Re: [Qemu-devel] [PATCH v8 2/7] Qemu-Xen-vTPM: Create a new file xen_pvdev.c

[Stefano Stabellini]

On Sun, 17 May 2015, Quan Xu wrote:
> for some common part of xen frontend and backend, such as xendevs
> queue and xenstore update functions.
> 
> Signed-off-by: Quan Xu <address@hidden>

Hi Quan,

could you please separate out the code movement from any other changes?
This patch would become two patches: the first would only move code from
xen_backend.c to xen_pvdev.c, no other changes except for the ones
actually required to build the code (Makefile.objs).  The second patch
would rename xen_be_find_xendev to xen_find_xendev and any other changes
to the code that you making here.  That way I can very easily go and
look only at the things you actually modify.

Thanks,

Stefano


>  hw/display/xenfb.c           |   4 +-
>  hw/xen/Makefile.objs         |   2 +-
>  hw/xen/xen_backend.c         | 353 -------------------------------
>  hw/xen/xen_pvdev.c           | 481 
> +++++++++++++++++++++++++++++++++++++++++++
>  include/hw/xen/xen_backend.h |  13 +-
>  5 files changed, 496 insertions(+), 357 deletions(-)
>  create mode 100644 hw/xen/xen_pvdev.c
> 
> diff --git a/hw/display/xenfb.c b/hw/display/xenfb.c
> index 5e324ef..10751df 100644
> --- a/hw/display/xenfb.c
> +++ b/hw/display/xenfb.c
> @@ -988,8 +988,8 @@ void xen_init_display(int domid)
>  wait_more:
>      i++;
>      main_loop_wait(true);
> -    xfb = xen_be_find_xendev("vfb", domid, 0);
> -    xin = xen_be_find_xendev("vkbd", domid, 0);
> +    xfb = xen_find_xendev("vfb", domid, 0);
> +    xin = xen_find_xendev("vkbd", domid, 0);
>      if (!xfb || !xin) {
>          if (i < 256) {
>              usleep(10000);
> diff --git a/hw/xen/Makefile.objs b/hw/xen/Makefile.objs
> index a0ca0aa..9ac9f7c 100644
> --- a/hw/xen/Makefile.objs
> +++ b/hw/xen/Makefile.objs
> @@ -1,5 +1,5 @@
>  # xen backend driver support
> -common-obj-$(CONFIG_XEN_BACKEND) += xen_backend.o xen_devconfig.o
> +common-obj-$(CONFIG_XEN_BACKEND) += xen_backend.o xen_devconfig.o xen_pvdev.o
>  
>  obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen-host-pci-device.o
>  obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen_pt.o xen_pt_config_init.o 
> xen_pt_msi.o
> diff --git a/hw/xen/xen_backend.c b/hw/xen/xen_backend.c
> index b2cb22b..844f918 100644
> --- a/hw/xen/xen_backend.c
> +++ b/hw/xen/xen_backend.c
> @@ -44,86 +44,11 @@
>  /* ------------------------------------------------------------- */
>  
>  /* public */
> -XenXC xen_xc = XC_HANDLER_INITIAL_VALUE;
> -struct xs_handle *xenstore = NULL;
>  const char *xen_protocol;
>  
>  /* private */
> -static QTAILQ_HEAD(XenDeviceHead, XenDevice) xendevs = 
> QTAILQ_HEAD_INITIALIZER(xendevs);
>  static int debug = 0;
>  
> -/* ------------------------------------------------------------- */
> -
> -int xenstore_write_str(const char *base, const char *node, const char *val)
> -{
> -    char abspath[XEN_BUFSIZE];
> -
> -    snprintf(abspath, sizeof(abspath), "%s/%s", base, node);
> -    if (!xs_write(xenstore, 0, abspath, val, strlen(val))) {
> -        return -1;
> -    }
> -    return 0;
> -}
> -
> -char *xenstore_read_str(const char *base, const char *node)
> -{
> -    char abspath[XEN_BUFSIZE];
> -    unsigned int len;
> -    char *str, *ret = NULL;
> -
> -    snprintf(abspath, sizeof(abspath), "%s/%s", base, node);
> -    str = xs_read(xenstore, 0, abspath, &len);
> -    if (str != NULL) {
> -        /* move to qemu-allocated memory to make sure
> -         * callers can savely g_free() stuff. */
> -        ret = g_strdup(str);
> -        free(str);
> -    }
> -    return ret;
> -}
> -
