vhost_xen/xenstore_parse.c

/*-
 *   BSD LICENSE
 *
 *   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
 *   All rights reserved.
 *
 *   Redistribution and use in source and binary forms, with or without
 *   modification, are permitted provided that the following conditions
 *   are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * 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.
 *     * Neither the name of Intel Corporation nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
 *   OWNER 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 <stdint.h>
#include <unistd.h>
#include <inttypes.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <xen/sys/gntalloc.h>
#include <xen/sys/gntdev.h>
#include <xen/xen-compat.h>
#if __XEN_LATEST_INTERFACE_VERSION__ < 0x00040200
#include <xs.h>
#else
#include <xenstore.h>
#endif

#include <rte_common.h>
#include <rte_memory.h>
#include <rte_eal.h>
#include <rte_malloc.h>
#include <rte_string_fns.h>
#include <rte_log.h>
#include <rte_debug.h>

#include "xen_vhost.h"

/* xenstore handle */
static struct xs_handle *xs = NULL;

/* gntdev file descriptor to map grant pages */
static int d_fd = -1;

/*
 *  The grant node format in xenstore for vring/mpool is like:
 *  idx#_rx_vring_gref = "gref1#, gref2#, gref3#"
 *  idx#_mempool_gref  = "gref1#, gref2#, gref3#"
 *  each gref# is the grant reference for a shared page.
 *  In each shared page, we store the grant_node_item items.
 */
struct grant_node_item {
    uint32_t gref;
    uint32_t pfn;
} __attribute__((packed));

int cmdline_parse_etheraddr(void *tk, const char *srcbuf,
    void *res, unsigned ressize);

/* Map grant ref refid at addr_ori*/
static void *
xen_grant_mmap(void *addr_ori, int domid, int refid, uint64_t *pindex)
{
    struct ioctl_gntdev_map_grant_ref arg;
    void *addr = NULL;
    int pg_sz = getpagesize();

    arg.count = 1;
    arg.refs[0].domid = domid;
    arg.refs[0].ref = refid;

    int rv = ioctl(d_fd, IOCTL_GNTDEV_MAP_GRANT_REF, &arg);
    if (rv) {
        RTE_LOG(ERR, XENHOST, "  %s: (%d,%d) %s (ioctl failed)\n", __func__,
                domid, refid, strerror(errno));
        return NULL;
    }

    if (addr_ori == NULL)
        addr = mmap(addr_ori, pg_sz, PROT_READ|PROT_WRITE, MAP_SHARED,
                d_fd, arg.index);
    else
        addr = mmap(addr_ori, pg_sz, PROT_READ|PROT_WRITE, MAP_SHARED | MAP_FIXED,
                d_fd, arg.index);

    if (addr == MAP_FAILED) {
        RTE_LOG(ERR, XENHOST, "  %s: (%d, %d) %s (map failed)\n", __func__,
                domid, refid, strerror(errno));
        return NULL;
    }

    if (pindex)
        *pindex = arg.index;

    return addr;
}

/* Unmap one grant ref, and munmap must be called before this */
static int
xen_unmap_grant_ref(uint64_t index)
{
    struct ioctl_gntdev_unmap_grant_ref arg;
    int rv;

    arg.count = 1;
    arg.index = index;
    rv = ioctl(d_fd, IOCTL_GNTDEV_UNMAP_GRANT_REF, &arg);
    if (rv) {
        RTE_LOG(ERR, XENHOST, "  %s: index 0x%" PRIx64 "unmap failed\n", __func__, index);
        return -1;
    }
    return 0;
}

/*
 * Reserve a virtual address space.
 * On success, returns the pointer. On failure, returns NULL.
 */
static void *
get_xen_virtual(size_t size, size_t page_sz)
{
    void *addr;
    uintptr_t aligned_addr;

    addr = mmap(NULL, size + page_sz, PROT_READ, MAP_SHARED | MAP_ANONYMOUS, -1, 0);
    if (addr == MAP_FAILED) {
        RTE_LOG(ERR, XENHOST, "failed get a virtual area\n");
        return NULL;
    }

    aligned_addr = RTE_ALIGN_CEIL((uintptr_t)addr, page_sz);
    munmap(addr, aligned_addr - (uintptr_t)addr);
    munmap((void *)(aligned_addr + size), page_sz + (uintptr_t)addr - aligned_addr);
    addr = (void *)(aligned_addr);

    return addr;
}

static void
free_xen_virtual(void *addr, size_t size, size_t page_sz __rte_unused)
{
    if (addr)
        munmap(addr, size);
}

