[Qemu-devel] [PATCH v3 6/7] Add new vhost-user netdev backend

[Antonios Motakis <a.motakis@virtualopensystems.com>]

Add a new QEMU netdev backend that is intended to invoke vhost_net
with the vhost-user backend. Also decouple virtio-net from the tap
backend.

Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
Signed-off-by: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
---
 hmp-commands.hx          |   4 +-
 hw/net/vhost_net.c       |  66 ++++++++++++++++++++++------
 hw/net/virtio-net.c      |  42 ++++++++----------
 hw/virtio/vhost.c        |   1 -
 include/net/vhost-user.h |  17 ++++++++
 include/net/vhost_net.h  |   1 +
 net/Makefile.objs        |   2 +-
 net/clients.h            |   3 ++
 net/hub.c                |   1 +
 net/net.c                |   2 +
 net/vhost-user.c         | 111 +++++++++++++++++++++++++++++++++++++++++++++++
 qapi-schema.json         |  18 +++++++-
 qemu-options.hx          |   3 ++
 13 files changed, 227 insertions(+), 44 deletions(-)
 create mode 100644 include/net/vhost-user.h
 create mode 100644 net/vhost-user.c

diff --git a/hmp-commands.hx b/hmp-commands.hx
index ebe8e78..d5a3774 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1190,7 +1190,7 @@ ETEXI
     {
         .name       = "host_net_add",
         .args_type  = "device:s,opts:s?",
-        .params     = "tap|user|socket|vde|netmap|dump [options]",
+        .params     = "tap|user|socket|vde|netmap|vhost-user|dump [options]",
         .help       = "add host VLAN client",
         .mhandler.cmd = net_host_device_add,
     },
@@ -1218,7 +1218,7 @@ ETEXI
     {
         .name       = "netdev_add",
         .args_type  = "netdev:O",
-        .params     = "[user|tap|socket|hubport|netmap],id=str[,prop=value][,...]",
+        .params     = "[user|tap|socket|hubport|netmap|vhost-user],id=str[,prop=value][,...]",
         .help       = "add host network device",
         .mhandler.cmd = hmp_netdev_add,
     },
diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
index 3614e6c..e42f4d6 100644
--- a/hw/net/vhost_net.c
+++ b/hw/net/vhost_net.c
@@ -15,6 +15,7 @@
 
 #include "net/net.h"
 #include "net/tap.h"
+#include "net/vhost-user.h"
 
 #include "hw/virtio/virtio-net.h"
 #include "net/vhost_net.h"
@@ -174,15 +175,20 @@ static int vhost_net_start_one(struct vhost_net *net,
         goto fail_start;
     }
 
-    net->nc->info->poll(net->nc, false);
-    qemu_set_fd_handler(net->backend, NULL, NULL, NULL);
-    file.fd = net->backend;
-    for (file.index = 0; file.index < net->dev.nvqs; ++file.index) {
-        const VhostOps *vhost_ops = net->dev.vhost_ops;
-        r = vhost_ops->vhost_call(&net->dev, VHOST_NET_SET_BACKEND, &file);
-        if (r < 0) {
-            r = -errno;
-            goto fail;
+    if (net->nc->info->poll) {
+        net->nc->info->poll(net->nc, false);
+    }
+
+    if (net->nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP) {
+        qemu_set_fd_handler(net->backend, NULL, NULL, NULL);
+        file.fd = net->backend;
+        for (file.index = 0; file.index < net->dev.nvqs; ++file.index) {
+            const VhostOps *vhost_ops = net->dev.vhost_ops;
+            r = vhost_ops->vhost_call(&net->dev, VHOST_NET_SET_BACKEND, &file);
+            if (r < 0) {
+                r = -errno;
+                goto fail;
+            }
         }
     }
     return 0;
@@ -193,7 +199,9 @@ fail:
         int r = vhost_ops->vhost_call(&net->dev, VHOST_NET_SET_BACKEND, &file);
         assert(r >= 0);
     }
-    net->nc->info->poll(net->nc, true);
+    if (net->nc->info->poll) {
+        net->nc->info->poll(net->nc, true);
+    }
     vhost_dev_stop(&net->dev, dev);
 fail_start:
     vhost_dev_disable_notifiers(&net->dev, dev);
@@ -215,7 +223,9 @@ static void vhost_net_stop_one(struct vhost_net *net,
         int r = vhost_ops->vhost_call(&net->dev, VHOST_NET_SET_BACKEND, &file);
         assert(r >= 0);
     }
-    net->nc->info->poll(net->nc, true);
+    if (net->nc->info->poll) {
+        net->nc->info->poll(net->nc, true);
+    }
     vhost_dev_stop(&net->dev, dev);
     vhost_dev_disable_notifiers(&net->dev, dev);
 }
@@ -235,7 +245,7 @@ int vhost_net_start(VirtIODevice *dev, NetClientState *ncs,
     }
 
