Merge remote-tracking branch 'stefanha/net-next' into staging

# By Vincenzo Maffione (2) and others
# Via Stefan Hajnoczi
* stefanha/net-next:
  net: Update netdev peer on link change
  virtio-net: don't update mac_table in error state
  MAINTAINERS: Add netmap maintainers
  net: Adding netmap network backend

Message-id: 1386594692-21278-1-git-send-email-stefanha@redhat.com
Signed-off-by: NAnthony Liguori <aliguori@amazon.com>

MAINTAINERS

@@ -710,6 +710,14 @@ S: Maintained
 F: net/
 T: git git://github.com/stefanha/qemu.git net
 
+Netmap network backend
+M: Luigi Rizzo <rizzo@iet.unipi.it>
+M: Giuseppe Lettieri <g.lettieri@iet.unipi.it>
+M: Vincenzo Maffione <v.maffione@gmail.com>
+W: http://info.iet.unipi.it/~luigi/netmap/
+S: Maintained
+F: net/netmap.c
+
 Network Block Device (NBD)
 M: Paolo Bonzini <pbonzini@redhat.com>
 S: Odd Fixes

configure

@@ -169,6 +169,7 @@ curl=""
 curses=""
 docs=""
 fdt=""
+netmap="no"
 pixman=""
 sdl=""
 virtfs=""
@@ -488,6 +489,7 @@ FreeBSD)
   audio_possible_drivers="oss sdl esd pa"
   # needed for kinfo_getvmmap(3) in libutil.h
   LIBS="-lutil $LIBS"
+  netmap=""  # enable netmap autodetect
 ;;
 DragonFly)
   bsd="yes"
@@ -797,6 +799,10 @@ for opt do
   ;;
   --enable-vde) vde="yes"
   ;;
+  --disable-netmap) netmap="no"
+  ;;
+  --enable-netmap) netmap="yes"
+  ;;
   --disable-xen) xen="no"
   ;;
   --enable-xen) xen="yes"
@@ -1182,6 +1188,8 @@ echo "  --disable-uuid           disable uuid support"
 echo "  --enable-uuid            enable uuid support"
 echo "  --disable-vde            disable support for vde network"
 echo "  --enable-vde             enable support for vde network"
+echo "  --disable-netmap         disable support for netmap network"
+echo "  --enable-netmap          enable support for netmap network"
 echo "  --disable-linux-aio      disable Linux AIO support"
 echo "  --enable-linux-aio       enable Linux AIO support"
 echo "  --disable-cap-ng         disable libcap-ng support"
@@ -2094,6 +2102,26 @@ EOF
   fi
 fi
 
+##########################################
+# netmap headers probe
+if test "$netmap" != "no" ; then
+  cat > $TMPC << EOF
+#include <inttypes.h>
+#include <net/if.h>
+#include <net/netmap.h>
+#include <net/netmap_user.h>
+int main(void) { return 0; }
+EOF
+  if compile_prog "" "" ; then
+    netmap=yes
+  else
+    if test "$netmap" = "yes" ; then
+      feature_not_found "netmap"
+    fi
+    netmap=no
+  fi
+fi
+
 ##########################################
 # libcap-ng library probe
 if test "$cap_ng" != "no" ; then
@@ -3751,6 +3779,7 @@ echo "uname -r          $uname_release"
 echo "GUEST_BASE        $guest_base"
 echo "PIE               $pie"
 echo "vde support       $vde"
+echo "netmap support    $netmap"
 echo "Linux AIO support $linux_aio"
 echo "ATTR/XATTR support $attr"
 echo "Install blobs     $blobs"
@@ -3888,6 +3917,9 @@ fi
 if test "$vde" = "yes" ; then
   echo "CONFIG_VDE=y" >> $config_host_mak
 fi
+if test "$netmap" = "yes" ; then
+  echo "CONFIG_NETMAP=y" >> $config_host_mak
+fi
 if test "$cap_ng" = "yes" ; then
   echo "CONFIG_LIBCAP=y" >> $config_host_mak
 fi

