/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2012 Chelsio Communications, Inc.
 * 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.
 */
#include <sys/cdefs.h>
#include "opt_inet.h"
#include "opt_inet6.h"

#include <sys/param.h>
#include <sys/eventhandler.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/bus.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/rwlock.h>
#include <sys/socket.h>
#include <sys/sbuf.h>
#include <netinet/in.h>

#include "common/common.h"
#include "common/t4_msg.h"
#include "t4_l2t.h"

/*
 * Module locking notes:  There is a RW lock protecting the L2 table as a
 * whole plus a spinlock per L2T entry.  Entry lookups and allocations happen
 * under the protection of the table lock, individual entry changes happen
 * while holding that entry's spinlock.  The table lock nests outside the
 * entry locks.  Allocations of new entries take the table lock as writers so
 * no other lookups can happen while allocating new entries.  Entry updates
 * take the table lock as readers so multiple entries can be updated in
 * parallel.  An L2T entry can be dropped by decrementing its reference count
 * and therefore can happen in parallel with entry allocation but no entry
 * can change state or increment its ref count during allocation as both of
 * these perform lookups.
 *
 * Note: We do not take references to ifnets in this module because both
 * the TOE and the sockets already hold references to the interfaces and the
 * lifetime of an L2T entry is fully contained in the lifetime of the TOE.
 */

/*
 * Allocate a free L2T entry.  Must be called with l2t_data.lock held.
 */
struct l2t_entry *
t4_alloc_l2e(struct l2t_data *d)
{
        struct l2t_entry *end, *e, **p;

        rw_assert(&d->lock, RA_WLOCKED);
        if (__predict_false(d->l2t_stopped))
                return (NULL);
        if (!atomic_load_acq_int(&d->nfree))
                return (NULL);

        /* there's definitely a free entry */
        for (e = d->rover, end = &d->l2tab[d->l2t_size]; e != end; ++e)
                if (atomic_load_acq_int(&e->refcnt) == 0)
                        goto found;

        for (e = d->l2tab; atomic_load_acq_int(&e->refcnt); ++e)
                continue;
found:
        d->rover = e + 1;
        atomic_subtract_int(&d->nfree, 1);

        /*
         * The entry we found may be an inactive entry that is
         * presently in the hash table.  We need to remove it.
         */
        if (e->state < L2T_STATE_SWITCHING) {
                for (p = &d->l2tab[e->hash].first; *p; p = &(*p)->next) {
                        if (*p == e) {
                                *p = e->next;
                                e->next = NULL;
                                break;
                        }
                }
        }

        e->state = L2T_STATE_UNUSED;
        return (e);
}

static struct l2t_entry *
find_or_alloc_l2e(struct l2t_data *d, uint16_t vlan, uint8_t port, uint8_t *dmac)
{
        struct l2t_entry *end, *e, **p;
        struct l2t_entry *first_free = NULL;

        for (e = &d->l2tab[0], end = &d->l2tab[d->l2t_size]; e != end; ++e) {
                if (atomic_load_acq_int(&e->refcnt) == 0) {
                        if (!first_free)
                                first_free = e;
                } else if (e->state == L2T_STATE_SWITCHING &&
                    memcmp(e->dmac, dmac, ETHER_ADDR_LEN) == 0 &&
                    e->vlan == vlan && e->hw_port == port)
                        return (e);     /* Found existing entry that matches. */
        }

        if (first_free == NULL)
                return (NULL);  /* No match and no room for a new entry. */

