From 2a84bf822cae38f67458043cd379a22e0fd22485 Mon Sep 17 00:00:00 2001

From: Leonardo Bras <leobras@redhat.com>

Date: Wed, 18 May 2022 02:52:25 -0300

Subject: [PATCH 19/37] migration: Add zero-copy-send parameter for QMP/HMP for

 Linux

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RH-Author: Leonardo Brás <leobras@redhat.com>

RH-MergeRequest: 191: MSG_ZEROCOPY + Multifd @ rhel8.7

RH-Commit: [19/26] 44ec703088cad75fd6e504958527e81d3261c9df

RH-Bugzilla: 2072049

RH-Acked-by: Peter Xu <peterx@redhat.com>

RH-Acked-by: Daniel P. Berrangé <berrange@redhat.com>

RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Add property that allows zero-copy migration of memory pages

on the sending side, and also includes a helper function

migrate_use_zero_copy_send() to check if it's enabled.

No code is introduced to actually do the migration, but it allow

future implementations to enable/disable this feature.

On non-Linux builds this parameter is compiled-out.

Signed-off-by: Leonardo Bras <leobras@redhat.com>

Reviewed-by: Peter Xu <peterx@redhat.com>

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

Reviewed-by: Juan Quintela <quintela@redhat.com>

Acked-by: Markus Armbruster <armbru@redhat.com>

Message-Id: <20220513062836.965425-5-leobras@redhat.com>

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

(cherry picked from commit abb6295b3ace5d17c3a65936913fc346616dbf14)

Signed-off-by: Leonardo Bras <leobras@redhat.com>

---

 migration/migration.c | 32 ++++++++++++++++++++++++++++++++

 migration/migration.h |  5 +++++

 migration/socket.c    | 11 +++++++++--

 monitor/hmp-cmds.c    |  6 ++++++

 qapi/migration.json   | 24 ++++++++++++++++++++++++

 5 files changed, 76 insertions(+), 2 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c

index 8a13294da6..b0fc3f68bd 100644

--- a/migration/migration.c

+++ b/migration/migration.c

@@ -888,6 +888,10 @@ MigrationParameters *qmp_query_migrate_parameters(Error **errp)

     params->multifd_zlib_level = s->parameters.multifd_zlib_level;

     params->has_multifd_zstd_level = true;

     params->multifd_zstd_level = s->parameters.multifd_zstd_level;

+#ifdef CONFIG_LINUX

+    params->has_zero_copy_send = true;

+    params->zero_copy_send = s->parameters.zero_copy_send;

+#endif

     params->has_xbzrle_cache_size = true;

     params->xbzrle_cache_size = s->parameters.xbzrle_cache_size;

     params->has_max_postcopy_bandwidth = true;

@@ -1541,6 +1545,11 @@ static void migrate_params_test_apply(MigrateSetParameters *params,

     if (params->has_multifd_compression) {

         dest->multifd_compression = params->multifd_compression;

     }

+#ifdef CONFIG_LINUX

+    if (params->has_zero_copy_send) {

+        dest->zero_copy_send = params->zero_copy_send;

+    }

+#endif

     if (params->has_xbzrle_cache_size) {

         dest->xbzrle_cache_size = params->xbzrle_cache_size;

     }

@@ -1653,6 +1662,11 @@ static void migrate_params_apply(MigrateSetParameters *params, Error **errp)

     if (params->has_multifd_compression) {

         s->parameters.multifd_compression = params->multifd_compression;

     }

+#ifdef CONFIG_LINUX

+    if (params->has_zero_copy_send) {

+        s->parameters.zero_copy_send = params->zero_copy_send;

+    }

+#endif

     if (params->has_xbzrle_cache_size) {

         s->parameters.xbzrle_cache_size = params->xbzrle_cache_size;

         xbzrle_cache_resize(params->xbzrle_cache_size, errp);

@@ -2543,6 +2557,17 @@ int migrate_multifd_zstd_level(void)

     return s->parameters.multifd_zstd_level;

 }

+#ifdef CONFIG_LINUX

+bool migrate_use_zero_copy_send(void)

+{

+    MigrationState *s;

+

+    s = migrate_get_current();

+

+    return s->parameters.zero_copy_send;

+}

+#endif

+

 int migrate_use_xbzrle(void)

 {

     MigrationState *s;

@@ -4193,6 +4218,10 @@ static Property migration_properties[] = {

     DEFINE_PROP_UINT8("multifd-zstd-level", MigrationState,

                       parameters.multifd_zstd_level,

                       DEFAULT_MIGRATE_MULTIFD_ZSTD_LEVEL),

+#ifdef CONFIG_LINUX

+    DEFINE_PROP_BOOL("zero_copy_send", MigrationState,

+                      parameters.zero_copy_send, false),

+#endif

     DEFINE_PROP_SIZE("xbzrle-cache-size", MigrationState,

                       parameters.xbzrle_cache_size,

                       DEFAULT_MIGRATE_XBZRLE_CACHE_SIZE),

@@ -4290,6 +4319,9 @@ static void migration_instance_init(Object *obj)

     params->has_multifd_compression = true;

     params->has_multifd_zlib_level = true;

     params->has_multifd_zstd_level = true;

+#ifdef CONFIG_LINUX

+    params->has_zero_copy_send = true;

+#endif

     params->has_xbzrle_cache_size = true;

     params->has_max_postcopy_bandwidth = true;

     params->has_max_cpu_throttle = true;

diff --git a/migration/migration.h b/migration/migration.h

index d016cedd9d..908098939f 100644

--- a/migration/migration.h

+++ b/migration/migration.h

@@ -339,6 +339,11 @@ MultiFDCompression migrate_multifd_compression(void);

 int migrate_multifd_zlib_level(void);

 int migrate_multifd_zstd_level(void);

