xen/os/xvdi.c

	xvdi.c revision 551bc2a66868b5cb5be6b70ab9f55515e77a39a9
/*
 * 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 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

/*
 * Xen virtual device driver interfaces
 */

/*
 * todo:
 * + name space clean up:
 *  xvdi_* - public xen interfaces, for use by all leaf drivers
 *  xd_* - public xen data structures
 *  i_xvdi_* - implementation private functions
 *  xendev_* - xendev driver interfaces, both internal and in cb_ops/bus_ops
 * + add mdb dcmds to dump ring status
 * + implement xvdi_xxx to wrap xenbus_xxx read/write function
 * + convert (xendev_ring_t *) into xvdi_ring_handle_t
 */
#include <sys/conf.h>
#include <sys/param.h>
#include <sys/kmem.h>
#include <vm/seg_kmem.h>
#include <sys/debug.h>
#include <sys/modctl.h>
#include <sys/autoconf.h>
#include <sys/ddi_impldefs.h>
#include <sys/ddi_subrdefs.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
#include <sys/sunndi.h>
#include <sys/sunldi.h>
#include <sys/fs/dv_node.h>
#include <sys/avintr.h>
#include <sys/psm.h>
#include <sys/spl.h>
#include <sys/promif.h>
#include <sys/list.h>
#include <sys/bootconf.h>
#include <sys/bootsvcs.h>
#include <sys/bootinfo.h>
#include <sys/note.h>
#ifdef XPV_HVM_DRIVER
#include <sys/xpv_support.h>
#include <sys/hypervisor.h>
#include <public/grant_table.h>
#include <public/xen.h>
#include <public/io/xenbus.h>
#include <public/io/xs_wire.h>
#include <public/event_channel.h>
#include <public/io/xenbus.h>
#else /* XPV_HVM_DRIVER */
#include <sys/hypervisor.h>
#include <sys/xen_mmu.h>
#include <xen/sys/xenbus_impl.h>
#include <sys/evtchn_impl.h>
#endif /* XPV_HVM_DRIVER */
#include <sys/gnttab.h>
#include <xen/sys/xendev.h>
#include <vm/hat_i86.h>
#include <sys/scsi/generic/inquiry.h>
#include <util/sscanf.h>
#include <xen/public/io/xs_wire.h>


static void xvdi_ring_init_sring(xendev_ring_t *);
static void xvdi_ring_init_front_ring(xendev_ring_t *, size_t, size_t);
#ifndef XPV_HVM_DRIVER
static void xvdi_ring_init_back_ring(xendev_ring_t *, size_t, size_t);
#endif
static void xvdi_reinit_ring(dev_info_t *, grant_ref_t *, xendev_ring_t *);

static int i_xvdi_add_watches(dev_info_t *);
static void i_xvdi_rem_watches(dev_info_t *);

static int i_xvdi_add_watch_oestate(dev_info_t *);
static void i_xvdi_rem_watch_oestate(dev_info_t *);
static void i_xvdi_oestate_cb(struct xenbus_device *, XenbusState);
static void i_xvdi_oestate_handler(void *);

static int i_xvdi_add_watch_hpstate(dev_info_t *);
static void i_xvdi_rem_watch_hpstate(dev_info_t *);
static void i_xvdi_hpstate_cb(struct xenbus_watch *, const char **,
    unsigned int);
static void i_xvdi_hpstate_handler(void *);

static int i_xvdi_add_watch_bepath(dev_info_t *);
static void i_xvdi_rem_watch_bepath(dev_info_t *);
static void i_xvdi_bepath_cb(struct xenbus_watch *, const char **,
    unsigned in);

static void xendev_offline_device(void *);

static void i_xvdi_probe_path_cb(struct xenbus_watch *, const char **,
    unsigned int);
static void i_xvdi_probe_path_handler(void *);

typedef struct xd_cfg {
    xendev_devclass_t devclass;
    char *xsdev;
    char *xs_path_fe;
    char *xs_path_be;
    char *node_fe;
    char *node_be;
    char *device_type;
    int xd_ipl;
    int flags;
} i_xd_cfg_t;

#define XD_DOM_ZERO 0x01    /* dom0 only. */
#define XD_DOM_GUEST    0x02    /* Guest domains (i.e. non-dom0). */
#define XD_DOM_IO   0x04    /* IO domains. */

#define XD_DOM_ALL  (XD_DOM_ZERO | XD_DOM_GUEST)

static i_xd_cfg_t xdci[] = {
    { XEN_CONSOLE, NULL, NULL, NULL, "xencons", NULL,
        "console", IPL_CONS, XD_DOM_ALL, },

    { XEN_VNET, "vif", "device/vif", "backend/vif", "xnf", "xnb",
        "network", IPL_VIF, XD_DOM_ALL, },

    { XEN_VBLK, "vbd", "device/vbd", "backend/vbd", "xdf", "xdb",
        "block", IPL_VBD, XD_DOM_ALL, },

    { XEN_XENBUS, NULL, NULL, NULL, "xenbus", NULL,
        NULL, 0, XD_DOM_ALL, },

    { XEN_DOMCAPS, NULL, NULL, NULL, "domcaps", NULL,
        NULL, 0, XD_DOM_ALL, },

    { XEN_BALLOON, NULL, NULL, NULL, "balloon", NULL,
        NULL, 0, XD_DOM_ALL, },

    { XEN_EVTCHN, NULL, NULL, NULL, "evtchn", NULL,
        NULL, 0, XD_DOM_ZERO, },

    { XEN_PRIVCMD, NULL, NULL, NULL, "privcmd", NULL,
        NULL, 0, XD_DOM_ZERO, },
};
#define NXDC    (sizeof (xdci) / sizeof (xdci[0]))

static void i_xvdi_enum_fe(dev_info_t *, i_xd_cfg_t *);
static void i_xvdi_enum_be(dev_info_t *, i_xd_cfg_t *);
static void i_xvdi_enum_worker(dev_info_t *, i_xd_cfg_t *, char *);

/*
 * Xen device channel device access and DMA attributes
 */
static ddi_device_acc_attr_t xendev_dc_accattr = {
    DDI_DEVICE_ATTR_V0, DDI_NEVERSWAP_ACC, DDI_STRICTORDER_ACC
};

static ddi_dma_attr_t xendev_dc_dmaattr = {
    DMA_ATTR_V0,        /* version of this structure */
    0,          /* lowest usable address */
    0xffffffffffffffffULL,  /* highest usable address */
    0x7fffffff,     /* maximum DMAable byte count */
    MMU_PAGESIZE,       /* alignment in bytes */
    0x7ff,          /* bitmap of burst sizes */
    1,          /* minimum transfer */
    0xffffffffU,        /* maximum transfer */
    0xffffffffffffffffULL,  /* maximum segment length */
    1,          /* maximum number of segments */
    1,          /* granularity */
    0,          /* flags (reserved) */
};

static dev_info_t *xendev_dip = NULL;

#define XVDI_DBG_STATE  0x01
#define XVDI_DBG_PROBE  0x02

#ifdef DEBUG
int i_xvdi_debug = 0;

#define XVDI_DPRINTF(flag, format, ...)         \
{                           \
    if (i_xvdi_debug & (flag))          \
        prom_printf((format), __VA_ARGS__); \
}
#else
#define XVDI_DPRINTF(flag, format, ...)
#endif /* DEBUG */

static i_xd_cfg_t *
i_xvdi_devclass2cfg(xendev_devclass_t devclass)
{
    i_xd_cfg_t *xdcp;
    int i;

    for (i = 0, xdcp = xdci; i < NXDC; i++, xdcp++)
        if (xdcp->devclass == devclass)
            return (xdcp);

    return (NULL);
}

int
xvdi_init_dev(dev_info_t *dip)
{
    xendev_devclass_t devcls;
    int vdevnum;
    domid_t domid;
    struct xendev_ppd *pdp;
    i_xd_cfg_t *xdcp;
    boolean_t backend;
    char xsnamebuf[TYPICALMAXPATHLEN];
    char *xsname;

    devcls = ddi_prop_get_int(DDI_DEV_T_ANY, dip,
        DDI_PROP_DONTPASS, "devclass", XEN_INVAL);
    vdevnum = ddi_prop_get_int(DDI_DEV_T_ANY, dip,
        DDI_PROP_DONTPASS, "vdev", -1);
    domid = (domid_t)ddi_prop_get_int(DDI_DEV_T_ANY, dip,
        DDI_PROP_DONTPASS, "domain", DOMID_SELF);

    backend = (domid != DOMID_SELF);
    xdcp = i_xvdi_devclass2cfg(devcls);
    if (xdcp->device_type != NULL)
        (void) ndi_prop_update_string(DDI_DEV_T_NONE, dip,
            "device_type", xdcp->device_type);

    pdp = kmem_zalloc(sizeof (*pdp), KM_SLEEP);
    pdp->xd_domain = domid;
    pdp->xd_vdevnum = vdevnum;
    pdp->xd_devclass = devcls;
    pdp->xd_evtchn = INVALID_EVTCHN;
    mutex_init(&pdp->xd_lk, NULL, MUTEX_DRIVER, NULL);
    ddi_set_parent_data(dip, pdp);