        /*
         * The entry we found may be an inactive entry that is
         * presently in the hash table.  We need to remove it.
         */
        e = first_free;
        if (e->state < L2T_STATE_SWITCHING) {
                for (p = &d->l2tab[e->hash].first; *p; p = &(*p)->next) {
                        if (*p == e) {
                                *p = e->next;
                                e->next = NULL;
                                break;
                        }
                }
        }
        e->state = L2T_STATE_UNUSED;
        return (e);
}

static void
mk_write_l2e(struct adapter *sc, struct l2t_entry *e, int sync, int reply,
    void *dst)
{
        struct cpl_l2t_write_req *req;
        int idx;

        req = dst;
        idx = e->idx + sc->vres.l2t.start;
        INIT_TP_WR(req, 0);
        OPCODE_TID(req) = htonl(MK_OPCODE_TID(CPL_L2T_WRITE_REQ, idx |
            V_SYNC_WR(sync) | V_TID_QID(e->iqid)));
        req->params = htons(V_L2T_W_PORT(e->hw_port) | V_L2T_W_NOREPLY(!reply));
        req->l2t_idx = htons(idx);
        req->vlan = htons(e->vlan);
        memcpy(req->dst_mac, e->dmac, sizeof(req->dst_mac));
}

/*
 * Write an L2T entry.  Must be called with the entry locked.
 * The write may be synchronous or asynchronous.
 */
int
t4_write_l2e(struct l2t_entry *e, int sync)
{
        struct sge_wrq *wrq;
        struct adapter *sc;
        struct wrq_cookie cookie;
        struct cpl_l2t_write_req *req;

        mtx_assert(&e->lock, MA_OWNED);
        MPASS(e->wrq != NULL);

        wrq = e->wrq;
        sc = wrq->adapter;

        req = start_wrq_wr(wrq, howmany(sizeof(*req), 16), &cookie);
        if (req == NULL)
                return (ENOMEM);

        mk_write_l2e(sc, e, sync, sync, req);

        commit_wrq_wr(wrq, req, &cookie);

        if (sync && e->state != L2T_STATE_SWITCHING)
                e->state = L2T_STATE_SYNC_WRITE;

        return (0);
}

/*
 * Allocate an L2T entry for use by a TLS connection.  These entries are
 * associated with a specific VLAN and destination MAC that never changes.
 * However, multiple TLS connections might share a single entry.
 *
 * If a new L2T entry is allocated, a work request to initialize it is
 * written to 'txq' and 'ndesc' will be set to 1.  Otherwise, 'ndesc'
 * will be set to 0.
 *
 * To avoid races, separate L2T entries are reserved for individual
 * queues since the L2T entry update is written to a txq just prior to
 * TLS work requests that will depend on it being written.
 */
struct l2t_entry *
t4_l2t_alloc_tls(struct adapter *sc, struct sge_txq *txq, void *dst,
    int *ndesc, uint16_t vlan, uint8_t port, uint8_t *eth_addr)
{
        struct l2t_data *d;
        struct l2t_entry *e;
        int i;

        TXQ_LOCK_ASSERT_OWNED(txq);

        d = sc->l2t;
        *ndesc = 0;

        rw_rlock(&d->lock);

        /* First, try to find an existing entry. */
        for (i = 0; i < d->l2t_size; i++) {
                e = &d->l2tab[i];
                if (e->state != L2T_STATE_TLS)
                        continue;
                if (e->vlan == vlan && e->hw_port == port &&
                    e->wrq == (struct sge_wrq *)txq &&
                    memcmp(e->dmac, eth_addr, ETHER_ADDR_LEN) == 0) {
                        if (atomic_fetchadd_int(&e->refcnt, 1) == 0) {
                                /*
                                 * This entry wasn't held but is still
                                 * valid, so decrement nfree.
                                 */
                                atomic_subtract_int(&d->nfree, 1);
                        }
                        KASSERT(e->refcnt > 0,
                            ("%s: refcount overflow", __func__));
                        rw_runlock(&d->lock);
                        return (e);
                }
        }

        /*
         * Don't bother rechecking if the upgrade fails since the txq is
         * already locked.
         */
        if (!rw_try_upgrade(&d->lock)) {
                rw_runlock(&d->lock);
                rw_wlock(&d->lock);
        }

        /* Match not found, allocate a new entry. */
        e = t4_alloc_l2e(d);
        if (e == NULL) {
                rw_wunlock(&d->lock);
                return (e);
        }