> -int xenstore_write_int(const char *base, const char *node, int ival)
> -{
> -    char val[12];
> -
> -    snprintf(val, sizeof(val), "%d", ival);
> -    return xenstore_write_str(base, node, val);
> -}
> -
> -int xenstore_write_int64(const char *base, const char *node, int64_t ival)
> -{
> -    char val[21];
> -
> -    snprintf(val, sizeof(val), "%"PRId64, ival);
> -    return xenstore_write_str(base, node, val);
> -}
> -
> -int xenstore_read_int(const char *base, const char *node, int *ival)
> -{
> -    char *val;
> -    int rc = -1;
> -
> -    val = xenstore_read_str(base, node);
> -    if (val && 1 == sscanf(val, "%d", ival)) {
> -        rc = 0;
> -    }
> -    g_free(val);
> -    return rc;
> -}
> -
> -int xenstore_read_uint64(const char *base, const char *node, uint64_t *uval)
> -{
> -    char *val;
> -    int rc = -1;
> -
> -    val = xenstore_read_str(base, node);
> -    if (val && 1 == sscanf(val, "%"SCNu64, uval)) {
> -        rc = 0;
> -    }
> -    g_free(val);
> -    return rc;
> -}
> -
>  int xenstore_write_be_str(struct XenDevice *xendev, const char *node, const 
> char *val)
>  {
>      return xenstore_write_str(xendev->be, node, val);
> @@ -195,183 +120,6 @@ int xen_be_set_state(struct XenDevice *xendev, enum 
> xenbus_state state)
>  }
>  
>  /* ------------------------------------------------------------- */
> -
> -struct XenDevice *xen_be_find_xendev(const char *type, int dom, int dev)
> -{
> -    struct XenDevice *xendev;
> -
> -    QTAILQ_FOREACH(xendev, &xendevs, next) {
> -        if (xendev->dom != dom) {
> -            continue;
> -        }
> -        if (xendev->dev != dev) {
> -            continue;
> -        }
> -        if (strcmp(xendev->type, type) != 0) {
> -            continue;
> -        }
> -        return xendev;
> -    }
> -    return NULL;
> -}
> -
> -/*
> - * get xen backend device, allocate a new one if it doesn't exist.
> - */
> -static struct XenDevice *xen_be_get_xendev(const char *type, int dom, int 
> dev,
> -                                           struct XenDevOps *ops)
> -{
> -    struct XenDevice *xendev;
> -
> -    xendev = xen_be_find_xendev(type, dom, dev);
> -    if (xendev) {
> -        return xendev;
> -    }
> -
> -    /* init new xendev */
> -    xendev = g_malloc0(ops->size);
> -    xendev->type  = type;
> -    xendev->dom   = dom;
> -    xendev->dev   = dev;
> -    xendev->ops   = ops;
> -
> -    snprintf(xendev->be, sizeof(xendev->be), "backend/%s/%d/%d",
> -             xendev->type, xendev->dom, xendev->dev);
> -    snprintf(xendev->name, sizeof(xendev->name), "%s-%d",
> -             xendev->type, xendev->dev);
> -
> -    xendev->debug      = debug;
> -    xendev->local_port = -1;
> -
> -    xendev->evtchndev = xen_xc_evtchn_open(NULL, 0);
> -    if (xendev->evtchndev == XC_HANDLER_INITIAL_VALUE) {
> -        xen_be_printf(NULL, 0, "can't open evtchn device\n");
> -        g_free(xendev);
> -        return NULL;
> -    }
> -    fcntl(xc_evtchn_fd(xendev->evtchndev), F_SETFD, FD_CLOEXEC);
> -
> -    if (ops->flags & DEVOPS_FLAG_NEED_GNTDEV) {
> -        xendev->gnttabdev = xen_xc_gnttab_open(NULL, 0);
> -        if (xendev->gnttabdev == XC_HANDLER_INITIAL_VALUE) {
> -            xen_be_printf(NULL, 0, "can't open gnttab device\n");
> -            xc_evtchn_close(xendev->evtchndev);
> -            g_free(xendev);
> -            return NULL;
> -        }
> -    } else {
> -        xendev->gnttabdev = XC_HANDLER_INITIAL_VALUE;
> -    }
> -
> -    QTAILQ_INSERT_TAIL(&xendevs, xendev, next);
> -
> -    if (xendev->ops->alloc) {
> -        xendev->ops->alloc(xendev);
> -    }
> -
> -    return xendev;
> -}
> -
> -/*
> - * release xen backend device.
