xref: /freebsd-14.2/sys/dev/netmap/netmap_vale.c (revision b6e66be2)

/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (C) 2013-2016 Universita` di Pisa
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */


#if defined(__FreeBSD__)
#include <sys/cdefs.h> /* prerequisite */
__FBSDID("$FreeBSD$");

#include <sys/types.h>
#include <sys/errno.h>
#include <sys/param.h>	/* defines used in kernel.h */
#include <sys/kernel.h>	/* types used in module initialization */
#include <sys/conf.h>	/* cdevsw struct, UID, GID */
#include <sys/sockio.h>
#include <sys/socketvar.h>	/* struct socket */
#include <sys/malloc.h>
#include <sys/poll.h>
#include <sys/rwlock.h>
#include <sys/socket.h> /* sockaddrs */
#include <sys/selinfo.h>
#include <sys/sysctl.h>
#include <net/if.h>
#include <net/if_var.h>
#include <net/bpf.h>		/* BIOCIMMEDIATE */
#include <machine/bus.h>	/* bus_dmamap_* */
#include <sys/endian.h>
#include <sys/refcount.h>
#include <sys/smp.h>


#elif defined(linux)

#include "bsd_glue.h"

#elif defined(__APPLE__)

#warning OSX support is only partial
#include "osx_glue.h"

#elif defined(_WIN32)
#include "win_glue.h"

#else

#error	Unsupported platform

#endif /* unsupported */

/*
 * common headers
 */

#include <net/netmap.h>
#include <dev/netmap/netmap_kern.h>
#include <dev/netmap/netmap_mem2.h>
#include <dev/netmap/netmap_bdg.h>

#ifdef WITH_VALE

/*
 * system parameters (most of them in netmap_kern.h)
 * NM_BDG_NAME	prefix for switch port names, default "vale"
 * NM_BDG_MAXPORTS	number of ports
 * NM_BRIDGES	max number of switches in the system.
 *	XXX should become a sysctl or tunable
 *
 * Switch ports are named valeX:Y where X is the switch name and Y
 * is the port. If Y matches a physical interface name, the port is
 * connected to a physical device.
 *
 * Unlike physical interfaces, switch ports use their own memory region
 * for rings and buffers.
 * The virtual interfaces use per-queue lock instead of core lock.
 * In the tx loop, we aggregate traffic in batches to make all operations
 * faster. The batch size is bridge_batch.
 */
#define NM_BDG_MAXRINGS		16	/* XXX unclear how many. */
#define NM_BDG_MAXSLOTS		4096	/* XXX same as above */
#define NM_BRIDGE_RINGSIZE	1024	/* in the device */
#define NM_BDG_BATCH		1024	/* entries in the forwarding buffer */
/* actual size of the tables */
#define NM_BDG_BATCH_MAX	(NM_BDG_BATCH + NETMAP_MAX_FRAGS)
/* NM_FT_NULL terminates a list of slots in the ft */
#define NM_FT_NULL		NM_BDG_BATCH_MAX


/*
 * bridge_batch is set via sysctl to the max batch size to be
 * used in the bridge. The actual value may be larger as the
 * last packet in the block may overflow the size.
 */
static int bridge_batch = NM_BDG_BATCH; /* bridge batch size */
SYSBEGIN(vars_vale);
SYSCTL_DECL(_dev_netmap);
SYSCTL_INT(_dev_netmap, OID_AUTO, bridge_batch, CTLFLAG_RW, &bridge_batch, 0,
		"Max batch size to be used in the bridge");
SYSEND;

static int netmap_vale_vp_create(struct nmreq_header *hdr, struct ifnet *,
		struct netmap_mem_d *nmd, struct netmap_vp_adapter **);
static int netmap_vale_vp_bdg_attach(const char *, struct netmap_adapter *,
		struct nm_bridge *);
static int netmap_vale_bwrap_attach(const char *, struct netmap_adapter *);

/*
 * For each output interface, nm_vale_q is used to construct a list.
 * bq_len is the number of output buffers (we can have coalescing
 * during the copy).
 */
struct nm_vale_q {
	uint16_t bq_head;
	uint16_t bq_tail;
	uint32_t bq_len;	/* number of buffers */
};

/* Holds the default callbacks */
struct netmap_bdg_ops vale_bdg_ops = {
	.lookup = netmap_vale_learning,
	.config = NULL,
	.dtor = NULL,
	.vp_create = netmap_vale_vp_create,
	.bwrap_attach = netmap_vale_bwrap_attach,
	.name = NM_BDG_NAME,
};

/*
 * this is a slightly optimized copy routine which rounds
 * to multiple of 64 bytes and is often faster than dealing
 * with other odd sizes. We assume there is enough room
 * in the source and destination buffers.
 *
 * XXX only for multiples of 64 bytes, non overlapped.
 */
static inline void
pkt_copy(void *_src, void *_dst, int l)
{
	uint64_t *src = _src;
	uint64_t *dst = _dst;
	if (unlikely(l >= 1024)) {
		memcpy(dst, src, l);
		return;
	}
	for (; likely(l > 0); l-=64) {
		*dst++ = *src++;
		*dst++ = *src++;
		*dst++ = *src++;
		*dst++ = *src++;
		*dst++ = *src++;
		*dst++ = *src++;
		*dst++ = *src++;
		*dst++ = *src++;
	}
}


/*
 * Free the forwarding tables for rings attached to switch ports.
 */
static void
nm_free_bdgfwd(struct netmap_adapter *na)
{
	int nrings, i;
	struct netmap_kring **kring;

	NMG_LOCK_ASSERT();
	nrings = na->num_tx_rings;
	kring = na->tx_rings;
	for (i = 0; i < nrings; i++) {
		if (kring[i]->nkr_ft) {
			nm_os_free(kring[i]->nkr_ft);
			kring[i]->nkr_ft = NULL; /* protect from freeing twice */
		}
	}
}


/*
 * Allocate the forwarding tables for the rings attached to the bridge ports.
 */
static int
nm_alloc_bdgfwd(struct netmap_adapter *na)
{
	int nrings, l, i, num_dstq;
	struct netmap_kring **kring;

	NMG_LOCK_ASSERT();
	/* all port:rings + broadcast */
	num_dstq = NM_BDG_MAXPORTS * NM_BDG_MAXRINGS + 1;
	l = sizeof(struct nm_bdg_fwd) * NM_BDG_BATCH_MAX;
	l += sizeof(struct nm_vale_q) * num_dstq;
	l += sizeof(uint16_t) * NM_BDG_BATCH_MAX;

	nrings = netmap_real_rings(na, NR_TX);
	kring = na->tx_rings;
	for (i = 0; i < nrings; i++) {
		struct nm_bdg_fwd *ft;
		struct nm_vale_q *dstq;
		int j;

		ft = nm_os_malloc(l);
		if (!ft) {
			nm_free_bdgfwd(na);
			return ENOMEM;
		}
		dstq = (struct nm_vale_q *)(ft + NM_BDG_BATCH_MAX);
		for (j = 0; j < num_dstq; j++) {
			dstq[j].bq_head = dstq[j].bq_tail = NM_FT_NULL;
			dstq[j].bq_len = 0;
		}
		kring[i]->nkr_ft = ft;
	}
	return 0;
}