        /* Initialize the entry. */
        e->state = L2T_STATE_TLS;
        e->vlan = vlan;
        e->hw_port = port;
        e->iqid = sc->sge.fwq.abs_id;
        e->wrq = (struct sge_wrq *)txq;
        memcpy(e->dmac, eth_addr, ETHER_ADDR_LEN);
        atomic_store_rel_int(&e->refcnt, 1);
        rw_wunlock(&d->lock);

        /* Write out the work request. */
        *ndesc = howmany(sizeof(struct cpl_l2t_write_req), EQ_ESIZE);
        MPASS(*ndesc == 1);
        mk_write_l2e(sc, e, 1, 0, dst);

        return (e);
}

/*
 * Allocate an L2T entry for use by a switching rule.  Such need to be
 * explicitly freed and while busy they are not on any hash chain, so normal
 * address resolution updates do not see them.
 */
struct l2t_entry *
t4_l2t_alloc_switching(struct adapter *sc, uint16_t vlan, uint8_t port,
    uint8_t *eth_addr)
{
        struct l2t_data *d = sc->l2t;
        struct l2t_entry *e;
        int rc;

        rw_wlock(&d->lock);
        if (__predict_false(d->l2t_stopped))
                e = NULL;
        else
                e = find_or_alloc_l2e(d, vlan, port, eth_addr);
        if (e) {
                if (atomic_load_acq_int(&e->refcnt) == 0) {
                        mtx_lock(&e->lock);    /* avoid race with t4_l2t_free */
                        e->wrq = &sc->sge.ctrlq[0];
                        e->iqid = sc->sge.fwq.abs_id;
                        e->state = L2T_STATE_SWITCHING;
                        e->vlan = vlan;
                        e->hw_port = port;
                        memcpy(e->dmac, eth_addr, ETHER_ADDR_LEN);
                        atomic_store_rel_int(&e->refcnt, 1);
                        atomic_subtract_int(&d->nfree, 1);
                        rc = t4_write_l2e(e, 0);
                        mtx_unlock(&e->lock);
                        if (rc != 0)
                                e = NULL;
                } else {
                        MPASS(e->vlan == vlan);
                        MPASS(e->hw_port == port);
                        atomic_add_int(&e->refcnt, 1);
                }
        }
        rw_wunlock(&d->lock);
        return (e);
}

int
t4_init_l2t(struct adapter *sc, int flags)
{
        int i, l2t_size;
        struct l2t_data *d;

        l2t_size = sc->vres.l2t.size;
        if (l2t_size < 2)       /* At least 1 bucket for IP and 1 for IPv6 */
                return (EINVAL);

        d = malloc(sizeof(*d) + l2t_size * sizeof (struct l2t_entry), M_CXGBE,
            M_ZERO | flags);
        if (!d)
                return (ENOMEM);

        d->l2t_size = l2t_size;
        d->l2t_stopped = false;
        d->rover = d->l2tab;
        atomic_store_rel_int(&d->nfree, l2t_size);
        rw_init(&d->lock, "L2T");

        for (i = 0; i < l2t_size; i++) {
                struct l2t_entry *e = &d->l2tab[i];

                e->idx = i;
                e->state = L2T_STATE_UNUSED;
                mtx_init(&e->lock, "L2T_E", NULL, MTX_DEF);
                STAILQ_INIT(&e->wr_list);
                atomic_store_rel_int(&e->refcnt, 0);
        }

        sc->l2t = d;

        return (0);
}

int
t4_free_l2t(struct adapter *sc)
{
        struct l2t_data *d = sc->l2t;
        int i;

        for (i = 0; i < d->l2t_size; i++)
                mtx_destroy(&d->l2tab[i].lock);
        rw_destroy(&d->lock);
        free(d, M_CXGBE);

        return (0);
}

int
t4_stop_l2t(struct adapter *sc)
{
        struct l2t_data *d = sc->l2t;

        if (d == NULL)
                return (0);
        rw_wlock(&d->lock);
        d->l2t_stopped = true;
        rw_wunlock(&d->lock);

        return (0);
}

int
t4_restart_l2t(struct adapter *sc)
{
        struct l2t_data *d = sc->l2t;

