }
> + break;
> + }
> + default:
> + g_assert_not_reached();
> + break;
> + }
> +}
>
> - assert(params->has_mode);
> - monitor_printf(mon, "%s: %s\n",
> - MigrationParameter_str(MIGRATION_PARAMETER_MODE),
> - qapi_enum_lookup(&MigMode_lookup, params->mode));
> +void hmp_info_migrate_parameters(Monitor *mon, const QDict *qdict)
> +{
> + MigrationParameters *params = qmp_query_migrate_parameters(NULL);
> + g_autoptr(QDict) d;
> + const QDictEntry *e;
>
> - if (params->has_direct_io) {
> - monitor_printf(mon, "%s: %s\n",
> - MigrationParameter_str(
> - MIGRATION_PARAMETER_DIRECT_IO),
> - params->direct_io ? "on" : "off");
> - }
> + assert(params);
>
> - if (params->has_x_rdma_chunk_size) {
> - monitor_printf(mon, "%s: %" PRIu64 "\n",
> - MigrationParameter_str(
> - MIGRATION_PARAMETER_X_RDMA_CHUNK_SIZE),
> - params->x_rdma_chunk_size);
> - }
> + d = migrate_params_to_dict(params, NULL);
> + for (e = qdict_first(d); e; e = qdict_next(d, e)) {
> + g_autofree char *label = g_strdup_printf("%s:", qdict_entry_key(e));
>
> - assert(params->has_cpr_exec_command);
> - monitor_print_cpr_exec_command(mon, params->cpr_exec_command);
> + hmp_migrate_print_qobject(mon, label, qdict_entry_value(e));
> + monitor_printf(mon, "\n");
> }
>
> qapi_free_MigrationParameters(params);
> --
> 2.53.0
>
--
Peter Xu
next prev parent reply other threads:[~2026-09-04 12:04 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-02 22:15 [PATCH 00/18] migration: MigrationParameters changes Fabiano Rosas
2026-09-02 22:15 ` [PATCH 01/18] checkpatch: Fix checking of newlines in error messages Fabiano Rosas
2026-09-03 17:37 ` Peter Xu
2026-09-03 17:46 ` Fabiano Rosas
2026-09-03 18:00 ` Peter Xu
2026-09-03 18:35 ` Fabiano Rosas
2026-09-04 8:56 ` Markus Armbruster
2026-09-04 9:15 ` Peter Maydell
2026-09-04 12:09 ` Peter Xu
2026-09-04 14:00 ` Markus Armbruster
2026-09-02 22:15 ` [PATCH 02/18] migration/options.c: Don't export migrate_tls_opts_free Fabiano Rosas
2026-09-02 22:15 ` [PATCH 03/18] migration: Rename variables in qmp_migrate_set_parameters Fabiano Rosas
2026-09-03 17:44 ` Peter Xu
2026-09-02 22:15 ` [PATCH 04/18] migration: Use QAPI_CLONE_MEMBERS in migrate_params_apply Fabiano Rosas
2026-09-02 22:15 ` [PATCH 05/18] migration: Merge parameter structs instead of assigning one by one Fabiano Rosas
2026-09-03 18:20 ` Peter Xu
2026-09-03 19:03 ` Fabiano Rosas
2026-09-02 22:15 ` [PATCH 06/18] migration: Open code migrate_params_apply Fabiano Rosas
2026-09-02 22:15 ` [PATCH 07/18] migration: Stop freeing s->parameters members individually Fabiano Rosas
2026-09-02 22:15 ` [PATCH 08/18] migration: Use migrate_params_free during finalize Fabiano Rosas
2026-09-02 22:15 ` [PATCH 09/18] tests/qtest/migration: Add a test for HMP Fabiano Rosas
2026-09-03 20:38 ` Peter Xu
2026-09-03 20:42 ` Peter Xu
2026-09-02 22:15 ` [PATCH 10/18] migration: Validate that all params are set for query Fabiano Rosas
2026-09-03 18:59 ` Peter Xu
2026-09-04 15:11 ` Fabiano Rosas
2026-09-02 22:15 ` [PATCH 11/18] migration: Use keyval input visitor in HMP set command Fabiano Rosas
2026-09-03 19:44 ` Peter Xu
2026-09-03 20:24 ` Dr. David Alan Gilbert
2026-09-04 15:26 ` Peter Xu
2026-09-04 9:45 ` Markus Armbruster
2026-09-02 22:15 ` [PATCH 12/18] migration: Change HMP 'info migrate_parameters' output Fabiano Rosas
2026-09-03 20:25 ` Peter Xu
2026-09-02 22:15 ` [PATCH 13/18] migration: Use output visitor in info command Fabiano Rosas
2026-09-04 12:04 ` Peter Xu [this message]
2026-09-04 13:41 ` Fabiano Rosas
2026-09-04 14:54 ` Peter Xu
2026-09-04 15:08 ` Fabiano Rosas
2026-09-02 22:15 ` [PATCH 14/18] migration: Rewrite migrate_set_parameter_completion using QDict Fabiano Rosas
2026-09-03 20:23 ` Peter Xu
2026-09-02 22:15 ` [PATCH 15/18] qapi/migration: Remove MigrationParameter Fabiano Rosas
2026-09-04 9:07 ` Markus Armbruster
2026-09-04 12:24 ` Peter Xu
2026-09-04 13:49 ` Fabiano Rosas
2026-09-02 22:15 ` [PATCH 16/18] migration: Add capabilities into MigrationParameters Fabiano Rosas
2026-09-04 9:53 ` Markus Armbruster
2026-09-04 13:58 ` Fabiano Rosas
2026-09-02 22:15 ` [PATCH 17/18] migration: Remove s->capabilities Fabiano Rosas
2026-09-04 12:15 ` Peter Xu
2026-09-02 22:15 ` [PATCH 18/18] qapi/migration: Deprecate capabilities commands Fabiano Rosas
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