/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Xen network backend - mac client edition.
 *
 * A driver that sits above an existing GLDv3/Nemo MAC driver and
 * relays packets to/from that driver from/to a guest domain.
 */

#ifdef DEBUG
#define XNBO_DEBUG 1
#endif /* DEBUG */

#include "xnb.h"

#include <sys/sunddi.h>
#include <sys/ddi.h>
#include <sys/modctl.h>
#include <sys/strsubr.h>
#include <sys/mac_client.h>
#include <sys/mac_provider.h>
#include <sys/mac_client_priv.h>
#include <sys/mac.h>
#include <net/if.h>
#include <sys/dlpi.h>
#include <sys/pattr.h>
#include <xen/sys/xenbus_impl.h>
#include <xen/sys/xendev.h>
#include <sys/sdt.h>
#include <sys/note.h>

#ifdef XNBO_DEBUG
boolean_t xnbo_cksum_offload_to_peer = B_TRUE;
boolean_t xnbo_cksum_offload_from_peer = B_TRUE;
#endif /* XNBO_DEBUG */

/* Track multicast addresses. */
typedef struct xmca {
        struct xmca *next;
        ether_addr_t addr;
} xmca_t;

/* State about this device instance. */
typedef struct xnbo {
        mac_handle_t            o_mh;
        mac_client_handle_t     o_mch;
        mac_unicast_handle_t    o_mah;
        mac_promisc_handle_t    o_mphp;
        boolean_t               o_running;
        boolean_t               o_promiscuous;
        uint32_t                o_hcksum_capab;
        xmca_t                  *o_mca;
        char                    o_link_name[LIFNAMSIZ];
        boolean_t               o_need_rx_filter;
        boolean_t               o_need_setphysaddr;
        boolean_t               o_multicast_control;
} xnbo_t;

static void xnbo_close_mac(xnb_t *);
static void i_xnbo_close_mac(xnb_t *, boolean_t);

/*
 * Packets from the peer come here.  We pass them to the mac device.
 */
static void
xnbo_to_mac(xnb_t *xnbp, mblk_t *mp)
{
        xnbo_t *xnbop = xnbp->xnb_flavour_data;

        ASSERT(mp != NULL);

        if (!xnbop->o_running) {
                xnbp->xnb_stat_tx_too_early++;
                goto fail;
        }

        if (mac_tx(xnbop->o_mch, mp, 0,
            MAC_DROP_ON_NO_DESC, NULL) != (mac_tx_cookie_t)NULL) {
                xnbp->xnb_stat_mac_full++;
        }

        return;

fail:
        freemsgchain(mp);
}

/*
 * Process the checksum flags `flags' provided by the peer for the
 * packet `mp'.
 */
static mblk_t *
xnbo_cksum_from_peer(xnb_t *xnbp, mblk_t *mp, uint16_t flags)
{
        xnbo_t *xnbop = xnbp->xnb_flavour_data;

        ASSERT(mp->b_next == NULL);

        if ((flags & NETTXF_csum_blank) != 0) {
                uint32_t capab = xnbop->o_hcksum_capab;

#ifdef XNBO_DEBUG
                if (!xnbo_cksum_offload_from_peer)
                        capab = 0;
#endif /* XNBO_DEBUG */

                /*
                 * The checksum in the packet is blank.  Determine
                 * whether we can do hardware offload and, if so,
                 * update the flags on the mblk according.  If not,
                 * calculate and insert the checksum using software.
                 */
                mp = xnb_process_cksum_flags(xnbp, mp, capab);
        }

        return (mp);
}

/*
 * Calculate the checksum flags to be relayed to the peer for the
 * packet `mp'.
 */
static uint16_t
xnbo_cksum_to_peer(xnb_t *xnbp, mblk_t *mp)
{
        _NOTE(ARGUNUSED(xnbp));
        uint16_t r = 0;
        uint32_t pflags, csum;

