migration/multifd: Add new migration option zero-page-detection.

This new parameter controls where the zero page checking is running.
1. If this parameter is set to 'legacy', zero page checking is
done in the migration main thread.
2. If this parameter is set to 'none', zero page checking is disabled.

Signed-off-by: Hao Xiang <hao.xiang@bytedance.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Link: https://lore.kernel.org/r/20240311180015.3359271-4-hao.xiang@linux.dev
Signed-off-by: Peter Xu <peterx@redhat.com>

diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
index b45e90edb2a2d4b8b83390372d46af146d9983d9..71a21bf24ecf49a58693f4ef1ba35907c3577000 100644 (file)
--- a/hw/core/qdev-properties-system.c
+++ b/hw/core/qdev-properties-system.c
@@ -693,6 +693,16 @@ const PropertyInfo qdev_prop_granule_mode = {
     .set_default_value = qdev_propinfo_set_default_value_enum,
 };
 
+const PropertyInfo qdev_prop_zero_page_detection = {
+    .name = "ZeroPageDetection",
+    .description = "zero_page_detection values, "
+                   "none,legacy",
+    .enum_table = &ZeroPageDetection_lookup,
+    .get = qdev_propinfo_get_enum,
+    .set = qdev_propinfo_set_enum,
+    .set_default_value = qdev_propinfo_set_default_value_enum,
+};
+
 /* --- Reserved Region --- */
 
 /*

diff --git a/include/hw/qdev-properties-system.h b/include/hw/qdev-properties-system.h
index 626be87dd3c96d11d437c7d3acdf8256f8405562..438f65389f785ca77b0a2dfe7f86cf825534a34d 100644 (file)
--- a/include/hw/qdev-properties-system.h
+++ b/include/hw/qdev-properties-system.h
@@ -9,6 +9,7 @@ extern const PropertyInfo qdev_prop_reserved_region;
 extern const PropertyInfo qdev_prop_multifd_compression;
 extern const PropertyInfo qdev_prop_mig_mode;
 extern const PropertyInfo qdev_prop_granule_mode;
+extern const PropertyInfo qdev_prop_zero_page_detection;
 extern const PropertyInfo qdev_prop_losttickpolicy;
 extern const PropertyInfo qdev_prop_blockdev_on_error;
 extern const PropertyInfo qdev_prop_bios_chs_trans;
@@ -50,6 +51,9 @@ extern const PropertyInfo qdev_prop_iothread_vq_mapping_list;
                        MigMode)
 #define DEFINE_PROP_GRANULE_MODE(_n, _s, _f, _d) \
     DEFINE_PROP_SIGNED(_n, _s, _f, _d, qdev_prop_granule_mode, GranuleMode)
+#define DEFINE_PROP_ZERO_PAGE_DETECTION(_n, _s, _f, _d) \
+    DEFINE_PROP_SIGNED(_n, _s, _f, _d, qdev_prop_zero_page_detection, \
+                       ZeroPageDetection)
 #define DEFINE_PROP_LOSTTICKPOLICY(_n, _s, _f, _d) \
     DEFINE_PROP_SIGNED(_n, _s, _f, _d, qdev_prop_losttickpolicy, \
                         LostTickPolicy)

diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c
index 99b49df5dd6f3074fad33e573f0c516766620657..7e96ae6ffdae59b48d02f6ce4c46333ea9c82ad4 100644 (file)
--- a/migration/migration-hmp-cmds.c
+++ b/migration/migration-hmp-cmds.c
@@ -344,6 +344,11 @@ void hmp_info_migrate_parameters(Monitor *mon, const QDict *qdict)
         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 " bytes\n",
             MigrationParameter_str(MIGRATION_PARAMETER_XBZRLE_CACHE_SIZE),
             params->xbzrle_cache_size);
@@ -634,6 +639,10 @@ 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;
+    case MIGRATION_PARAMETER_ZERO_PAGE_DETECTION:
+        p->has_zero_page_detection = true;
+        visit_type_ZeroPageDetection(v, param, &p->zero_page_detection, &err);
+        break;
     case MIGRATION_PARAMETER_XBZRLE_CACHE_SIZE:
         p->has_xbzrle_cache_size = true;
         if (!visit_type_size(v, param, &cache_size, &err)) {

diff --git a/migration/options.c b/migration/options.c
index 09178c6f60b1a225dd0800e1ca4cf3b52b4c064a..8f2a3a2fa5b8cc6f9456c64352a52568d3ab6745 100644 (file)
--- a/migration/options.c
+++ b/migration/options.c
@@ -179,6 +179,9 @@ Property migration_properties[] = {
     DEFINE_PROP_MIG_MODE("mode", MigrationState,
                       parameters.mode,
                       MIG_MODE_NORMAL),
+    DEFINE_PROP_ZERO_PAGE_DETECTION("zero-page-detection", MigrationState,
+                       parameters.zero_page_detection,
+                       ZERO_PAGE_DETECTION_LEGACY),
 
     /* Migration capabilities */
     DEFINE_PROP_MIG_CAP("x-xbzrle", MIGRATION_CAPABILITY_XBZRLE),
@@ -938,6 +941,13 @@ uint64_t migrate_xbzrle_cache_size(void)
     return s->parameters.xbzrle_cache_size;
 }
 