/* Allows external modules to create bridges in exclusive mode,
 * returns an authentication token that the external module will need
 * to provide during nm_bdg_ctl_{attach, detach}(), netmap_bdg_regops(),
 * and nm_bdg_update_private_data() operations.
 * Successfully executed if ret != NULL and *return_status == 0.
 */
void *
netmap_vale_create(const char *bdg_name, int *return_status)
{
	struct nm_bridge *b = NULL;
	void *ret = NULL;

	NMG_LOCK();
	b = nm_find_bridge(bdg_name, 0 /* don't create */, NULL);
	if (b) {
		*return_status = EEXIST;
		goto unlock_bdg_create;
	}

	b = nm_find_bridge(bdg_name, 1 /* create */, &vale_bdg_ops);
	if (!b) {
		*return_status = ENOMEM;
		goto unlock_bdg_create;
	}

	b->bdg_flags |= NM_BDG_ACTIVE | NM_BDG_EXCLUSIVE;
	ret = nm_bdg_get_auth_token(b);
	*return_status = 0;

unlock_bdg_create:
	NMG_UNLOCK();
	return ret;
}

/* Allows external modules to destroy a bridge created through
 * netmap_bdg_create(), the bridge must be empty.
 */
int
netmap_vale_destroy(const char *bdg_name, void *auth_token)
{
	struct nm_bridge *b = NULL;
	int ret = 0;

	NMG_LOCK();
	b = nm_find_bridge(bdg_name, 0 /* don't create */, NULL);
	if (!b) {
		ret = ENXIO;
		goto unlock_bdg_free;
	}

	if (!nm_bdg_valid_auth_token(b, auth_token)) {
		ret = EACCES;
		goto unlock_bdg_free;
	}
	if (!(b->bdg_flags & NM_BDG_EXCLUSIVE)) {
		ret = EINVAL;
		goto unlock_bdg_free;
	}

	b->bdg_flags &= ~(NM_BDG_EXCLUSIVE | NM_BDG_ACTIVE);
	ret = netmap_bdg_free(b);
	if (ret) {
		b->bdg_flags |= NM_BDG_EXCLUSIVE | NM_BDG_ACTIVE;
	}

unlock_bdg_free:
	NMG_UNLOCK();
	return ret;
}

/* Process NETMAP_REQ_VALE_LIST. */
int
netmap_vale_list(struct nmreq_header *hdr)
{
	struct nmreq_vale_list *req =
		(struct nmreq_vale_list *)(uintptr_t)hdr->nr_body;
	int namelen = strlen(hdr->nr_name);
	struct nm_bridge *b, *bridges;
	struct netmap_vp_adapter *vpna;
	int error = 0, i, j;
	u_int num_bridges;

	netmap_bns_getbridges(&bridges, &num_bridges);

	/* this is used to enumerate bridges and ports */
	if (namelen) { /* look up indexes of bridge and port */
		if (strncmp(hdr->nr_name, NM_BDG_NAME,
					strlen(NM_BDG_NAME))) {
			return EINVAL;
		}
		NMG_LOCK();
		b = nm_find_bridge(hdr->nr_name, 0 /* don't create */, NULL);
		if (!b) {
			NMG_UNLOCK();
			return ENOENT;
		}

		req->nr_bridge_idx = b - bridges; /* bridge index */
		req->nr_port_idx = NM_BDG_NOPORT;
		for (j = 0; j < b->bdg_active_ports; j++) {
			i = b->bdg_port_index[j];
			vpna = b->bdg_ports[i];
			if (vpna == NULL) {
				nm_prerr("This should not happen");
				continue;
			}
			/* the former and the latter identify a
			 * virtual port and a NIC, respectively
			 */
			if (!strcmp(vpna->up.name, hdr->nr_name)) {
				req->nr_port_idx = i; /* port index */
				break;
			}
		}
		NMG_UNLOCK();
	} else {
		/* return the first non-empty entry starting from
		 * bridge nr_arg1 and port nr_arg2.
		 *
		 * Users can detect the end of the same bridge by
		 * seeing the new and old value of nr_arg1, and can
		 * detect the end of all the bridge by error != 0
		 */
		i = req->nr_bridge_idx;
		j = req->nr_port_idx;

		NMG_LOCK();
		for (error = ENOENT; i < NM_BRIDGES; i++) {
			b = bridges + i;
			for ( ; j < NM_BDG_MAXPORTS; j++) {
				if (b->bdg_ports[j] == NULL)
					continue;
				vpna = b->bdg_ports[j];
				/* write back the VALE switch name */
				strlcpy(hdr->nr_name, vpna->up.name,
					sizeof(hdr->nr_name));
				error = 0;
				goto out;
			}
			j = 0; /* following bridges scan from 0 */
		}
	out:
		req->nr_bridge_idx = i;
		req->nr_port_idx = j;
		NMG_UNLOCK();
	}

	return error;
}

/* Process NETMAP_REQ_VALE_ATTACH.
 */
int
netmap_vale_attach(struct nmreq_header *hdr, void *auth_token)
{
	struct nmreq_vale_attach *req =
		(struct nmreq_vale_attach *)(uintptr_t)hdr->nr_body;
	struct netmap_vp_adapter * vpna;
	struct netmap_adapter *na = NULL;
	struct netmap_mem_d *nmd = NULL;
	struct nm_bridge *b = NULL;
	int error;

	NMG_LOCK();
	/* permission check for modified bridges */
	b = nm_find_bridge(hdr->nr_name, 0 /* don't create */, NULL);
	if (b && !nm_bdg_valid_auth_token(b, auth_token)) {
		error = EACCES;
		goto unlock_exit;
	}

	if (req->reg.nr_mem_id) {
		nmd = netmap_mem_find(req->reg.nr_mem_id);
		if (nmd == NULL) {
			error = EINVAL;
			goto unlock_exit;
		}
	}

	/* check for existing one */
	error = netmap_get_vale_na(hdr, &na, nmd, 0);
	if (na) {
		error = EBUSY;
		goto unref_exit;
	}
	error = netmap_get_vale_na(hdr, &na,
				nmd, 1 /* create if not exists */);
	if (error) { /* no device */
		goto unlock_exit;
	}

	if (na == NULL) { /* VALE prefix missing */
		error = EINVAL;
		goto unlock_exit;
	}

	if (NETMAP_OWNED_BY_ANY(na)) {
		error = EBUSY;
		goto unref_exit;
	}

	if (na->nm_bdg_ctl) {
		/* nop for VALE ports. The bwrap needs to put the hwna
		 * in netmap mode (see netmap_bwrap_bdg_ctl)
		 */
		error = na->nm_bdg_ctl(hdr, na);
		if (error)
			goto unref_exit;
		ND("registered %s to netmap-mode", na->name);
	}
	vpna = (struct netmap_vp_adapter *)na;
	req->port_index = vpna->bdg_port;

	if (nmd)
		netmap_mem_put(nmd);

	NMG_UNLOCK();
	return 0;

unref_exit:
	netmap_adapter_put(na);
unlock_exit:
	if (nmd)
		netmap_mem_put(nmd);

	NMG_UNLOCK();
	return error;
}

/* Process NETMAP_REQ_VALE_DETACH.
 */
int
netmap_vale_detach(struct nmreq_header *hdr, void *auth_token)
{
	struct nmreq_vale_detach *nmreq_det = (void *)(uintptr_t)hdr->nr_body;
	struct netmap_vp_adapter *vpna;
	struct netmap_adapter *na;
	struct nm_bridge *b = NULL;
	int error;

	NMG_LOCK();
	/* permission check for modified bridges */
	b = nm_find_bridge(hdr->nr_name, 0 /* don't create */, NULL);
	if (b && !nm_bdg_valid_auth_token(b, auth_token)) {
		error = EACCES;
		goto unlock_exit;
	}

	error = netmap_get_vale_na(hdr, &na, NULL, 0 /* don't create */);
	if (error) { /* no device, or another bridge or user owns the device */
		goto unlock_exit;
	}

	if (na == NULL) { /* VALE prefix missing */
		error = EINVAL;
		goto unlock_exit;
	} else if (nm_is_bwrap(na) &&
		   ((struct netmap_bwrap_adapter *)na)->na_polling_state) {
		/* Don't detach a NIC with polling */
		error = EBUSY;
		goto unref_exit;
	}

	vpna = (struct netmap_vp_adapter *)na;
	if (na->na_vp != vpna) {
		/* trying to detach first attach of VALE persistent port attached
		 * to 2 bridges
		 */
		error = EBUSY;
		goto unref_exit;
	}
	nmreq_det->port_index = vpna->bdg_port;

	if (na->nm_bdg_ctl) {
		/* remove the port from bridge. The bwrap
		 * also needs to put the hwna in normal mode
		 */
		error = na->nm_bdg_ctl(hdr, na);
	}

unref_exit:
	netmap_adapter_put(na);
unlock_exit:
	NMG_UNLOCK();
	return error;

}


/* nm_dtor callback for ephemeral VALE ports */
static void
netmap_vale_vp_dtor(struct netmap_adapter *na)
{
	struct netmap_vp_adapter *vpna = (struct netmap_vp_adapter*)na;
	struct nm_bridge *b = vpna->na_bdg;

	ND("%s has %d references", na->name, na->na_refcount);

	if (b) {
		netmap_bdg_detach_common(b, vpna->bdg_port, -1);
	}

	if (na->ifp != NULL && !nm_iszombie(na)) {
		NM_DETACH_NA(na->ifp);
		if (vpna->autodelete) {
			ND("releasing %s", na->ifp->if_xname);
			NMG_UNLOCK();
			nm_os_vi_detach(na->ifp);
			NMG_LOCK();
		}
	}
}



/* nm_krings_create callback for VALE ports.
 * Calls the standard netmap_krings_create, then adds leases on rx
 * rings and bdgfwd on tx rings.
 */
static int
netmap_vale_vp_krings_create(struct netmap_adapter *na)
{
	u_int tailroom;
	int error, i;
	uint32_t *leases;
	u_int nrx = netmap_real_rings(na, NR_RX);

	/*
	 * Leases are attached to RX rings on vale ports
	 */
	tailroom = sizeof(uint32_t) * na->num_rx_desc * nrx;

	error = netmap_krings_create(na, tailroom);
	if (error)
		return error;

	leases = na->tailroom;

	for (i = 0; i < nrx; i++) { /* Receive rings */
		na->rx_rings[i]->nkr_leases = leases;
		leases += na->num_rx_desc;
	}

	error = nm_alloc_bdgfwd(na);
	if (error) {
		netmap_krings_delete(na);
		return error;
	}

	return 0;
}


/* nm_krings_delete callback for VALE ports. */
static void
netmap_vale_vp_krings_delete(struct netmap_adapter *na)
{
	nm_free_bdgfwd(na);
	netmap_krings_delete(na);
}


static int
nm_vale_flush(struct nm_bdg_fwd *ft, u_int n,
	struct netmap_vp_adapter *na, u_int ring_nr);


/*
 * main dispatch routine for the bridge.
 * Grab packets from a kring, move them into the ft structure
 * associated to the tx (input) port. Max one instance per port,
 * filtered on input (ioctl, poll or XXX).
 * Returns the next position in the ring.
 */
static int
nm_vale_preflush(struct netmap_kring *kring, u_int end)
{
	struct netmap_vp_adapter *na =
		(struct netmap_vp_adapter*)kring->na;
	struct netmap_ring *ring = kring->ring;
	struct nm_bdg_fwd *ft;
	u_int ring_nr = kring->ring_id;
	u_int j = kring->nr_hwcur, lim = kring->nkr_num_slots - 1;
	u_int ft_i = 0;	/* start from 0 */
	u_int frags = 1; /* how many frags ? */
	struct nm_bridge *b = na->na_bdg;

	/* To protect against modifications to the bridge we acquire a
	 * shared lock, waiting if we can sleep (if the source port is
	 * attached to a user process) or with a trylock otherwise (NICs).
	 */
	ND("wait rlock for %d packets", ((j > end ? lim+1 : 0) + end) - j);
	if (na->up.na_flags & NAF_BDG_MAYSLEEP)
		BDG_RLOCK(b);
	else if (!BDG_RTRYLOCK(b))
		return j;
	ND(5, "rlock acquired for %d packets", ((j > end ? lim+1 : 0) + end) - j);
	ft = kring->nkr_ft;

	for (; likely(j != end); j = nm_next(j, lim)) {
		struct netmap_slot *slot = &ring->slot[j];
		char *buf;

		ft[ft_i].ft_len = slot->len;
		ft[ft_i].ft_flags = slot->flags;
		ft[ft_i].ft_offset = 0;

		ND("flags is 0x%x", slot->flags);
		/* we do not use the buf changed flag, but we still need to reset it */
		slot->flags &= ~NS_BUF_CHANGED;

		/* this slot goes into a list so initialize the link field */
		ft[ft_i].ft_next = NM_FT_NULL;
		buf = ft[ft_i].ft_buf = (slot->flags & NS_INDIRECT) ?
			(void *)(uintptr_t)slot->ptr : NMB(&na->up, slot);
		if (unlikely(buf == NULL)) {
			nm_prlim(5, "NULL %s buffer pointer from %s slot %d len %d",
				(slot->flags & NS_INDIRECT) ? "INDIRECT" : "DIRECT",
				kring->name, j, ft[ft_i].ft_len);
			buf = ft[ft_i].ft_buf = NETMAP_BUF_BASE(&na->up);
			ft[ft_i].ft_len = 0;
			ft[ft_i].ft_flags = 0;
		}
		__builtin_prefetch(buf);
		++ft_i;
		if (slot->flags & NS_MOREFRAG) {
			frags++;
			continue;
		}
		if (unlikely(netmap_verbose && frags > 1))
			RD(5, "%d frags at %d", frags, ft_i - frags);
		ft[ft_i - frags].ft_frags = frags;
		frags = 1;
		if (unlikely((int)ft_i >= bridge_batch))
			ft_i = nm_vale_flush(ft, ft_i, na, ring_nr);
	}
	if (frags > 1) {
		/* Here ft_i > 0, ft[ft_i-1].flags has NS_MOREFRAG, and we
		 * have to fix frags count. */
		frags--;
		ft[ft_i - 1].ft_flags &= ~NS_MOREFRAG;
		ft[ft_i - frags].ft_frags = frags;
		nm_prlim(5, "Truncate incomplete fragment at %d (%d frags)", ft_i, frags);
	}
	if (ft_i)
		ft_i = nm_vale_flush(ft, ft_i, na, ring_nr);
	BDG_RUNLOCK(b);
	return j;
}