    /*
     * devices that do not need to interact with xenstore
     */
    if (vdevnum == -1) {
        (void) ndi_prop_update_string(DDI_DEV_T_NONE, dip,
            "unit-address", "0");
        if (devcls == XEN_CONSOLE)
            (void) ndi_prop_update_string(DDI_DEV_T_NONE, dip,
                "pm-hardware-state", "needs-suspend-resume");
        return (DDI_SUCCESS);
    }

    /*
     * PV devices that need to probe xenstore
     */

    (void) ndi_prop_update_string(DDI_DEV_T_NONE, dip,
        "pm-hardware-state", "needs-suspend-resume");

    xsname = xsnamebuf;
    if (!backend)
        (void) snprintf(xsnamebuf, sizeof (xsnamebuf),
            "%s/%d", xdcp->xs_path_fe, vdevnum);
    else
        (void) snprintf(xsnamebuf, sizeof (xsnamebuf),
            "%s/%d/%d", xdcp->xs_path_be, domid, vdevnum);
    if ((xenbus_read_driver_state(xsname) >= XenbusStateClosing)) {
        /* Don't try to init a dev that may be closing */
        mutex_destroy(&pdp->xd_lk);
        kmem_free(pdp, sizeof (*pdp));
        ddi_set_parent_data(dip, NULL);
        return (DDI_FAILURE);
    }

    pdp->xd_xsdev.nodename = i_ddi_strdup(xsname, KM_SLEEP);
    pdp->xd_xsdev.devicetype = xdcp->xsdev;
    pdp->xd_xsdev.frontend = (backend ? 0 : 1);
    pdp->xd_xsdev.data = dip;
    pdp->xd_xsdev.otherend_id = (backend ? domid : -1);
    if (i_xvdi_add_watches(dip) != DDI_SUCCESS) {
        cmn_err(CE_WARN, "xvdi_init_dev: "
            "cannot add watches for %s", xsname);
        xvdi_uninit_dev(dip);
        return (DDI_FAILURE);
    }

    /*
     * frontend device will use "unit-addr" as
     * the bus address, which will be set here
     */
    if (!backend) {
        void *prop_str;
        unsigned int prop_len, addr;

        switch (devcls) {
        case XEN_VNET:
            if (xenbus_read(XBT_NULL, xsname, "mac", &prop_str,
                &prop_len) == 0) {
                (void) ndi_prop_update_string(DDI_DEV_T_NONE,
                    dip, "mac", prop_str);
                kmem_free(prop_str, prop_len);
            }
            prop_str = NULL;
            if (xenbus_scanf(XBT_NULL, xsname, "handle", "%u",
                &addr) == 0) {
                char unitaddr[9]; /* hold 32-bit hex */

                (void) snprintf(unitaddr, 9, "%x", addr);
                (void) ndi_prop_update_string(DDI_DEV_T_NONE,
                    dip, "unit-address", unitaddr);
            }
            break;
        case XEN_VBLK:
            if (xenbus_read(XBT_NULL, pdp->xd_xsdev.otherend,
                "dev", &prop_str, &prop_len) == 0) {
                (void) ndi_prop_update_string(DDI_DEV_T_NONE,
                    dip, "unit-address", prop_str);
                kmem_free(prop_str, prop_len);
            }
#ifdef XPV_HVM_DRIVER
            /*
             * The mapping between the 'dev' name and the
             * device ID maintained by Xenstore has to be
             * tracked explicitly in HVM domains.
             */
            prop_str = strrchr(pdp->xd_xsdev.otherend, '/');
            if (prop_str != NULL) {
                prop_str = ((caddr_t)prop_str) + 1;
                (void) ndi_prop_update_string(DDI_DEV_T_NONE,
                    dip, "xenstore-id", prop_str);
            }
#endif /* XPV_HVM_DRIVER */
            break;
        default:
            break;
        }
    }

    return (DDI_SUCCESS);
}

void
xvdi_uninit_dev(dev_info_t *dip)
{
    struct xendev_ppd *pdp = ddi_get_parent_data(dip);

    if (pdp != NULL) {
        /* Remove any registered callbacks. */
        xvdi_remove_event_handler(dip, NULL);

        /* Remove any registered watches. */
        i_xvdi_rem_watches(dip);

        /* tell other end to close */
        if (pdp->xd_xsdev.otherend_id != (domid_t)-1)
            (void) xvdi_switch_state(dip, XBT_NULL,
                XenbusStateClosed);

        if (pdp->xd_xsdev.nodename != NULL)
            kmem_free((char *)(pdp->xd_xsdev.nodename),
                strlen(pdp->xd_xsdev.nodename) + 1);

        ddi_set_parent_data(dip, NULL);

        mutex_destroy(&pdp->xd_lk);
        kmem_free(pdp, sizeof (*pdp));
    }
}

/*
 * Bind the event channel for this device instance.
 * Currently we only support one evtchn per device instance.
 */
int
xvdi_bind_evtchn(dev_info_t *dip, evtchn_port_t evtchn)
{
    struct xendev_ppd *pdp;
    domid_t oeid;
    int r;

    pdp = ddi_get_parent_data(dip);
    ASSERT(pdp != NULL);
    ASSERT(pdp->xd_evtchn == INVALID_EVTCHN);

    mutex_enter(&pdp->xd_lk);
    if (pdp->xd_devclass == XEN_CONSOLE) {
        if (!DOMAIN_IS_INITDOMAIN(xen_info)) {
            pdp->xd_evtchn = xen_info->console.domU.evtchn;
        } else {
            pdp->xd_evtchn = INVALID_EVTCHN;
            mutex_exit(&pdp->xd_lk);
            return (DDI_SUCCESS);
        }
    } else {
        oeid = pdp->xd_xsdev.otherend_id;
        if (oeid == (domid_t)-1) {
            mutex_exit(&pdp->xd_lk);
            return (DDI_FAILURE);
        }

        if ((r = xen_bind_interdomain(oeid, evtchn, &pdp->xd_evtchn))) {
            xvdi_dev_error(dip, r, "bind event channel");
            mutex_exit(&pdp->xd_lk);
            return (DDI_FAILURE);
        }
    }
#ifndef XPV_HVM_DRIVER
    pdp->xd_ispec.intrspec_vec = ec_bind_evtchn_to_irq(pdp->xd_evtchn);
#endif
    mutex_exit(&pdp->xd_lk);

    return (DDI_SUCCESS);
}

/*
 * Allocate an event channel for this device instance.
 * Currently we only support one evtchn per device instance.
 */
int
xvdi_alloc_evtchn(dev_info_t *dip)
{
    struct xendev_ppd *pdp;
    domid_t oeid;
    int rv;

    pdp = ddi_get_parent_data(dip);
    ASSERT(pdp != NULL);
    ASSERT(pdp->xd_evtchn == INVALID_EVTCHN);

    mutex_enter(&pdp->xd_lk);
    if (pdp->xd_devclass == XEN_CONSOLE) {
        if (!DOMAIN_IS_INITDOMAIN(xen_info)) {
            pdp->xd_evtchn = xen_info->console.domU.evtchn;
        } else {
            pdp->xd_evtchn = INVALID_EVTCHN;
            mutex_exit(&pdp->xd_lk);
            return (DDI_SUCCESS);
        }
    } else {
        oeid = pdp->xd_xsdev.otherend_id;
        if (oeid == (domid_t)-1) {
            mutex_exit(&pdp->xd_lk);
            return (DDI_FAILURE);
        }

        if ((rv = xen_alloc_unbound_evtchn(oeid, &pdp->xd_evtchn))) {
            xvdi_dev_error(dip, rv, "bind event channel");
            mutex_exit(&pdp->xd_lk);
            return (DDI_FAILURE);
        }
    }
#ifndef XPV_HVM_DRIVER
    pdp->xd_ispec.intrspec_vec = ec_bind_evtchn_to_irq(pdp->xd_evtchn);
#endif
    mutex_exit(&pdp->xd_lk);

    return (DDI_SUCCESS);
}

/*
 * Unbind the event channel for this device instance.
 * Currently we only support one evtchn per device instance.
 */
void
xvdi_free_evtchn(dev_info_t *dip)
{
    struct xendev_ppd *pdp;

    pdp = ddi_get_parent_data(dip);
    ASSERT(pdp != NULL);

    mutex_enter(&pdp->xd_lk);
    if (pdp->xd_evtchn != INVALID_EVTCHN) {
#ifndef XPV_HVM_DRIVER
        ec_unbind_irq(pdp->xd_ispec.intrspec_vec);
        pdp->xd_ispec.intrspec_vec = 0;
#endif
        pdp->xd_evtchn = INVALID_EVTCHN;
    }
    mutex_exit(&pdp->xd_lk);
}

#ifndef XPV_HVM_DRIVER
/*
 * Map an inter-domain communication ring for a virtual device.
 * This is used by backend drivers.
 */
int
xvdi_map_ring(dev_info_t *dip, size_t nentry, size_t entrysize,
    grant_ref_t gref, xendev_ring_t **ringpp)
{
    domid_t oeid;
    gnttab_map_grant_ref_t mapop;
    gnttab_unmap_grant_ref_t unmapop;
    caddr_t ringva;
    ddi_acc_hdl_t *ap;
    ddi_acc_impl_t *iap;
    xendev_ring_t *ring;
    int err;
    char errstr[] = "mapping in ring buffer";

    ring = kmem_zalloc(sizeof (xendev_ring_t), KM_SLEEP);
    oeid = xvdi_get_oeid(dip);