> - */
> -static struct XenDevice *xen_be_del_xendev(int dom, int dev)
> -{
> -    struct XenDevice *xendev, *xnext;
> -
> -    /*
> -     * This is pretty much like QTAILQ_FOREACH(xendev, &xendevs, next) but
> -     * we save the next pointer in xnext because we might free xendev.
> -     */
> -    xnext = xendevs.tqh_first;
> -    while (xnext) {
> -        xendev = xnext;
> -        xnext = xendev->next.tqe_next;
> -
> -        if (xendev->dom != dom) {
> -            continue;
> -        }
> -        if (xendev->dev != dev && dev != -1) {
> -            continue;
> -        }
> -
> -        if (xendev->ops->free) {
> -            xendev->ops->free(xendev);
> -        }
> -
> -        if (xendev->fe) {
> -            char token[XEN_BUFSIZE];
> -            snprintf(token, sizeof(token), "fe:%p", xendev);
> -            xs_unwatch(xenstore, xendev->fe, token);
> -            g_free(xendev->fe);
> -        }
> -
> -        if (xendev->evtchndev != XC_HANDLER_INITIAL_VALUE) {
> -            xc_evtchn_close(xendev->evtchndev);
> -        }
> -        if (xendev->gnttabdev != XC_HANDLER_INITIAL_VALUE) {
> -            xc_gnttab_close(xendev->gnttabdev);
> -        }
> -
> -        QTAILQ_REMOVE(&xendevs, xendev, next);
> -        g_free(xendev);
> -    }
> -    return NULL;
> -}
> -
> -/*
> - * Sync internal data structures on xenstore updates.
> - * Node specifies the changed field.  node = NULL means
> - * update all fields (used for initialization).
> - */
> -static void xen_be_backend_changed(struct XenDevice *xendev, const char 
> *node)
> -{
> -    if (node == NULL  ||  strcmp(node, "online") == 0) {
> -        if (xenstore_read_be_int(xendev, "online", &xendev->online) == -1) {
> -            xendev->online = 0;
> -        }
> -    }
> -
> -    if (node) {
> -        xen_be_printf(xendev, 2, "backend update: %s\n", node);
> -        if (xendev->ops->backend_changed) {
> -            xendev->ops->backend_changed(xendev, node);
> -        }
> -    }
> -}
> -
> -static void xen_be_frontend_changed(struct XenDevice *xendev, const char 
> *node)
> -{
> -    int fe_state;
> -
> -    if (node == NULL  ||  strcmp(node, "state") == 0) {
> -        if (xenstore_read_fe_int(xendev, "state", &fe_state) == -1) {
> -            fe_state = XenbusStateUnknown;
> -        }
> -        if (xendev->fe_state != fe_state) {
> -            xen_be_printf(xendev, 1, "frontend state: %s -> %s\n",
> -                          xenbus_strstate(xendev->fe_state),
> -                          xenbus_strstate(fe_state));
> -        }
> -        xendev->fe_state = fe_state;
> -    }
> -    if (node == NULL  ||  strcmp(node, "protocol") == 0) {
> -        g_free(xendev->protocol);
> -        xendev->protocol = xenstore_read_fe_str(xendev, "protocol");
> -        if (xendev->protocol) {
> -            xen_be_printf(xendev, 1, "frontend protocol: %s\n", 
> xendev->protocol);
> -        }
> -    }
> -
> -    if (node) {
> -        xen_be_printf(xendev, 2, "frontend update: %s\n", node);
> -        if (xendev->ops->frontend_changed) {
> -            xendev->ops->frontend_changed(xendev, node);
> -        }
> -    }
> -}
> -
> -/* ------------------------------------------------------------- */
>  /* Check for possible state transitions and perform them.        */
>  
>  /*
> @@ -611,81 +359,6 @@ static int xenstore_scan(const char *type, int dom, 
> struct XenDevOps *ops)
>      return 0;
>  }
>  
> -static void xenstore_update_be(char *watch, char *type, int dom,
> -                               struct XenDevOps *ops)
> -{
> -    struct XenDevice *xendev;
> -    char path[XEN_BUFSIZE], *bepath;
> -    unsigned int len, dev;
> -
> -    len = snprintf(path, sizeof(path), "backend/%s/%d", type, dom);
> -    if (strncmp(path, watch, len) != 0) {
> -        return;
> -    }
> -    if (sscanf(watch+len, "/%u/%255s", &dev, path) != 2) {
> -        strcpy(path, "");
> -        if (sscanf(watch+len, "/%u", &dev) != 1) {
> -            dev = -1;
> -        }
> -    }
> -    if (dev == -1) {
> -        return;
> -    }
> -