#ifdef XNBO_DEBUG
        if (!xnbo_cksum_offload_to_peer)
                return (0);
#endif /* XNBO_DEBUG */

        /*
         * We might also check for HCK_PARTIALCKSUM here and,
         * providing that the partial checksum covers the TCP/UDP
         * payload, return NETRXF_data_validated.
         *
         * It seems that it's probably not worthwhile, as even MAC
         * devices which advertise HCKSUM_INET_PARTIAL in their
         * capabilities tend to use HCK_FULLCKSUM on the receive side
         * - they are actually saying that in the output path the
         * caller must use HCK_PARTIALCKSUM.
         *
         * Then again, if a NIC supports HCK_PARTIALCKSUM in its'
         * output path, the host IP stack will use it. If such packets
         * are destined for the peer (i.e. looped around) we would
         * gain some advantage.
         */

        mac_hcksum_get(mp, NULL, NULL, NULL, &csum, &pflags);

        /*
         * If the MAC driver has asserted that the checksum is
         * good, let the peer know.
         */
        if (((pflags & HCK_FULLCKSUM) != 0) &&
            (((pflags & HCK_FULLCKSUM_OK) != 0) ||
            (csum == 0xffff)))
                r |= NETRXF_data_validated;

        return (r);
}

/*
 * Packets from the mac device come here.  We pass them to the peer.
 */
/*ARGSUSED*/
static void
xnbo_from_mac(void *arg, mac_resource_handle_t mrh, mblk_t *mp,
    boolean_t loopback)
{
        xnb_t *xnbp = arg;

        mp = xnb_copy_to_peer(xnbp, mp);

        if (mp != NULL)
                freemsgchain(mp);
}

/*
 * Packets from the mac device come here. We pass them to the peer if
 * the destination mac address matches or it's a multicast/broadcast
 * address.
 */
static void
xnbo_from_mac_filter(void *arg, mac_resource_handle_t mrh, mblk_t *mp,
    boolean_t loopback)
{
        _NOTE(ARGUNUSED(loopback));
        xnb_t *xnbp = arg;
        xnbo_t *xnbop = xnbp->xnb_flavour_data;
        mblk_t *next, *keep, *keep_head, *free, *free_head;

        keep = keep_head = free = free_head = NULL;

#define ADD(list, bp)                           \
        if (list != NULL)                       \
                list->b_next = bp;              \
        else                                    \
                list##_head = bp;               \
        list = bp;

        for (; mp != NULL; mp = next) {
                mac_header_info_t hdr_info;

                next = mp->b_next;
                mp->b_next = NULL;

                if (mac_header_info(xnbop->o_mh, mp, &hdr_info) != 0) {
                        ADD(free, mp);
                        continue;
                }

                if ((hdr_info.mhi_dsttype == MAC_ADDRTYPE_BROADCAST) ||
                    (hdr_info.mhi_dsttype == MAC_ADDRTYPE_MULTICAST)) {
                        ADD(keep, mp);
                        continue;
                }

                if (bcmp(hdr_info.mhi_daddr, xnbp->xnb_mac_addr,
                    sizeof (xnbp->xnb_mac_addr)) == 0) {
                        ADD(keep, mp);
                        continue;
                }

                ADD(free, mp);
        }
#undef  ADD

        if (keep_head != NULL)
                xnbo_from_mac(xnbp, mrh, keep_head, B_FALSE);

        if (free_head != NULL)
                freemsgchain(free_head);
}

static boolean_t
xnbo_open_mac(xnb_t *xnbp, char *mac)
{
        xnbo_t *xnbop = xnbp->xnb_flavour_data;
        int err;
        const mac_info_t *mi;
        void (*rx_fn)(void *, mac_resource_handle_t, mblk_t *, boolean_t);
        struct ether_addr ea;
        uint_t max_sdu;
        mac_diag_t diag;