    /* alloc va in backend dom for ring buffer */
    ringva = vmem_xalloc(heap_arena, PAGESIZE, PAGESIZE,
        0, 0, 0, 0, VM_SLEEP);

    /* map in ring page */
    hat_prepare_mapping(kas.a_hat, ringva);
    mapop.host_addr = (uint64_t)(uintptr_t)ringva;
    mapop.flags = GNTMAP_host_map;
    mapop.ref = gref;
    mapop.dom = oeid;
    err = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &mapop, 1);
    if (err) {
        xvdi_fatal_error(dip, err, errstr);
        goto errout1;
    }

    if (mapop.status != 0) {
        xvdi_fatal_error(dip, err, errstr);
        goto errout2;
    }
    ring->xr_vaddr = ringva;
    ring->xr_grant_hdl = mapop.handle;
    ring->xr_gref = gref;

    /*
     * init an acc handle and associate it w/ this ring
     * this is only for backend drivers. we get the memory by calling
     * vmem_xalloc(), instead of calling any ddi function, so we have
     * to init an acc handle by ourselves
     */
    ring->xr_acc_hdl = impl_acc_hdl_alloc(KM_SLEEP, NULL);
    ap = impl_acc_hdl_get(ring->xr_acc_hdl);
    ap->ah_vers = VERS_ACCHDL;
    ap->ah_dip = dip;
    ap->ah_xfermodes = DDI_DMA_CONSISTENT;
    ap->ah_acc = xendev_dc_accattr;
    iap = (ddi_acc_impl_t *)ap->ah_platform_private;
    iap->ahi_acc_attr |= DDI_ACCATTR_CPU_VADDR;
    impl_acc_hdl_init(ap);
    ap->ah_offset = 0;
    ap->ah_len = (off_t)PAGESIZE;
    ap->ah_addr = ring->xr_vaddr;

    /* init backend ring */
    xvdi_ring_init_back_ring(ring, nentry, entrysize);

    *ringpp = ring;

    return (DDI_SUCCESS);

errout2:
    /* unmap ring page */
    unmapop.host_addr = (uint64_t)(uintptr_t)ringva;
    unmapop.handle = ring->xr_grant_hdl;
    unmapop.dev_bus_addr = NULL;
    (void) HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &unmapop, 1);
    hat_release_mapping(kas.a_hat, ringva);
errout1:
    vmem_xfree(heap_arena, ringva, PAGESIZE);
    kmem_free(ring, sizeof (xendev_ring_t));
    return (DDI_FAILURE);
}

/*
 * Unmap a ring for a virtual device.
 * This is used by backend drivers.
 */
void
xvdi_unmap_ring(xendev_ring_t *ring)
{
    gnttab_unmap_grant_ref_t unmapop;

    ASSERT((ring != NULL) && (ring->xr_vaddr != NULL));

    impl_acc_hdl_free(ring->xr_acc_hdl);
    unmapop.host_addr = (uint64_t)(uintptr_t)ring->xr_vaddr;
    unmapop.handle = ring->xr_grant_hdl;
    unmapop.dev_bus_addr = NULL;
    (void) HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &unmapop, 1);
    hat_release_mapping(kas.a_hat, ring->xr_vaddr);
    vmem_xfree(heap_arena, ring->xr_vaddr, PAGESIZE);
    kmem_free(ring, sizeof (xendev_ring_t));
}
#endif /* XPV_HVM_DRIVER */

/*
 * Re-initialise an inter-domain communications ring for the backend domain.
 * ring will be re-initialized after re-grant succeed
 * ring will be freed if fails to re-grant access to backend domain
 * so, don't keep useful data in the ring
 * used only in frontend driver
 */
static void
xvdi_reinit_ring(dev_info_t *dip, grant_ref_t *gref, xendev_ring_t *ringp)
{
    paddr_t rpaddr;
    maddr_t rmaddr;

    ASSERT((ringp != NULL) && (ringp->xr_paddr != 0));
    rpaddr = ringp->xr_paddr;

    rmaddr = DOMAIN_IS_INITDOMAIN(xen_info) ? rpaddr : pa_to_ma(rpaddr);
    gnttab_grant_foreign_access_ref(ringp->xr_gref, xvdi_get_oeid(dip),
        rmaddr >> PAGESHIFT, 0);
    *gref = ringp->xr_gref;

    /* init frontend ring */
    xvdi_ring_init_sring(ringp);
    xvdi_ring_init_front_ring(ringp, ringp->xr_sring.fr.nr_ents,
        ringp->xr_entry_size);
}

/*
 * allocate Xen inter-domain communications ring for Xen virtual devices
 * used only in frontend driver
 * if *ringpp is not NULL, we'll simply re-init it
 */
int
xvdi_alloc_ring(dev_info_t *dip, size_t nentry, size_t entrysize,
    grant_ref_t *gref, xendev_ring_t **ringpp)
{
    size_t len;
    xendev_ring_t *ring;
    ddi_dma_cookie_t dma_cookie;
    uint_t ncookies;
    grant_ref_t ring_gref;
    domid_t oeid;
    maddr_t rmaddr;

    if (*ringpp) {
        xvdi_reinit_ring(dip, gref, *ringpp);
        return (DDI_SUCCESS);
    }

    *ringpp = ring = kmem_zalloc(sizeof (xendev_ring_t), KM_SLEEP);
    oeid = xvdi_get_oeid(dip);

    /*
     * Allocate page for this ring buffer
     */
    if (ddi_dma_alloc_handle(dip, &xendev_dc_dmaattr, DDI_DMA_SLEEP,
        0, &ring->xr_dma_hdl) != DDI_SUCCESS)
        goto err;

    if (ddi_dma_mem_alloc(ring->xr_dma_hdl, PAGESIZE,
        &xendev_dc_accattr, DDI_DMA_CONSISTENT, DDI_DMA_SLEEP, 0,
        &ring->xr_vaddr, &len, &ring->xr_acc_hdl) != DDI_SUCCESS) {
        ddi_dma_free_handle(&ring->xr_dma_hdl);
        goto err;
    }

    if (ddi_dma_addr_bind_handle(ring->xr_dma_hdl, NULL,
        ring->xr_vaddr, len, DDI_DMA_RDWR | DDI_DMA_CONSISTENT,
        DDI_DMA_SLEEP, 0, &dma_cookie, &ncookies) != DDI_DMA_MAPPED) {
        ddi_dma_mem_free(&ring->xr_acc_hdl);
        ring->xr_vaddr = NULL;
        ddi_dma_free_handle(&ring->xr_dma_hdl);
        goto err;
    }
    ASSERT(ncookies == 1);
    ring->xr_paddr = dma_cookie.dmac_laddress;
    rmaddr = DOMAIN_IS_INITDOMAIN(xen_info) ? ring->xr_paddr :
        pa_to_ma(ring->xr_paddr);

    if ((ring_gref = gnttab_grant_foreign_access(oeid,
        rmaddr >> PAGESHIFT, 0)) == (grant_ref_t)-1) {
        (void) ddi_dma_unbind_handle(ring->xr_dma_hdl);
        ddi_dma_mem_free(&ring->xr_acc_hdl);
        ring->xr_vaddr = NULL;
        ddi_dma_free_handle(&ring->xr_dma_hdl);
        goto err;
    }
    *gref = ring->xr_gref = ring_gref;

    /* init frontend ring */
    xvdi_ring_init_sring(ring);
    xvdi_ring_init_front_ring(ring, nentry, entrysize);

    return (DDI_SUCCESS);

err:
    kmem_free(ring, sizeof (xendev_ring_t));
    return (DDI_FAILURE);
}

/*
 * Release ring buffers allocated for Xen devices
 * used for frontend driver
 */
void
xvdi_free_ring(xendev_ring_t *ring)
{
    ASSERT((ring != NULL) && (ring->xr_vaddr != NULL));

    (void) gnttab_end_foreign_access_ref(ring->xr_gref, 0);
    (void) ddi_dma_unbind_handle(ring->xr_dma_hdl);
    ddi_dma_mem_free(&ring->xr_acc_hdl);
    ddi_dma_free_handle(&ring->xr_dma_hdl);
    kmem_free(ring, sizeof (xendev_ring_t));
}

dev_info_t *
xvdi_create_dev(dev_info_t *parent, xendev_devclass_t devclass,
    domid_t dom, int vdev)
{
    dev_info_t *dip;
    boolean_t backend;
    i_xd_cfg_t *xdcp;
    char xsnamebuf[TYPICALMAXPATHLEN];
    char *type, *node = NULL, *xsname = NULL;
    unsigned int tlen;
    int ret;

    ASSERT(DEVI_BUSY_OWNED(parent));

    backend = (dom != DOMID_SELF);
    xdcp = i_xvdi_devclass2cfg(devclass);
    ASSERT(xdcp != NULL);

    if (vdev != -1) {
        if (!backend) {
            (void) snprintf(xsnamebuf, sizeof (xsnamebuf),
                "%s/%d", xdcp->xs_path_fe, vdev);
            xsname = xsnamebuf;
            node = xdcp->node_fe;
        } else {
            (void) snprintf(xsnamebuf, sizeof (xsnamebuf),
                "%s/%d/%d", xdcp->xs_path_be, dom, vdev);
            xsname = xsnamebuf;
            node = xdcp->node_be;
        }
    } else {
        node = xdcp->node_fe;
    }

