vhost-user-test: added proper TestServer *dest initialization in test_migrate()

server->bus in _test_server_free() could be NULL, since TestServer
*dest in test_migrate() was not properly initialized like TestServer *s.
Added init_virtio_dev(dest) and uninit_virtio_dev(dest), so the fields
are properly set and when test_server_free(dest); is called, they can
be correctly freed.

The reason for that is init_virtio_dev() calls qpci_init_pc(), that
creates a QPCIBusPC * (returned as QPCIBus *), while test_server_free()
calls qpci_free_pc(), that frees the QPCIBus *. Not calling
init_virtio_dev() would leave the QPCIBus * of TestServer unset.

Problem came out once I modified  pci-pc.c and pci-pc.h, modifying
QPCIBusPC by adding another field before QPCIBus bus. Re-running the
tests showed vhost-user-test failing.

Signed-off-by: Emanuele Giuseppe Esposito <e.emanuelegiuseppe@gmail.com>
Message-Id: <1530022733-29581-1-git-send-email-esposem@usi.ch>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tests/vhost-user-test.c

@@ -537,6 +537,7 @@ static gboolean _test_server_free(TestServer *server)
     g_free(server->mig_path);
 
     g_free(server->chr_name);
+    g_assert(server->bus);
     qpci_free_pc(server->bus);
 
     g_free(server);
@@ -684,6 +685,7 @@ static void test_migrate(void)
     g_free(cmd);
 
     init_virtio_dev(s, 1u << VIRTIO_NET_F_MAC);
+    init_virtio_dev(dest, 1u << VIRTIO_NET_F_MAC);
     wait_for_fds(s);
     size = get_log_size(s);
     g_assert_cmpint(size, ==, (2 * 1024 * 1024) / (VHOST_LOG_PAGE * 8));
@@ -739,6 +741,7 @@ static void test_migrate(void)
     read_guest_mem_server(dest);
 
     uninit_virtio_dev(s);
+    uninit_virtio_dev(dest);
 
     g_source_destroy(source);
     g_source_unref(source);