hmp-commands.hx

@@ -1190,7 +1190,7 @@ ETEXI
     {
         .name       = "host_net_add",
         .args_type  = "device:s,opts:s?",
-        .params     = "tap|user|socket|vde|dump [options]",
+        .params     = "tap|user|socket|vde|netmap|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],id=str[,prop=value][,...]",
+        .params     = "[user|tap|socket|hubport|netmap],id=str[,prop=value][,...]",
         .help       = "add host network device",
         .mhandler.cmd = hmp_netdev_add,
     },

hw/net/virtio-net.c

@@ -610,11 +610,11 @@ static int virtio_net_handle_mac(VirtIONet *n, uint8_t cmd,
         return VIRTIO_NET_ERR;
     }
 
-    n->mac_table.in_use = 0;
-    n->mac_table.first_multi = 0;
-    n->mac_table.uni_overflow = 0;
-    n->mac_table.multi_overflow = 0;
-    memset(n->mac_table.macs, 0, MAC_TABLE_ENTRIES * ETH_ALEN);
+    int in_use = 0;
+    int first_multi = 0;
+    uint8_t uni_overflow = 0;
+    uint8_t multi_overflow = 0;
+    uint8_t *macs = g_malloc0(MAC_TABLE_ENTRIES * ETH_ALEN);
 
     s = iov_to_buf(iov, iov_cnt, 0, &mac_data.entries,
                    sizeof(mac_data.entries));
@@ -629,19 +629,19 @@ static int virtio_net_handle_mac(VirtIONet *n, uint8_t cmd,
     }
 
     if (mac_data.entries <= MAC_TABLE_ENTRIES) {
-        s = iov_to_buf(iov, iov_cnt, 0, n->mac_table.macs,
+        s = iov_to_buf(iov, iov_cnt, 0, macs,
                        mac_data.entries * ETH_ALEN);
         if (s != mac_data.entries * ETH_ALEN) {
             goto error;
         }
-        n->mac_table.in_use += mac_data.entries;
+        in_use += mac_data.entries;
     } else {
-        n->mac_table.uni_overflow = 1;
+        uni_overflow = 1;
     }
 
     iov_discard_front(&iov, &iov_cnt, mac_data.entries * ETH_ALEN);
 
-    n->mac_table.first_multi = n->mac_table.in_use;
+    first_multi = in_use;
 
     s = iov_to_buf(iov, iov_cnt, 0, &mac_data.entries,
                    sizeof(mac_data.entries));
@@ -656,24 +656,29 @@ static int virtio_net_handle_mac(VirtIONet *n, uint8_t cmd,
         goto error;
     }
 
-    if (n->mac_table.in_use + mac_data.entries <= MAC_TABLE_ENTRIES) {
-        s = iov_to_buf(iov, iov_cnt, 0,
-                       &n->mac_table.macs[n->mac_table.in_use * ETH_ALEN],
+    if (in_use + mac_data.entries <= MAC_TABLE_ENTRIES) {
+        s = iov_to_buf(iov, iov_cnt, 0, &macs[in_use * ETH_ALEN],
                        mac_data.entries * ETH_ALEN);
         if (s != mac_data.entries * ETH_ALEN) {
             goto error;
         }
-        n->mac_table.in_use += mac_data.entries;
+        in_use += mac_data.entries;
     } else {
-        n->mac_table.multi_overflow = 1;
+        multi_overflow = 1;
     }
 