    /* Must have a driver to use. */
    if (node == NULL)
        return (NULL);

    /*
     * We need to check the state of this device before we go
     * further, otherwise we'll end up with a dead loop if
     * anything goes wrong.
     */
    if ((xsname != NULL) &&
        (xenbus_read_driver_state(xsname) >= XenbusStateClosing))
        return (NULL);

    ndi_devi_alloc_sleep(parent, node, DEVI_SID_NODEID, &dip);

    /*
     * Driver binding uses the compatible property _before_ the
     * node name, so we set the node name to the 'model' of the
     * device (i.e. 'xnb' or 'xdb') and, if 'type' is present,
     * encode both the model and the type in a compatible property
     * (i.e. 'xnb,netfront' or 'xnb,SUNW_mac').  This allows a
     * driver binding based on the <model,type> pair _before_ a
     * binding based on the node name.
     */
    if ((xsname != NULL) &&
        (xenbus_read(XBT_NULL, xsname, "type", (void *)&type, &tlen)
        == 0)) {
        size_t clen;
        char *c[1];

        clen = strlen(node) + strlen(type) + 2;
        c[0] = kmem_alloc(clen, KM_SLEEP);
        (void) snprintf(c[0], clen, "%s,%s", node, type);

        (void) ndi_prop_update_string_array(DDI_DEV_T_NONE,
            dip, "compatible", (char **)c, 1);

        kmem_free(c[0], clen);
        kmem_free(type, tlen);
    }

    (void) ndi_prop_update_int(DDI_DEV_T_NONE, dip, "devclass", devclass);
    (void) ndi_prop_update_int(DDI_DEV_T_NONE, dip, "domain", dom);
    (void) ndi_prop_update_int(DDI_DEV_T_NONE, dip, "vdev", vdev);

    if (i_ddi_devi_attached(parent))
        ret = ndi_devi_online(dip, 0);
    else
        ret = ndi_devi_bind_driver(dip, 0);
    if (ret != NDI_SUCCESS)
        (void) ndi_devi_offline(dip, NDI_DEVI_REMOVE);

    return (dip);
}

/*
 * xendev_enum_class()
 */
void
xendev_enum_class(dev_info_t *parent, xendev_devclass_t devclass)
{
    i_xd_cfg_t *xdcp;

    xdcp = i_xvdi_devclass2cfg(devclass);
    ASSERT(xdcp != NULL);

    if (xdcp->xsdev == NULL) {
        int circ;

        /*
         * Don't need to probe this kind of device from the
         * store, just create one if it doesn't exist.
         */

        ndi_devi_enter(parent, &circ);
        if (xvdi_find_dev(parent, devclass, DOMID_SELF, -1)
            == NULL)
            (void) xvdi_create_dev(parent, devclass,
                DOMID_SELF, -1);
        ndi_devi_exit(parent, circ);
    } else {
        /*
         * Probe this kind of device from the store, both
         * frontend and backend.
         */

        i_xvdi_enum_fe(parent, xdcp);
        i_xvdi_enum_be(parent, xdcp);
    }
}

/*
 * xendev_enum_all()
 */
void
xendev_enum_all(dev_info_t *parent, boolean_t store_unavailable)
{
    int i;
    i_xd_cfg_t *xdcp;
    boolean_t dom0 = DOMAIN_IS_INITDOMAIN(xen_info);
    boolean_t domU = !dom0;

    for (i = 0, xdcp = xdci; i < NXDC; i++, xdcp++) {

        if (dom0 && !(xdcp->flags & XD_DOM_ZERO))
            continue;

        if (domU && !(xdcp->flags & XD_DOM_GUEST))
            continue;

        /*
         * Dom0 relies on watchpoints to create non-soft
         * devices - don't attempt to iterate over the store.
         */
        if (dom0 && (xdcp->xsdev != NULL))
            continue;

        /*
         * If the store is not yet available, don't attempt to
         * iterate.
         */
        if (store_unavailable && (xdcp->xsdev != NULL))
            continue;

        xendev_enum_class(parent, xdcp->devclass);
    }
}

xendev_devclass_t
xendev_nodename_to_devclass(char *nodename)
{
    int i;
    i_xd_cfg_t *xdcp;

    /*
     * This relies on the convention that variants of a base
     * driver share the same prefix and that there are no drivers
     * which share a common prefix with the name of any other base
     * drivers.
     *
     * So for a base driver 'xnb' (which is the name listed in
     * xdci) the variants all begin with the string 'xnb' (in fact
     * they are 'xnbe', 'xnbo' and 'xnbu') and there are no other
     * base drivers which have the prefix 'xnb'.
     */
    ASSERT(nodename != NULL);
    for (i = 0, xdcp = xdci; i < NXDC; i++, xdcp++) {
        if (((xdcp->node_fe != NULL) &&
            (strncmp(nodename, xdcp->node_fe,
            strlen(xdcp->node_fe)) == 0)) ||
            ((xdcp->node_be != NULL) &&
            (strncmp(nodename, xdcp->node_be,
            strlen(xdcp->node_be)) == 0)))

            return (xdcp->devclass);
    }
    return (XEN_INVAL);
}

int
xendev_devclass_ipl(xendev_devclass_t devclass)
{
    i_xd_cfg_t *xdcp;

    xdcp = i_xvdi_devclass2cfg(devclass);
    ASSERT(xdcp != NULL);

    return (xdcp->xd_ipl);
}

/*
 * Determine if a devinfo instance exists of a particular device
 * class, domain and xenstore virtual device number.
 */
dev_info_t *
xvdi_find_dev(dev_info_t *parent, xendev_devclass_t devclass,
    domid_t dom, int vdev)
{
    dev_info_t *dip;

    ASSERT(DEVI_BUSY_OWNED(parent));

    switch (devclass) {
    case XEN_CONSOLE:
    case XEN_XENBUS:
    case XEN_DOMCAPS:
    case XEN_BALLOON:
    case XEN_EVTCHN:
    case XEN_PRIVCMD:
        /* Console and soft devices have no vdev. */
        vdev = -1;
        break;
    default:
        break;
    }

    for (dip = ddi_get_child(parent); dip != NULL;
        dip = ddi_get_next_sibling(dip)) {
        int *vdevnump, *domidp, *devclsp, vdevnum;
        uint_t ndomid, nvdevnum, ndevcls;
        xendev_devclass_t devcls;
        domid_t domid;
        struct xendev_ppd *pdp = ddi_get_parent_data(dip);

        if (pdp == NULL) {
            if (ddi_prop_lookup_int_array(DDI_DEV_T_ANY, dip,
                DDI_PROP_DONTPASS, "domain", &domidp, &ndomid) !=
                DDI_PROP_SUCCESS)
                continue;
            ASSERT(ndomid == 1);
            domid = (domid_t)*domidp;
            ddi_prop_free(domidp);

            if (ddi_prop_lookup_int_array(DDI_DEV_T_ANY, dip,
                DDI_PROP_DONTPASS, "vdev", &vdevnump, &nvdevnum) !=
                DDI_PROP_SUCCESS)
                continue;
            ASSERT(nvdevnum == 1);
            vdevnum = *vdevnump;
            ddi_prop_free(vdevnump);

            if (ddi_prop_lookup_int_array(DDI_DEV_T_ANY, dip,
                DDI_PROP_DONTPASS, "devclass", &devclsp,
                &ndevcls) != DDI_PROP_SUCCESS)
                continue;
            ASSERT(ndevcls == 1);
            devcls = (xendev_devclass_t)*devclsp;
            ddi_prop_free(devclsp);
        } else {
            domid = pdp->xd_domain;
            vdevnum = pdp->xd_vdevnum;
            devcls = pdp->xd_devclass;
        }

        if ((domid == dom) && (vdevnum == vdev) && (devcls == devclass))
            return (dip);
    }
    return (NULL);
}

int
xvdi_get_evtchn(dev_info_t *xdip)
{
    struct xendev_ppd *pdp = ddi_get_parent_data(xdip);

    ASSERT(pdp != NULL);
    return (pdp->xd_evtchn);
}

int
xvdi_get_vdevnum(dev_info_t *xdip)
{
    struct xendev_ppd *pdp = ddi_get_parent_data(xdip);

    ASSERT(pdp != NULL);
    return (pdp->xd_vdevnum);
}

char *
xvdi_get_xsname(dev_info_t *xdip)
{
    struct xendev_ppd *pdp = ddi_get_parent_data(xdip);

    ASSERT(pdp != NULL);
    return ((char *)(pdp->xd_xsdev.nodename));
}

char *
xvdi_get_oename(dev_info_t *xdip)
{
    struct xendev_ppd *pdp = ddi_get_parent_data(xdip);

    ASSERT(pdp != NULL);
    if (pdp->xd_devclass == XEN_CONSOLE)
        return (NULL);
    return ((char *)(pdp->xd_xsdev.otherend));
}

struct xenbus_device *
xvdi_get_xsd(dev_info_t *xdip)
{
    struct xendev_ppd *pdp = ddi_get_parent_data(xdip);

