The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/xen/xenbus/xenbusb_back.c

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    1 /******************************************************************************
    2  * Talks to Xen Store to figure out what devices we have.
    3  *
    4  * Copyright (C) 2009, 2010 Spectra Logic Corporation
    5  * Copyright (C) 2008 Doug Rabson
    6  * Copyright (C) 2005 Rusty Russell, IBM Corporation
    7  * Copyright (C) 2005 Mike Wray, Hewlett-Packard
    8  * Copyright (C) 2005 XenSource Ltd
    9  * 
   10  * This file may be distributed separately from the Linux kernel, or
   11  * incorporated into other software packages, subject to the following license:
   12  * 
   13  * Permission is hereby granted, free of charge, to any person obtaining a copy
   14  * of this source file (the "Software"), to deal in the Software without
   15  * restriction, including without limitation the rights to use, copy, modify,
   16  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
   17  * and to permit persons to whom the Software is furnished to do so, subject to
   18  * the following conditions:
   19  * 
   20  * The above copyright notice and this permission notice shall be included in
   21  * all copies or substantial portions of the Software.
   22  * 
   23  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   24  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   25  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   26  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   27  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
   28  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
   29  * IN THE SOFTWARE.
   30  */
   31 
   32 /**
   33  * \file xenbusb_back.c
   34  *
   35  * XenBus management of the NewBus bus containing the backend instances of
   36  * Xen split devices.
   37  */
   38 #include <sys/cdefs.h>
   39 __FBSDID("$FreeBSD: releng/10.0/sys/xen/xenbus/xenbusb_back.c 225704 2011-09-20 23:44:34Z gibbs $");
   40 
   41 #include <sys/param.h>
   42 #include <sys/bus.h>
   43 #include <sys/kernel.h>
   44 #include <sys/lock.h>
   45 #include <sys/malloc.h>
   46 #include <sys/module.h>
   47 #include <sys/sbuf.h>
   48 #include <sys/sysctl.h>
   49 #include <sys/syslog.h>
   50 #include <sys/systm.h>
   51 #include <sys/sx.h>
   52 #include <sys/taskqueue.h>
   53 
   54 #include <machine/xen/xen-os.h>
   55 #include <machine/stdarg.h>
   56 
   57 #include <xen/gnttab.h>
   58 #include <xen/xenbus/xenbusvar.h>
   59 #include <xen/xenbus/xenbusb.h>
   60 
   61 
   62 /*------------------ Private Device Attachment Functions  --------------------*/
   63 /**
   64  * \brief Probe for the existance of the XenBus back bus.
   65  *
   66  * \param dev  NewBus device_t for this XenBus back bus instance.
   67  *
   68  * \return  Always returns 0 indicating success.
   69  */
   70 static int 
   71 xenbusb_back_probe(device_t dev)
   72 {
   73         device_set_desc(dev, "Xen Backend Devices");
   74 
   75         return (0);
   76 }
   77 
   78 /**
   79  * \brief Attach the XenBus back bus.
   80  *
   81  * \param dev  NewBus device_t for this XenBus back bus instance.
   82  *
   83  * \return  On success, 0. Otherwise an errno value indicating the
   84  *          type of failure.
   85  */
   86 static int
   87 xenbusb_back_attach(device_t dev)
   88 {
   89         struct xenbusb_softc *xbs;
   90         int error;
   91 
   92         xbs = device_get_softc(dev);
   93         error = xenbusb_attach(dev, "backend", /*id_components*/2);
   94 
   95         /*
   96          * Backend devices operate to serve other domains,
   97          * so there is no need to hold up boot processing
   98          * while connections to foreign domains are made.
   99          */
  100         mtx_lock(&xbs->xbs_lock);
  101         if ((xbs->xbs_flags & XBS_ATTACH_CH_ACTIVE) != 0) {
  102                 xbs->xbs_flags &= ~XBS_ATTACH_CH_ACTIVE;
  103                 mtx_unlock(&xbs->xbs_lock);
  104                 config_intrhook_disestablish(&xbs->xbs_attach_ch);
  105         } else {
  106                 mtx_unlock(&xbs->xbs_lock);
  107         }
  108 
  109         return (error);
  110 }
  111 
  112 /**
  113  * \brief Enumerate all devices of the given type on this bus.