> -    xendev = xen_be_get_xendev(type, dom, dev, ops);
> -    if (xendev != NULL) {
> -        bepath = xs_read(xenstore, 0, xendev->be, &len);
> -        if (bepath == NULL) {
> -            xen_be_del_xendev(dom, dev);
> -        } else {
> -            free(bepath);
> -            xen_be_backend_changed(xendev, path);
> -            xen_be_check_state(xendev);
> -        }
> -    }
> -}
> -
> -static void xenstore_update_fe(char *watch, struct XenDevice *xendev)
> -{
> -    char *node;
> -    unsigned int len;
> -
> -    len = strlen(xendev->fe);
> -    if (strncmp(xendev->fe, watch, len) != 0) {
> -        return;
> -    }
> -    if (watch[len] != '/') {
> -        return;
> -    }
> -    node = watch + len + 1;
> -
> -    xen_be_frontend_changed(xendev, node);
> -    xen_be_check_state(xendev);
> -}
> -
> -static void xenstore_update(void *unused)
> -{
> -    char **vec = NULL;
> -    intptr_t type, ops, ptr;
> -    unsigned int dom, count;
> -
> -    vec = xs_read_watch(xenstore, &count);
> -    if (vec == NULL) {
> -        goto cleanup;
> -    }
> -
> -    if (sscanf(vec[XS_WATCH_TOKEN], "be:%" PRIxPTR ":%d:%" PRIxPTR,
> -               &type, &dom, &ops) == 3) {
> -        xenstore_update_be(vec[XS_WATCH_PATH], (void*)type, dom, (void*)ops);
> -    }
> -    if (sscanf(vec[XS_WATCH_TOKEN], "fe:%" PRIxPTR, &ptr) == 1) {
> -        xenstore_update_fe(vec[XS_WATCH_PATH], (void*)ptr);
> -    }
> -
> -cleanup:
> -    free(vec);
> -}
> -
>  static void xen_be_evtchn_event(void *opaque)
>  {
>      struct XenDevice *xendev = opaque;
> @@ -706,32 +379,6 @@ static void xen_be_evtchn_event(void *opaque)
>  
>  /* -------------------------------------------------------------------- */
>  
> -int xen_be_init(void)
> -{
> -    xenstore = xs_daemon_open();
> -    if (!xenstore) {
> -        xen_be_printf(NULL, 0, "can't connect to xenstored\n");
> -        return -1;
> -    }
> -
> -    if (qemu_set_fd_handler(xs_fileno(xenstore), xenstore_update, NULL, 
> NULL) < 0) {
> -        goto err;
> -    }
> -
> -    if (xen_xc == XC_HANDLER_INITIAL_VALUE) {
> -        /* Check if xen_init() have been called */
> -        goto err;
> -    }
> -    return 0;
> -
> -err:
> -    qemu_set_fd_handler(xs_fileno(xenstore), NULL, NULL, NULL);
> -    xs_daemon_close(xenstore);
> -    xenstore = NULL;
> -
> -    return -1;
> -}
> -
>  int xen_be_register(const char *type, struct XenDevOps *ops)
>  {
>      return xenstore_scan(type, xen_domid, ops);
> diff --git a/hw/xen/xen_pvdev.c b/hw/xen/xen_pvdev.c
> new file mode 100644
> index 0000000..dac8639
> --- /dev/null
> +++ b/hw/xen/xen_pvdev.c
> @@ -0,0 +1,481 @@
> +/*
> + * Xen para-virtualization device
> + *
> + *  Copyright (c) 2015 Intel Corporation
> + *  Authors:
> + *    Quan Xu <address@hidden>
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see 
> <http://www.gnu.org/licenses/>
> + */
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <stdarg.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <fcntl.h>
> +#include <inttypes.h>
> +#include <sys/types.h>
> +#include <sys/stat.h>
> +#include <sys/mman.h>
> +#include <sys/signal.h>
> +
> +#include "hw/hw.h"
> +#include "sysemu/char.h"
> +#include "qemu/log.h"
> +#include "hw/xen/xen_backend.h"
> +
> +#include <xen/grant_table.h>
> +
> +static QTAILQ_HEAD(XenDeviceHead, XenDevice) xendevs =
> +           QTAILQ_HEAD_INITIALIZER(xendevs);
> +static int debug;
> +
> +/* public */
> +XenXC xen_xc = XC_HANDLER_INITIAL_VALUE;
> +struct xs_handle *xenstore;
> +
> +/*
> + * find Xen device
> + */
> +struct XenDevice *xen_find_xendev(const char *type, int dom, int dev)
> +{
> +    struct XenDevice *xendev;
> +
> +    QTAILQ_FOREACH(xendev, &xendevs, next) {
> +        if (xendev->dom != dom) {
> +            continue;
> +        }
> +        if (xendev->dev != dev) {
> +            continue;
> +        }
> +        if (strcmp(xendev->type, type) != 0) {
> +            continue;
> +        }
> +        return xendev;
> +    }
> +    return NULL;
> +}
> +
> +/*
> + * get xen backend device, allocate a new one if it doesn't exist.