/*
 * Returns val str in xenstore.
 * @param path
 *  Full path string for key
 * @return
 *  Pointer to Val str, NULL on failure
 */
static char *
xen_read_node(char *path, uint32_t *len)
{
    char *buf;

    buf = xs_read(xs, XBT_NULL, path, len);
    return buf;
}

static int
cal_pagenum(struct xen_gnt *gnt)
{
    unsigned int i;
    /*
     * the items in the page are in the format of
     * gref#,pfn#,...,gref#,pfn#
     * FIXME, 0 is reserved by system, use it as terminator.
     */
    for (i = 0; i < (PAGE_PFNNUM) / 2; i++) {
        if (gnt->gref_pfn[i * 2].gref <= 0)
            break;
    }

    return i;
}

/* Frees memory allocated to a grant node */
static void
xen_free_gntnode(struct xen_gntnode *gntnode)
{
    if (gntnode == NULL)
        return;
    free(gntnode->gnt_info);
    free(gntnode);
}

/*
 * Parse a grant node.
 * @param domid
 *  Guest domain id.
 * @param path
 *  Full path string for a grant node, like for the following (key, val) pair
 *  idx#_mempool_gref = "gref#, gref#, gref#"
 *  path = 'local/domain/domid/control/dpdk/idx#_mempool_gref'
 *  gref# is a shared page contain packed (gref,pfn) entries
 * @return
 *  Returns the pointer to xen_gntnode
 */
static struct xen_gntnode *
parse_gntnode(int dom_id, char *path)
{
    char **gref_list = NULL;
    uint32_t i, len, gref_num;
    void *addr = NULL;
    char *buf = NULL;
    struct xen_gntnode *gntnode = NULL;
    struct xen_gnt *gnt = NULL;
    int pg_sz = getpagesize();
    char *end;
    uint64_t index;

    if ((buf = xen_read_node(path, &len)) == NULL)
        goto err;

    gref_list = malloc(MAX_GREF_PER_NODE * sizeof(char *));
    if (gref_list == NULL)
        goto err;

    gref_num = rte_strsplit(buf, len, gref_list, MAX_GREF_PER_NODE,
            XEN_GREF_SPLITTOKEN);
    if (gref_num == 0) {
        RTE_LOG(ERR, XENHOST, "  %s: invalid grant node format\n", __func__);
        goto err;
    }

    gntnode = calloc(1, sizeof(struct xen_gntnode));
    gnt = calloc(gref_num, sizeof(struct xen_gnt));
    if (gnt == NULL || gntnode == NULL)
        goto err;

    for (i = 0; i < gref_num; i++) {
        errno = 0;
        gnt[i].gref = strtol(gref_list[i], &end, 0);
        if (errno != 0 || end == NULL || end == gref_list[i] ||
            (*end != '\0' &&  *end != XEN_GREF_SPLITTOKEN)) {
            RTE_LOG(ERR, XENHOST, "  %s: parse grant node item failed\n", __func__);
            goto err;
        }
        addr = xen_grant_mmap(NULL, dom_id, gnt[i].gref, &index);
        if (addr == NULL) {
            RTE_LOG(ERR, XENHOST, "  %s: map gref %u failed\n", __func__, gnt[i].gref);
            goto err;
        }
        RTE_LOG(INFO, XENHOST, "      %s: map gref %u to %p\n", __func__, gnt[i].gref, addr);
        memcpy(gnt[i].gref_pfn, addr, pg_sz);
        if (munmap(addr, pg_sz)) {
            RTE_LOG(INFO, XENHOST, "  %s: unmap gref %u failed\n", __func__, gnt[i].gref);
            goto err;
        }
        if (xen_unmap_grant_ref(index)) {
            RTE_LOG(INFO, XENHOST, "  %s: release gref %u failed\n", __func__, gnt[i].gref);
            goto err;
        }