/* ----- FreeBSD if_bridge hash function ------- */

/*
 * The following hash function is adapted from "Hash Functions" by Bob Jenkins
 * ("Algorithm Alley", Dr. Dobbs Journal, September 1997).
 *
 * http://www.burtleburtle.net/bob/hash/spooky.html
 */
#define mix(a, b, c)                                                    \
do {                                                                    \
	a -= b; a -= c; a ^= (c >> 13);                                 \
	b -= c; b -= a; b ^= (a << 8);                                  \
	c -= a; c -= b; c ^= (b >> 13);                                 \
	a -= b; a -= c; a ^= (c >> 12);                                 \
	b -= c; b -= a; b ^= (a << 16);                                 \
	c -= a; c -= b; c ^= (b >> 5);                                  \
	a -= b; a -= c; a ^= (c >> 3);                                  \
	b -= c; b -= a; b ^= (a << 10);                                 \
	c -= a; c -= b; c ^= (b >> 15);                                 \
} while (/*CONSTCOND*/0)


static __inline uint32_t
nm_vale_rthash(const uint8_t *addr)
{
	uint32_t a = 0x9e3779b9, b = 0x9e3779b9, c = 0; // hask key

	b += addr[5] << 8;
	b += addr[4];
	a += addr[3] << 24;
	a += addr[2] << 16;
	a += addr[1] << 8;
	a += addr[0];

	mix(a, b, c);
#define BRIDGE_RTHASH_MASK	(NM_BDG_HASH-1)
	return (c & BRIDGE_RTHASH_MASK);
}

#undef mix


/*
 * Lookup function for a learning bridge.
 * Update the hash table with the source address,
 * and then returns the destination port index, and the
 * ring in *dst_ring (at the moment, always use ring 0)
 */
uint32_t
netmap_vale_learning(struct nm_bdg_fwd *ft, uint8_t *dst_ring,
		struct netmap_vp_adapter *na, void *private_data)
{
	uint8_t *buf = ((uint8_t *)ft->ft_buf) + ft->ft_offset;
	u_int buf_len = ft->ft_len - ft->ft_offset;
	struct nm_hash_ent *ht = private_data;
	uint32_t sh, dh;
	u_int dst, mysrc = na->bdg_port;
	uint64_t smac, dmac;
	uint8_t indbuf[12];

	if (buf_len < 14) {
		return NM_BDG_NOPORT;
	}

	if (ft->ft_flags & NS_INDIRECT) {
		if (copyin(buf, indbuf, sizeof(indbuf))) {
			return NM_BDG_NOPORT;
		}
		buf = indbuf;
	}

	dmac = le64toh(*(uint64_t *)(buf)) & 0xffffffffffff;
	smac = le64toh(*(uint64_t *)(buf + 4));
	smac >>= 16;

	/*
	 * The hash is somewhat expensive, there might be some
	 * worthwhile optimizations here.
	 */
	if (((buf[6] & 1) == 0) && (na->last_smac != smac)) { /* valid src */
		uint8_t *s = buf+6;
		sh = nm_vale_rthash(s); /* hash of source */
		/* update source port forwarding entry */
		na->last_smac = ht[sh].mac = smac;	/* XXX expire ? */
		ht[sh].ports = mysrc;
		if (netmap_debug & NM_DEBUG_VALE)
		    nm_prinf("src %02x:%02x:%02x:%02x:%02x:%02x on port %d",
			s[0], s[1], s[2], s[3], s[4], s[5], mysrc);
	}
	dst = NM_BDG_BROADCAST;
	if ((buf[0] & 1) == 0) { /* unicast */
		dh = nm_vale_rthash(buf); /* hash of dst */
		if (ht[dh].mac == dmac) {	/* found dst */
			dst = ht[dh].ports;
		}
	}
	return dst;
}


/*
 * Available space in the ring. Only used in VALE code
 * and only with is_rx = 1
 */
static inline uint32_t
nm_kr_space(struct netmap_kring *k, int is_rx)
{
	int space;

	if (is_rx) {
		int busy = k->nkr_hwlease - k->nr_hwcur;
		if (busy < 0)
			busy += k->nkr_num_slots;
		space = k->nkr_num_slots - 1 - busy;
	} else {
		/* XXX never used in this branch */
		space = k->nr_hwtail - k->nkr_hwlease;
		if (space < 0)
			space += k->nkr_num_slots;
	}
#if 0
	// sanity check
	if (k->nkr_hwlease >= k->nkr_num_slots ||
		k->nr_hwcur >= k->nkr_num_slots ||
		k->nr_tail >= k->nkr_num_slots ||
		busy < 0 ||
		busy >= k->nkr_num_slots) {
		D("invalid kring, cur %d tail %d lease %d lease_idx %d lim %d",			k->nr_hwcur, k->nr_hwtail, k->nkr_hwlease,
			k->nkr_lease_idx, k->nkr_num_slots);
	}
#endif
	return space;
}




/* make a lease on the kring for N positions. return the
 * lease index
 * XXX only used in VALE code and with is_rx = 1
 */
static inline uint32_t
nm_kr_lease(struct netmap_kring *k, u_int n, int is_rx)
{
	uint32_t lim = k->nkr_num_slots - 1;
	uint32_t lease_idx = k->nkr_lease_idx;

	k->nkr_leases[lease_idx] = NR_NOSLOT;
	k->nkr_lease_idx = nm_next(lease_idx, lim);

#ifdef CONFIG_NETMAP_DEBUG
	if (n > nm_kr_space(k, is_rx)) {
		nm_prerr("invalid request for %d slots", n);
		panic("x");
	}
#endif /* CONFIG NETMAP_DEBUG */
	/* XXX verify that there are n slots */
	k->nkr_hwlease += n;
	if (k->nkr_hwlease > lim)
		k->nkr_hwlease -= lim + 1;

#ifdef CONFIG_NETMAP_DEBUG
	if (k->nkr_hwlease >= k->nkr_num_slots ||
		k->nr_hwcur >= k->nkr_num_slots ||
		k->nr_hwtail >= k->nkr_num_slots ||
		k->nkr_lease_idx >= k->nkr_num_slots) {
		nm_prerr("invalid kring %s, cur %d tail %d lease %d lease_idx %d lim %d",
			k->na->name,
			k->nr_hwcur, k->nr_hwtail, k->nkr_hwlease,
			k->nkr_lease_idx, k->nkr_num_slots);
	}
#endif /* CONFIG_NETMAP_DEBUG */
	return lease_idx;
}