     for (i = 0; i < total_queues; i++) {
-        r = vhost_net_start_one(tap_get_vhost_net(ncs[i].peer), dev, i * 2);
+        r = vhost_net_start_one(get_vhost_net(ncs[i].peer), dev, i * 2);
 
         if (r < 0) {
             goto err;
@@ -252,7 +262,7 @@ int vhost_net_start(VirtIODevice *dev, NetClientState *ncs,
 
 err:
     while (--i >= 0) {
-        vhost_net_stop_one(tap_get_vhost_net(ncs[i].peer), dev);
+        vhost_net_stop_one(get_vhost_net(ncs[i].peer), dev);
     }
     return r;
 }
@@ -273,7 +283,7 @@ void vhost_net_stop(VirtIODevice *dev, NetClientState *ncs,
     assert(r >= 0);
 
     for (i = 0; i < total_queues; i++) {
-        vhost_net_stop_one(tap_get_vhost_net(ncs[i].peer), dev);
+        vhost_net_stop_one(get_vhost_net(ncs[i].peer), dev);
     }
 }
 
@@ -293,6 +303,29 @@ void vhost_net_virtqueue_mask(VHostNetState *net, VirtIODevice *dev,
 {
     vhost_virtqueue_mask(&net->dev, dev, idx, mask);
 }
+
+VHostNetState *get_vhost_net(NetClientState *nc)
+{
+    VHostNetState *vhost_net = 0;
+
+    if (!nc) {
+        return 0;
+    }
+
+    switch (nc->info->type) {
+    case NET_CLIENT_OPTIONS_KIND_TAP:
+        vhost_net = tap_get_vhost_net(nc);
+        break;
+    case NET_CLIENT_OPTIONS_KIND_VHOST_USER:
+        vhost_net = vhost_user_get_vhost_net(nc);
+        break;
+    default:
+        break;
+    }
+
+    return vhost_net;
+}
+
 #else
 struct vhost_net *vhost_net_init(VhostNetOptions *options)
 {
@@ -338,4 +371,9 @@ void vhost_net_virtqueue_mask(VHostNetState *net, VirtIODevice *dev,
                               int idx, bool mask)
 {
 }
+
+VHostNetState *get_vhost_net(NetClientState *nc)
+{
+    return 0;
+}
 #endif
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index d312b9c..8f0e3a0 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -105,14 +105,7 @@ static void virtio_net_vhost_status(VirtIONet *n, uint8_t status)
     NetClientState *nc = qemu_get_queue(n->nic);
     int queues = n->multiqueue ? n->max_queues : 1;
 
-    if (!nc->peer) {
-        return;
-    }
-    if (nc->peer->info->type != NET_CLIENT_OPTIONS_KIND_TAP) {
-        return;
-    }
-
-    if (!tap_get_vhost_net(nc->peer)) {
+    if (!get_vhost_net(nc->peer)) {
         return;
     }
 
@@ -122,7 +115,7 @@ static void virtio_net_vhost_status(VirtIONet *n, uint8_t status)
     }
     if (!n->vhost_started) {
         int r;
-        if (!vhost_net_query(tap_get_vhost_net(nc->peer), vdev)) {
+        if (!vhost_net_query(get_vhost_net(nc->peer), vdev)) {
             return;
         }
         n->vhost_started = 1;
@@ -325,11 +318,16 @@ static void peer_test_vnet_hdr(VirtIONet *n)
         return;
     }
 
-    if (nc->peer->info->type != NET_CLIENT_OPTIONS_KIND_TAP) {
-        return;
+    switch (nc->peer->info->type) {
+    case NET_CLIENT_OPTIONS_KIND_TAP:
+        n->has_vnet_hdr = tap_has_vnet_hdr(nc->peer);
+        break;
+    case NET_CLIENT_OPTIONS_KIND_VHOST_USER:
+        n->has_vnet_hdr = 0;
+        break;
+    default:
+        break;
     }
-
-    n->has_vnet_hdr = tap_has_vnet_hdr(nc->peer);
 }
 
 static int peer_has_vnet_hdr(VirtIONet *n)
@@ -437,13 +435,10 @@ static uint32_t virtio_net_get_features(VirtIODevice *vdev, uint32_t features)
         features &= ~(0x1 << VIRTIO_NET_F_HOST_UFO);
     }
 