+ZeroPageDetection migrate_zero_page_detection(void)
+{
+    MigrationState *s = migrate_get_current();
+
+    return s->parameters.zero_page_detection;
+}
+
 /* parameter setters */
 
 void migrate_set_block_incremental(bool value)
@@ -1048,6 +1058,8 @@ MigrationParameters *qmp_query_migrate_parameters(Error **errp)
     params->vcpu_dirty_limit = s->parameters.vcpu_dirty_limit;
     params->has_mode = true;
     params->mode = s->parameters.mode;
+    params->has_zero_page_detection = true;
+    params->zero_page_detection = s->parameters.zero_page_detection;
 
     return params;
 }
@@ -1084,6 +1096,7 @@ void migrate_params_init(MigrationParameters *params)
     params->has_x_vcpu_dirty_limit_period = true;
     params->has_vcpu_dirty_limit = true;
     params->has_mode = true;
+    params->has_zero_page_detection = true;
 }
 
 /*
@@ -1398,6 +1411,10 @@ static void migrate_params_test_apply(MigrateSetParameters *params,
     if (params->has_mode) {
         dest->mode = params->mode;
     }
+
+    if (params->has_zero_page_detection) {
+        dest->zero_page_detection = params->zero_page_detection;
+    }
 }
 
 static void migrate_params_apply(MigrateSetParameters *params, Error **errp)
@@ -1548,6 +1565,10 @@ static void migrate_params_apply(MigrateSetParameters *params, Error **errp)
     if (params->has_mode) {
         s->parameters.mode = params->mode;
     }
+
+    if (params->has_zero_page_detection) {
+        s->parameters.zero_page_detection = params->zero_page_detection;
+    }
 }
 
 void qmp_migrate_set_parameters(MigrateSetParameters *params, Error **errp)

diff --git a/migration/options.h b/migration/options.h
index b6b69c2bb7b0503a404d1fbf6ff46f267820a623..ab8199e20784c0540b74f7d9f3b6369777363c93 100644 (file)
--- a/migration/options.h
+++ b/migration/options.h
@@ -90,6 +90,7 @@ const char *migrate_tls_authz(void);
 const char *migrate_tls_creds(void);
 const char *migrate_tls_hostname(void);
 uint64_t migrate_xbzrle_cache_size(void);
+ZeroPageDetection migrate_zero_page_detection(void);
 
 /* parameters setters */
 

diff --git a/migration/ram.c b/migration/ram.c
index dec2e73f8e72a9267af2431b524c3738b81cfbe4..260529f264ea6e35079721369b0f35f4eb8ce2a0 100644 (file)
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1140,6 +1140,10 @@ static int save_zero_page(RAMState *rs, PageSearchStatus *pss,
     QEMUFile *file = pss->pss_channel;
     int len = 0;
 
+    if (migrate_zero_page_detection() == ZERO_PAGE_DETECTION_NONE) {
+        return 0;
+    }
+
     if (!buffer_is_zero(p, TARGET_PAGE_SIZE)) {
         return 0;
     }

diff --git a/qapi/migration.json b/qapi/migration.json
index 51d188b902dc7f54dd52b0672090801b8aab8dd0..83fdef73b9055858655b5a140fc48c1e7f0764d3 100644 (file)
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -670,6 +670,18 @@
 { 'enum': 'MigMode',
   'data': [ 'normal', 'cpr-reboot' ] }
 
+##
+# @ZeroPageDetection:
+#
+# @none: Do not perform zero page checking.
+#
+# @legacy: Perform zero page checking in main migration thread.
+#
+# Since: 9.0
+##
+{ 'enum': 'ZeroPageDetection',
+  'data': [ 'none', 'legacy' ] }
+
 ##
 # @BitmapMigrationBitmapAliasTransform:
 #
@@ -891,6 +903,10 @@
 # @mode: Migration mode. See description in @MigMode. Default is 'normal'.
 #        (Since 8.2)
 #
+# @zero-page-detection: Whether and how to detect zero pages.
+#     See description in @ZeroPageDetection.  Default is 'legacy'.
+#     (since 9.0)
+#
 # Features:
 #
 # @deprecated: Member @block-incremental is deprecated.  Use
@@ -924,7 +940,8 @@
            'block-bitmap-mapping',
            { 'name': 'x-vcpu-dirty-limit-period', 'features': ['unstable'] },
            'vcpu-dirty-limit',
-           'mode'] }
+           'mode',
+           'zero-page-detection'] }
 
 ##
 # @MigrateSetParameters:
@@ -1083,6 +1100,10 @@
 # @mode: Migration mode. See description in @MigMode. Default is 'normal'.
 #        (Since 8.2)
 #
+# @zero-page-detection: Whether and how to detect zero pages.
+#     See description in @ZeroPageDetection.  Default is 'legacy'.
+#     (since 9.0)
+#
 # Features:
 #
 # @deprecated: Member @block-incremental is deprecated.  Use
@@ -1136,7 +1157,8 @@
             '*x-vcpu-dirty-limit-period': { 'type': 'uint64',
                                             'features': [ 'unstable' ] },
             '*vcpu-dirty-limit': 'uint64',
-            '*mode': 'MigMode'} }
+            '*mode': 'MigMode',
+            '*zero-page-detection': 'ZeroPageDetection'} }
 
 ##
 # @migrate-set-parameters:
@@ -1311,6 +1333,10 @@
 # @mode: Migration mode. See description in @MigMode. Default is 'normal'.
 #        (Since 8.2)
 #
+# @zero-page-detection: Whether and how to detect zero pages.
+#     See description in @ZeroPageDetection.  Default is 'legacy'.
+#     (since 9.0)
+#
 # Features:
 #
 # @deprecated: Member @block-incremental is deprecated.  Use
@@ -1361,7 +1387,8 @@
             '*x-vcpu-dirty-limit-period': { 'type': 'uint64',
                                             'features': [ 'unstable' ] },
             '*vcpu-dirty-limit': 'uint64',
-            '*mode': 'MigMode'} }
+            '*mode': 'MigMode',
+            '*zero-page-detection': 'ZeroPageDetection'} }
 
 ##
 # @query-migrate-parameters: