The only two users of memory_backend as of now (cpr-exec, cpr-transfer)
uses memfd as backend, now we fully support it.  We can move memory_backend
usage to mem_type and drop it.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 tests/qtest/migration/framework.h |  5 -----
 tests/qtest/migration/cpr-tests.c |  6 ++----
 tests/qtest/migration/framework.c | 10 +++-------
 3 files changed, 5 insertions(+), 16 deletions(-)

diff --git a/tests/qtest/migration/framework.h b/tests/qtest/migration/framework.h
index 9dec21c344..ed85ed502d 100644
--- a/tests/qtest/migration/framework.h
+++ b/tests/qtest/migration/framework.h
@@ -134,11 +134,6 @@ typedef struct {
     bool suspend_me;
     /* enable OOB QMP capability */
     bool oob;
-    /*
-     * Format string for the main memory backend, containing one %s where the
-     * size is plugged in.  If omitted, "-m %s" is used.
-     */
-    const char *memory_backend;
 
     /* Do not connect to target monitor and qtest sockets in qtest_init */
     bool defer_target_connect;
diff --git a/tests/qtest/migration/cpr-tests.c b/tests/qtest/migration/cpr-tests.c
index 70f8e69633..2a186c6f35 100644
--- a/tests/qtest/migration/cpr-tests.c
+++ b/tests/qtest/migration/cpr-tests.c
@@ -89,8 +89,7 @@ static void test_mode_transfer_common(bool incoming_defer)
         .start.opts_source = opts,
         .start.opts_target = opts_target,
         .start.defer_target_connect = true,
-        .start.memory_backend = "-object memory-backend-memfd,id=pc.ram,size=%s"
-                                " -machine memory-backend=pc.ram",
+        .start.mem_type = MEM_TYPE_MEMFD,
         .listen_uri = incoming_defer ? "defer" : uri,
         .connect_channels = connect_channels,
         .cpr_channel = cpr_channel,
@@ -235,8 +234,7 @@ static void test_mode_exec(void)
     MigrateCommon args = {
         .start.only_source = true,
         .start.opts_source = "-machine aux-ram-share=on -nodefaults",
-        .start.memory_backend = "-object memory-backend-memfd,id=pc.ram,size=%s"
-                                " -machine memory-backend=pc.ram",
+        .start.mem_type = MEM_TYPE_MEMFD,
         .connect_uri = uri,
         .listen_uri = listen_uri,
         .start_hook = test_mode_exec_start,
diff --git a/tests/qtest/migration/framework.c b/tests/qtest/migration/framework.c
index 4d1663356a..81eae09c92 100644
--- a/tests/qtest/migration/framework.c
+++ b/tests/qtest/migration/framework.c
@@ -366,13 +366,9 @@ int migrate_args(char **from, char **to, const char *uri, MigrateStart *args)
         ignore_stderr = "";
     }
 
-    if (args->memory_backend) {
-        memory_backend = g_strdup_printf(args->memory_backend, memory_size);
-    } else {
-        mem_object = migrate_mem_type_get_opts(args->mem_type, memory_size);
-        memory_backend = g_strdup_printf("-machine memory-backend=%s %s",
-                                         MIG_MEM_ID, mem_object);
-    }
+    mem_object = migrate_mem_type_get_opts(args->mem_type, memory_size);
+    memory_backend = g_strdup_printf("-machine memory-backend=%s %s",
+                                     MIG_MEM_ID, mem_object);
 
     if (args->use_dirty_ring) {
         kvm_opts = ",dirty-ring-size=4096";
-- 
2.50.1