From 7e2a037f3f349c21201152cecce32d8c8ff0bea0 Mon Sep 17 00:00:00 2001

From: Leonardo Bras <leobras@redhat.com>

Date: Mon, 20 Jun 2022 02:39:45 -0300

Subject: [PATCH 17/18] migration: Change zero_copy_send from migration

 parameter to migration capability

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

RH-MergeRequest: 95: MSG_ZEROCOPY + Multifd

RH-Commit: [11/11] e4a955607947896a49398ac8400241a0adac51a1 (LeoBras/centos-qemu-kvm)

RH-Bugzilla: 1968509

RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

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

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

When originally implemented, zero_copy_send was designed as a Migration

paramenter.

But taking into account how is that supposed to work, and how

the difference between a capability and a parameter, it only makes sense

that zero-copy-send would work better as a capability.

Taking into account how recently the change got merged, it was decided

that it's still time to make it right, and convert zero_copy_send into

a Migration capability.

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

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

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

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

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

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

  dgilbert: always define the capability, even on non-Linux but error if

set; avoids build problems with the capability

(cherry picked from commit 1abaec9a1b2c23f7aa94709a422128d9e42c3e0b)

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

---

 migration/migration.c | 58 +++++++++++++++++++------------------------

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

 qapi/migration.json   | 33 +++++++-----------------

 3 files changed, 34 insertions(+), 63 deletions(-)

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

index 102236fba0..2a141bfaf3 100644

--- a/migration/migration.c

+++ b/migration/migration.c

@@ -163,7 +163,8 @@ INITIALIZE_MIGRATE_CAPS_SET(check_caps_background_snapshot,

     MIGRATION_CAPABILITY_COMPRESS,

     MIGRATION_CAPABILITY_XBZRLE,

     MIGRATION_CAPABILITY_X_COLO,

-    MIGRATION_CAPABILITY_VALIDATE_UUID);

+    MIGRATION_CAPABILITY_VALIDATE_UUID,

+    MIGRATION_CAPABILITY_ZERO_COPY_SEND);

 /* When we add fault tolerance, we could have several

    migrations at once.  For now we don't need to add

@@ -899,10 +900,6 @@ 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;

@@ -1263,6 +1260,24 @@ static bool migrate_caps_check(bool *cap_list,

         }

     }

+#ifdef CONFIG_LINUX

+    if (cap_list[MIGRATION_CAPABILITY_ZERO_COPY_SEND] &&

+        (!cap_list[MIGRATION_CAPABILITY_MULTIFD] ||

+         migrate_use_compression() ||

+         migrate_use_tls())) {

+        error_setg(errp,

+                   "Zero copy only available for non-compressed non-TLS multifd migration");

+        return false;

+    }

+#else

+    if (cap_list[MIGRATION_CAPABILITY_ZERO_COPY_SEND]) {

+        error_setg(errp,

+                   "Zero copy currently only available on Linux");

+        return false;

+    }

+#endif

+

+

     /* incoming side only */

     if (runstate_check(RUN_STATE_INMIGRATE) &&

         !migrate_multifd_is_allowed() &&

@@ -1485,16 +1500,6 @@ static bool migrate_params_check(MigrationParameters *params, Error **errp)

         error_prepend(errp, "Invalid mapping given for block-bitmap-mapping: ");

         return false;

     }

-#ifdef CONFIG_LINUX

-    if (params->zero_copy_send &&

-        (!migrate_use_multifd() ||

-         params->multifd_compression != MULTIFD_COMPRESSION_NONE ||

-         (params->tls_creds && *params->tls_creds))) {

-        error_setg(errp,

-                   "Zero copy only available for non-compressed non-TLS multifd migration");

-        return false;

-    }

-#endif

     return true;

 }

@@ -1568,11 +1573,6 @@ 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;

     }

@@ -1685,11 +1685,6 @@ 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);

@@ -2587,7 +2582,7 @@ bool migrate_use_zero_copy_send(void)

     s = migrate_get_current();

-    return s->parameters.zero_copy_send;

+    return s->enabled_capabilities[MIGRATION_CAPABILITY_ZERO_COPY_SEND];

 }

 #endif

@@ -4243,10 +4238,6 @@ 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),

@@ -4284,6 +4275,10 @@ static Property migration_properties[] = {

     DEFINE_PROP_MIG_CAP("x-multifd", MIGRATION_CAPABILITY_MULTIFD),

     DEFINE_PROP_MIG_CAP("x-background-snapshot",

             MIGRATION_CAPABILITY_BACKGROUND_SNAPSHOT),

+#ifdef CONFIG_LINUX

+    DEFINE_PROP_MIG_CAP("x-zero-copy-send",

+            MIGRATION_CAPABILITY_ZERO_COPY_SEND),

+#endif

     DEFINE_PROP_END_OF_LIST(),

 };

@@ -4344,9 +4339,6 @@ 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/monitor/hmp-cmds.c b/monitor/hmp-cmds.c

index 55b48d3733..634968498b 100644

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

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

@@ -1309,12 +1309,6 @@ 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 4d833ecdd6..5105790cd0 100644

--- a/qapi/migration.json

+++ b/qapi/migration.json

@@ -463,6 +463,13 @@

 #                       procedure starts. The VM RAM is saved with running VM.

 #                       (since 6.0)

 #

+# @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.

+#                  (since 7.1)

+#

 # Features:

 # @unstable: Members @x-colo and @x-ignore-shared are experimental.

 #

@@ -476,7 +483,8 @@

            'block', 'return-path', 'pause-before-switchover', 'multifd',

            'dirty-bitmaps', 'postcopy-blocktime', 'late-block-activate',

            { 'name': 'x-ignore-shared', 'features': [ 'unstable' ] },

-           'validate-uuid', 'background-snapshot'] }

+           'validate-uuid', 'background-snapshot',

+           'zero-copy-send'] }

 ##

 # @MigrationCapabilityStatus:

@@ -741,12 +749,6 @@

 #                      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

@@ -787,7 +789,6 @@

            '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' ] }

 ##

@@ -914,13 +915,6 @@

 #                      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

@@ -975,7 +969,6 @@

             '*multifd-compression': 'MultiFDCompression',

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

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

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

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

 ##

@@ -1122,13 +1115,6 @@

 #                      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

@@ -1181,7 +1167,6 @@

             '*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