migration/multifd: Add new migration test cases for legacy zero page …

…checking.

Now that zero page checking is done on the multifd sender threads by
default, we still provide an option for backward compatibility. This
change adds a qtest migration test case to set the zero-page-detection
option to "legacy" and run multifd migration with zero page checking on the
migration main thread.

Signed-off-by: Hao Xiang <hao.xiang@bytedance.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/20240311180015.3359271-8-hao.xiang@linux.dev
Signed-off-by: Peter Xu <peterx@redhat.com>

tests/qtest/migration-test.c

@@ -2771,6 +2771,24 @@ test_migrate_precopy_tcp_multifd_start(QTestState *from,
     return test_migrate_precopy_tcp_multifd_start_common(from, to, "none");
 }
 
+static void *
+test_migrate_precopy_tcp_multifd_start_zero_page_legacy(QTestState *from,
+                                                        QTestState *to)
+{
+    test_migrate_precopy_tcp_multifd_start_common(from, to, "none");
+    migrate_set_parameter_str(from, "zero-page-detection", "legacy");
+    return NULL;
+}
+
+static void *
+test_migration_precopy_tcp_multifd_start_no_zero_page(QTestState *from,
+                                                      QTestState *to)
+{
+    test_migrate_precopy_tcp_multifd_start_common(from, to, "none");
+    migrate_set_parameter_str(from, "zero-page-detection", "none");
+    return NULL;
+}
+
 static void *
 test_migrate_precopy_tcp_multifd_zlib_start(QTestState *from,
                                             QTestState *to)
@@ -2812,6 +2830,36 @@ static void test_multifd_tcp_none(void)
     test_precopy_common(&args);
 }
 
+static void test_multifd_tcp_zero_page_legacy(void)
+{
+    MigrateCommon args = {
+        .listen_uri = "defer",
+        .start_hook = test_migrate_precopy_tcp_multifd_start_zero_page_legacy,
+        /*
+         * Multifd is more complicated than most of the features, it
+         * directly takes guest page buffers when sending, make sure
+         * everything will work alright even if guest page is changing.
+         */
+        .live = true,
+    };
+    test_precopy_common(&args);
+}
+
+static void test_multifd_tcp_no_zero_page(void)
+{
+    MigrateCommon args = {
+        .listen_uri = "defer",
+        .start_hook = test_migration_precopy_tcp_multifd_start_no_zero_page,
+        /*
+         * Multifd is more complicated than most of the features, it
+         * directly takes guest page buffers when sending, make sure
+         * everything will work alright even if guest page is changing.
+         */
+        .live = true,
+    };
+    test_precopy_common(&args);
+}
+
 static void test_multifd_tcp_zlib(void)
 {
     MigrateCommon args = {
@@ -3729,6 +3777,10 @@ int main(int argc, char **argv)
     }
     migration_test_add("/migration/multifd/tcp/plain/none",
                        test_multifd_tcp_none);
+    migration_test_add("/migration/multifd/tcp/plain/zero-page/legacy",
+                       test_multifd_tcp_zero_page_legacy);
+    migration_test_add("/migration/multifd/tcp/plain/zero-page/none",
+                       test_multifd_tcp_no_zero_page);
     migration_test_add("/migration/multifd/tcp/plain/cancel",
                        test_multifd_tcp_cancel);
     migration_test_add("/migration/multifd/tcp/plain/zlib",