        if ((err = mac_open_by_linkname(mac, &xnbop->o_mh)) != 0) {
                cmn_err(CE_WARN, "xnbo_open_mac: "
                    "cannot open mac for link %s (%d)", mac, err);
                return (B_FALSE);
        }
        ASSERT(xnbop->o_mh != NULL);

        mi = mac_info(xnbop->o_mh);
        ASSERT(mi != NULL);

        if (mi->mi_media != DL_ETHER) {
                cmn_err(CE_WARN, "xnbo_open_mac: "
                    "device is not DL_ETHER (%d)", mi->mi_media);
                i_xnbo_close_mac(xnbp, B_TRUE);
                return (B_FALSE);
        }
        if (mi->mi_media != mi->mi_nativemedia) {
                cmn_err(CE_WARN, "xnbo_open_mac: "
                    "device media and native media mismatch (%d != %d)",
                    mi->mi_media, mi->mi_nativemedia);
                i_xnbo_close_mac(xnbp, B_TRUE);
                return (B_FALSE);
        }

        mac_sdu_get(xnbop->o_mh, NULL, &max_sdu);
        if (max_sdu > XNBMAXPKT) {
                cmn_err(CE_WARN, "xnbo_open_mac: mac device SDU too big (%d)",
                    max_sdu);
                i_xnbo_close_mac(xnbp, B_TRUE);
                return (B_FALSE);
        }

        /*
         * MAC_OPEN_FLAGS_MULTI_PRIMARY is relevant when we are migrating a
         * guest on the localhost itself. In this case we would have the MAC
         * client open for the guest being migrated *and* also for the
         * migrated guest (i.e. the former will be active till the migration
         * is complete when the latter will be activated). This flag states
         * that it is OK for mac_unicast_add to add the primary MAC unicast
         * address multiple times.
         */
        if (mac_client_open(xnbop->o_mh, &xnbop->o_mch, NULL,
            MAC_OPEN_FLAGS_USE_DATALINK_NAME |
            MAC_OPEN_FLAGS_MULTI_PRIMARY) != 0) {
                cmn_err(CE_WARN, "xnbo_open_mac: "
                    "error (%d) opening mac client", err);
                i_xnbo_close_mac(xnbp, B_TRUE);
                return (B_FALSE);
        }

        if (xnbop->o_need_rx_filter)
                rx_fn = xnbo_from_mac_filter;
        else
                rx_fn = xnbo_from_mac;

        err = mac_unicast_add_set_rx(xnbop->o_mch, NULL, MAC_UNICAST_PRIMARY,
            &xnbop->o_mah, 0, &diag, xnbop->o_multicast_control ? rx_fn : NULL,
            xnbp);
        if (err != 0) {
                cmn_err(CE_WARN, "xnbo_open_mac: failed to get the primary "
                    "MAC address of %s: %d", mac, err);
                i_xnbo_close_mac(xnbp, B_TRUE);
                return (B_FALSE);
        }
        if (!xnbop->o_multicast_control) {
                err = mac_promisc_add(xnbop->o_mch, MAC_CLIENT_PROMISC_ALL,
                    rx_fn, xnbp, &xnbop->o_mphp, MAC_PROMISC_FLAGS_NO_TX_LOOP |
                    MAC_PROMISC_FLAGS_VLAN_TAG_STRIP);
                if (err != 0) {
                        cmn_err(CE_WARN, "xnbo_open_mac: "
                            "cannot enable promiscuous mode of %s: %d",
                            mac, err);
                        i_xnbo_close_mac(xnbp, B_TRUE);
                        return (B_FALSE);
                }
                xnbop->o_promiscuous = B_TRUE;
        }

        if (xnbop->o_need_setphysaddr) {
                err = mac_unicast_primary_set(xnbop->o_mh, xnbp->xnb_mac_addr);
                /* Warn, but continue on. */
                if (err != 0) {
                        bcopy(xnbp->xnb_mac_addr, ea.ether_addr_octet,
                            ETHERADDRL);
                        cmn_err(CE_WARN, "xnbo_open_mac: "
                            "cannot set MAC address of %s to "
                            "%s: %d", mac, ether_sprintf(&ea), err);
                }
        }