    }

    gntnode->gnt_num  = gref_num;
    gntnode->gnt_info = gnt;

    free(buf);
    free(gref_list);
    return gntnode;

err:
    free(gnt);
    free(gntnode);
    free(gref_list);
    free(buf);
    return NULL;
}

/*
 * This function maps grant node of vring or mbuf pool to a continous virtual address space,
 * and returns mapped address, pfn array, index array
 * @param gntnode
 *  Pointer to grant node
 * @param domid
 *  Guest domain id
 * @param ppfn
 *  Pointer to pfn array, caller should free this array
 * @param pgs
 *  Pointer to number of pages
 * @param ppindex
 *  Pointer to index array, used to release grefs when to free this node
 * @return
 *  Pointer to mapped virtual address, NULL on failure
 */
static void *
map_gntnode(struct xen_gntnode *gntnode, int domid, uint32_t **ppfn, uint32_t *pgs, uint64_t **ppindex)
{
    struct xen_gnt *gnt;
    uint32_t i, j;
    size_t total_pages = 0;
    void *addr;
    uint32_t *pfn;
    uint64_t *pindex;
    uint32_t pfn_num = 0;
    int pg_sz;

    if (gntnode == NULL)
        return NULL;

    pg_sz = getpagesize();
    for (i = 0; i < gntnode->gnt_num; i++) {
        gnt = gntnode->gnt_info + i;
        total_pages += cal_pagenum(gnt);
    }
    if ((addr = get_xen_virtual(total_pages * pg_sz, pg_sz)) == NULL) {
        RTE_LOG(ERR, XENHOST, "  %s: failed get_xen_virtual\n", __func__);
        return NULL;
    }
    pfn = calloc(total_pages, (size_t)sizeof(uint32_t));
    pindex = calloc(total_pages, (size_t)sizeof(uint64_t));
    if (pfn == NULL || pindex == NULL) {
        free_xen_virtual(addr, total_pages * pg_sz, pg_sz);
        free(pfn);
        free(pindex);
        return NULL;
    }

    RTE_LOG(INFO, XENHOST, "    %s: total pages:%zu, map to [%p, %p]\n", __func__, total_pages, addr, RTE_PTR_ADD(addr, total_pages * pg_sz - 1));
    for (i = 0; i < gntnode->gnt_num; i++) {
        gnt = gntnode->gnt_info + i;
        for (j = 0; j < (PAGE_PFNNUM) / 2; j++) {
            if ((gnt->gref_pfn[j * 2].gref) <= 0)
                goto _end;
            /*alternative: batch map, or through libxc*/
            if (xen_grant_mmap(RTE_PTR_ADD(addr, pfn_num * pg_sz),
                    domid,
                    gnt->gref_pfn[j * 2].gref,
                    &pindex[pfn_num]) == NULL) {
                goto mmap_failed;
            }
            pfn[pfn_num] = gnt->gref_pfn[j * 2 + 1].pfn_num;
            pfn_num++;
        }
    }

mmap_failed:
    if (pfn_num)
        munmap(addr, pfn_num * pg_sz);
    for (i = 0; i < pfn_num; i++) {
        xen_unmap_grant_ref(pindex[i]);
    }
    free(pindex);
    free(pfn);
    return NULL;

_end:
    if (ppindex)
        *ppindex = pindex;
    else
        free(pindex);
    if (ppfn)
        *ppfn = pfn;
    else
        free(pfn);
    if (pgs)
        *pgs = total_pages;

    return addr;
}

static int
parse_mpool_va(struct xen_mempool *mempool)
{
    char path[PATH_MAX] = {0};
    char *buf;
    uint32_t len;
    char *end;
    int ret = -1;

    errno = 0;
    snprintf(path, sizeof(path),
        XEN_VM_ROOTNODE_FMT"/%d_"XEN_GVA_SUFFIX,
        mempool->dom_id, mempool->pool_idx);

    if((buf = xen_read_node(path, &len)) == NULL)
        goto out;
    mempool->gva = (void *)strtoul(buf, &end, 16);
    if (errno != 0 || end == NULL || end == buf || *end != '\0') {
        mempool->gva = NULL;
        goto out;
    }
    ret = 0;
out:
    free(buf);
    return ret;
}