> + */
> +struct XenDevice *xen_be_get_xendev(const char *type, int dom, int dev,
> +                                    struct XenDevOps *ops)
> +{
> +    struct XenDevice *xendev;
> +
> +    xendev = xen_find_xendev(type, dom, dev);
> +    if (xendev) {
> +        return xendev;
> +    }
> +
> +    /* init new xendev */
> +    xendev = g_malloc0(ops->size);
> +    xendev->type  = type;
> +    xendev->dom   = dom;
> +    xendev->dev   = dev;
> +    xendev->ops   = ops;
> +
> +    snprintf(xendev->be, sizeof(xendev->be), "backend/%s/%d/%d",
> +             xendev->type, xendev->dom, xendev->dev);
> +    snprintf(xendev->name, sizeof(xendev->name), "%s-%d",
> +             xendev->type, xendev->dev);
> +
> +    xendev->debug      = debug;
> +    xendev->local_port = -1;
> +
> +    xendev->evtchndev = xen_xc_evtchn_open(NULL, 0);
> +    if (xendev->evtchndev == XC_HANDLER_INITIAL_VALUE) {
> +        xen_be_printf(NULL, 0, "can't open evtchn device\n");
> +        g_free(xendev);
> +        return NULL;
> +    }
> +    fcntl(xc_evtchn_fd(xendev->evtchndev), F_SETFD, FD_CLOEXEC);
> +
> +    if (ops->flags & DEVOPS_FLAG_NEED_GNTDEV) {
> +        xendev->gnttabdev = xen_xc_gnttab_open(NULL, 0);
> +        if (xendev->gnttabdev == XC_HANDLER_INITIAL_VALUE) {
> +            xen_be_printf(NULL, 0, "can't open gnttab device\n");
> +            xc_evtchn_close(xendev->evtchndev);
> +            g_free(xendev);
> +            return NULL;
> +        }
> +    } else {
> +        xendev->gnttabdev = XC_HANDLER_INITIAL_VALUE;
> +    }
> +
> +    QTAILQ_INSERT_TAIL(&xendevs, xendev, next);
> +
> +    if (xendev->ops->alloc) {
> +        xendev->ops->alloc(xendev);
> +    }
> +
> +    return xendev;
> +}
> +
> +/*
> + * get xen fe device, allocate a new one if it doesn't exist.
> + */
> +struct XenDevice *xen_fe_get_xendev(const char *type, int dom, int dev,
> +                                    char *backend, struct XenDevOps *ops)
> +{
> +    struct XenDevice *xendev;
> +
> +    xendev = xen_find_xendev(type, dom, dev);
> +    if (xendev) {
> +        return xendev;
> +    }
> +
> +    /* init new xendev */
> +    xendev = g_malloc0(ops->size);
> +    xendev->type  = type;
> +    xendev->dom   = dom;
> +    xendev->dev   = dev;
> +    xendev->ops   = ops;
> +
> +    /*return if the ops->flags is not DEVOPS_FLAG_FE*/
> +    if (!(ops->flags & DEVOPS_FLAG_FE)) {
> +        return NULL;
> +    }
> +
> +    snprintf(xendev->be, sizeof(xendev->be), "%s", backend);
> +    snprintf(xendev->name, sizeof(xendev->name), "%s-%d",
> +             xendev->type, xendev->dev);
> +
> +    xendev->debug = debug;
> +    xendev->local_port = -1;
> +
> +    xendev->evtchndev = xen_xc_evtchn_open(NULL, 0);
> +    if (xendev->evtchndev == XC_HANDLER_INITIAL_VALUE) {
> +        xen_be_printf(NULL, 0, "can't open evtchn device\n");
> +        g_free(xendev);
> +        return NULL;
> +    }
> +    fcntl(xc_evtchn_fd(xendev->evtchndev), F_SETFD, FD_CLOEXEC);
> +
> +    if (ops->flags & DEVOPS_FLAG_NEED_GNTDEV) {
> +        xendev->gnttabdev = xen_xc_gnttab_open(NULL, 0);
> +        if (xendev->gnttabdev == XC_HANDLER_INITIAL_VALUE) {
> +            xen_be_printf(NULL, 0, "can't open gnttab device\n");
> +            xc_evtchn_close(xendev->evtchndev);
> +            g_free(xendev);
> +            return NULL;
> +        }
> +    } else {
> +        xendev->gnttabdev = XC_HANDLER_INITIAL_VALUE;
> +    }
> +
> +    QTAILQ_INSERT_TAIL(&xendevs, xendev, next);
> +
> +    if (xendev->ops->alloc) {
> +        xendev->ops->alloc(xendev);
> +    }
> +
> +    return xendev;
> +}
> +
> +/*
> + * release xen device
> + */
> +
> +struct XenDevice *xen_del_xendev(int dom, int dev)
> +{
> +    struct XenDevice *xendev, *xnext;
> +
> +    /*
> +     * This is pretty much like QTAILQ_FOREACH(xendev, &xendevs, next) but
> +     * we save the next pointer in xnext because we might free xendev.
> +     */
> +    xnext = xendevs.tqh_first;
> +    while (xnext) {
> +        xendev = xnext;
> +        xnext = xendev->next.tqe_next;
> +
> +        if (xendev->dom != dom) {
> +            continue;
> +        }
> +        if (xendev->dev != dev && dev != -1) {
> +            continue;
> +        }
> +
> +        if (xendev->ops->free) {
> +            xendev->ops->free(xendev);
> +        }
> +
> +        if (xendev->fe) {
> +            char token[XEN_BUFSIZE];
> +            snprintf(token, sizeof(token), "fe:%p", xendev);
> +            xs_unwatch(xenstore, xendev->fe, token);
> +            g_free(xendev->fe);
> +        }
> +
> +        if (xendev->evtchndev != XC_HANDLER_INITIAL_VALUE) {
> +            xc_evtchn_close(xendev->evtchndev);
> +        }
> +        if (xendev->gnttabdev != XC_HANDLER_INITIAL_VALUE) {
> +            xc_gnttab_close(xendev->gnttabdev);
> +        }
> +
> +        QTAILQ_REMOVE(&xendevs, xendev, next);
> +        g_free(xendev);
> +    }
> +    return NULL;
> +}
> +
> +/* ------------------------------------------------------------- */
> +
> +int xenstore_write_str(const char *base, const char *node, const char *val)
> +{
> +    char abspath[XEN_BUFSIZE];
> +
> +    snprintf(abspath, sizeof(abspath), "%s/%s", base, node);
> +    if (!xs_write(xenstore, 0, abspath, val, strlen(val))) {
> +        return -1;
> +    }
> +    return 0;
> +}
> +
> +char *xenstore_read_str(const char *base, const char *node)
> +{
> +    char abspath[XEN_BUFSIZE];
> +    unsigned int len;
> +    char *str, *ret = NULL;
> +
> +    snprintf(abspath, sizeof(abspath), "%s/%s", base, node);
> +    str = xs_read(xenstore, 0, abspath, &len);
> +    if (str != NULL) {
> +        /* move to qemu-allocated memory to make sure
> +         * callers can savely g_free() stuff. */
> +        ret = g_strdup(str);
> +        free(str);
> +    }
> +    return ret;
> +}
> +
> +int xenstore_write_int(const char *base, const char *node, int ival)
> +{
> +    char val[12];
> +
> +    snprintf(val, sizeof(val), "%d", ival);
> +    return xenstore_write_str(base, node, val);
> +}
> +
> +int xenstore_write_int64(const char *base, const char *node, int64_t ival)
> +{
> +    char val[21];
> +
> +    snprintf(val, sizeof(val), "%"PRId64, ival);
> +    return xenstore_write_str(base, node, val);
> +}
> +
> +int xenstore_read_int(const char *base, const char *node, int *ival)
> +{
> +    char *val;
> +    int rc = -1;
> +
> +    val = xenstore_read_str(base, node);
> +    if (val && 1 == sscanf(val, "%d", ival)) {
> +        rc = 0;
> +    }
> +    g_free(val);
> +    return rc;
> +}
> +
> +int xenstore_read_uint64(const char *base, const char *node, uint64_t *uval)
> +{
> +    char *val;
> +    int rc = -1;
> +
> +    val = xenstore_read_str(base, node);
> +    if (val && 1 == sscanf(val, "%"SCNu64, uval)) {
> +        rc = 0;
> +    }
> +    g_free(val);
> +    return rc;
> +}
> +
> +char *xenstore_get_domain_name(uint32_t domid)
> +{
> +    char *dom_path, *str, *ret = NULL;;
> +
> +    dom_path = xs_get_domain_path(xenstore, domid);
> +    str = xenstore_read_str(dom_path, "name");
> +    free(dom_path);
> +    if (str != NULL) {
> +        ret = g_strdup(str);
> +        free(str);
> +    }
> +
> +    return ret;
> +}
> +
> +/*
> + * Sync internal data structures on xenstore updates.
