Add new vhost-user netdev backend

Add a new QEMU netdev backend that is intended to invoke vhost_net with the
vhost-user backend. It uses an Unix socket chardev to establish a
communication with the 'slave' (client and server mode supported).

At runtime the netdev will handle OPEN/CLOSE events from the chardev. Upon
disconnection it will set link_down accordingly and notify virtio-net; the
virtio-net interface will go down.

Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
Signed-off-by: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

include/net/vhost-user.h

@@ -0,0 +1,17 @@
+/*
+ * vhost-user.h
+ *
+ * Copyright (c) 2013 Virtual Open Systems Sarl.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef VHOST_USER_H_
+#define VHOST_USER_H_
+
+struct vhost_net;
+struct vhost_net *vhost_user_get_vhost_net(NetClientState *nc);
+
+#endif /* VHOST_USER_H_ */

net/Makefile.objs

@@ -2,7 +2,7 @@ common-obj-y = net.o queue.o checksum.o util.o hub.o
 common-obj-y += socket.o
 common-obj-y += dump.o
 common-obj-y += eth.o
-common-obj-$(CONFIG_POSIX) += tap.o
+common-obj-$(CONFIG_POSIX) += tap.o vhost-user.o
 common-obj-$(CONFIG_LINUX) += tap-linux.o
 common-obj-$(CONFIG_WIN32) += tap-win32.o
 common-obj-$(CONFIG_BSD) += tap-bsd.o

net/clients.h

@@ -57,4 +57,7 @@ int net_init_netmap(const NetClientOptions *opts, const char *name,
                     NetClientState *peer);
 #endif
 
+int net_init_vhost_user(const NetClientOptions *opts, const char *name,
+                        NetClientState *peer);
+
 #endif /* QEMU_NET_CLIENTS_H */

net/vhost-user.c

@@ -0,0 +1,155 @@
+/*
+ * vhost-user.c
+ *
+ * Copyright (c) 2013 Virtual Open Systems Sarl.
+ *
+ * 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 "clients.h"
+#include "net/vhost_net.h"
+#include "net/vhost-user.h"
+#include "sysemu/char.h"
+#include "qemu/error-report.h"
+
+typedef struct VhostUserState {
+    NetClientState nc;
+    CharDriverState *chr;
+    bool vhostforce;
+    VHostNetState *vhost_net;
+} VhostUserState;
+
+VHostNetState *vhost_user_get_vhost_net(NetClientState *nc)
+{
+    VhostUserState *s = DO_UPCAST(VhostUserState, nc, nc);
+    return s->vhost_net;
+}
+
+static int vhost_user_running(VhostUserState *s)
+{
+    return (s->vhost_net) ? 1 : 0;
+}
+
+static int vhost_user_start(VhostUserState *s)
+{
+    VhostNetOptions options;
+
+    if (vhost_user_running(s)) {
+        return 0;
+    }
+
+    options.backend_type = VHOST_BACKEND_TYPE_USER;
+    options.net_backend = &s->nc;
+    options.opaque = s->chr;
+    options.force = s->vhostforce;
+
+    s->vhost_net = vhost_net_init(&options);
+
+    return vhost_user_running(s) ? 0 : -1;
+}
+
+static void vhost_user_stop(VhostUserState *s)
+{
+    if (vhost_user_running(s)) {
+        vhost_net_cleanup(s->vhost_net);
+    }
+
+    s->vhost_net = 0;
+}
+
+static void vhost_user_cleanup(NetClientState *nc)
+{
+    VhostUserState *s = DO_UPCAST(VhostUserState, nc, nc);
+
+    vhost_user_stop(s);
+    qemu_purge_queued_packets(nc);
+}
+
+static bool vhost_user_has_vnet_hdr(NetClientState *nc)
+{
+    assert(nc->info->type == NET_CLIENT_OPTIONS_KIND_VHOST_USER);
+
+    return true;
+}
+
+static bool vhost_user_has_ufo(NetClientState *nc)
+{
+    assert(nc->info->type == NET_CLIENT_OPTIONS_KIND_VHOST_USER);
+
+    return true;
+}
+
+static NetClientInfo net_vhost_user_info = {
+        .type = 0,
+        .size = sizeof(VhostUserState),
+        .cleanup = vhost_user_cleanup,
+        .has_vnet_hdr = vhost_user_has_vnet_hdr,
+        .has_ufo = vhost_user_has_ufo,
+};
+
+static void net_vhost_link_down(VhostUserState *s, bool link_down)
+{
+    s->nc.link_down = link_down;
+
+    if (s->nc.peer) {
+        s->nc.peer->link_down = link_down;
+    }
+
+    if (s->nc.info->link_status_changed) {
+        s->nc.info->link_status_changed(&s->nc);
+    }
+
+    if (s->nc.peer && s->nc.peer->info->link_status_changed) {
+        s->nc.peer->info->link_status_changed(s->nc.peer);
+    }
+}
+
+static void net_vhost_user_event(void *opaque, int event)
+{
+    VhostUserState *s = opaque;
+
+    switch (event) {
+    case CHR_EVENT_OPENED:
+        vhost_user_start(s);
+        net_vhost_link_down(s, false);
+        error_report("chardev \"%s\" went up\n", s->chr->label);
+        break;
+    case CHR_EVENT_CLOSED:
+        net_vhost_link_down(s, true);
+        vhost_user_stop(s);
+        error_report("chardev \"%s\" went down\n", s->chr->label);
+        break;
+    }
+}
+
+static int net_vhost_user_init(NetClientState *peer, const char *device,
+                               const char *name, CharDriverState *chr,
+                               bool vhostforce)
+{
+    NetClientState *nc;
+    VhostUserState *s;
+
+    nc = qemu_new_net_client(&net_vhost_user_info, peer, device, name);
+
+    snprintf(nc->info_str, sizeof(nc->info_str), "vhost-user to %s",
+             chr->label);
+
+    s = DO_UPCAST(VhostUserState, nc, nc);
+
+    /* We don't provide a receive callback */
+    s->nc.receive_disabled = 1;
+    s->chr = chr;
+    s->vhostforce = vhostforce;
+
+    qemu_chr_add_handlers(s->chr, NULL, NULL, net_vhost_user_event, s);
+
+    return 0;
+}
+
+int net_init_vhost_user(const NetClientOptions *opts, const char *name,
+                   NetClientState *peer)
+{
+    return net_vhost_user_init(peer, "vhost_user", 0, 0, 0);
+}