        if (!mac_capab_get(xnbop->o_mh, MAC_CAPAB_HCKSUM,
            &xnbop->o_hcksum_capab))
                xnbop->o_hcksum_capab = 0;

        xnbop->o_running = B_TRUE;

        return (B_TRUE);
}

static void
xnbo_close_mac(xnb_t *xnbp)
{
        i_xnbo_close_mac(xnbp, B_FALSE);
}

static void
i_xnbo_close_mac(xnb_t *xnbp, boolean_t locked)
{
        xnbo_t *xnbop = xnbp->xnb_flavour_data;
        xmca_t *loop;

        ASSERT(!locked || MUTEX_HELD(&xnbp->xnb_state_lock));

        if (xnbop->o_mh == NULL)
                return;

        if (xnbop->o_running)
                xnbop->o_running = B_FALSE;

        if (!locked)
                mutex_enter(&xnbp->xnb_state_lock);
        loop = xnbop->o_mca;
        xnbop->o_mca = NULL;
        if (!locked)
                mutex_exit(&xnbp->xnb_state_lock);

        while (loop != NULL) {
                xmca_t *next = loop->next;

                DTRACE_PROBE3(mcast_remove,
                    (char *), "close",
                    (void *), xnbp,
                    (etheraddr_t *), loop->addr);
                (void) mac_multicast_remove(xnbop->o_mch, loop->addr);
                kmem_free(loop, sizeof (*loop));
                loop = next;
        }

        if (xnbop->o_promiscuous) {
                if (xnbop->o_mphp != NULL) {
                        mac_promisc_remove(xnbop->o_mphp);
                        xnbop->o_mphp = NULL;
                }
                xnbop->o_promiscuous = B_FALSE;
        } else {
                if (xnbop->o_mch != NULL)
                        mac_rx_clear(xnbop->o_mch);
        }

        if (xnbop->o_mah != NULL) {
                (void) mac_unicast_remove(xnbop->o_mch, xnbop->o_mah);
                xnbop->o_mah = NULL;
        }

        if (xnbop->o_mch != NULL) {
                mac_client_close(xnbop->o_mch, 0);
                xnbop->o_mch = NULL;
        }

        mac_close(xnbop->o_mh);
        xnbop->o_mh = NULL;
}

/*
 * Hotplug has completed and we are connected to the peer. We have all
 * the information we need to exchange traffic, so open the MAC device
 * and configure it appropriately.
 */
static boolean_t
xnbo_start_connect(xnb_t *xnbp)
{
        xnbo_t *xnbop = xnbp->xnb_flavour_data;

        return (xnbo_open_mac(xnbp, xnbop->o_link_name));
}

/*
 * The guest has successfully synchronize with this instance. We read
 * the configuration of the guest from xenstore to check whether the
 * guest requests multicast control. If not (the default) we make a
 * note that the MAC device needs to be used in promiscious mode.
 */
static boolean_t
xnbo_peer_connected(xnb_t *xnbp)
{
        char *oename;
        int request;
        xnbo_t *xnbop = xnbp->xnb_flavour_data;

        oename = xvdi_get_oename(xnbp->xnb_devinfo);

        if (xenbus_scanf(XBT_NULL, oename,
            "request-multicast-control", "%d", &request) != 0)
                request = 0;
        xnbop->o_multicast_control = (request > 0);

        return (B_TRUE);
}

/*
 * The guest domain has closed down the inter-domain connection. We
 * close the underlying MAC device.
 */
static void
xnbo_peer_disconnected(xnb_t *xnbp)
{
        xnbo_close_mac(xnbp);
}