> + * Node specifies the changed field.  node = NULL means
> + * update all fields (used for initialization).
> + */
> +void xen_be_backend_changed(struct XenDevice *xendev, const char *node)
> +{
> +    if (node == NULL  ||  strcmp(node, "online") == 0) {
> +        if (xenstore_read_be_int(xendev, "online", &xendev->online) == -1) {
> +            xendev->online = 0;
> +        }
> +    }
> +
> +    if (node) {
> +        xen_be_printf(xendev, 2, "backend update: %s\n", node);
> +        if (xendev->ops->backend_changed) {
> +            xendev->ops->backend_changed(xendev, node);
> +        }
> +    }
> +}
> +
> +void xen_be_frontend_changed(struct XenDevice *xendev, const char *node)
> +{
> +    int fe_state;
> +
> +    if (node == NULL  ||  strcmp(node, "state") == 0) {
> +        if (xenstore_read_fe_int(xendev, "state", &fe_state) == -1) {
> +            fe_state = XenbusStateUnknown;
> +        }
> +        if (xendev->fe_state != fe_state) {
> +            xen_be_printf(xendev, 1, "frontend state: %s -> %s\n",
> +                          xenbus_strstate(xendev->fe_state),
> +                          xenbus_strstate(fe_state));
> +        }
> +        xendev->fe_state = fe_state;
> +    }
> +    if (node == NULL  ||  strcmp(node, "protocol") == 0) {
> +        g_free(xendev->protocol);
> +        xendev->protocol = xenstore_read_fe_str(xendev, "protocol");
> +        if (xendev->protocol) {
> +            xen_be_printf(xendev, 1, "frontend protocol: %s\n",
> +                          xendev->protocol);
> +        }
> +    }
> +
> +    if (node) {
> +        xen_be_printf(xendev, 2, "frontend update: %s\n", node);
> +        if (xendev->ops->frontend_changed) {
> +            xendev->ops->frontend_changed(xendev, node);
> +        }
> +    }
> +}
> +
> +static void xenstore_update_be(char *watch, char *type, int dom,
> +                        struct XenDevOps *ops)
> +{
> +    struct XenDevice *xendev;
> +    char path[XEN_BUFSIZE], *bepath;
> +    unsigned int len, dev;
> +
> +    len = snprintf(path, sizeof(path), "backend/%s/%d", type, dom);
> +
> +    if (strstr(watch, path) == NULL) {
> +        return;
> +    }
> +    if (sscanf(watch+len, "/%u/%255s", &dev, path) != 2) {
> +        strcpy(path, "");
> +        if (sscanf(watch+len, "/%u", &dev) != 1) {
> +            dev = -1;
> +        }
> +    }
> +    if (dev == -1) {
> +        return;
> +    }
> +
> +    xendev = xen_be_get_xendev(type, dom, dev, ops);
> +    if (xendev != NULL) {
> +        bepath = xs_read(xenstore, 0, xendev->be, &len);
> +        if (bepath == NULL) {
> +            xen_del_xendev(dom, dev);
> +        } else {
> +            free(bepath);
> +            xen_be_backend_changed(xendev, path);
> +            if (!(ops->flags & DEVOPS_FLAG_FE)) {
> +                xen_be_check_state(xendev);
> +            }
> +        }
> +    }
> +}
> +
> +static void xenstore_update_fe(char *watch, struct XenDevice *xendev)
> +{
> +    char *node;
> +    unsigned int len;
> +
> +    len = strlen(xendev->fe);
> +    if (strncmp(xendev->fe, watch, len) != 0) {
> +        return;
> +    }
> +    if (watch[len] != '/') {