/*
 *
 * This flush routine supports only unicast and broadcast but a large
 * number of ports, and lets us replace the learn and dispatch functions.
 */
int
nm_vale_flush(struct nm_bdg_fwd *ft, u_int n, struct netmap_vp_adapter *na,
		u_int ring_nr)
{
	struct nm_vale_q *dst_ents, *brddst;
	uint16_t num_dsts = 0, *dsts;
	struct nm_bridge *b = na->na_bdg;
	u_int i, me = na->bdg_port;

	/*
	 * The work area (pointed by ft) is followed by an array of
	 * pointers to queues , dst_ents; there are NM_BDG_MAXRINGS
	 * queues per port plus one for the broadcast traffic.
	 * Then we have an array of destination indexes.
	 */
	dst_ents = (struct nm_vale_q *)(ft + NM_BDG_BATCH_MAX);
	dsts = (uint16_t *)(dst_ents + NM_BDG_MAXPORTS * NM_BDG_MAXRINGS + 1);

	/* first pass: find a destination for each packet in the batch */
	for (i = 0; likely(i < n); i += ft[i].ft_frags) {
		uint8_t dst_ring = ring_nr; /* default, same ring as origin */
		uint16_t dst_port, d_i;
		struct nm_vale_q *d;
		struct nm_bdg_fwd *start_ft = NULL;

		ND("slot %d frags %d", i, ft[i].ft_frags);

		if (na->up.virt_hdr_len < ft[i].ft_len) {
			ft[i].ft_offset = na->up.virt_hdr_len;
			start_ft = &ft[i];
		} else if (na->up.virt_hdr_len == ft[i].ft_len && ft[i].ft_flags & NS_MOREFRAG) {
			ft[i].ft_offset = ft[i].ft_len;
			start_ft = &ft[i+1];
		} else {
			/* Drop the packet if the virtio-net header is not into the first
			 * fragment nor at the very beginning of the second.
			 */
			continue;
		}
		dst_port = b->bdg_ops.lookup(start_ft, &dst_ring, na, b->private_data);
		if (netmap_verbose > 255)
			RD(5, "slot %d port %d -> %d", i, me, dst_port);
		if (dst_port >= NM_BDG_NOPORT)
			continue; /* this packet is identified to be dropped */
		else if (dst_port == NM_BDG_BROADCAST)
			dst_ring = 0; /* broadcasts always go to ring 0 */
		else if (unlikely(dst_port == me ||
		    !b->bdg_ports[dst_port]))
			continue;

		/* get a position in the scratch pad */
		d_i = dst_port * NM_BDG_MAXRINGS + dst_ring;
		d = dst_ents + d_i;

		/* append the first fragment to the list */
		if (d->bq_head == NM_FT_NULL) { /* new destination */
			d->bq_head = d->bq_tail = i;
			/* remember this position to be scanned later */
			if (dst_port != NM_BDG_BROADCAST)
				dsts[num_dsts++] = d_i;
		} else {
			ft[d->bq_tail].ft_next = i;
			d->bq_tail = i;
		}
		d->bq_len += ft[i].ft_frags;
	}

	/*
	 * Broadcast traffic goes to ring 0 on all destinations.
	 * So we need to add these rings to the list of ports to scan.
	 * XXX at the moment we scan all NM_BDG_MAXPORTS ports, which is
	 * expensive. We should keep a compact list of active destinations
	 * so we could shorten this loop.
	 */
	brddst = dst_ents + NM_BDG_BROADCAST * NM_BDG_MAXRINGS;
	if (brddst->bq_head != NM_FT_NULL) {
		u_int j;
		for (j = 0; likely(j < b->bdg_active_ports); j++) {
			uint16_t d_i;
			i = b->bdg_port_index[j];
			if (unlikely(i == me))
				continue;
			d_i = i * NM_BDG_MAXRINGS;
			if (dst_ents[d_i].bq_head == NM_FT_NULL)
				dsts[num_dsts++] = d_i;
		}
	}

	ND(5, "pass 1 done %d pkts %d dsts", n, num_dsts);
	/* second pass: scan destinations */
	for (i = 0; i < num_dsts; i++) {
		struct netmap_vp_adapter *dst_na;
		struct netmap_kring *kring;
		struct netmap_ring *ring;
		u_int dst_nr, lim, j, d_i, next, brd_next;
		u_int needed, howmany;
		int retry = netmap_txsync_retry;
		struct nm_vale_q *d;
		uint32_t my_start = 0, lease_idx = 0;
		int nrings;
		int virt_hdr_mismatch = 0;

		d_i = dsts[i];
		ND("second pass %d port %d", i, d_i);
		d = dst_ents + d_i;
		// XXX fix the division
		dst_na = b->bdg_ports[d_i/NM_BDG_MAXRINGS];
		/* protect from the lookup function returning an inactive
		 * destination port
		 */
		if (unlikely(dst_na == NULL))
			goto cleanup;
		if (dst_na->up.na_flags & NAF_SW_ONLY)
			goto cleanup;
		/*
		 * The interface may be in !netmap mode in two cases:
		 * - when na is attached but not activated yet;
		 * - when na is being deactivated but is still attached.
		 */
		if (unlikely(!nm_netmap_on(&dst_na->up))) {
			ND("not in netmap mode!");
			goto cleanup;
		}

		/* there is at least one either unicast or broadcast packet */
		brd_next = brddst->bq_head;
		next = d->bq_head;
		/* we need to reserve this many slots. If fewer are
		 * available, some packets will be dropped.
		 * Packets may have multiple fragments, so we may not use
		 * there is a chance that we may not use all of the slots
		 * we have claimed, so we will need to handle the leftover
		 * ones when we regain the lock.
		 */
		needed = d->bq_len + brddst->bq_len;

		if (unlikely(dst_na->up.virt_hdr_len != na->up.virt_hdr_len)) {
			if (netmap_verbose) {
				RD(3, "virt_hdr_mismatch, src %d dst %d", na->up.virt_hdr_len,
						dst_na->up.virt_hdr_len);
			}
			/* There is a virtio-net header/offloadings mismatch between
			 * source and destination. The slower mismatch datapath will
			 * be used to cope with all the mismatches.
			 */
			virt_hdr_mismatch = 1;
			if (dst_na->mfs < na->mfs) {
				/* We may need to do segmentation offloadings, and so
				 * we may need a number of destination slots greater
				 * than the number of input slots ('needed').
				 * We look for the smallest integer 'x' which satisfies:
				 *	needed * na->mfs + x * H <= x * na->mfs
				 * where 'H' is the length of the longest header that may
				 * be replicated in the segmentation process (e.g. for
				 * TCPv4 we must account for ethernet header, IP header
				 * and TCPv4 header).
				 */
				KASSERT(dst_na->mfs > 0, ("vpna->mfs is 0"));
				needed = (needed * na->mfs) /
						(dst_na->mfs - WORST_CASE_GSO_HEADER) + 1;
				ND(3, "srcmtu=%u, dstmtu=%u, x=%u", na->mfs, dst_na->mfs, needed);
			}
		}