+#ifdef CONFIG_LINUX

+bool migrate_use_zero_copy_send(void);

+#else

+#define migrate_use_zero_copy_send() (false)

+#endif

 int migrate_use_xbzrle(void);

 uint64_t migrate_xbzrle_cache_size(void);

 bool migrate_colo_enabled(void);

diff --git a/migration/socket.c b/migration/socket.c

index 05705a32d8..3754d8f72c 100644

--- a/migration/socket.c

+++ b/migration/socket.c

@@ -74,9 +74,16 @@ static void socket_outgoing_migration(QIOTask *task,

     if (qio_task_propagate_error(task, &err)) {

         trace_migration_socket_outgoing_error(error_get_pretty(err));

-    } else {

-        trace_migration_socket_outgoing_connected(data->hostname);

+           goto out;

     }

+

+    trace_migration_socket_outgoing_connected(data->hostname);

+

+    if (migrate_use_zero_copy_send()) {

+        error_setg(&err, "Zero copy send not available in migration");

+    }

+

+out:

     migration_channel_connect(data->s, sioc, data->hostname, err);

     object_unref(OBJECT(sioc));

 }

diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c

index 2669156b28..e02da5008b 100644

--- a/monitor/hmp-cmds.c

+++ b/monitor/hmp-cmds.c

@@ -1297,6 +1297,12 @@ void hmp_migrate_set_parameter(Monitor *mon, const QDict *qdict)

         p->has_multifd_zstd_level = true;

         visit_type_uint8(v, param, &p->multifd_zstd_level, &err;;

         break;

+#ifdef CONFIG_LINUX

+    case MIGRATION_PARAMETER_ZERO_COPY_SEND:

+        p->has_zero_copy_send = true;

+        visit_type_bool(v, param, &p->zero_copy_send, &err;;

+        break;

+#endif

     case MIGRATION_PARAMETER_XBZRLE_CACHE_SIZE:

         p->has_xbzrle_cache_size = true;

         if (!visit_type_size(v, param, &cache_size, &err)) {

diff --git a/qapi/migration.json b/qapi/migration.json

index bbfd48cf0b..59b5c5780b 100644

--- a/qapi/migration.json

+++ b/qapi/migration.json

@@ -730,6 +730,13 @@

 #                      will consume more CPU.

 #                      Defaults to 1. (Since 5.0)

 #

+# @zero-copy-send: Controls behavior on sending memory pages on migration.

+#                  When true, enables a zero-copy mechanism for sending

+#                  memory pages, if host supports it.

+#                  Requires that QEMU be permitted to use locked memory

+#                  for guest RAM pages.

+#                  Defaults to false. (Since 7.1)

+#

 # @block-bitmap-mapping: Maps block nodes and bitmaps on them to

 #                        aliases for the purpose of dirty bitmap migration.  Such

 #                        aliases may for example be the corresponding names on the

@@ -769,6 +776,7 @@

            'xbzrle-cache-size', 'max-postcopy-bandwidth',

            'max-cpu-throttle', 'multifd-compression',

            'multifd-zlib-level' ,'multifd-zstd-level',

+           { 'name': 'zero-copy-send', 'if' : 'CONFIG_LINUX'},

            'block-bitmap-mapping' ] }

 ##

@@ -895,6 +903,13 @@

 #                      will consume more CPU.

 #                      Defaults to 1. (Since 5.0)

 #

+# @zero-copy-send: Controls behavior on sending memory pages on migration.

+#                  When true, enables a zero-copy mechanism for sending

+#                  memory pages, if host supports it.

+#                  Requires that QEMU be permitted to use locked memory

+#                  for guest RAM pages.

+#                  Defaults to false. (Since 7.1)

+#

 # @block-bitmap-mapping: Maps block nodes and bitmaps on them to

 #                        aliases for the purpose of dirty bitmap migration.  Such

 #                        aliases may for example be the corresponding names on the

@@ -949,6 +964,7 @@

             '*multifd-compression': 'MultiFDCompression',

             '*multifd-zlib-level': 'uint8',

             '*multifd-zstd-level': 'uint8',

+            '*zero-copy-send': { 'type': 'bool', 'if': 'CONFIG_LINUX' },

             '*block-bitmap-mapping': [ 'BitmapMigrationNodeAlias' ] } }

 ##

@@ -1095,6 +1111,13 @@

 #                      will consume more CPU.

 #                      Defaults to 1. (Since 5.0)

 #

+# @zero-copy-send: Controls behavior on sending memory pages on migration.

+#                  When true, enables a zero-copy mechanism for sending

+#                  memory pages, if host supports it.

+#                  Requires that QEMU be permitted to use locked memory

+#                  for guest RAM pages.

+#                  Defaults to false. (Since 7.1)

+#

 # @block-bitmap-mapping: Maps block nodes and bitmaps on them to

 #                        aliases for the purpose of dirty bitmap migration.  Such

 #                        aliases may for example be the corresponding names on the

@@ -1147,6 +1170,7 @@

             '*multifd-compression': 'MultiFDCompression',

             '*multifd-zlib-level': 'uint8',

             '*multifd-zstd-level': 'uint8',

+            '*zero-copy-send': { 'type': 'bool', 'if': 'CONFIG_LINUX' },

             '*block-bitmap-mapping': [ 'BitmapMigrationNodeAlias' ] } }

 ##

-- 

2.35.3