-    if (!nc->peer || nc->peer->info->type != NET_CLIENT_OPTIONS_KIND_TAP) {
+    if (!get_vhost_net(nc->peer)) {
         return features;
     }
-    if (!tap_get_vhost_net(nc->peer)) {
-        return features;
-    }
-    return vhost_net_get_features(tap_get_vhost_net(nc->peer), features);
+    return vhost_net_get_features(get_vhost_net(nc->peer), features);
 }
 
 static uint32_t virtio_net_bad_features(VirtIODevice *vdev)
@@ -507,13 +502,10 @@ static void virtio_net_set_features(VirtIODevice *vdev, uint32_t features)
     for (i = 0;  i < n->max_queues; i++) {
         NetClientState *nc = qemu_get_subqueue(n->nic, i);
 
-        if (!nc->peer || nc->peer->info->type != NET_CLIENT_OPTIONS_KIND_TAP) {
-            continue;
-        }
-        if (!tap_get_vhost_net(nc->peer)) {
+        if (!get_vhost_net(nc->peer)) {
             continue;
         }
-        vhost_net_ack_features(tap_get_vhost_net(nc->peer), features);
+        vhost_net_ack_features(get_vhost_net(nc->peer), features);
     }
 }
 
@@ -1443,7 +1435,7 @@ static bool virtio_net_guest_notifier_pending(VirtIODevice *vdev, int idx)
     VirtIONet *n = VIRTIO_NET(vdev);
     NetClientState *nc = qemu_get_subqueue(n->nic, vq2q(idx));
     assert(n->vhost_started);
-    return vhost_net_virtqueue_pending(tap_get_vhost_net(nc->peer), idx);
+    return vhost_net_virtqueue_pending(get_vhost_net(nc->peer), idx);
 }
 
 static void virtio_net_guest_notifier_mask(VirtIODevice *vdev, int idx,
@@ -1452,7 +1444,7 @@ static void virtio_net_guest_notifier_mask(VirtIODevice *vdev, int idx,
     VirtIONet *n = VIRTIO_NET(vdev);
     NetClientState *nc = qemu_get_subqueue(n->nic, vq2q(idx));
     assert(n->vhost_started);
-    vhost_net_virtqueue_mask(tap_get_vhost_net(nc->peer),
+    vhost_net_virtqueue_mask(get_vhost_net(nc->peer),
                              vdev, idx, mask);
 }
 
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index a1137e1..fe622fb 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -14,7 +14,6 @@
  */
 
 #include "hw/virtio/vhost.h"
-#include "hw/virtio/vhost-backend.h"
 #include "hw/hw.h"
 #include "qemu/atomic.h"
 #include "qemu/range.h"
diff --git a/include/net/vhost-user.h b/include/net/vhost-user.h
new file mode 100644
index 0000000..85109f6
--- /dev/null
+++ b/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_ */
diff --git a/include/net/vhost_net.h b/include/net/vhost_net.h
index 1169562..abd3d0b 100644
--- a/include/net/vhost_net.h
+++ b/include/net/vhost_net.h
@@ -31,4 +31,5 @@ void vhost_net_ack_features(VHostNetState *net, unsigned features);
 bool vhost_net_virtqueue_pending(VHostNetState *net, int n);
 void vhost_net_virtqueue_mask(VHostNetState *net, VirtIODevice *dev,
                               int idx, bool mask);
+VHostNetState *get_vhost_net(NetClientState *nc);
 #endif
diff --git a/net/Makefile.objs b/net/Makefile.objs
index c25fe69..301f6b6 100644
--- a/net/Makefile.objs
+++ b/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
diff --git a/net/clients.h b/net/clients.h
index 7322ff5..7f3d4ae 100644
--- a/net/clients.h
+++ b/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 */
diff --git a/net/hub.c b/net/hub.c
index 33a99c9..7e0f2d6 100644
--- a/net/hub.c
+++ b/net/hub.c
@@ -322,6 +322,7 @@ void net_hub_check_clients(void)
             case NET_CLIENT_OPTIONS_KIND_TAP:
             case NET_CLIENT_OPTIONS_KIND_SOCKET:
             case NET_CLIENT_OPTIONS_KIND_VDE:
+            case NET_CLIENT_OPTIONS_KIND_VHOST_USER:
                 has_host_dev = 1;
                 break;
             default:
diff --git a/net/net.c b/net/net.c
index 9db88cc..0f057c5 100644
--- a/net/net.c
+++ b/net/net.c
@@ -734,6 +734,7 @@ static int (* const net_client_init_fun[NET_CLIENT_OPTIONS_KIND_MAX])(
         [NET_CLIENT_OPTIONS_KIND_BRIDGE]    = net_init_bridge,
 #endif
         [NET_CLIENT_OPTIONS_KIND_HUBPORT]   = net_init_hubport,
+        [NET_CLIENT_OPTIONS_KIND_VHOST_USER] = net_init_vhost_user,
 };
 