		ND(5, "pass 2 dst %d is %x %s",
			i, d_i, is_vp ? "virtual" : "nic/host");
		dst_nr = d_i & (NM_BDG_MAXRINGS-1);
		nrings = dst_na->up.num_rx_rings;
		if (dst_nr >= nrings)
			dst_nr = dst_nr % nrings;
		kring = dst_na->up.rx_rings[dst_nr];
		ring = kring->ring;
		/* the destination ring may have not been opened for RX */
		if (unlikely(ring == NULL || kring->nr_mode != NKR_NETMAP_ON))
			goto cleanup;
		lim = kring->nkr_num_slots - 1;

retry:

		if (dst_na->retry && retry) {
			/* try to get some free slot from the previous run */
			kring->nm_notify(kring, NAF_FORCE_RECLAIM);
			/* actually useful only for bwraps, since there
			 * the notify will trigger a txsync on the hwna. VALE ports
			 * have dst_na->retry == 0
			 */
		}
		/* reserve the buffers in the queue and an entry
		 * to report completion, and drop lock.
		 * XXX this might become a helper function.
		 */
		mtx_lock(&kring->q_lock);
		if (kring->nkr_stopped) {
			mtx_unlock(&kring->q_lock);
			goto cleanup;
		}
		my_start = j = kring->nkr_hwlease;
		howmany = nm_kr_space(kring, 1);
		if (needed < howmany)
			howmany = needed;
		lease_idx = nm_kr_lease(kring, howmany, 1);
		mtx_unlock(&kring->q_lock);

		/* only retry if we need more than available slots */
		if (retry && needed <= howmany)
			retry = 0;

		/* copy to the destination queue */
		while (howmany > 0) {
			struct netmap_slot *slot;
			struct nm_bdg_fwd *ft_p, *ft_end;
			u_int cnt;

			/* find the queue from which we pick next packet.
			 * NM_FT_NULL is always higher than valid indexes
			 * so we never dereference it if the other list
			 * has packets (and if both are empty we never
			 * get here).
			 */
			if (next < brd_next) {
				ft_p = ft + next;
				next = ft_p->ft_next;
			} else { /* insert broadcast */
				ft_p = ft + brd_next;
				brd_next = ft_p->ft_next;
			}
			cnt = ft_p->ft_frags; // cnt > 0
			if (unlikely(cnt > howmany))
			    break; /* no more space */
			if (netmap_verbose && cnt > 1)
				RD(5, "rx %d frags to %d", cnt, j);
			ft_end = ft_p + cnt;
			if (unlikely(virt_hdr_mismatch)) {
				bdg_mismatch_datapath(na, dst_na, ft_p, ring, &j, lim, &howmany);
			} else {
				howmany -= cnt;
				do {
					char *dst, *src = ft_p->ft_buf;
					size_t copy_len = ft_p->ft_len, dst_len = copy_len;

					slot = &ring->slot[j];
					dst = NMB(&dst_na->up, slot);

					ND("send [%d] %d(%d) bytes at %s:%d",
							i, (int)copy_len, (int)dst_len,
							NM_IFPNAME(dst_ifp), j);
					/* round to a multiple of 64 */
					copy_len = (copy_len + 63) & ~63;

					if (unlikely(copy_len > NETMAP_BUF_SIZE(&dst_na->up) ||
						     copy_len > NETMAP_BUF_SIZE(&na->up))) {
						RD(5, "invalid len %d, down to 64", (int)copy_len);
						copy_len = dst_len = 64; // XXX
					}
					if (ft_p->ft_flags & NS_INDIRECT) {
						if (copyin(src, dst, copy_len)) {
							// invalid user pointer, pretend len is 0
							dst_len = 0;
						}
					} else {
						//memcpy(dst, src, copy_len);
						pkt_copy(src, dst, (int)copy_len);
					}
					slot->len = dst_len;
					slot->flags = (cnt << 8)| NS_MOREFRAG;
					j = nm_next(j, lim);
					needed--;
					ft_p++;
				} while (ft_p != ft_end);
				slot->flags = (cnt << 8); /* clear flag on last entry */
			}
			/* are we done ? */
			if (next == NM_FT_NULL && brd_next == NM_FT_NULL)
				break;
		}
		{
		    /* current position */
		    uint32_t *p = kring->nkr_leases; /* shorthand */
		    uint32_t update_pos;
		    int still_locked = 1;

		    mtx_lock(&kring->q_lock);
		    if (unlikely(howmany > 0)) {
			/* not used all bufs. If i am the last one
			 * i can recover the slots, otherwise must
			 * fill them with 0 to mark empty packets.
			 */
			ND("leftover %d bufs", howmany);
			if (nm_next(lease_idx, lim) == kring->nkr_lease_idx) {
			    /* yes i am the last one */
			    ND("roll back nkr_hwlease to %d", j);
			    kring->nkr_hwlease = j;
			} else {
			    while (howmany-- > 0) {
				ring->slot[j].len = 0;
				ring->slot[j].flags = 0;
				j = nm_next(j, lim);
			    }
			}
		    }
		    p[lease_idx] = j; /* report I am done */

		    update_pos = kring->nr_hwtail;

		    if (my_start == update_pos) {
			/* all slots before my_start have been reported,
			 * so scan subsequent leases to see if other ranges
			 * have been completed, and to a selwakeup or txsync.
		         */
			while (lease_idx != kring->nkr_lease_idx &&
				p[lease_idx] != NR_NOSLOT) {
			    j = p[lease_idx];
			    p[lease_idx] = NR_NOSLOT;
			    lease_idx = nm_next(lease_idx, lim);
			}
			/* j is the new 'write' position. j != my_start
			 * means there are new buffers to report
			 */
			if (likely(j != my_start)) {
				kring->nr_hwtail = j;
				still_locked = 0;
				mtx_unlock(&kring->q_lock);
				kring->nm_notify(kring, 0);
				/* this is netmap_notify for VALE ports and
				 * netmap_bwrap_notify for bwrap. The latter will
				 * trigger a txsync on the underlying hwna
				 */
				if (dst_na->retry && retry--) {
					/* XXX this is going to call nm_notify again.
					 * Only useful for bwrap in virtual machines
					 */
					goto retry;
				}
			}
		    }
		    if (still_locked)
			mtx_unlock(&kring->q_lock);
		}
cleanup:
		d->bq_head = d->bq_tail = NM_FT_NULL; /* cleanup */
		d->bq_len = 0;
	}
	brddst->bq_head = brddst->bq_tail = NM_FT_NULL; /* cleanup */
	brddst->bq_len = 0;
	return 0;
}