+    n->mac_table.in_use = in_use;
+    n->mac_table.first_multi = first_multi;
+    n->mac_table.uni_overflow = uni_overflow;
+    n->mac_table.multi_overflow = multi_overflow;
+    memcpy(n->mac_table.macs, macs, MAC_TABLE_ENTRIES * ETH_ALEN);
+    g_free(macs);
     rxfilter_notify(nc);
 
     return VIRTIO_NET_OK;
 
 error:
-    rxfilter_notify(nc);
+    g_free(macs);
     return VIRTIO_NET_ERR;
 }
 

net/Makefile.objs

@@ -11,3 +11,4 @@ common-obj-$(CONFIG_AIX) += tap-aix.o
 common-obj-$(CONFIG_HAIKU) += tap-haiku.o
 common-obj-$(CONFIG_SLIRP) += slirp.o
 common-obj-$(CONFIG_VDE) += vde.o
+common-obj-$(CONFIG_NETMAP) += netmap.o

net/clients.h

@@ -52,4 +52,9 @@ int net_init_vde(const NetClientOptions *opts, const char *name,
                  NetClientState *peer);
 #endif
 
+#ifdef CONFIG_NETMAP
+int net_init_netmap(const NetClientOptions *opts, const char *name,
+                    NetClientState *peer);
+#endif
+
 #endif /* QEMU_NET_CLIENTS_H */

net/net.c

@@ -725,6 +725,9 @@ static int (* const net_client_init_fun[NET_CLIENT_OPTIONS_KIND_MAX])(
         [NET_CLIENT_OPTIONS_KIND_SOCKET]    = net_init_socket,
 #ifdef CONFIG_VDE
         [NET_CLIENT_OPTIONS_KIND_VDE]       = net_init_vde,
+#endif
+#ifdef CONFIG_NETMAP
+        [NET_CLIENT_OPTIONS_KIND_NETMAP]    = net_init_netmap,
 #endif
         [NET_CLIENT_OPTIONS_KIND_DUMP]      = net_init_dump,
 #ifdef CONFIG_NET_BRIDGE
@@ -757,6 +760,9 @@ static int net_client_init1(const void *object, int is_netdev, Error **errp)
 #ifdef CONFIG_VDE
         case NET_CLIENT_OPTIONS_KIND_VDE:
 #endif
+#ifdef CONFIG_NETMAP
+        case NET_CLIENT_OPTIONS_KIND_NETMAP:
+#endif
 #ifdef CONFIG_NET_BRIDGE
         case NET_CLIENT_OPTIONS_KIND_BRIDGE:
 #endif
@@ -1065,15 +1071,23 @@ void qmp_set_link(const char *name, bool up, Error **errp)
         nc->info->link_status_changed(nc);
     }
 
-    /* Notify peer. Don't update peer link status: this makes it possible to
-     * disconnect from host network without notifying the guest.
-     * FIXME: is disconnected link status change operation useful?
-     *
-     * Current behaviour is compatible with qemu vlans where there could be
-     * multiple clients that can still communicate with each other in
-     * disconnected mode. For now maintain this compatibility. */
-    if (nc->peer && nc->peer->info->link_status_changed) {
-        nc->peer->info->link_status_changed(nc->peer);
+    if (nc->peer) {
+        /* Change peer link only if the peer is NIC and then notify peer.
+         * If the peer is a HUBPORT or a backend, we do not change the
+         * link status.
+         *
+         * This behavior is compatible with qemu vlans where there could be
+         * multiple clients that can still communicate with each other in
+         * disconnected mode. For now maintain this compatibility.
+         */
+        if (nc->peer->info->type == NET_CLIENT_OPTIONS_KIND_NIC) {
+            for (i = 0; i < queues; i++) {
+                ncs[i]->peer->link_down = !up;
+            }
+        }
+        if (nc->peer->info->link_status_changed) {
+            nc->peer->info->link_status_changed(nc->peer);
+        }
     }
 }
 