    ASSERT(pdp != NULL);
    return (&pdp->xd_xsdev);
}

domid_t
xvdi_get_oeid(dev_info_t *xdip)
{
    struct xendev_ppd *pdp = ddi_get_parent_data(xdip);

    ASSERT(pdp != NULL);
    if (pdp->xd_devclass == XEN_CONSOLE)
        return ((domid_t)-1);
    return ((domid_t)(pdp->xd_xsdev.otherend_id));
}

void
xvdi_dev_error(dev_info_t *dip, int errno, char *errstr)
{
    struct xendev_ppd *pdp = ddi_get_parent_data(dip);

    ASSERT(pdp != NULL);
    xenbus_dev_error(&pdp->xd_xsdev, errno, errstr);
}

void
xvdi_fatal_error(dev_info_t *dip, int errno, char *errstr)
{
    struct xendev_ppd *pdp = ddi_get_parent_data(dip);

    ASSERT(pdp != NULL);
    xenbus_dev_fatal(&pdp->xd_xsdev, errno, errstr);
}

static void
i_xvdi_oestate_handler(void *arg)
{
    dev_info_t *dip = arg;
    struct xendev_ppd *pdp = ddi_get_parent_data(dip);
    XenbusState oestate = pdp->xd_xsdev.otherend_state;
    ddi_eventcookie_t evc;

    mutex_enter(&pdp->xd_lk);

    if (pdp->xd_oe_ehid != NULL) {
        /* send notification to driver */
        if (ddi_get_eventcookie(dip, XS_OE_STATE,
            &evc) == DDI_SUCCESS) {
            mutex_exit(&pdp->xd_lk);
            (void) ndi_post_event(dip, dip, evc, &oestate);
            mutex_enter(&pdp->xd_lk);
        }
    } else {
        /*
         * take default action, if driver hasn't registered its
         * event handler yet
         */
        if (oestate == XenbusStateClosing) {
            (void) xvdi_switch_state(dip, XBT_NULL,
                XenbusStateClosed);
        } else if (oestate == XenbusStateClosed) {
            (void) xvdi_switch_state(dip, XBT_NULL,
                XenbusStateClosed);
            (void) xvdi_post_event(dip, XEN_HP_REMOVE);
        }
    }

    mutex_exit(&pdp->xd_lk);

    /*
     * We'll try to remove the devinfo node of this device if the
     * other end has closed.
     */
    if (oestate == XenbusStateClosed)
        (void) ddi_taskq_dispatch(DEVI(ddi_get_parent(dip))->devi_taskq,
            xendev_offline_device, dip, DDI_SLEEP);
}

static void
i_xvdi_hpstate_handler(void *arg)
{
    dev_info_t *dip = (dev_info_t *)arg;
    struct xendev_ppd *pdp = ddi_get_parent_data(dip);
    ddi_eventcookie_t evc;
    char *hp_status;
    unsigned int hpl;

    mutex_enter(&pdp->xd_lk);
    if ((ddi_get_eventcookie(dip, XS_HP_STATE, &evc) == DDI_SUCCESS) &&
        (xenbus_read(XBT_NULL, pdp->xd_hp_watch.node, "",
        (void *)&hp_status, &hpl) == 0)) {

        xendev_hotplug_state_t new_state = Unrecognized;

        if (strcmp(hp_status, "connected") == 0)
            new_state = Connected;

        mutex_exit(&pdp->xd_lk);

        (void) ndi_post_event(dip, dip, evc, &new_state);
        kmem_free(hp_status, hpl);
        return;
    }
    mutex_exit(&pdp->xd_lk);
}

void
xvdi_notify_oe(dev_info_t *dip)
{
    struct xendev_ppd *pdp;

    pdp = ddi_get_parent_data(dip);
    ASSERT(pdp->xd_evtchn != INVALID_EVTCHN);
    ec_notify_via_evtchn(pdp->xd_evtchn);
}

static void
i_xvdi_bepath_cb(struct xenbus_watch *w, const char **vec, unsigned int len)
{
    dev_info_t *dip = (dev_info_t *)w->dev;
    struct xendev_ppd *pdp = ddi_get_parent_data(dip);
    char *be = NULL;
    unsigned int bel;

    ASSERT(len > XS_WATCH_PATH);
    ASSERT(vec[XS_WATCH_PATH] != NULL);

    /*
     * If the backend is not the same as that we already stored,
     * re-set our watch for its' state.
     */
    if ((xenbus_read(XBT_NULL, "", vec[XS_WATCH_PATH], (void *)be, &bel)
        == 0) && (strcmp(be, pdp->xd_xsdev.otherend) != 0))
        (void) i_xvdi_add_watch_oestate(dip);

    if (be != NULL) {
        ASSERT(bel > 0);
        kmem_free(be, bel);
    }
}

static int
i_xvdi_add_watch_oestate(dev_info_t *dip)
{
    struct xendev_ppd *pdp = ddi_get_parent_data(dip);

    ASSERT(pdp != NULL);
    ASSERT(pdp->xd_xsdev.nodename != NULL);
    ASSERT(mutex_owned(&pdp->xd_lk));

    /*
     * Create taskq for delivering other end state change event to
     * this device later.
     *
     * Set nthreads to 1 to make sure that events can be delivered
     * in order.
     *
     * Note: It is _not_ guaranteed that driver can see every
     * xenstore change under the path that it is watching. If two
     * changes happen consecutively in a very short amount of
     * time, it is likely that the driver will see only the last
     * one.
     */
    if (pdp->xd_oe_taskq == NULL)
        if ((pdp->xd_oe_taskq = ddi_taskq_create(dip,
            "xendev_oe_taskq", 1, TASKQ_DEFAULTPRI, 0)) == NULL)
            return (DDI_FAILURE);

    /*
     * Watch for changes to the XenbusState of otherend.
     */
    pdp->xd_xsdev.otherend_state = XenbusStateUnknown;
    pdp->xd_xsdev.otherend_changed = i_xvdi_oestate_cb;

    if (talk_to_otherend(&pdp->xd_xsdev) != 0) {
        i_xvdi_rem_watch_oestate(dip);
        return (DDI_FAILURE);
    }

    return (DDI_SUCCESS);
}

static void
i_xvdi_rem_watch_oestate(dev_info_t *dip)
{
    struct xendev_ppd *pdp;
    struct xenbus_device *dev;

    pdp = ddi_get_parent_data(dip);
    ASSERT(pdp != NULL);
    ASSERT(mutex_owned(&pdp->xd_lk));

    dev = &pdp->xd_xsdev;

    /* Unwatch for changes to XenbusState of otherend */
    if (dev->otherend_watch.node != NULL) {
        mutex_exit(&pdp->xd_lk);
        unregister_xenbus_watch(&dev->otherend_watch);
        mutex_enter(&pdp->xd_lk);
    }

    /* make sure no event handler is running */
    if (pdp->xd_oe_taskq != NULL) {
        mutex_exit(&pdp->xd_lk);
        ddi_taskq_destroy(pdp->xd_oe_taskq);
        mutex_enter(&pdp->xd_lk);
        pdp->xd_oe_taskq = NULL;
    }

    /* clean up */
    dev->otherend_state = XenbusStateUnknown;
    dev->otherend_id = (domid_t)-1;
    if (dev->otherend_watch.node != NULL)
        kmem_free((void *)dev->otherend_watch.node,
            strlen(dev->otherend_watch.node) + 1);
    dev->otherend_watch.node = NULL;
    if (dev->otherend != NULL)
        kmem_free((void *)dev->otherend, strlen(dev->otherend) + 1);
    dev->otherend = NULL;
}

static int
i_xvdi_add_watch_hpstate(dev_info_t *dip)
{
    struct xendev_ppd *pdp = ddi_get_parent_data(dip);

    ASSERT(pdp != NULL);
    ASSERT(pdp->xd_xsdev.frontend == 0);
    ASSERT(mutex_owned(&pdp->xd_lk));

    /*
     * Create taskq for delivering hotplug status change event to
     * this device later.
     *
     * Set nthreads to 1 to make sure that events can be delivered
     * in order.
     *
     * Note: It is _not_ guaranteed that driver can see every
     * hotplug status change under the path that it is
     * watching. If two changes happen consecutively in a very
     * short amount of time, it is likely that the driver only
     * sees the last one.
     */
    if (pdp->xd_hp_taskq == NULL)
        if ((pdp->xd_hp_taskq = ddi_taskq_create(dip,
            "xendev_hp_taskq", 1, TASKQ_DEFAULTPRI, 0)) == NULL)
            return (DDI_FAILURE);

    if (pdp->xd_hp_watch.node == NULL) {
        size_t len;
        char *path;

        ASSERT(pdp->xd_xsdev.nodename != NULL);

        len = strlen(pdp->xd_xsdev.nodename) +
            strlen("/hotplug-status") + 1;
        path = kmem_alloc(len, KM_SLEEP);
        (void) snprintf(path, len, "%s/hotplug-status",
            pdp->xd_xsdev.nodename);

        pdp->xd_hp_watch.node = path;
        pdp->xd_hp_watch.callback = i_xvdi_hpstate_cb;
        pdp->xd_hp_watch.dev = (struct xenbus_device *)dip; /* yuck! */
        if (register_xenbus_watch(&pdp->xd_hp_watch) != 0) {
            i_xvdi_rem_watch_hpstate(dip);
            return (DDI_FAILURE);
        }
    }

    return (DDI_SUCCESS);
}

static void
i_xvdi_rem_watch_hpstate(dev_info_t *dip)
{
    struct xendev_ppd *pdp;
    pdp = ddi_get_parent_data(dip);