/*
 * map mbuf pool
 */
static int
map_mempoolnode(struct xen_gntnode *gntnode,
            struct xen_mempool *mempool)
{
    if (gntnode == NULL || mempool == NULL)
        return -1;

    mempool->hva =
        map_gntnode(gntnode, mempool->dom_id, &mempool->mempfn_tbl, &mempool->mempfn_num, &mempool->pindex);

    RTE_LOG(INFO, XENHOST, "  %s: map mempool at %p\n", __func__, (void *)mempool->hva);
    if (mempool->hva)
        return 0;
    else {
        return -1;
    }
}

void
cleanup_mempool(struct xen_mempool *mempool)
{
    int pg_sz = getpagesize();
    uint32_t i;

    if (mempool->hva)
        munmap(mempool->hva, mempool->mempfn_num * pg_sz);
    mempool->hva = NULL;

    if (mempool->pindex) {
        RTE_LOG(INFO, XENHOST, "  %s: unmap dom %02u mempool%02u %u grefs\n",
            __func__,
            mempool->dom_id,
            mempool->pool_idx,
            mempool->mempfn_num);
        for (i = 0; i < mempool->mempfn_num; i ++) {
            xen_unmap_grant_ref(mempool->pindex[i]);
        }
    }
    mempool->pindex = NULL;

    free(mempool->mempfn_tbl);
    mempool->mempfn_tbl = NULL;
}

/*
 * process mempool node idx#_mempool_gref, idx = 0, 1, 2...
 * untill we encounter a node that doesn't exist.
 */
int
parse_mempoolnode(struct xen_guest *guest)
{
    uint32_t i, len;
    char path[PATH_MAX] = {0};
    struct xen_gntnode *gntnode = NULL;
    struct xen_mempool *mempool = NULL;
    char *buf;

    bzero(&guest->mempool, MAX_XENVIRT_MEMPOOL * sizeof(guest->mempool[0]));
    guest->pool_num = 0;

    while (1) {
        /* check if null terminated */
        snprintf(path, sizeof(path),
            XEN_VM_ROOTNODE_FMT"/%d_"XEN_MEMPOOL_SUFFIX,
            guest->dom_id,
            guest->pool_num);

        if ((buf = xen_read_node(path, &len)) != NULL) {
            /* this node exists */
            free(buf);
        } else {
            if (guest->pool_num == 0) {
                RTE_LOG(ERR, PMD, "no mempool found\n");
                return -1;
            }
            break;
        }

        mempool = &guest->mempool[guest->pool_num];
        mempool->dom_id = guest->dom_id;
        mempool->pool_idx = guest->pool_num;

        RTE_LOG(INFO, XENHOST, "  %s: mempool %u parse gntnode %s\n", __func__, guest->pool_num, path);
        gntnode = parse_gntnode(guest->dom_id, path);
        if (gntnode == NULL)
            goto err;

        if (parse_mpool_va(mempool))
            goto err;

        RTE_LOG(INFO, XENHOST, "  %s: mempool %u map gntnode %s\n", __func__, guest->pool_num, path);
        if (map_mempoolnode(gntnode, mempool))
            goto err;

        xen_free_gntnode(gntnode);
        guest->pool_num++;
    }

    return 0;
err:
    if (gntnode)
        xen_free_gntnode(gntnode);
    for (i = 0; i <  MAX_XENVIRT_MEMPOOL ; i++) {
        cleanup_mempool(&guest->mempool[i]);
    }
    /* reinitialise mempool */
    bzero(&guest->mempool, MAX_XENVIRT_MEMPOOL * sizeof(guest->mempool[0]));
    return -1;
}

static int
xen_map_vringflag(struct xen_vring *vring)
{
    char path[PATH_MAX] = {0};
    char *buf;
    uint32_t len,gref;
    int pg_sz = getpagesize();
    char *end;