net/netmap.c

+/*
+ * netmap access for qemu
+ *
+ * Copyright (c) 2012-2013 Luigi Rizzo
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+
+#include <sys/ioctl.h>
+#include <net/if.h>
+#include <sys/mman.h>
+#include <stdint.h>
+#include <net/netmap.h>
+#include <net/netmap_user.h>
+
+#include "net/net.h"
+#include "clients.h"
+#include "sysemu/sysemu.h"
+#include "qemu/error-report.h"
+#include "qemu/iov.h"
+
+/* Private netmap device info. */
+typedef struct NetmapPriv {
+    int                 fd;
+    size_t              memsize;
+    void                *mem;
+    struct netmap_if    *nifp;
+    struct netmap_ring  *rx;
+    struct netmap_ring  *tx;
+    char                fdname[PATH_MAX];        /* Normally "/dev/netmap". */
+    char                ifname[IFNAMSIZ];
+} NetmapPriv;
+
+typedef struct NetmapState {
+    NetClientState      nc;
+    NetmapPriv          me;
+    bool                read_poll;
+    bool                write_poll;
+    struct iovec        iov[IOV_MAX];
+} NetmapState;
+
+#define D(format, ...)                                          \
+    do {                                                        \
+        struct timeval __xxts;                                  \
+        gettimeofday(&__xxts, NULL);                            \
+        printf("%03d.%06d %s [%d] " format "\n",                \
+                (int)__xxts.tv_sec % 1000, (int)__xxts.tv_usec, \
+                __func__, __LINE__, ##__VA_ARGS__);         \
+    } while (0)
+
+/* Rate limited version of "D", lps indicates how many per second */
+#define RD(lps, format, ...)                                    \
+    do {                                                        \
+        static int t0, __cnt;                                   \
+        struct timeval __xxts;                                  \
+        gettimeofday(&__xxts, NULL);                            \
+        if (t0 != __xxts.tv_sec) {                              \
+            t0 = __xxts.tv_sec;                                 \
+            __cnt = 0;                                          \
+        }                                                       \
+        if (__cnt++ < lps) {                                    \
+            D(format, ##__VA_ARGS__);                           \
+        }                                                       \
+    } while (0)
+
+
+#ifndef __FreeBSD__
+#define pkt_copy bcopy
+#else
+/* A fast copy routine only for multiples of 64 bytes, non overlapped. */
+static inline void
+pkt_copy(const void *_src, void *_dst, int l)
+{
+    const uint64_t *src = _src;
+    uint64_t *dst = _dst;
+    if (unlikely(l >= 1024)) {
+        bcopy(src, dst, l);
+        return;
+    }
+    for (; l > 0; l -= 64) {
+        *dst++ = *src++;
+        *dst++ = *src++;
+        *dst++ = *src++;
+        *dst++ = *src++;
+        *dst++ = *src++;
+        *dst++ = *src++;
+        *dst++ = *src++;
+        *dst++ = *src++;
+    }
+}
+#endif /* __FreeBSD__ */
+
+/*
+ * Open a netmap device. We assume there is only one queue
+ * (which is the case for the VALE bridge).
+ */
+static int netmap_open(NetmapPriv *me)
+{
+    int fd;
+    int err;
+    size_t l;
+    struct nmreq req;
+
+    me->fd = fd = open(me->fdname, O_RDWR);
+    if (fd < 0) {
+        error_report("Unable to open netmap device '%s' (%s)",
+                        me->fdname, strerror(errno));
+        return -1;
+    }
+    memset(&req, 0, sizeof(req));
+    pstrcpy(req.nr_name, sizeof(req.nr_name), me->ifname);
+    req.nr_ringid = NETMAP_NO_TX_POLL;
+    req.nr_version = NETMAP_API;
+    err = ioctl(fd, NIOCREGIF, &req);
+    if (err) {
+        error_report("Unable to register %s: %s", me->ifname, strerror(errno));
+        goto error;
+    }
+    l = me->memsize = req.nr_memsize;
+
+    me->mem = mmap(0, l, PROT_WRITE | PROT_READ, MAP_SHARED, fd, 0);
+    if (me->mem == MAP_FAILED) {
+        error_report("Unable to mmap netmap shared memory: %s",
+                        strerror(errno));