        if (d == NULL)
                return (0);
        rw_wlock(&d->lock);
        d->l2t_stopped = false;
        rw_wunlock(&d->lock);

        return (0);
}

int
do_l2t_write_rpl(struct sge_iq *iq, const struct rss_header *rss,
    struct mbuf *m)
{
        struct adapter *sc = iq->adapter;
        const struct cpl_l2t_write_rpl *rpl = (const void *)(rss + 1);
        const u_int hwidx = GET_TID(rpl) & ~(F_SYNC_WR | V_TID_QID(M_TID_QID));
        const bool sync = GET_TID(rpl) & F_SYNC_WR;

        MPASS(iq->abs_id == G_TID_QID(GET_TID(rpl)));

        if (__predict_false(hwidx < sc->vres.l2t.start) ||
            __predict_false(hwidx >= sc->vres.l2t.start + sc->vres.l2t.size) ||
            __predict_false(rpl->status != CPL_ERR_NONE)) {
                CH_ERR(sc, "%s: hwidx %u, rpl %u, sync %u; L2T st %u, sz %u\n",
                       __func__, hwidx, rpl->status, sync, sc->vres.l2t.start,
                       sc->vres.l2t.size);
                return (EINVAL);
        }

        return (0);
}

static inline unsigned int
vlan_prio(const struct l2t_entry *e)
{
        return e->vlan >> 13;
}

static char
l2e_state(const struct l2t_entry *e)
{
        switch (e->state) {
        case L2T_STATE_VALID: return 'V';  /* valid, fast-path entry */
        case L2T_STATE_STALE: return 'S';  /* needs revalidation, but usable */
        case L2T_STATE_SYNC_WRITE: return 'W';
        case L2T_STATE_RESOLVING: return STAILQ_EMPTY(&e->wr_list) ? 'R' : 'A';
        case L2T_STATE_SWITCHING: return 'X';
        case L2T_STATE_TLS: return 'T';
        default: return 'U';
        }
}

int
sysctl_l2t(SYSCTL_HANDLER_ARGS)
{
        struct adapter *sc = arg1;
        struct l2t_data *l2t = sc->l2t;
        struct l2t_entry *e;
        struct sbuf *sb;
        int rc, i, header = 0;
        char ip[INET6_ADDRSTRLEN];

        if (l2t == NULL)
                return (ENXIO);

        rc = sysctl_wire_old_buffer(req, 0);
        if (rc != 0)
                return (rc);

        sb = sbuf_new_for_sysctl(NULL, NULL, 4096, req);
        if (sb == NULL)
                return (ENOMEM);

        e = &l2t->l2tab[0];
        for (i = 0; i < l2t->l2t_size; i++, e++) {
                mtx_lock(&e->lock);
                if (e->state == L2T_STATE_UNUSED)
                        goto skip;

                if (header == 0) {
                        sbuf_printf(sb, " Idx IP address      "
                            "Ethernet address  VLAN/P LP State Users Port");
                        header = 1;
                }
                if (e->state >= L2T_STATE_SWITCHING)
                        ip[0] = 0;
                else {
                        inet_ntop(e->ipv6 ? AF_INET6 : AF_INET, &e->addr[0],
                            &ip[0], sizeof(ip));
                }

                /*
                 * XXX: IPv6 addresses may not align properly in the output.
                 */
                sbuf_printf(sb, "\n%4u %-15s %02x:%02x:%02x:%02x:%02x:%02x %4d"
                           " %u %2u   %c   %5u %s",
                           e->idx, ip, e->dmac[0], e->dmac[1], e->dmac[2],
                           e->dmac[3], e->dmac[4], e->dmac[5],
                           e->vlan & 0xfff, vlan_prio(e), e->hw_port,
                           l2e_state(e), atomic_load_acq_int(&e->refcnt),
                           e->ifp ? if_name(e->ifp) : "-");
skip:
                mtx_unlock(&e->lock);
        }

        rc = sbuf_finish(sb);
        sbuf_delete(sb);

        return (rc);
}