/*
 * The hotplug script has completed. We read information from xenstore
 * about our configuration, most notably the name of the MAC device we
 * should use.
 */
static boolean_t
xnbo_hotplug_connected(xnb_t *xnbp)
{
        char *xsname;
        xnbo_t *xnbop = xnbp->xnb_flavour_data;
        int need;

        xsname = xvdi_get_xsname(xnbp->xnb_devinfo);

        if (xenbus_scanf(XBT_NULL, xsname,
            "nic", "%s", xnbop->o_link_name) != 0) {
                cmn_err(CE_WARN, "xnbo_connect: "
                    "cannot read nic name from %s", xsname);
                return (B_FALSE);
        }

        if (xenbus_scanf(XBT_NULL, xsname,
            "SUNW-need-rx-filter", "%d", &need) != 0)
                need = 0;
        xnbop->o_need_rx_filter = (need > 0);

        if (xenbus_scanf(XBT_NULL, xsname,
            "SUNW-need-set-physaddr", "%d", &need) != 0)
                need = 0;
        xnbop->o_need_setphysaddr = (need > 0);

        return (B_TRUE);
}

/*
 * Find the multicast address `addr', return B_TRUE if it is one that
 * we receive. If `remove', remove it from the set received.
 */
static boolean_t
xnbo_mcast_find(xnb_t *xnbp, ether_addr_t *addr, boolean_t remove)
{
        xnbo_t *xnbop = xnbp->xnb_flavour_data;
        xmca_t *prev, *del, *this;

        ASSERT(MUTEX_HELD(&xnbp->xnb_state_lock));
        ASSERT(xnbop->o_promiscuous == B_FALSE);

        prev = del = NULL;

        this = xnbop->o_mca;

        while (this != NULL) {
                if (bcmp(&this->addr, addr, sizeof (this->addr)) == 0) {
                        del = this;
                        if (remove) {
                                if (prev == NULL)
                                        xnbop->o_mca = this->next;
                                else
                                        prev->next = this->next;
                        }
                        break;
                }

                prev = this;
                this = this->next;
        }

        if (del == NULL)
                return (B_FALSE);

        if (remove) {
                DTRACE_PROBE3(mcast_remove,
                    (char *), "remove",
                    (void *), xnbp,
                    (etheraddr_t *), del->addr);
                mac_multicast_remove(xnbop->o_mch, del->addr);
                kmem_free(del, sizeof (*del));
        }

        return (B_TRUE);
}

/*
 * Add the multicast address `addr' to the set received.
 */
static boolean_t
xnbo_mcast_add(xnb_t *xnbp, ether_addr_t *addr)
{
        xnbo_t *xnbop = xnbp->xnb_flavour_data;
        boolean_t r = B_FALSE;

        ASSERT(xnbop->o_promiscuous == B_FALSE);

        mutex_enter(&xnbp->xnb_state_lock);

        if (xnbo_mcast_find(xnbp, addr, B_FALSE)) {
                r = B_TRUE;
        } else if (mac_multicast_add(xnbop->o_mch,
            (const uint8_t *)addr) == 0) {
                xmca_t *mca;

                DTRACE_PROBE3(mcast_add,
                    (char *), "add",
                    (void *), xnbp,
                    (etheraddr_t *), addr);

                mca = kmem_alloc(sizeof (*mca), KM_SLEEP);
                bcopy(addr, &mca->addr, sizeof (mca->addr));

                mca->next = xnbop->o_mca;
                xnbop->o_mca = mca;

                r = B_TRUE;
        }

        mutex_exit(&xnbp->xnb_state_lock);

        return (r);
}

/*
 * Remove the multicast address `addr' from the set received.
 */
static boolean_t
xnbo_mcast_del(xnb_t *xnbp, ether_addr_t *addr)
{
        boolean_t r;

        mutex_enter(&xnbp->xnb_state_lock);
        r = xnbo_mcast_find(xnbp, addr, B_TRUE);
        mutex_exit(&xnbp->xnb_state_lock);