 
@@ -767,6 +768,7 @@ static int net_client_init1(const void *object, int is_netdev, Error **errp)
         case NET_CLIENT_OPTIONS_KIND_BRIDGE:
 #endif
         case NET_CLIENT_OPTIONS_KIND_HUBPORT:
+        case NET_CLIENT_OPTIONS_KIND_VHOST_USER:
             break;
 
         default:
diff --git a/net/vhost-user.c b/net/vhost-user.c
new file mode 100644
index 0000000..6fd5afc
--- /dev/null
+++ b/net/vhost-user.c
@@ -0,0 +1,111 @@
+/*
+ * 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 "qemu/error-report.h"
+
+typedef struct VhostUserState {
+    NetClientState nc;
+    VHostNetState *vhost_net;
+    char *devpath;
+} VhostUserState;
+
+VHostNetState *vhost_user_get_vhost_net(NetClientState *nc)
+{
+    VhostUserState *s = DO_UPCAST(VhostUserState, nc, nc);
+    assert(nc->info->type == NET_CLIENT_OPTIONS_KIND_VHOST_USER);
+    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 1;
+    }
+
+    options.backend_type = VHOST_BACKEND_TYPE_USER;
+    options.net_backend = &s->nc;
+    options.devpath = s->devpath;
+    options.devfd = -1;
+    options.force = 1;
+
+    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 NetClientInfo net_vhost_user_info = {
+        .type = NET_CLIENT_OPTIONS_KIND_VHOST_USER,
+        .size = sizeof(VhostUserState),
+        .cleanup = vhost_user_cleanup,
+};
+
+static int net_vhost_user_init(NetClientState *peer, const char *device,
+                          const char *name, const char *filename)
+{
+    NetClientState *nc;
+    VhostUserState *s;
+    int r;
+
+    nc = qemu_new_net_client(&net_vhost_user_info, peer, device, name);
+
+    snprintf(nc->info_str, sizeof(nc->info_str), "vhost-user to %s", filename);
+
+    s = DO_UPCAST(VhostUserState, nc, nc);
+
+    /* We don't provide a receive callback */
+    s->nc.receive_disabled = 1;
+
+    s->devpath = g_strdup(filename);
+
+    r = vhost_user_start(s);
+
+    return r;
+}
+
+int net_init_vhost_user(const NetClientOptions *opts, const char *name,
+                   NetClientState *peer)
+{
+    const char *file;
+    const NetdevVhostUserOptions *vhost_user;
+
+    assert(opts->kind == NET_CLIENT_OPTIONS_KIND_VHOST_USER);
+    vhost_user = opts->vhost_user;
+
+    file = vhost_user->file;
+
+    return net_vhost_user_init(peer, "vhost_user", name, file);
+}
diff --git a/qapi-schema.json b/qapi-schema.json
index d6f8615..dd4f5bd 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -3030,6 +3030,21 @@
     '*devname':    'str' } }
 
 ##
+# @NetdevVhostUserOptions
+#
+# Vhost-user network backend
+#
+# @file: control socket path
+#
+# Since 2.0
+##
+{ 'type': 'NetdevVhostUserOptions',
+  'data': {
+    'file': 'str' } }
+
+##
+
+##
 # @NetClientOptions
 #
 # A discriminated record of network device traits.
@@ -3047,7 +3062,8 @@
     'dump':     'NetdevDumpOptions',
     'bridge':   'NetdevBridgeOptions',
     'hubport':  'NetdevHubPortOptions',
-    'netmap':   'NetdevNetmapOptions' } }
+    'netmap':   'NetdevNetmapOptions',
+    'vhost-user': 'NetdevVhostUserOptions' } }
 
 ##
 # @NetLegacy
diff --git a/qemu-options.hx b/qemu-options.hx
index bd70777..501e6b9 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1422,6 +1422,8 @@ DEF("net", HAS_ARG, QEMU_OPTION_net,
     "                VALE port (created on the fly) called 'name' ('nmname' is name of the \n"
     "                netmap device, defaults to '/dev/netmap')\n"
 #endif
+    "-net vhost-user,file=name\n"
+    "                connect to a unix domain socket implementing vhost-user backend\n"
     "-net dump[,vlan=n][,file=f][,len=n]\n"
     "                dump traffic on vlan 'n' to file 'f' (max n bytes per packet)\n"
     "-net none       use it alone to have zero network devices. If no -net option\n"
@@ -1439,6 +1441,7 @@ DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
 #ifdef CONFIG_NETMAP
     "netmap|"
 #endif
+    "vhost-user|"
     "socket|"
     "hubport],id=str[,option][,option][,...]\n", QEMU_ARCH_ALL)
 STEXI
-- 
1.8.3.2