  114  *
  115  * \param dev   NewBus device_t for this XenBus backend bus instance.
  116  * \param type  String indicating the device sub-tree (e.g. "vfb", "vif")
  117  *              to enumerate. 
  118  *
  119  * \return  On success, 0. Otherwise an errno value indicating the
  120  *          type of failure.
  121  *
  122  * Devices that are found are entered into the NewBus hierarchy via
  123  * xenbusb_add_device().  xenbusb_add_device() ignores duplicate detects
  124  * and ignores duplicate devices, so it can be called unconditionally
  125  * for any device found in the XenStore.
  126  *
  127  * The backend XenStore hierarchy has the following format:
  128  *
  129  *     backend/<device type>/<frontend vm id>/<device id>
  130  *
  131  */
  132 static int
  133 xenbusb_back_enumerate_type(device_t dev, const char *type)
  134 {
  135         struct xenbusb_softc *xbs;
  136         const char **vms;
  137         u_int vm_idx;
  138         u_int vm_count;
  139         int error;
  140 
  141         xbs = device_get_softc(dev);
  142         error = xs_directory(XST_NIL, xbs->xbs_node, type, &vm_count, &vms);
  143         if (error)
  144                 return (error);
  145         for (vm_idx = 0; vm_idx < vm_count; vm_idx++) {
  146                 struct sbuf *vm_path;
  147                 const char *vm;
  148                 const char **devs;
  149                 u_int dev_idx;
  150                 u_int dev_count;
  151 
  152                 vm = vms[vm_idx];
  153 
  154                 vm_path = xs_join(type, vm);
  155                 error = xs_directory(XST_NIL, xbs->xbs_node, sbuf_data(vm_path),
  156                     &dev_count, &devs);
  157                 sbuf_delete(vm_path);
  158                 if (error)
  159                         break;
  160 
  161                 for (dev_idx = 0; dev_idx < dev_count; dev_idx++) {
  162                         const char *dev_num;
  163                         struct sbuf *id;
  164                         
  165                         dev_num = devs[dev_idx];
  166                         id = xs_join(vm, dev_num);
  167                         xenbusb_add_device(dev, type, sbuf_data(id));
  168                         sbuf_delete(id);
  169                 }
  170                 free(devs, M_XENSTORE);
  171         }
  172 
  173         free(vms, M_XENSTORE);
  174 
  175         return (0);
  176 }
  177 
  178 /**
  179  * \brief Determine and store the XenStore path for the other end of
  180  *        a split device whose local end is represented by ivars.
  181  *
  182  * \param dev    NewBus device_t for this XenBus backend bus instance.
  183  * \param ivars  Instance variables from the XenBus child device for
  184  *               which to perform this function.
  185  *
  186  * \return  On success, 0. Otherwise an errno value indicating the
  187  *          type of failure.
  188  *
  189  * If successful, the xd_otherend_path field of the child's instance
  190  * variables will be updated.
  191  *
  192  */
  193 static int
  194 xenbusb_back_get_otherend_node(device_t dev, struct xenbus_device_ivars *ivars)
  195 {
  196         char *otherend_path;
  197         int error;
  198 
  199         if (ivars->xd_otherend_path != NULL) {
  200                 free(ivars->xd_otherend_path, M_XENBUS);
  201                 ivars->xd_otherend_path = NULL;
  202         }
  203                 
  204         error = xs_gather(XST_NIL, ivars->xd_node,
  205             "frontend-id", "%i", &ivars->xd_otherend_id,
  206             "frontend", NULL, &otherend_path,
  207             NULL);
  208 
  209         if (error == 0) {
  210                 ivars->xd_otherend_path = strdup(otherend_path, M_XENBUS);
  211                 ivars->xd_otherend_path_len = strlen(otherend_path);
  212                 free(otherend_path, M_XENSTORE);
  213         }
  214         return (error);
  215 }
  216 
  217 /**
  218  * \brief Backend XenBus method implementing responses to peer state changes.
  219  * 
  220  * \param bus       The XenBus bus parent of child.
  221  * \param child     The XenBus child whose peer stat has changed.
  222  * \param state     The current state of the peer.