        return (r);
}

static int
xnbo_attach(dev_info_t *dip, ddi_attach_cmd_t cmd)
{
        static xnb_flavour_t flavour = {
                xnbo_to_mac, xnbo_peer_connected, xnbo_peer_disconnected,
                xnbo_hotplug_connected, xnbo_start_connect,
                xnbo_cksum_from_peer, xnbo_cksum_to_peer,
                xnbo_mcast_add, xnbo_mcast_del,
        };
        xnbo_t *xnbop;

        switch (cmd) {
        case DDI_ATTACH:
                break;
        case DDI_RESUME:
                return (DDI_SUCCESS);
        default:
                return (DDI_FAILURE);
        }

        xnbop = kmem_zalloc(sizeof (*xnbop), KM_SLEEP);

        if (xnb_attach(dip, &flavour, xnbop) != DDI_SUCCESS) {
                kmem_free(xnbop, sizeof (*xnbop));
                return (DDI_FAILURE);
        }

        return (DDI_SUCCESS);
}

static int
xnbo_detach(dev_info_t *dip, ddi_detach_cmd_t cmd)
{
        xnb_t *xnbp = ddi_get_driver_private(dip);
        xnbo_t *xnbop = xnbp->xnb_flavour_data;

        switch (cmd) {
        case DDI_DETACH:
                break;
        case DDI_SUSPEND:
                return (DDI_SUCCESS);
        default:
                return (DDI_FAILURE);
        }

        mutex_enter(&xnbp->xnb_tx_lock);
        mutex_enter(&xnbp->xnb_rx_lock);

        if (!xnbp->xnb_detachable || xnbp->xnb_connected ||
            (xnbp->xnb_tx_buf_count > 0)) {
                mutex_exit(&xnbp->xnb_rx_lock);
                mutex_exit(&xnbp->xnb_tx_lock);

                return (DDI_FAILURE);
        }

        mutex_exit(&xnbp->xnb_rx_lock);
        mutex_exit(&xnbp->xnb_tx_lock);

        xnbo_close_mac(xnbp);
        kmem_free(xnbop, sizeof (*xnbop));

        xnb_detach(dip);

        return (DDI_SUCCESS);
}

static struct cb_ops cb_ops = {
        nulldev,                /* open */
        nulldev,                /* close */
        nodev,                  /* strategy */
        nodev,                  /* print */
        nodev,                  /* dump */
        nodev,                  /* read */
        nodev,                  /* write */
        nodev,                  /* ioctl */
        nodev,                  /* devmap */
        nodev,                  /* mmap */
        nodev,                  /* segmap */
        nochpoll,               /* poll */
        ddi_prop_op,            /* cb_prop_op */
        0,                      /* streamtab  */
        D_NEW | D_MP | D_64BIT  /* Driver compatibility flag */
};

static struct dev_ops ops = {
        DEVO_REV,               /* devo_rev */
        0,                      /* devo_refcnt  */
        nulldev,                /* devo_getinfo */
        nulldev,                /* devo_identify */
        nulldev,                /* devo_probe */
        xnbo_attach,            /* devo_attach */
        xnbo_detach,            /* devo_detach */
        nodev,                  /* devo_reset */
        &cb_ops,                /* devo_cb_ops */
        (struct bus_ops *)0,    /* devo_bus_ops */
        NULL,                   /* devo_power */
        ddi_quiesce_not_needed,         /* devo_quiesce */
};

static struct modldrv modldrv = {
        &mod_driverops, "xnbo driver", &ops,
};

static struct modlinkage modlinkage = {
        MODREV_1, &modldrv, NULL
};

int
_init(void)
{
        return (mod_install(&modlinkage));
}

int
_info(struct modinfo *modinfop)
{
        return (mod_info(&modlinkage, modinfop));
}

int
_fini(void)
{
        return (mod_remove(&modlinkage));
}