    ASSERT(pdp != NULL);
    ASSERT(pdp->xd_xsdev.frontend == 0);
    ASSERT(mutex_owned(&pdp->xd_lk));

    /* Unwatch for changes to "hotplug-status" node for backend device. */
    if (pdp->xd_hp_watch.node != NULL) {
        mutex_exit(&pdp->xd_lk);
        unregister_xenbus_watch(&pdp->xd_hp_watch);
        mutex_enter(&pdp->xd_lk);
    }

    /* Make sure no event handler is running. */
    if (pdp->xd_hp_taskq != NULL) {
        mutex_exit(&pdp->xd_lk);
        ddi_taskq_destroy(pdp->xd_hp_taskq);
        mutex_enter(&pdp->xd_lk);
        pdp->xd_hp_taskq = NULL;
    }

    /* Clean up. */
    if (pdp->xd_hp_watch.node != NULL) {
        kmem_free((void *)pdp->xd_hp_watch.node,
            strlen(pdp->xd_hp_watch.node) + 1);
        pdp->xd_hp_watch.node = NULL;
    }
}

static int
i_xvdi_add_watches(dev_info_t *dip)
{
    struct xendev_ppd *pdp = ddi_get_parent_data(dip);

    ASSERT(pdp != NULL);

    mutex_enter(&pdp->xd_lk);

    if (i_xvdi_add_watch_oestate(dip) != DDI_SUCCESS) {
        mutex_exit(&pdp->xd_lk);
        return (DDI_FAILURE);
    }

    if (pdp->xd_xsdev.frontend == 1) {
        /*
         * Frontend devices must watch for the backend path
         * changing.
         */
        if (i_xvdi_add_watch_bepath(dip) != DDI_SUCCESS)
            goto unwatch_and_fail;
    } else {
        /*
         * Backend devices must watch for hotplug events.
         */
        if (i_xvdi_add_watch_hpstate(dip) != DDI_SUCCESS)
            goto unwatch_and_fail;
    }

    mutex_exit(&pdp->xd_lk);

    return (DDI_SUCCESS);

unwatch_and_fail:
    i_xvdi_rem_watch_oestate(dip);
    mutex_exit(&pdp->xd_lk);

    return (DDI_FAILURE);
}

static void
i_xvdi_rem_watches(dev_info_t *dip)
{
    struct xendev_ppd *pdp = ddi_get_parent_data(dip);

    ASSERT(pdp != NULL);

    mutex_enter(&pdp->xd_lk);

    i_xvdi_rem_watch_oestate(dip);

    if (pdp->xd_xsdev.frontend == 1)
        i_xvdi_rem_watch_bepath(dip);
    else
        i_xvdi_rem_watch_hpstate(dip);

    mutex_exit(&pdp->xd_lk);
}

static int
i_xvdi_add_watch_bepath(dev_info_t *dip)
{
    struct xendev_ppd *pdp = ddi_get_parent_data(dip);

    ASSERT(pdp != NULL);
    ASSERT(pdp->xd_xsdev.frontend == 1);

    /*
     * Frontend devices need to watch for the backend path changing.
     */
    if (pdp->xd_bepath_watch.node == NULL) {
        size_t len;
        char *path;

        ASSERT(pdp->xd_xsdev.nodename != NULL);

        len = strlen(pdp->xd_xsdev.nodename) + strlen("/backend") + 1;
        path = kmem_alloc(len, KM_SLEEP);
        (void) snprintf(path, len, "%s/backend",
            pdp->xd_xsdev.nodename);

        pdp->xd_bepath_watch.node = path;
        pdp->xd_bepath_watch.callback = i_xvdi_bepath_cb;
        pdp->xd_bepath_watch.dev = (struct xenbus_device *)dip;
        if (register_xenbus_watch(&pdp->xd_bepath_watch) != 0) {
            kmem_free(path, len);
            pdp->xd_bepath_watch.node = NULL;
            return (DDI_FAILURE);
        }
    }

    return (DDI_SUCCESS);
}

static void
i_xvdi_rem_watch_bepath(dev_info_t *dip)
{
    struct xendev_ppd *pdp = ddi_get_parent_data(dip);

    ASSERT(pdp != NULL);
    ASSERT(pdp->xd_xsdev.frontend == 1);
    ASSERT(mutex_owned(&pdp->xd_lk));

    if (pdp->xd_bepath_watch.node != NULL) {
        mutex_exit(&pdp->xd_lk);
        unregister_xenbus_watch(&pdp->xd_bepath_watch);
        mutex_enter(&pdp->xd_lk);

        kmem_free((void *)(pdp->xd_bepath_watch.node),
            strlen(pdp->xd_bepath_watch.node) + 1);
        pdp->xd_bepath_watch.node = NULL;
    }
}

int
xvdi_switch_state(dev_info_t *dip, xenbus_transaction_t xbt,
    XenbusState newState)
{
    int rv;
    struct xendev_ppd *pdp;

    pdp = ddi_get_parent_data(dip);
    ASSERT(pdp != NULL);

    XVDI_DPRINTF(XVDI_DBG_STATE,
        "xvdi_switch_state: dip 0x%p moves to %d",
        (void *)dip, newState);

    rv = xenbus_switch_state(&pdp->xd_xsdev, xbt, newState);
    if (rv > 0)
        cmn_err(CE_WARN, "xvdi_switch_state: change state failed");

    return (rv);
}

/*
 * Notify hotplug script running in userland
 */
int
xvdi_post_event(dev_info_t *dip, xendev_hotplug_cmd_t hpc)
{
    struct xendev_ppd *pdp;
    nvlist_t *attr_list = NULL;
    i_xd_cfg_t *xdcp;
    sysevent_id_t eid;
    int err;
    char devname[256]; /* XXPV dme: ? */

    pdp = ddi_get_parent_data(dip);
    ASSERT(pdp != NULL);

    xdcp = i_xvdi_devclass2cfg(pdp->xd_devclass);
    ASSERT(xdcp != NULL);

    (void) snprintf(devname, sizeof (devname) - 1, "%s%d",
        ddi_driver_name(dip),  ddi_get_instance(dip));

    err = nvlist_alloc(&attr_list, NV_UNIQUE_NAME, KM_NOSLEEP);
    if (err != DDI_SUCCESS)
        goto failure;

    err = nvlist_add_int32(attr_list, "domain", pdp->xd_domain);
    if (err != DDI_SUCCESS)
        goto failure;
    err = nvlist_add_int32(attr_list, "vdev", pdp->xd_vdevnum);
    if (err != DDI_SUCCESS)
        goto failure;
    err = nvlist_add_string(attr_list, "devclass", xdcp->xsdev);
    if (err != DDI_SUCCESS)
        goto failure;
    err = nvlist_add_string(attr_list, "device", devname);
    if (err != DDI_SUCCESS)
        goto failure;
    err = nvlist_add_string(attr_list, "fob",
        ((pdp->xd_xsdev.frontend == 1) ? "frontend" : "backend"));
    if (err != DDI_SUCCESS)
        goto failure;

    switch (hpc) {
    case XEN_HP_ADD:
        err = ddi_log_sysevent(dip, DDI_VENDOR_SUNW, "EC_xendev",
            "add", attr_list, &eid, DDI_NOSLEEP);
        break;
    case XEN_HP_REMOVE:
        err = ddi_log_sysevent(dip, DDI_VENDOR_SUNW, "EC_xendev",
            "remove", attr_list, &eid, DDI_NOSLEEP);
        break;
    default:
        err = DDI_FAILURE;
        goto failure;
    }

failure:
    if (attr_list != NULL)
        nvlist_free(attr_list);

    return (err);
}

/* ARGSUSED */
static void
i_xvdi_probe_path_cb(struct xenbus_watch *w, const char **vec,
    unsigned int len)
{
    char *path;

    if (xendev_dip == NULL)
        xendev_dip = ddi_find_devinfo("xpvd", -1, 0);

    path = i_ddi_strdup((char *)vec[XS_WATCH_PATH], KM_SLEEP);

    (void) ddi_taskq_dispatch(DEVI(xendev_dip)->devi_taskq,
        i_xvdi_probe_path_handler, (void *)path, DDI_SLEEP);
}

static void
i_xvdi_watch_device(char *path)
{
    struct xenbus_watch *w;

    ASSERT(path != NULL);

    w = kmem_zalloc(sizeof (*w), KM_SLEEP);
    w->node = path;
    w->callback = &i_xvdi_probe_path_cb;
    w->dev = NULL;

    if (register_xenbus_watch(w) != 0) {
        cmn_err(CE_WARN, "i_xvdi_watch_device: "
            "cannot set watch on %s", path);
        kmem_free(w, sizeof (*w));
        return;
    }
}

void
xvdi_watch_devices(int newstate)
{
    int devclass;

    /*
     * Watch for devices being created in the store.
     */
    if (newstate == XENSTORE_DOWN)
        return;
    for (devclass = 0; devclass < NXDC; devclass++) {
        if (xdci[devclass].xs_path_fe != NULL)
            i_xvdi_watch_device(xdci[devclass].xs_path_fe);
        if (xdci[devclass].xs_path_be != NULL)
            i_xvdi_watch_device(xdci[devclass].xs_path_be);
    }
}