/* nm_txsync callback for VALE ports */
static int
netmap_vale_vp_txsync(struct netmap_kring *kring, int flags)
{
	struct netmap_vp_adapter *na =
		(struct netmap_vp_adapter *)kring->na;
	u_int done;
	u_int const lim = kring->nkr_num_slots - 1;
	u_int const head = kring->rhead;

	if (bridge_batch <= 0) { /* testing only */
		done = head; // used all
		goto done;
	}
	if (!na->na_bdg) {
		done = head;
		goto done;
	}
	if (bridge_batch > NM_BDG_BATCH)
		bridge_batch = NM_BDG_BATCH;

	done = nm_vale_preflush(kring, head);
done:
	if (done != head)
		nm_prerr("early break at %d/ %d, tail %d", done, head, kring->nr_hwtail);
	/*
	 * packets between 'done' and 'cur' are left unsent.
	 */
	kring->nr_hwcur = done;
	kring->nr_hwtail = nm_prev(done, lim);
	if (netmap_debug & NM_DEBUG_TXSYNC)
		nm_prinf("%s ring %d flags %d", na->up.name, kring->ring_id, flags);
	return 0;
}


/* create a netmap_vp_adapter that describes a VALE port.
 * Only persistent VALE ports have a non-null ifp.
 */
static int
netmap_vale_vp_create(struct nmreq_header *hdr, struct ifnet *ifp,
		struct netmap_mem_d *nmd, struct netmap_vp_adapter **ret)
{
	struct nmreq_register *req = (struct nmreq_register *)(uintptr_t)hdr->nr_body;
	struct netmap_vp_adapter *vpna;
	struct netmap_adapter *na;
	int error = 0;
	u_int npipes = 0;
	u_int extrabufs = 0;

	if (hdr->nr_reqtype != NETMAP_REQ_REGISTER) {
		return EINVAL;
	}

	vpna = nm_os_malloc(sizeof(*vpna));
	if (vpna == NULL)
		return ENOMEM;

 	na = &vpna->up;

	na->ifp = ifp;
	strlcpy(na->name, hdr->nr_name, sizeof(na->name));

	/* bound checking */
	na->num_tx_rings = req->nr_tx_rings;
	nm_bound_var(&na->num_tx_rings, 1, 1, NM_BDG_MAXRINGS, NULL);
	req->nr_tx_rings = na->num_tx_rings; /* write back */
	na->num_rx_rings = req->nr_rx_rings;
	nm_bound_var(&na->num_rx_rings, 1, 1, NM_BDG_MAXRINGS, NULL);
	req->nr_rx_rings = na->num_rx_rings; /* write back */
	nm_bound_var(&req->nr_tx_slots, NM_BRIDGE_RINGSIZE,
			1, NM_BDG_MAXSLOTS, NULL);
	na->num_tx_desc = req->nr_tx_slots;
	nm_bound_var(&req->nr_rx_slots, NM_BRIDGE_RINGSIZE,
			1, NM_BDG_MAXSLOTS, NULL);
	/* validate number of pipes. We want at least 1,
	 * but probably can do with some more.
	 * So let's use 2 as default (when 0 is supplied)
	 */
	nm_bound_var(&npipes, 2, 1, NM_MAXPIPES, NULL);
	/* validate extra bufs */
	extrabufs = req->nr_extra_bufs;
	nm_bound_var(&extrabufs, 0, 0,
			128*NM_BDG_MAXSLOTS, NULL);
	req->nr_extra_bufs = extrabufs; /* write back */
	na->num_rx_desc = req->nr_rx_slots;
	/* Set the mfs to a default value, as it is needed on the VALE
	 * mismatch datapath. XXX We should set it according to the MTU
	 * known to the kernel. */
	vpna->mfs = NM_BDG_MFS_DEFAULT;
	vpna->last_smac = ~0llu;
	/*if (vpna->mfs > netmap_buf_size)  TODO netmap_buf_size is zero??
		vpna->mfs = netmap_buf_size; */
	if (netmap_verbose)
		nm_prinf("max frame size %u", vpna->mfs);

	na->na_flags |= NAF_BDG_MAYSLEEP;
	/* persistent VALE ports look like hw devices
	 * with a native netmap adapter
	 */
	if (ifp)
		na->na_flags |= NAF_NATIVE;
	na->nm_txsync = netmap_vale_vp_txsync;
	na->nm_rxsync = netmap_vp_rxsync; /* use the one provided by bdg */
	na->nm_register = netmap_vp_reg;  /* use the one provided by bdg */
	na->nm_krings_create = netmap_vale_vp_krings_create;
	na->nm_krings_delete = netmap_vale_vp_krings_delete;
	na->nm_dtor = netmap_vale_vp_dtor;
	ND("nr_mem_id %d", req->nr_mem_id);
	na->nm_mem = nmd ?
		netmap_mem_get(nmd):
		netmap_mem_private_new(
			na->num_tx_rings, na->num_tx_desc,
			na->num_rx_rings, na->num_rx_desc,
			req->nr_extra_bufs, npipes, &error);
	if (na->nm_mem == NULL)
		goto err;
	na->nm_bdg_attach = netmap_vale_vp_bdg_attach;
	/* other nmd fields are set in the common routine */
	error = netmap_attach_common(na);
	if (error)
		goto err;
	*ret = vpna;
	return 0;

err:
	if (na->nm_mem != NULL)
		netmap_mem_put(na->nm_mem);
	nm_os_free(vpna);
	return error;
}

/* nm_bdg_attach callback for VALE ports
 * The na_vp port is this same netmap_adapter. There is no host port.
 */
static int
netmap_vale_vp_bdg_attach(const char *name, struct netmap_adapter *na,
		struct nm_bridge *b)
{
	struct netmap_vp_adapter *vpna = (struct netmap_vp_adapter *)na;

	if ((b->bdg_flags & NM_BDG_NEED_BWRAP) || vpna->na_bdg) {
		return NM_NEED_BWRAP;
	}
	na->na_vp = vpna;
	strlcpy(na->name, name, sizeof(na->name));
	na->na_hostvp = NULL;
	return 0;
}

static int
netmap_vale_bwrap_krings_create(struct netmap_adapter *na)
{
	int error;

	/* impersonate a netmap_vp_adapter */
	error = netmap_vale_vp_krings_create(na);
	if (error)
		return error;
	error = netmap_bwrap_krings_create_common(na);
	if (error) {
		netmap_vale_vp_krings_delete(na);
	}
	return error;
}

static void
netmap_vale_bwrap_krings_delete(struct netmap_adapter *na)
{
	netmap_bwrap_krings_delete_common(na);
	netmap_vale_vp_krings_delete(na);
}

static int
netmap_vale_bwrap_attach(const char *nr_name, struct netmap_adapter *hwna)
{
	struct netmap_bwrap_adapter *bna;
	struct netmap_adapter *na = NULL;
	struct netmap_adapter *hostna = NULL;
	int error;

	bna = nm_os_malloc(sizeof(*bna));
	if (bna == NULL) {
		return ENOMEM;
	}
	na = &bna->up.up;
	strlcpy(na->name, nr_name, sizeof(na->name));
	na->nm_register = netmap_bwrap_reg;
	na->nm_txsync = netmap_vale_vp_txsync;
	// na->nm_rxsync = netmap_bwrap_rxsync;
	na->nm_krings_create = netmap_vale_bwrap_krings_create;
	na->nm_krings_delete = netmap_vale_bwrap_krings_delete;
	na->nm_notify = netmap_bwrap_notify;
	bna->up.retry = 1; /* XXX maybe this should depend on the hwna */
	/* Set the mfs, needed on the VALE mismatch datapath. */
	bna->up.mfs = NM_BDG_MFS_DEFAULT;

	if (hwna->na_flags & NAF_HOST_RINGS) {
		hostna = &bna->host.up;
		hostna->nm_notify = netmap_bwrap_notify;
		bna->host.mfs = NM_BDG_MFS_DEFAULT;
	}

	error = netmap_bwrap_attach_common(na, hwna);
	if (error) {
		nm_os_free(bna);
	}
	return error;
}

int
netmap_get_vale_na(struct nmreq_header *hdr, struct netmap_adapter **na,
		struct netmap_mem_d *nmd, int create)
{
	return netmap_get_bdg_na(hdr, na, nmd, create, &vale_bdg_ops);
}


