vhost-net-user: add stubs for when no virtio-net device is present

hw/net/vhost_net.c needs functions that are declared in net/vhost-user.c: the
vhost-user code is always compiled into QEMU, only the constructor
net_init_vhost_user is unreachable.  Also, net/vhost-user.c needs functions
declared in hw/virtio/vhost-stub.c even if no virtio device exists.

Break this dependency.  First, add a minimal version of net/vhost-user.c,
with no functionality and no dependency on vhost code.  Second, #ifdef out
the calls back to net/vhost-user.c from hw/net/vhost_net.c.

While at it, this patch fixes the CONFIG_VHOST_NET_USE*D* typo.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <1543851204-41186-3-git-send-email-pbonzini@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1550165756-21617-3-git-send-email-pbonzini@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

3 files changed, 27 insertions, 2 deletions

diff --git a/net/Makefile.objs b/net/Makefile.objs
index b2bf88a0ef..df2b409066 100644
--- a/net/Makefile.objs
+++ b/net/Makefile.objs
@@ -3,7 +3,9 @@ common-obj-y += socket.o
 common-obj-y += dump.o
 common-obj-y += eth.o
 common-obj-$(CONFIG_L2TPV3) += l2tpv3.o
-common-obj-$(CONFIG_POSIX) += vhost-user.o
+common-obj-$(call land,$(CONFIG_VIRTIO_NET),$(CONFIG_VHOST_NET_USER)) += vhost-user.o
+common-obj-$(call land,$(call lnot,$(CONFIG_VIRTIO_NET)),$(CONFIG_VHOST_NET_USER)) += vhost-user-stub.o
+common-obj-$(CONFIG_ALL) += vhost-user-stub.o
 common-obj-$(CONFIG_SLIRP) += slirp.o
 common-obj-$(CONFIG_VDE) += vde.o
 common-obj-$(CONFIG_NETMAP) += netmap.o
diff --git a/net/net.c b/net/net.c
index 5dcff7fe2a..f3a3c5444c 100644
--- a/net/net.c
+++ b/net/net.c
@@ -961,7 +961,7 @@ static int (* const net_client_init_fun[NET_CLIENT_DRIVER__MAX])(
         [NET_CLIENT_DRIVER_BRIDGE]    = net_init_bridge,
 #endif
         [NET_CLIENT_DRIVER_HUBPORT]   = net_init_hubport,
-#ifdef CONFIG_VHOST_NET_USED
+#ifdef CONFIG_VHOST_NET_USER
         [NET_CLIENT_DRIVER_VHOST_USER] = net_init_vhost_user,
 #endif
 #ifdef CONFIG_L2TPV3
diff --git a/net/vhost-user-stub.c b/net/vhost-user-stub.c
new file mode 100644
index 0000000000..52ab4e13f1
--- /dev/null
+++ b/net/vhost-user-stub.c
@@ -0,0 +1,23 @@
+/*
+ * vhost-user-stub.c
+ *
+ * Copyright (c) 2018 Red Hat, Inc.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "clients.h"
+#include "net/vhost_net.h"
+#include "net/vhost-user.h"
+#include "qemu/error-report.h"
+#include "qapi/error.h"
+
+int net_init_vhost_user(const Netdev *netdev, const char *name,
+                        NetClientState *peer, Error **errp)
+{
+    error_setg(errp, "vhost-user requires frontend driver virtio-net-*");
+    return -1;
+}