/*
 * Iterate over the store looking for backend devices to create.
 */
static void
i_xvdi_enum_be(dev_info_t *parent, i_xd_cfg_t *xdcp)
{
    char **domains;
    unsigned int ndomains;
    int ldomains, i;

    if ((domains = xenbus_directory(XBT_NULL, xdcp->xs_path_be, "",
        &ndomains)) == NULL)
        return;

    for (i = 0, ldomains = 0; i < ndomains; i++) {
        ldomains += strlen(domains[i]) + 1 + sizeof (char *);

        i_xvdi_enum_worker(parent, xdcp, domains[i]);
    }
    kmem_free(domains, ldomains);
}

/*
 * Iterate over the store looking for frontend devices to create.
 */
static void
i_xvdi_enum_fe(dev_info_t *parent, i_xd_cfg_t *xdcp)
{
    i_xvdi_enum_worker(parent, xdcp, NULL);
}

static void
i_xvdi_enum_worker(dev_info_t *parent, i_xd_cfg_t *xdcp,
    char *domain)
{
    char *path, *domain_path, *ep;
    char **devices;
    unsigned int ndevices;
    int ldevices, j, circ;
    domid_t dom;

    if (domain == NULL) {
        dom = DOMID_SELF;
        path = xdcp->xs_path_fe;
        domain_path = "";
    } else {
        (void) ddi_strtol(domain, &ep, 0, (long *)&dom);
        path = xdcp->xs_path_be;
        domain_path = domain;
    }

    if ((devices = xenbus_directory(XBT_NULL, path, domain_path,
        &ndevices)) == NULL)
        return;

    for (j = 0, ldevices = 0; j < ndevices; j++) {
        int vdev;

        ldevices += strlen(devices[j]) + 1 + sizeof (char *);
        (void) ddi_strtol(devices[j], &ep, 0, (long *)&vdev);

        ndi_devi_enter(parent, &circ);

        if (xvdi_find_dev(parent, xdcp->devclass, dom, vdev)
            == NULL)
            (void) xvdi_create_dev(parent, xdcp->devclass,
                dom, vdev);

        ndi_devi_exit(parent, circ);
    }
    kmem_free(devices, ldevices);
}

/*
 * Leaf drivers should call this in their detach() routine during suspend.
 */
void
xvdi_suspend(dev_info_t *dip)
{
    i_xvdi_rem_watches(dip);
}

/*
 * Leaf drivers should call this in their attach() routine during resume.
 */
int
xvdi_resume(dev_info_t *dip)
{
    return (i_xvdi_add_watches(dip));
}

/*
 * Add event handler for the leaf driver
 * to handle event triggered by the change in xenstore
 */
int
xvdi_add_event_handler(dev_info_t *dip, char *name,
    void (*evthandler)(dev_info_t *, ddi_eventcookie_t, void *, void *))
{
    ddi_eventcookie_t ecv;
    struct xendev_ppd *pdp = ddi_get_parent_data(dip);
    ddi_callback_id_t *cbid;

    ASSERT(pdp != NULL);

    mutex_enter(&pdp->xd_lk);

    if (strcmp(name, XS_OE_STATE) == 0) {
        ASSERT(pdp->xd_xsdev.otherend != NULL);

        cbid = &pdp->xd_oe_ehid;
    } else if (strcmp(name, XS_HP_STATE) == 0) {
        if (pdp->xd_xsdev.frontend == 1) {
            mutex_exit(&pdp->xd_lk);
            return (DDI_FAILURE);
        }

        ASSERT(pdp->xd_hp_watch.node != NULL);

        cbid = &pdp->xd_hp_ehid;
    } else {
        /* Unsupported watch. */
        mutex_exit(&pdp->xd_lk);
        return (DDI_FAILURE);
    }

    /*
     * No event handler provided, take default action to handle
     * event.
     */
    if (evthandler == NULL) {
        mutex_exit(&pdp->xd_lk);
        return (DDI_SUCCESS);
    }

    ASSERT(*cbid == NULL);

    if (ddi_get_eventcookie(dip, name, &ecv) != DDI_SUCCESS) {
        cmn_err(CE_WARN, "failed to find %s cookie for %s@%s",
            name, ddi_get_name(dip), ddi_get_name_addr(dip));
        mutex_exit(&pdp->xd_lk);
        return (DDI_FAILURE);
    }
    if (ddi_add_event_handler(dip, ecv, evthandler, NULL, cbid)
        != DDI_SUCCESS) {
        cmn_err(CE_WARN, "failed to add %s event handler for %s@%s",
            name, ddi_get_name(dip), ddi_get_name_addr(dip));
        *cbid = NULL;
        mutex_exit(&pdp->xd_lk);
        return (DDI_FAILURE);
    }

    mutex_exit(&pdp->xd_lk);

    return (DDI_SUCCESS);
}

/*
 * Remove event handler for the leaf driver and unwatch xenstore
 * so, driver will not be notified when xenstore entry changed later
 */
void
xvdi_remove_event_handler(dev_info_t *dip, char *name)
{
    struct xendev_ppd *pdp;
    boolean_t rem_oe = B_FALSE, rem_hp = B_FALSE;
    ddi_callback_id_t oeid = NULL, hpid = NULL;

    pdp = ddi_get_parent_data(dip);
    ASSERT(pdp != NULL);

    if (name == NULL) {
        rem_oe = B_TRUE;
        rem_hp = B_TRUE;
    } else if (strcmp(name, XS_OE_STATE) == 0) {
        rem_oe = B_TRUE;
    } else if (strcmp(name, XS_HP_STATE) == 0) {
        rem_hp = B_TRUE;
    } else {
        cmn_err(CE_WARN, "event %s not supported, cannot remove", name);
        return;
    }

    mutex_enter(&pdp->xd_lk);

    if (rem_oe && (pdp->xd_oe_ehid != NULL)) {
        oeid = pdp->xd_oe_ehid;
        pdp->xd_oe_ehid = NULL;
    }

    if (rem_hp && (pdp->xd_hp_ehid != NULL)) {
        hpid = pdp->xd_hp_ehid;
        pdp->xd_hp_ehid = NULL;
    }

    mutex_exit(&pdp->xd_lk);

    if (oeid != NULL)
        (void) ddi_remove_event_handler(oeid);
    if (hpid != NULL)
        (void) ddi_remove_event_handler(hpid);
}


/*
 * common ring interfaces
 */

#define FRONT_RING(_ringp)  (&(_ringp)->xr_sring.fr)
#define BACK_RING(_ringp)   (&(_ringp)->xr_sring.br)
#define GET_RING_SIZE(_ringp)   RING_SIZE(FRONT_RING(ringp))
#define GET_RING_ENTRY_FE(_ringp, _idx)     \
    (FRONT_RING(_ringp)->sring->ring +  \
    (_ringp)->xr_entry_size * ((_idx) & (GET_RING_SIZE(_ringp) - 1)))
#define GET_RING_ENTRY_BE(_ringp, _idx)     \
    (BACK_RING(_ringp)->sring->ring +   \
    (_ringp)->xr_entry_size * ((_idx) & (GET_RING_SIZE(_ringp) - 1)))

unsigned int
xvdi_ring_avail_slots(xendev_ring_t *ringp)
{
    comif_ring_fe_t *frp;
    comif_ring_be_t *brp;

    if (ringp->xr_frontend) {
        frp = FRONT_RING(ringp);
        return (GET_RING_SIZE(ringp) -
            (frp->req_prod_pvt - frp->rsp_cons));
    } else {
        brp = BACK_RING(ringp);
        return (GET_RING_SIZE(ringp) -
            (brp->rsp_prod_pvt - brp->req_cons));
    }
}

int
xvdi_ring_has_unconsumed_requests(xendev_ring_t *ringp)
{
    comif_ring_be_t *brp;

    ASSERT(!ringp->xr_frontend);
    brp = BACK_RING(ringp);
    return ((brp->req_cons !=
        ddi_get32(ringp->xr_acc_hdl, &brp->sring->req_prod)) &&
        ((brp->req_cons - brp->rsp_prod_pvt) != RING_SIZE(brp)));
}

int
xvdi_ring_has_incomp_request(xendev_ring_t *ringp)
{
    comif_ring_fe_t *frp;

    ASSERT(ringp->xr_frontend);
    frp = FRONT_RING(ringp);
    return (frp->req_prod_pvt !=
        ddi_get32(ringp->xr_acc_hdl, &frp->sring->rsp_prod));
}

int
xvdi_ring_has_unconsumed_responses(xendev_ring_t *ringp)
{
    comif_ring_fe_t *frp;

    ASSERT(ringp->xr_frontend);
    frp = FRONT_RING(ringp);
    return (frp->rsp_cons !=
        ddi_get32(ringp->xr_acc_hdl, &frp->sring->rsp_prod));
}

