Archipelago » qemu

/*

 * 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 <stdio.h>

#define NETMAP_WITH_LIBS

#include <net/netmap.h>

#include <net/netmap_user.h>

#include "net/net.h"

#include "net/tap.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];

    int                 vnet_hdr_len;  /* Current virtio-net header length. */

} NetmapState;

#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 (nm_ring_empty(ring)) {

        /* 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 = ring->head = nm_ring_next(ring, i);

    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;

    if (unlikely(!ring)) {

        /* Drop the packet. */

        return iov_size(iov, iovcnt);

    }

    last = i = ring->cur;

    if (nm_ring_space(ring) < 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(nm_ring_empty(ring))) {

                /* 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 = nm_ring_next(ring, i);

            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->head. */

    ring->cur = ring->head = i;

    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 (!nm_ring_empty(ring) && 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 = ring->head = nm_ring_next(ring, i);

        } while (!nm_ring_empty(ring) && morefrag);

        if (unlikely(nm_ring_empty(ring) && 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;

}

/* Offloading manipulation support callbacks. */

static bool netmap_has_ufo(NetClientState *nc)

{

    return true;

}

static bool netmap_has_vnet_hdr(NetClientState *nc)

{

    return true;

}

static bool netmap_has_vnet_hdr_len(NetClientState *nc, int len)

{

    return len == 0 || len == sizeof(struct virtio_net_hdr) ||

                len == sizeof(struct virtio_net_hdr_mrg_rxbuf);

}

static void netmap_using_vnet_hdr(NetClientState *nc, bool enable)

{

}

static void netmap_set_vnet_hdr_len(NetClientState *nc, int len)

{

    NetmapState *s = DO_UPCAST(NetmapState, nc, nc);

    int err;

    struct nmreq req;

    /* Issue a NETMAP_BDG_VNET_HDR command to change the virtio-net header

     * length for the netmap adapter associated to 'me->ifname'.

     */

    memset(&req, 0, sizeof(req));

    pstrcpy(req.nr_name, sizeof(req.nr_name), s->me.ifname);

    req.nr_version = NETMAP_API;

    req.nr_cmd = NETMAP_BDG_VNET_HDR;

    req.nr_arg1 = len;

    err = ioctl(s->me.fd, NIOCREGIF, &req);

    if (err) {

        error_report("Unable to execute NETMAP_BDG_VNET_HDR on %s: %s",

                     s->me.ifname, strerror(errno));

    } else {

        /* Keep track of the current length. */

        s->vnet_hdr_len = len;

    }

}

static void netmap_set_offload(NetClientState *nc, int csum, int tso4, int tso6,

                               int ecn, int ufo)

{

    NetmapState *s = DO_UPCAST(NetmapState, nc, nc);

    /* Setting a virtio-net header length greater than zero automatically

     * enables the offloadings.

     */

    if (!s->vnet_hdr_len) {

        netmap_set_vnet_hdr_len(nc, sizeof(struct virtio_net_hdr));

    }

}

/* 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,

    .has_ufo = netmap_has_ufo,

    .has_vnet_hdr = netmap_has_vnet_hdr,

    .has_vnet_hdr_len = netmap_has_vnet_hdr_len,

    .using_vnet_hdr = netmap_using_vnet_hdr,

    .set_offload = netmap_set_offload,

    .set_vnet_hdr_len = netmap_set_vnet_hdr_len,

};

/* 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;

    s->vnet_hdr_len = 0;

    netmap_read_poll(s, true); /* Initially only poll for reads. */

    return 0;

}