/* creates a persistent VALE port */
int
nm_vi_create(struct nmreq_header *hdr)
{
	struct nmreq_vale_newif *req =
		(struct nmreq_vale_newif *)(uintptr_t)hdr->nr_body;
	int error = 0;
	/* Build a nmreq_register out of the nmreq_vale_newif,
	 * so that we can call netmap_get_bdg_na(). */
	struct nmreq_register regreq;
	bzero(&regreq, sizeof(regreq));
	regreq.nr_tx_slots = req->nr_tx_slots;
	regreq.nr_rx_slots = req->nr_rx_slots;
	regreq.nr_tx_rings = req->nr_tx_rings;
	regreq.nr_rx_rings = req->nr_rx_rings;
	regreq.nr_mem_id = req->nr_mem_id;
	hdr->nr_reqtype = NETMAP_REQ_REGISTER;
	hdr->nr_body = (uintptr_t)&regreq;
	error = netmap_vi_create(hdr, 0 /* no autodelete */);
	hdr->nr_reqtype = NETMAP_REQ_VALE_NEWIF;
	hdr->nr_body = (uintptr_t)req;
	/* Write back to the original struct. */
	req->nr_tx_slots = regreq.nr_tx_slots;
	req->nr_rx_slots = regreq.nr_rx_slots;
	req->nr_tx_rings = regreq.nr_tx_rings;
	req->nr_rx_rings = regreq.nr_rx_rings;
	req->nr_mem_id = regreq.nr_mem_id;
	return error;
}

/* remove a persistent VALE port from the system */
int
nm_vi_destroy(const char *name)
{
	struct ifnet *ifp;
	struct netmap_vp_adapter *vpna;
	int error;

	ifp = ifunit_ref(name);
	if (!ifp)
		return ENXIO;
	NMG_LOCK();
	/* make sure this is actually a VALE port */
	if (!NM_NA_VALID(ifp) || NA(ifp)->nm_register != netmap_vp_reg) {
		error = EINVAL;
		goto err;
	}

	vpna = (struct netmap_vp_adapter *)NA(ifp);

	/* we can only destroy ports that were created via NETMAP_BDG_NEWIF */
	if (vpna->autodelete) {
		error = EINVAL;
		goto err;
	}

	/* also make sure that nobody is using the inferface */
	if (NETMAP_OWNED_BY_ANY(&vpna->up) ||
	    vpna->up.na_refcount > 1 /* any ref besides the one in nm_vi_create()? */) {
		error = EBUSY;
		goto err;
	}

	NMG_UNLOCK();

	if (netmap_verbose)
		nm_prinf("destroying a persistent vale interface %s", ifp->if_xname);
	/* Linux requires all the references are released
	 * before unregister
	 */
	netmap_detach(ifp);
	if_rele(ifp);
	nm_os_vi_detach(ifp);
	return 0;

err:
	NMG_UNLOCK();
	if_rele(ifp);
	return error;
}

static int
nm_update_info(struct nmreq_register *req, struct netmap_adapter *na)
{
	req->nr_rx_rings = na->num_rx_rings;
	req->nr_tx_rings = na->num_tx_rings;
	req->nr_rx_slots = na->num_rx_desc;
	req->nr_tx_slots = na->num_tx_desc;
	return netmap_mem_get_info(na->nm_mem, &req->nr_memsize, NULL,
					&req->nr_mem_id);
}


/*
 * Create a virtual interface registered to the system.
 * The interface will be attached to a bridge later.
 */
int
netmap_vi_create(struct nmreq_header *hdr, int autodelete)
{
	struct nmreq_register *req = (struct nmreq_register *)(uintptr_t)hdr->nr_body;
	struct ifnet *ifp;
	struct netmap_vp_adapter *vpna;
	struct netmap_mem_d *nmd = NULL;
	int error;

	if (hdr->nr_reqtype != NETMAP_REQ_REGISTER) {
		return EINVAL;
	}

	/* don't include VALE prefix */
	if (!strncmp(hdr->nr_name, NM_BDG_NAME, strlen(NM_BDG_NAME)))
		return EINVAL;
	if (strlen(hdr->nr_name) >= IFNAMSIZ) {
		return EINVAL;
	}
	ifp = ifunit_ref(hdr->nr_name);
	if (ifp) { /* already exist, cannot create new one */
		error = EEXIST;
		NMG_LOCK();
		if (NM_NA_VALID(ifp)) {
			int update_err = nm_update_info(req, NA(ifp));
			if (update_err)
				error = update_err;
		}
		NMG_UNLOCK();
		if_rele(ifp);
		return error;
	}
	error = nm_os_vi_persist(hdr->nr_name, &ifp);
	if (error)
		return error;

	NMG_LOCK();
	if (req->nr_mem_id) {
		nmd = netmap_mem_find(req->nr_mem_id);
		if (nmd == NULL) {
			error = EINVAL;
			goto err_1;
		}
	}
	/* netmap_vp_create creates a struct netmap_vp_adapter */
	error = netmap_vale_vp_create(hdr, ifp, nmd, &vpna);
	if (error) {
		if (netmap_debug & NM_DEBUG_VALE)
			nm_prerr("error %d", error);
		goto err_1;
	}
	/* persist-specific routines */
	vpna->up.nm_bdg_ctl = netmap_vp_bdg_ctl;
	if (!autodelete) {
		netmap_adapter_get(&vpna->up);
	} else {
		vpna->autodelete = 1;
	}
	NM_ATTACH_NA(ifp, &vpna->up);
	/* return the updated info */
	error = nm_update_info(req, &vpna->up);
	if (error) {
		goto err_2;
	}
	ND("returning nr_mem_id %d", req->nr_mem_id);
	if (nmd)
		netmap_mem_put(nmd);
	NMG_UNLOCK();
	ND("created %s", ifp->if_xname);
	return 0;

err_2:
	netmap_detach(ifp);
err_1:
	if (nmd)
		netmap_mem_put(nmd);
	NMG_UNLOCK();
	nm_os_vi_detach(ifp);

	return error;
}

#endif /* WITH_VALE */