migration-test: Create kvm_opts

So arch_dirty_ring option becomes one option like the others.

Reviewed-by: Peter Xu <peterx@redhat.com>
Message-ID: <20230608224943.3877-8-quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

tests/qtest/migration-test.c

@@ -608,6 +608,7 @@ static int test_migrate_start(QTestState **from, QTestState **to,
     g_autofree char *bootpath = NULL;
     g_autofree char *shmem_opts = NULL;
     g_autofree char *shmem_path = NULL;
+    const char *kvm_opts = NULL;
     const char *arch = qtest_get_arch();
     const char *memory_size;
 
@@ -683,13 +684,16 @@ static int test_migrate_start(QTestState **from, QTestState **to,
         shmem_opts = g_strdup("");
     }
 
+    if (args->use_dirty_ring) {
+        kvm_opts = ",dirty-ring-size=4096";
+    }
+
     cmd_source = g_strdup_printf("-accel kvm%s -accel tcg "
                                  "-name source,debug-threads=on "
                                  "-m %s "
                                  "-serial file:%s/src_serial "
                                  "%s %s %s %s %s",
-                                 args->use_dirty_ring ?
-                                 ",dirty-ring-size=4096" : "",
+                                 kvm_opts ? kvm_opts : "",
                                  memory_size, tmpfs,
                                  arch_opts ? arch_opts : "",
                                  arch_source ? arch_source : "",
@@ -709,8 +713,7 @@ static int test_migrate_start(QTestState **from, QTestState **to,
                                  "-serial file:%s/dest_serial "
                                  "-incoming %s "
                                  "%s %s %s %s %s",
-                                 args->use_dirty_ring ?
-                                 ",dirty-ring-size=4096" : "",
+                                 kvm_opts ? kvm_opts : "",
                                  memory_size, tmpfs, uri,
                                  arch_opts ? arch_opts : "",
                                  arch_target ? arch_target : "",