    snprintf(path, sizeof(path),
        XEN_VM_ROOTNODE_FMT"/%d_"XEN_VRINGFLAG_SUFFIX,
        vring->dom_id, vring->virtio_idx);

    if((buf = xen_read_node(path, &len)) == NULL)
        goto err;

    errno = 0;
    gref = strtol(buf, &end, 0);
    if (errno != 0 || end == NULL || end == buf) {
        goto err;
    }
    vring->flag = xen_grant_mmap(0, vring->dom_id, gref, &vring->flag_index);
    if (vring->flag == NULL || *vring->flag == 0)
        goto err;

    free(buf);
    return 0;
err:
    free(buf);
    if (vring->flag) {
        munmap(vring->flag, pg_sz);
        vring->flag = NULL;
        xen_unmap_grant_ref(vring->flag_index);
    }
    return -1;
}


static int
xen_map_rxvringnode(struct xen_gntnode *gntnode,
                struct xen_vring *vring)
{
    vring->rxvring_addr =
        map_gntnode(gntnode, vring->dom_id, &vring->rxpfn_tbl, &vring->rxpfn_num, &vring->rx_pindex);
    RTE_LOG(INFO, XENHOST, "  %s: map rx vring at %p\n", __func__, (void *)vring->rxvring_addr);
    if (vring->rxvring_addr)
        return 0;
    else
        return -1;
}

static int
xen_map_txvringnode(struct xen_gntnode *gntnode,
                struct xen_vring *vring)
{
    vring->txvring_addr =
        map_gntnode(gntnode, vring->dom_id, &vring->txpfn_tbl, &vring->txpfn_num, &vring->tx_pindex);
    RTE_LOG(INFO, XENHOST, "  %s: map tx vring at %p\n", __func__, (void *)vring->txvring_addr);
    if (vring->txvring_addr)
        return 0;
    else
        return -1;
}

void
cleanup_vring(struct xen_vring *vring)
{
    int pg_sz = getpagesize();
    uint32_t i;

    RTE_LOG(INFO, XENHOST, "  %s: cleanup dom %u vring %u\n", __func__, vring->dom_id, vring->virtio_idx);
    if (vring->rxvring_addr) {
        munmap(vring->rxvring_addr, vring->rxpfn_num * pg_sz);
        RTE_LOG(INFO, XENHOST, "  %s: unmap rx vring [%p, %p]\n",
            __func__,
            vring->rxvring_addr,
            RTE_PTR_ADD(vring->rxvring_addr,
            vring->rxpfn_num * pg_sz - 1));
    }
    vring->rxvring_addr = NULL;


    if (vring->rx_pindex) {
        RTE_LOG(INFO, XENHOST, "  %s: unmap rx vring %u grefs\n", __func__, vring->rxpfn_num);
        for (i = 0; i < vring->rxpfn_num; i++) {
            xen_unmap_grant_ref(vring->rx_pindex[i]);
        }
    }
    vring->rx_pindex = NULL;

    free(vring->rxpfn_tbl);
    vring->rxpfn_tbl = NULL;

    if (vring->txvring_addr) {
        munmap(vring->txvring_addr, vring->txpfn_num * pg_sz);
        RTE_LOG(INFO, XENHOST, "  %s: unmap tx vring [%p, %p]\n",
            __func__,
            vring->txvring_addr,
            RTE_PTR_ADD(vring->txvring_addr,
            vring->txpfn_num * pg_sz - 1));
    }
    vring->txvring_addr = NULL;

    if (vring->tx_pindex) {
        RTE_LOG(INFO, XENHOST, "  %s: unmap tx vring %u grefs\n", __func__, vring->txpfn_num);
        for (i = 0; i < vring->txpfn_num; i++) {
            xen_unmap_grant_ref(vring->tx_pindex[i]);
        }
    }
    vring->tx_pindex = NULL;

    free(vring->txpfn_tbl);
    vring->txpfn_tbl = NULL;

