tap: add vhost/vhostfd options

This adds vhost binary option to tap, to enable vhost net accelerator.
Default is off for now, we'll be able to make default on long term
when we know it's stable.

vhostfd option can be used by management, to pass in the fd. Assigning
vhostfd implies vhost=on.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

diff --git a/net.c b/net.c
index 1092bdcaa50058444c9aa4da6c62b8a66ec744a5..3ede738cac8be5829cdd0a3350279be3c016cb95 100644 (file)
--- a/net.c
+++ b/net.c
@@ -976,6 +976,14 @@ static const struct {
                 .name = "vnet_hdr",
                 .type = QEMU_OPT_BOOL,
                 .help = "enable the IFF_VNET_HDR flag on the tap interface"
+            }, {
+                .name = "vhost",
+                .type = QEMU_OPT_BOOL,
+                .help = "enable vhost-net network accelerator",
+            }, {
+                .name = "vhostfd",
+                .type = QEMU_OPT_STRING,
+                .help = "file descriptor of an already opened vhost net device",
             },
 #endif /* _WIN32 */
             { /* end of list */ }

diff --git a/net/tap.c b/net/tap.c
index c19740b5842373cc5864e0c2fb8197c1edfe8d55..740665f5b60dd754dce6bf4c8aa060b62ca1e5e7 100644 (file)
--- a/net/tap.c
+++ b/net/tap.c
@@ -42,6 +42,8 @@
 
 #include "net/tap-linux.h"
 
+#include "hw/vhost_net.h"
+
 /* Maximum GSO packet size (64k) plus plenty of room for
  * the ethernet and virtio_net headers
  */
@@ -58,6 +60,7 @@ typedef struct TAPState {
     unsigned int has_vnet_hdr : 1;
     unsigned int using_vnet_hdr : 1;
     unsigned int has_ufo: 1;
+    VHostNetState *vhost_net;
 } TAPState;
 
 static int launch_script(const char *setup_script, const char *ifname, int fd);
@@ -253,6 +256,10 @@ static void tap_cleanup(VLANClientState *nc)
 {
     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 
+    if (s->vhost_net) {
+        vhost_net_cleanup(s->vhost_net);
+    }
+
     qemu_purge_queued_packets(nc);
 
     if (s->down_script[0])
@@ -308,6 +315,7 @@ static TAPState *net_tap_fd_init(VLANState *vlan,
     s->has_ufo = tap_probe_has_ufo(s->fd);
     tap_set_offload(&s->nc, 0, 0, 0, 0, 0);
     tap_read_poll(s, 1);
+    s->vhost_net = NULL;
     return s;
 }
 
@@ -457,5 +465,26 @@ int net_init_tap(QemuOpts *opts, Monitor *mon, const char *name, VLANState *vlan
         }
     }
 
+    if (qemu_opt_get_bool(opts, "vhost", !!qemu_opt_get(opts, "vhostfd"))) {
+        int vhostfd, r;
+        if (qemu_opt_get(opts, "vhostfd")) {
+            r = net_handle_fd_param(mon, qemu_opt_get(opts, "vhostfd"));
+            if (r == -1) {
+                return -1;
+            }
+            vhostfd = r;
+        } else {
+            vhostfd = -1;
+        }
+        s->vhost_net = vhost_net_init(&s->nc, vhostfd);
+        if (!s->vhost_net) {
+            error_report("vhost-net requested but could not be initialized");
+            return -1;
+        }
+    } else if (qemu_opt_get(opts, "vhostfd")) {
+        error_report("vhostfd= is not valid without vhost");
+        return -1;
+    }
+
     return 0;
 }

diff --git a/qemu-options.hx b/qemu-options.hx
index 719cbda83cbc66de61806971de874159515748f0..f4b3bfe90f253688fd357de46eb96497d33f7966 100644 (file)
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -892,7 +892,7 @@ DEF("net", HAS_ARG, QEMU_OPTION_net,
     "-net tap[,vlan=n][,name=str],ifname=name\n"
     "                connect the host TAP network interface to VLAN 'n'\n"
 #else
-    "-net tap[,vlan=n][,name=str][,fd=h][,ifname=name][,script=file][,downscript=dfile][,sndbuf=nbytes][,vnet_hdr=on|off]\n"
+    "-net tap[,vlan=n][,name=str][,fd=h][,ifname=name][,script=file][,downscript=dfile][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off][,vhostfd=h]\n"
     "                connect the host TAP network interface to VLAN 'n' and use the\n"
     "                network scripts 'file' (default=" DEFAULT_NETWORK_SCRIPT ")\n"
     "                and 'dfile' (default=" DEFAULT_NETWORK_DOWN_SCRIPT ")\n"
@@ -902,6 +902,8 @@ DEF("net", HAS_ARG, QEMU_OPTION_net,
     "                default of 'sndbuf=1048576' can be disabled using 'sndbuf=0')\n"
     "                use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag\n"
     "                use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition\n"
+    "                use vhost=on to enable experimental in kernel accelerator\n"
+    "                use 'vhostfd=h' to connect to an already opened vhost net device\n"
 #endif
     "-net socket[,vlan=n][,name=str][,fd=h][,listen=[host]:port][,connect=host:port]\n"
     "                connect the vlan 'n' to another VLAN using a socket connection\n"