/* NOTE: req_event will be increased as needed */
void *
xvdi_ring_get_request(xendev_ring_t *ringp)
{
    comif_ring_fe_t *frp;
    comif_ring_be_t *brp;

    if (ringp->xr_frontend) {
        /* for frontend ring */
        frp = FRONT_RING(ringp);
        if (!RING_FULL(frp))
            return (GET_RING_ENTRY_FE(ringp, frp->req_prod_pvt++));
        else
            return (NULL);
    } else {
        /* for backend ring */
        brp = BACK_RING(ringp);
        /* RING_FINAL_CHECK_FOR_REQUESTS() */
        if (xvdi_ring_has_unconsumed_requests(ringp))
            return (GET_RING_ENTRY_BE(ringp, brp->req_cons++));
        else {
            ddi_put32(ringp->xr_acc_hdl, &brp->sring->req_event,
                brp->req_cons + 1);
            membar_enter();
            if (xvdi_ring_has_unconsumed_requests(ringp))
                return (GET_RING_ENTRY_BE(ringp,
                    brp->req_cons++));
            else
                return (NULL);
        }
    }
}

int
xvdi_ring_push_request(xendev_ring_t *ringp)
{
    RING_IDX old, new, reqevt;
    comif_ring_fe_t *frp;

    /* only frontend should be able to push request */
    ASSERT(ringp->xr_frontend);

    /* RING_PUSH_REQUEST_AND_CHECK_NOTIFY() */
    frp = FRONT_RING(ringp);
    old = ddi_get32(ringp->xr_acc_hdl, &frp->sring->req_prod);
    new = frp->req_prod_pvt;
    ddi_put32(ringp->xr_acc_hdl, &frp->sring->req_prod, new);
    membar_enter();
    reqevt = ddi_get32(ringp->xr_acc_hdl, &frp->sring->req_event);
    return ((RING_IDX)(new - reqevt) < (RING_IDX)(new - old));
}

/* NOTE: rsp_event will be increased as needed */
void *
xvdi_ring_get_response(xendev_ring_t *ringp)
{
    comif_ring_fe_t *frp;
    comif_ring_be_t *brp;

    if (!ringp->xr_frontend) {
        /* for backend ring */
        brp = BACK_RING(ringp);
        return (GET_RING_ENTRY_BE(ringp, brp->rsp_prod_pvt++));
    } else {
        /* for frontend ring */
        frp = FRONT_RING(ringp);
        /* RING_FINAL_CHECK_FOR_RESPONSES() */
        if (xvdi_ring_has_unconsumed_responses(ringp))
            return (GET_RING_ENTRY_FE(ringp, frp->rsp_cons++));
        else {
            ddi_put32(ringp->xr_acc_hdl, &frp->sring->rsp_event,
                frp->rsp_cons + 1);
            membar_enter();
            if (xvdi_ring_has_unconsumed_responses(ringp))
                return (GET_RING_ENTRY_FE(ringp,
                    frp->rsp_cons++));
            else
                return (NULL);
        }
    }
}

int
xvdi_ring_push_response(xendev_ring_t *ringp)
{
    RING_IDX old, new, rspevt;
    comif_ring_be_t *brp;

    /* only backend should be able to push response */
    ASSERT(!ringp->xr_frontend);

    /* RING_PUSH_RESPONSE_AND_CHECK_NOTIFY() */
    brp = BACK_RING(ringp);
    old = ddi_get32(ringp->xr_acc_hdl, &brp->sring->rsp_prod);
    new = brp->rsp_prod_pvt;
    ddi_put32(ringp->xr_acc_hdl, &brp->sring->rsp_prod, new);
    membar_enter();
    rspevt = ddi_get32(ringp->xr_acc_hdl, &brp->sring->rsp_event);
    return ((RING_IDX)(new - rspevt) < (RING_IDX)(new - old));
}

static void
xvdi_ring_init_sring(xendev_ring_t *ringp)
{
    ddi_acc_handle_t acchdl;
    comif_sring_t *xsrp;
    int i;

    xsrp = (comif_sring_t *)ringp->xr_vaddr;
    acchdl = ringp->xr_acc_hdl;

    /* shared ring initialization */
    ddi_put32(acchdl, &xsrp->req_prod, 0);
    ddi_put32(acchdl, &xsrp->rsp_prod, 0);
    ddi_put32(acchdl, &xsrp->req_event, 1);
    ddi_put32(acchdl, &xsrp->rsp_event, 1);
    for (i = 0; i < sizeof (xsrp->pad); i++)
        ddi_put8(acchdl, xsrp->pad + i, 0);
}

static void
xvdi_ring_init_front_ring(xendev_ring_t *ringp, size_t nentry, size_t entrysize)
{
    comif_ring_fe_t *xfrp;

    xfrp = &ringp->xr_sring.fr;
    xfrp->req_prod_pvt = 0;
    xfrp->rsp_cons = 0;
    xfrp->nr_ents = nentry;
    xfrp->sring = (comif_sring_t *)ringp->xr_vaddr;

    ringp->xr_frontend = 1;
    ringp->xr_entry_size = entrysize;
}

#ifndef XPV_HVM_DRIVER
static void
xvdi_ring_init_back_ring(xendev_ring_t *ringp, size_t nentry, size_t entrysize)
{
    comif_ring_be_t *xbrp;

    xbrp = &ringp->xr_sring.br;
    xbrp->rsp_prod_pvt = 0;
    xbrp->req_cons = 0;
    xbrp->nr_ents = nentry;
    xbrp->sring = (comif_sring_t *)ringp->xr_vaddr;

    ringp->xr_frontend = 0;
    ringp->xr_entry_size = entrysize;
}
#endif /* XPV_HVM_DRIVER */

static void
xendev_offline_device(void *arg)
{
    dev_info_t *dip = (dev_info_t *)arg;
    char devname[MAXNAMELEN] = {0};

    /*
     * This is currently the only chance to delete a devinfo node, which
     * is _not_ always successful.
     */
    (void) ddi_deviname(dip, devname);
    (void) devfs_clean(ddi_get_parent(dip), devname + 1, DV_CLEAN_FORCE);
    (void) ndi_devi_offline(dip, NDI_DEVI_REMOVE);
}

static void
i_xvdi_oestate_cb(struct xenbus_device *dev, XenbusState oestate)
{
    dev_info_t *dip = (dev_info_t *)dev->data;
    struct xendev_ppd *pdp = ddi_get_parent_data(dip);

    /*
     * Don't trigger two consecutive ndi_devi_offline on the same
     * dip.
     */
    if ((oestate == XenbusStateClosed) &&
        (dev->otherend_state == XenbusStateClosed))
        return;

    dev->otherend_state = oestate;
    (void) ddi_taskq_dispatch(pdp->xd_oe_taskq,
        i_xvdi_oestate_handler, (void *)dip, DDI_SLEEP);
}

/*ARGSUSED*/
static void
i_xvdi_hpstate_cb(struct xenbus_watch *w, const char **vec,
    unsigned int len)
{
    dev_info_t *dip = (dev_info_t *)w->dev;
    struct xendev_ppd *pdp = ddi_get_parent_data(dip);

    (void) ddi_taskq_dispatch(pdp->xd_hp_taskq,
        i_xvdi_hpstate_handler, (void *)dip, DDI_SLEEP);
}

static void
i_xvdi_probe_path_handler(void *arg)
{
    dev_info_t *parent;
    char *path = arg, *p = NULL;
    int i, vdev, circ;
    i_xd_cfg_t *xdcp;
    boolean_t frontend;
    domid_t dom;

    for (i = 0, xdcp = &xdci[0]; i < NXDC; i++, xdcp++) {

        if ((xdcp->xs_path_fe != NULL) &&
            (strncmp(path, xdcp->xs_path_fe, strlen(xdcp->xs_path_fe))
            == 0)) {

            frontend = B_TRUE;
            p = path + strlen(xdcp->xs_path_fe);
            break;
        }

        if ((xdcp->xs_path_be != NULL) &&
            (strncmp(path, xdcp->xs_path_be, strlen(xdcp->xs_path_be))
            == 0)) {

            frontend = B_FALSE;
            p = path + strlen(xdcp->xs_path_be);
            break;
        }

    }

    if (p == NULL) {
        cmn_err(CE_WARN, "i_xvdi_probe_path_handler: "
            "unexpected path prefix in %s", path);
        goto done;
    }

    if (frontend) {
        dom = DOMID_SELF;
        if (sscanf(p, "/%d/", &vdev) != 1) {
            XVDI_DPRINTF(XVDI_DBG_PROBE,
                "i_xvdi_probe_path_handler: "
                "cannot parse frontend path %s",
                path);
            goto done;
        }
    } else {
        if (sscanf(p, "/%d/%d/", &dom, &vdev) != 2) {
            XVDI_DPRINTF(XVDI_DBG_PROBE,
                "i_xvdi_probe_path_handler: "
                "cannot parse backend path %s",
                path);
            goto done;
        }
    }

    parent = xendev_dip;
    ASSERT(parent != NULL);

    ndi_devi_enter(parent, &circ);

    if (xvdi_find_dev(parent, xdcp->devclass, dom, vdev) == NULL) {
        XVDI_DPRINTF(XVDI_DBG_PROBE,
            "i_xvdi_probe_path_handler: create for %s", path);
        (void) xvdi_create_dev(parent, xdcp->devclass, dom, vdev);
    } else {
        XVDI_DPRINTF(XVDI_DBG_PROBE,
            "i_xvdi_probe_path_handler: %s already exists", path);
    }

    ndi_devi_exit(parent, circ);

done:
    kmem_free(path, strlen(path) + 1);
}