+        me->mem = NULL;
+        goto error;
+    }
+
+    me->nifp = NETMAP_IF(me->mem, req.nr_offset);
+    me->tx = NETMAP_TXRING(me->nifp, 0);
+    me->rx = NETMAP_RXRING(me->nifp, 0);
+    return 0;
+
+error:
+    close(me->fd);
+    return -1;
+}
+
+/* Tell the event-loop if the netmap backend can send packets
+   to the frontend. */
+static int netmap_can_send(void *opaque)
+{
+    NetmapState *s = opaque;
+
+    return qemu_can_send_packet(&s->nc);
+}
+
+static void netmap_send(void *opaque);
+static void netmap_writable(void *opaque);
+
+/* Set the event-loop handlers for the netmap backend. */
+static void netmap_update_fd_handler(NetmapState *s)
+{
+    qemu_set_fd_handler2(s->me.fd,
+                         s->read_poll  ? netmap_can_send : NULL,
+                         s->read_poll  ? netmap_send     : NULL,
+                         s->write_poll ? netmap_writable : NULL,
+                         s);
+}
+
+/* Update the read handler. */
+static void netmap_read_poll(NetmapState *s, bool enable)
+{
+    if (s->read_poll != enable) { /* Do nothing if not changed. */
+        s->read_poll = enable;
+        netmap_update_fd_handler(s);
+    }
+}
+
+/* Update the write handler. */
+static void netmap_write_poll(NetmapState *s, bool enable)
+{
+    if (s->write_poll != enable) {
+        s->write_poll = enable;
+        netmap_update_fd_handler(s);
+    }
+}
+
+static void netmap_poll(NetClientState *nc, bool enable)
+{
+    NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
+
+    if (s->read_poll != enable || s->write_poll != enable) {
+        s->read_poll = enable;
+        s->read_poll = enable;
+        netmap_update_fd_handler(s);
+    }
+}
+
+/*
+ * The fd_write() callback, invoked if the fd is marked as
+ * writable after a poll. Unregister the handler and flush any
+ * buffered packets.
+ */
+static void netmap_writable(void *opaque)
+{
+    NetmapState *s = opaque;
+
+    netmap_write_poll(s, false);
+    qemu_flush_queued_packets(&s->nc);
+}
+
+static ssize_t netmap_receive(NetClientState *nc,
+      const uint8_t *buf, size_t size)
+{
+    NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
+    struct netmap_ring *ring = s->me.tx;
+    uint32_t i;
+    uint32_t idx;
+    uint8_t *dst;
+
+    if (unlikely(!ring)) {
+        /* Drop. */
+        return size;
+    }
+
+    if (unlikely(size > ring->nr_buf_size)) {
+        RD(5, "[netmap_receive] drop packet of size %d > %d\n",
+                                    (int)size, ring->nr_buf_size);
+        return size;
+    }
+
+    if (ring->avail == 0) {
+        /* No available slots in the netmap TX ring. */
+        netmap_write_poll(s, true);
+        return 0;
+    }
+
+    i = ring->cur;
+    idx = ring->slot[i].buf_idx;
+    dst = (uint8_t *)NETMAP_BUF(ring, idx);
+
+    ring->slot[i].len = size;
+    ring->slot[i].flags = 0;
+    pkt_copy(buf, dst, size);
+    ring->cur = NETMAP_RING_NEXT(ring, i);
+    ring->avail--;
+    ioctl(s->me.fd, NIOCTXSYNC, NULL);
+
+    return size;
+}
+
+static ssize_t netmap_receive_iov(NetClientState *nc,
+                    const struct iovec *iov, int iovcnt)
+{
+    NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
+    struct netmap_ring *ring = s->me.tx;
+    uint32_t last;
+    uint32_t idx;
+    uint8_t *dst;
+    int j;
+    uint32_t i;
+    uint32_t avail;
+
+    if (unlikely(!ring)) {
+        /* Drop the packet. */
+        return iov_size(iov, iovcnt);
+    }
+
+    i = ring->cur;
+    avail = ring->avail;
+
+    if (avail < iovcnt) {
+        /* Not enough netmap slots. */
+        netmap_write_poll(s, true);
+        return 0;
+    }
+
+    for (j = 0; j < iovcnt; j++) {
+        int iov_frag_size = iov[j].iov_len;
+        int offset = 0;
+        int nm_frag_size;
+
+        /* Split each iovec fragment over more netmap slots, if
+           necessary. */
+        while (iov_frag_size) {
+            nm_frag_size = MIN(iov_frag_size, ring->nr_buf_size);
+
+            if (unlikely(avail == 0)) {
