[Qemu-devel] [PATCH v7 12/13] Add the vhost-user netdev backend to command line

[Antonios Motakis]

The supplied chardev id will be inspected for supported options. Only
a socket backend, with a set path (i.e. a unix socket) and optionally
the server parameter set, will be allowed. Other options (nowait, telnet)
will make the chardev unusable and the netdev will not be initialised.

Signed-off-by: Antonios Motakis <address@hidden>
Signed-off-by: Nikolay Nikolaev <address@hidden>
---
 hmp-commands.hx     |  4 +--
 hw/net/vhost_net.c  |  4 +++
 hw/net/virtio-net.c |  3 ++
 net/hub.c           |  1 +
 net/net.c           |  2 ++
 net/vhost-user.c    | 91 +++++++++++++++++++++++++++++++++++++++++++++++++++--
 qapi-schema.json    | 18 ++++++++++-
 qemu-options.hx     | 16 ++++++++++
 8 files changed, 134 insertions(+), 5 deletions(-)

diff --git a/hmp-commands.hx b/hmp-commands.hx
index f3fc514..68128c1 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1195,7 +1195,7 @@ 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,
     },
@@ -1223,7 +1223,7 @@ 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 6b6268b..e630407 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"
@@ -322,6 +323,9 @@ VHostNetState *get_vhost_net(NetClientState *nc)
     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;
     }
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 72acd15..d49ee82 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -322,6 +322,9 @@ static void peer_test_vnet_hdr(VirtIONet *n)
     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;
     }
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 2c3af20..30f1273 100644
--- a/net/net.c
+++ b/net/net.c
@@ -731,6 +731,7 @@ 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,
 };
 
 
@@ -764,6 +765,7 @@ 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
index b25722c..f5bd211 100644
--- a/net/vhost-user.c
+++ b/net/vhost-user.c
@@ -12,6 +12,7 @@
 #include "net/vhost_net.h"
 #include "net/vhost-user.h"
 #include "sysemu/char.h"
+#include "qemu/config-file.h"
 #include "qemu/error-report.h"
 
 typedef struct VhostUserState {
@@ -20,9 +21,17 @@ typedef struct VhostUserState {
     VHostNetState *vhost_net;
 } VhostUserState;
 
+typedef struct VhostUserChardevProps {
+    bool is_socket;
+    bool is_unix;
+    bool is_server;
+    bool has_unsupported;
+} VhostUserChardevProps;
+
 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;
 }
 
@@ -67,7 +76,7 @@ static void vhost_user_cleanup(NetClientState *nc)
 }
 
 static NetClientInfo net_vhost_user_info = {
-        .type = 0,
+        .type = NET_CLIENT_OPTIONS_KIND_VHOST_USER,
         .size = sizeof(VhostUserState),
         .cleanup = vhost_user_cleanup,
 };
@@ -123,8 +132,86 @@ static int net_vhost_user_init(NetClientState *peer, const 
char *device,
     return 0;
 }
 
+static int net_vhost_chardev_opts(const char *name, const char *value,
+        void *opaque)
+{
+    VhostUserChardevProps *props = opaque;
+
+    if (strcmp(name, "backend") == 0 && strcmp(value, "socket") == 0) {
+        props->is_socket = 1;
+    } else if (strcmp(name, "path") == 0) {
+        props->is_unix = 1;
+    } else if (strcmp(name, "server") == 0) {
+        props->is_server = 1;
+    } else {
+        error_report("vhost-user does not support a chardev"
+                     " with the following option:\n %s = %s",
+                     name, value);
+        props->has_unsupported = 1;
+        return -1;
+    }
+    return 0;
+}
+
+static CharDriverState *net_vhost_parse_chardev(
+        const NetdevVhostUserOptions *opts)
+{
+    CharDriverState *chr = qemu_chr_find(opts->chardev);
+    VhostUserChardevProps props;
+
+    if (chr == NULL) {
+        error_report("chardev \"%s\" not found\n", opts->chardev);
+        return 0;
+    }
+
+    /* inspect chardev opts */
+    memset(&props, 0, sizeof(props));
+    qemu_opt_foreach(chr->opts, net_vhost_chardev_opts, &props, false);
+
+    if (!props.is_socket || !props.is_unix) {
+        error_report("chardev \"%s\" is not a unix socket\n",
+                     opts->chardev);
+        return 0;
+    }
+
+    if (props.has_unsupported) {
+        error_report("chardev \"%s\" has an unsupported option\n",
+                opts->chardev);
+        return 0;
+    }
+
+    qemu_chr_fe_claim_no_fail(chr);
+
+    return chr;
+}
+
 int net_init_vhost_user(const NetClientOptions *opts, const char *name,
                    NetClientState *peer)
 {
-    return net_vhost_user_init(peer, "vhost_user", 0, 0);
+    const NetdevVhostUserOptions *vhost_user_opts;
+    CharDriverState *chr;
+    QemuOpts *mem_opts;
+    unsigned int mem_share = 0;
+
+    assert(opts->kind == NET_CLIENT_OPTIONS_KIND_VHOST_USER);
+    vhost_user_opts = opts->vhost_user;
+
+    chr = net_vhost_parse_chardev(vhost_user_opts);
+    if (!chr) {
+        error_report("No suitable chardev found\n");
+        return -1;
+    }
+
+    /* verify mem-path is set and shared */
+    mem_opts = qemu_opts_find(qemu_find_opts("mem-path"), NULL);
+    if (mem_opts) {
+        mem_share = qemu_opt_get_bool(mem_opts, "share", 0);
+    }
+
+    if (!mem_share) {
+        error_report("vhost-user requires -mem-path /path,share=on");
+        return -1;
+    }
+
+    return net_vhost_user_init(peer, "vhost_user", name, chr);
 }
diff --git a/qapi-schema.json b/qapi-schema.json
index 05ced9d..51609a4 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -3104,6 +3104,21 @@
     '*devname':    'str' } }
 
 ##
+# @NetdevVhostUserOptions
+#
+# Vhost-user network backend
+#
+# @path: control socket path
+#
+# Since 2.0
+##
+{ 'type': 'NetdevVhostUserOptions',
+  'data': {
+    'chardev': 'str' } }
+
+##
+
+##
 # @NetClientOptions
 #
 # A discriminated record of network device traits.
@@ -3121,7 +3136,8 @@
     '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 60ecc95..2c59164 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1435,6 +1435,7 @@ 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
@@ -1766,6 +1767,21 @@ The hubport netdev lets you connect a NIC to a QEMU 
"vlan" instead of a single
 netdev.  @code{-net} and @code{-device} with parameter @option{vlan} create the
 required hub automatically.
 
address@hidden -netdev vhost-user,address@hidden
+
+Establish a vhost-user netdev, backedb by a chardev @var{id}. The chardev 
should
+be a unix domain socket backed one. The vhost-user uses a specifically defined
+protocol to pass vhost ioctl replacement messages to an application on the 
other
+end of the socket.
+
+Example:
address@hidden
+qemu -m 1024 -mem-path /hugetlbfs,prealloc=on,share=on \
+     -chardev socket,path=/path/to/socket \
+     -netdev type=vhost-user,id=net0,chardev=chr0 \
+     -device virtio-net-pci,netdev=net0
address@hidden example
+
 @item -net dump[,address@hidden,address@hidden,address@hidden
 Dump network traffic on VLAN @var{n} to file @var{file} 
(@file{qemu-vlan0.pcap} by default).
 At most @var{len} bytes (64k by default) per packet are stored. The file 
format is
-- 
1.8.3.2