[Qemu-devel] [PATCHv6 09/11] tap: add vhost/vhostfd options

[Michael S. Tsirkin]

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 <address@hidden>
---
 net.c           |    8 ++++++++
 net/tap.c       |   29 +++++++++++++++++++++++++++++
 qemu-options.hx |    4 +++-
 3 files changed, 40 insertions(+), 1 deletions(-)

diff --git a/net.c b/net.c
index e47f727..48d9fb0 100644
--- 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 fc59fd4..19c4fa2 100644
--- a/net/tap.c
+++ b/net/tap.c
@@ -41,6 +41,8 @@
 
 #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
  */
@@ -57,6 +59,7 @@ 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);
@@ -252,6 +255,10 @@ 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])
@@ -307,6 +314,7 @@ 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;
 }
 
@@ -456,5 +464,26 @@ 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) {
+            qemu_error("vhost-net requested but could not be initialized\n");
+            return -1;
+        }
+    } else if (qemu_opt_get(opts, "vhostfd")) {
+        qemu_error("vhostfd= is not valid without vhost\n");
+        return -1;
+    }
+
     return 0;
 }
diff --git a/qemu-options.hx b/qemu-options.hx
index fd50add..4d9f4da 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -895,7 +895,7 @@ 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"
@@ -905,6 +905,8 @@ 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"
-- 
1.7.0.18.g0d53a5