> +        return;
> +    }
> +    node = watch + len + 1;
> +
> +    xen_be_frontend_changed(xendev, node);
> +    xen_be_check_state(xendev);
> +}
> +
> +static void xenstore_update(void *unused)
> +{
> +    char **vec = NULL;
> +    intptr_t type, ops, ptr;
> +    unsigned int dom, count;
> +
> +    vec = xs_read_watch(xenstore, &count);
> +    if (vec == NULL) {
> +        goto cleanup;
> +    }
> +
> +    if (sscanf(vec[XS_WATCH_TOKEN], "be:%" PRIxPTR ":%d:%" PRIxPTR,
> +               &type, &dom, &ops) == 3) {
> +        xenstore_update_be(vec[XS_WATCH_PATH], (void *)type, dom, (void 
> *)ops);
> +    }
> +    if (sscanf(vec[XS_WATCH_TOKEN], "fe:%" PRIxPTR, &ptr) == 1) {
> +        xenstore_update_fe(vec[XS_WATCH_PATH], (void *)ptr);
> +    }
> +
> +cleanup:
> +    free(vec);
> +}
> +
> +int xen_be_init(void)
> +{
> +    xenstore = xs_daemon_open();
> +    if (!xenstore) {
> +        xen_be_printf(NULL, 0, "can't connect to xenstored\n");
> +        return -1;
> +    }
> +
> +    if (qemu_set_fd_handler(xs_fileno(xenstore), xenstore_update,
> +        NULL, NULL) < 0) {
> +        goto err;
> +    }
> +
> +    if (xen_xc == XC_HANDLER_INITIAL_VALUE) {
> +
> +        /* Check if xen_init() have been called */
> +        goto err;
> +    }
> +    return 0;
> +
> +err:
> +    qemu_set_fd_handler(xs_fileno(xenstore), NULL, NULL, NULL);
> +    xs_daemon_close(xenstore);
> +    xenstore = NULL;
> +
> +    return -1;
> +}
> diff --git a/include/hw/xen/xen_backend.h b/include/hw/xen/xen_backend.h
> index 3b4125e..65476bf 100644
> --- a/include/hw/xen/xen_backend.h
> +++ b/include/hw/xen/xen_backend.h
> @@ -15,6 +15,8 @@ struct XenDevice;
>  #define DEVOPS_FLAG_NEED_GNTDEV   1
>  /* don't expect frontend doing correct state transitions (aka console quirk) 
> */
>  #define DEVOPS_FLAG_IGNORE_STATE  2
> +/*dev is frontend device*/
> +#define DEVOPS_FLAG_FE            4
>  
>  struct XenDevOps {
>      size_t    size;
> @@ -77,9 +79,18 @@ int xenstore_read_fe_int(struct XenDevice *xendev, const 
> char *node, int *ival);
>  int xenstore_read_uint64(const char *base, const char *node, uint64_t *uval);
>  int xenstore_read_fe_uint64(struct XenDevice *xendev, const char *node, 
> uint64_t *uval);
>  
> +char *xenstore_get_domain_name(uint32_t domid);
> +
>  const char *xenbus_strstate(enum xenbus_state state);
> -struct XenDevice *xen_be_find_xendev(const char *type, int dom, int dev);
> +struct XenDevice *xen_find_xendev(const char *type, int dom, int dev);
> +struct XenDevice *xen_del_xendev(int dom, int dev);
> +struct XenDevice *xen_be_get_xendev(const char *type, int dom, int dev,
> +                                    struct XenDevOps *ops);
> +struct XenDevice *xen_fe_get_xendev(const char *type, int dom, int dev,
> +                                    char *backend, struct XenDevOps *ops);
>  void xen_be_check_state(struct XenDevice *xendev);
> +void xen_be_backend_changed(struct XenDevice *xendev, const char *node);
> +void xen_be_frontend_changed(struct XenDevice *xendev, const char *node);
>  
>  /* xen backend driver bits */
>  int xen_be_init(void);
> -- 
> 1.8.3.2
>