+                /* We run out of netmap slots while splitting the
+                   iovec fragments. */
+                netmap_write_poll(s, true);
+                return 0;
+            }
+
+            idx = ring->slot[i].buf_idx;
+            dst = (uint8_t *)NETMAP_BUF(ring, idx);
+
+            ring->slot[i].len = nm_frag_size;
+            ring->slot[i].flags = NS_MOREFRAG;
+            pkt_copy(iov[j].iov_base + offset, dst, nm_frag_size);
+
+            last = i;
+            i = NETMAP_RING_NEXT(ring, i);
+            avail--;
+
+            offset += nm_frag_size;
+            iov_frag_size -= nm_frag_size;
+        }
+    }
+    /* The last slot must not have NS_MOREFRAG set. */
+    ring->slot[last].flags &= ~NS_MOREFRAG;
+
+    /* Now update ring->cur and ring->avail. */
+    ring->cur = i;
+    ring->avail = avail;
+
+    ioctl(s->me.fd, NIOCTXSYNC, NULL);
+
+    return iov_size(iov, iovcnt);
+}
+
+/* Complete a previous send (backend --> guest) and enable the
+   fd_read callback. */
+static void netmap_send_completed(NetClientState *nc, ssize_t len)
+{
+    NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
+
+    netmap_read_poll(s, true);
+}
+
+static void netmap_send(void *opaque)
+{
+    NetmapState *s = opaque;
+    struct netmap_ring *ring = s->me.rx;
+
+    /* Keep sending while there are available packets into the netmap
+       RX ring and the forwarding path towards the peer is open. */
+    while (ring->avail > 0 && qemu_can_send_packet(&s->nc)) {
+        uint32_t i;
+        uint32_t idx;
+        bool morefrag;
+        int iovcnt = 0;
+        int iovsize;
+
+        do {
+            i = ring->cur;
+            idx = ring->slot[i].buf_idx;
+            morefrag = (ring->slot[i].flags & NS_MOREFRAG);
+            s->iov[iovcnt].iov_base = (u_char *)NETMAP_BUF(ring, idx);
+            s->iov[iovcnt].iov_len = ring->slot[i].len;
+            iovcnt++;
+
+            ring->cur = NETMAP_RING_NEXT(ring, i);
+            ring->avail--;
+        } while (ring->avail && morefrag);
+
+        if (unlikely(!ring->avail && morefrag)) {
+            RD(5, "[netmap_send] ran out of slots, with a pending"
+                   "incomplete packet\n");
+        }
+
+        iovsize = qemu_sendv_packet_async(&s->nc, s->iov, iovcnt,
+                                            netmap_send_completed);
+
+        if (iovsize == 0) {
+            /* The peer does not receive anymore. Packet is queued, stop
+             * reading from the backend until netmap_send_completed()
+             */
+            netmap_read_poll(s, false);
+            break;
+        }
+    }
+}
+
+/* Flush and close. */
+static void netmap_cleanup(NetClientState *nc)
+{
+    NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
+
+    qemu_purge_queued_packets(nc);
+
+    netmap_poll(nc, false);
+    munmap(s->me.mem, s->me.memsize);
+    close(s->me.fd);
+
+    s->me.fd = -1;
+}
+
+
+/* NetClientInfo methods */
+static NetClientInfo net_netmap_info = {
+    .type = NET_CLIENT_OPTIONS_KIND_NETMAP,
+    .size = sizeof(NetmapState),
+    .receive = netmap_receive,
+    .receive_iov = netmap_receive_iov,
+    .poll = netmap_poll,
+    .cleanup = netmap_cleanup,
+};
+
+/* The exported init function
+ *
+ * ... -net netmap,ifname="..."
+ */
+int net_init_netmap(const NetClientOptions *opts,
+        const char *name, NetClientState *peer)
+{
+    const NetdevNetmapOptions *netmap_opts = opts->netmap;
+    NetClientState *nc;
+    NetmapPriv me;
+    NetmapState *s;
+
+    pstrcpy(me.fdname, sizeof(me.fdname),
+        netmap_opts->has_devname ? netmap_opts->devname : "/dev/netmap");
+    /* Set default name for the port if not supplied. */
+    pstrcpy(me.ifname, sizeof(me.ifname), netmap_opts->ifname);
+    if (netmap_open(&me)) {
+        return -1;
+    }
+    /* Create the object. */
+    nc = qemu_new_net_client(&net_netmap_info, peer, "netmap", name);
+    s = DO_UPCAST(NetmapState, nc, nc);
+    s->me = me;
+    netmap_read_poll(s, true); /* Initially only poll for reads. */
+
+    return 0;
+}
+