    if (vring->flag) {
        if (!munmap((void *)vring->flag, pg_sz))
            RTE_LOG(INFO, XENHOST, "  %s: unmap flag page at %p\n", __func__, vring->flag);
        if (!xen_unmap_grant_ref(vring->flag_index))
            RTE_LOG(INFO, XENHOST, "  %s: release flag ref index 0x%" PRIx64 "\n", __func__, vring->flag_index);
    }
    vring->flag = NULL;
    return;
}



static int
xen_parse_etheraddr(struct xen_vring *vring)
{
    char path[PATH_MAX] = {0};
    char *buf;
    uint32_t len;
    int ret = -1;

    snprintf(path, sizeof(path),
        XEN_VM_ROOTNODE_FMT"/%d_"XEN_ADDR_SUFFIX,
        vring->dom_id, vring->virtio_idx);

    if ((buf = xen_read_node(path, &len)) == NULL)
        goto out;

    if (cmdline_parse_etheraddr(NULL, buf, &vring->addr,
            sizeof(vring->addr)) < 0)
        goto out;
    ret = 0;
out:
    free(buf);
    return ret;
}


int
parse_vringnode(struct xen_guest *guest, uint32_t virtio_idx)
{
    char path[PATH_MAX] = {0};
    struct xen_gntnode *rx_gntnode = NULL;
    struct xen_gntnode *tx_gntnode = NULL;
    struct xen_vring *vring = NULL;

    /*check if null terminated */
    snprintf(path, sizeof(path),
        XEN_VM_ROOTNODE_FMT"/%d_"XEN_RXVRING_SUFFIX,
        guest->dom_id,
        virtio_idx);

    RTE_LOG(INFO, XENHOST, "  %s: virtio %u parse rx gntnode %s\n", __func__, virtio_idx, path);
    rx_gntnode = parse_gntnode(guest->dom_id, path);
    if (rx_gntnode == NULL)
        goto err;

    /*check if null terminated */
    snprintf(path, sizeof(path),
        XEN_VM_ROOTNODE_FMT"/%d_"XEN_TXVRING_SUFFIX,
        guest->dom_id,
        virtio_idx);

    RTE_LOG(INFO, XENHOST, "  %s: virtio %u parse tx gntnode %s\n", __func__, virtio_idx, path);
    tx_gntnode = parse_gntnode(guest->dom_id, path);
    if (tx_gntnode == NULL)
        goto err;

    vring = &guest->vring[virtio_idx];
    bzero(vring, sizeof(*vring));
    vring->dom_id = guest->dom_id;
    vring->virtio_idx = virtio_idx;

    if (xen_parse_etheraddr(vring) != 0)
        goto err;

    RTE_LOG(INFO, XENHOST, "  %s: virtio %u map rx gntnode %s\n", __func__, virtio_idx, path);
    if (xen_map_rxvringnode(rx_gntnode, vring) != 0)
        goto err;

    RTE_LOG(INFO, XENHOST, "  %s: virtio %u map tx gntnode %s\n", __func__, virtio_idx, path);
    if (xen_map_txvringnode(tx_gntnode, vring) != 0)
        goto err;

    if (xen_map_vringflag(vring) != 0)
        goto err;

    guest->vring_num++;

    xen_free_gntnode(rx_gntnode);
    xen_free_gntnode(tx_gntnode);

    return 0;

err:
    if (rx_gntnode)
        xen_free_gntnode(rx_gntnode);
    if (tx_gntnode)
        xen_free_gntnode(tx_gntnode);
    if (vring) {
        cleanup_vring(vring);
        bzero(vring, sizeof(*vring));
    }
    return -1;
}

/*
 * Open xen grant dev driver
 * @return
 *  0 on success, -1 on failure.
 */
static int
xen_grant_init(void)
{
    d_fd = open(XEN_GNTDEV_FNAME, O_RDWR);

    return d_fd == -1? (-1): (0);
}

/*
 * Initialise xenstore handle and open grant dev driver.
 * @return
 *  0 on success, -1 on failure.
 */
int
xenhost_init(void)
{
    xs = xs_daemon_open();
    if (xs == NULL) {
        rte_panic("failed initialize xen daemon handler");
        return -1;
    }
    if (xen_grant_init())
        return -1;
    return 0;
}