qapi-schema.json

@@ -3008,6 +3008,27 @@
   'data': {
     'hubid':     'int32' } }
 
+##
+# @NetdevNetmapOptions
+#
+# Connect a client to a netmap-enabled NIC or to a VALE switch port
+#
+# @ifname: Either the name of an existing network interface supported by
+#          netmap, or the name of a VALE port (created on the fly).
+#          A VALE port name is in the form 'valeXXX:YYY', where XXX and
+#          YYY are non-negative integers. XXX identifies a switch and
+#          YYY identifies a port of the switch. VALE ports having the
+#          same XXX are therefore connected to the same switch.
+#
+# @devname: #optional path of the netmap device (default: '/dev/netmap').
+#
+# Since 1.8
+##
+{ 'type': 'NetdevNetmapOptions',
+  'data': {
+    'ifname':     'str',
+    '*devname':    'str' } }
+
 ##
 # @NetClientOptions
 #
@@ -3025,7 +3046,8 @@
     'vde':      'NetdevVdeOptions',
     'dump':     'NetdevDumpOptions',
     'bridge':   'NetdevBridgeOptions',
-    'hubport':  'NetdevHubPortOptions' } }
+    'hubport':  'NetdevHubPortOptions',
+    'netmap':   'NetdevNetmapOptions' } }
 
 ##
 # @NetLegacy

qemu-options.hx

@@ -1406,6 +1406,12 @@ DEF("net", HAS_ARG, QEMU_OPTION_net,
     "                on host and listening for incoming connections on 'socketpath'.\n"
     "                Use group 'groupname' and mode 'octalmode' to change default\n"
     "                ownership and permissions for communication port.\n"
+#endif
+#ifdef CONFIG_NETMAP
+    "-net netmap,ifname=name[,devname=nmname]\n"
+    "                attach to the existing netmap-enabled network interface 'name', or to a\n"
+    "                VALE port (created on the fly) called 'name' ('nmname' is name of the \n"
+    "                netmap device, defaults to '/dev/netmap')\n"
 #endif
     "-net dump[,vlan=n][,file=f][,len=n]\n"
     "                dump traffic on vlan 'n' to file 'f' (max n bytes per packet)\n"
@@ -1420,6 +1426,9 @@ DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
     "bridge|"
 #ifdef CONFIG_VDE
     "vde|"
+#endif
+#ifdef CONFIG_NETMAP
+    "netmap|"
 #endif
     "socket|"
     "hubport],id=str[,option][,option][,...]\n", QEMU_ARCH_ALL)