  223  */
  224 static void
  225 xenbusb_back_otherend_changed(device_t bus, device_t child,
  226                               enum xenbus_state peer_state)
  227 {
  228         /* Perform default processing of state. */
  229         xenbusb_otherend_changed(bus, child, peer_state);
  230 
  231         /*
  232          * "Online" devices are never fully detached in the
  233          * newbus sense.  Only the front<->back connection is
  234          * torn down.  If the front returns to the initialising
  235          * state after closing a previous connection, signal
  236          * our willingness to reconnect and that all necessary
  237          * XenStore data for feature negotiation is present.
  238          */
  239         if (peer_state == XenbusStateInitialising
  240          && xenbus_dev_is_online(child) != 0
  241          && xenbus_get_state(child) == XenbusStateClosed)
  242                 xenbus_set_state(child, XenbusStateInitWait);
  243 }
  244 
  245 /**
  246  * \brief Backend XenBus method implementing responses to local
  247  *        XenStore changes.
  248  * 
  249  * \param bus    The XenBus bus parent of child.
  250  * \param child  The XenBus child whose peer stat has changed.
  251  * \param_path   The tree relative sub-path to the modified node.  The empty
  252  *               string indicates the root of the tree was destroyed.
  253  */
  254 static void
  255 xenbusb_back_localend_changed(device_t bus, device_t child, const char *path)
  256 {
  257 
  258         xenbusb_localend_changed(bus, child, path);
  259 
  260         if (strcmp(path, "/state") != 0
  261          && strcmp(path, "/online") != 0)
  262                 return;
  263 
  264         if (xenbus_get_state(child) != XenbusStateClosed
  265          || xenbus_dev_is_online(child) != 0)
  266                 return;
  267 
  268         /*
  269          * Cleanup the hotplug entry in the XenStore if
  270          * present.  The control domain expects any userland
  271          * component associated with this device to destroy
  272          * this node in order to signify it is safe to 
  273          * teardown the device.  However, not all backends
  274          * rely on userland components, and those that
  275          * do should either use a communication channel
  276          * other than the XenStore, or ensure the hotplug
  277          * data is already cleaned up.
  278          *
  279          * This removal ensures that no matter what path
  280          * is taken to mark a back-end closed, the control
  281          * domain will understand that it is closed.
  282          */
  283         xs_rm(XST_NIL, xenbus_get_node(child), "hotplug-status");
  284 }
  285 
  286 /*-------------------- Private Device Attachment Data  -----------------------*/
  287 static device_method_t xenbusb_back_methods[] = { 
  288         /* Device interface */ 
  289         DEVMETHOD(device_identify,      xenbusb_identify),
  290         DEVMETHOD(device_probe,         xenbusb_back_probe), 
  291         DEVMETHOD(device_attach,        xenbusb_back_attach), 
  292         DEVMETHOD(device_detach,        bus_generic_detach), 
  293         DEVMETHOD(device_shutdown,      bus_generic_shutdown), 
  294         DEVMETHOD(device_suspend,       bus_generic_suspend), 
  295         DEVMETHOD(device_resume,        xenbusb_resume), 
  296  
  297         /* Bus Interface */ 
  298         DEVMETHOD(bus_print_child,      xenbusb_print_child),
  299         DEVMETHOD(bus_read_ivar,        xenbusb_read_ivar), 
  300         DEVMETHOD(bus_write_ivar,       xenbusb_write_ivar), 
  301         DEVMETHOD(bus_alloc_resource,   bus_generic_alloc_resource),
  302         DEVMETHOD(bus_release_resource, bus_generic_release_resource),
  303         DEVMETHOD(bus_activate_resource, bus_generic_activate_resource),
  304         DEVMETHOD(bus_deactivate_resource, bus_generic_deactivate_resource),
  305  
  306         /* XenBus Bus Interface */
  307         DEVMETHOD(xenbusb_enumerate_type, xenbusb_back_enumerate_type),
  308         DEVMETHOD(xenbusb_get_otherend_node, xenbusb_back_get_otherend_node),
  309         DEVMETHOD(xenbusb_otherend_changed, xenbusb_back_otherend_changed),
  310         DEVMETHOD(xenbusb_localend_changed, xenbusb_back_localend_changed),
  311         { 0, 0 } 
  312 }; 
  313 
  314 DEFINE_CLASS_0(xenbusb_back, xenbusb_back_driver, xenbusb_back_methods,
  315                sizeof(struct xenbusb_softc));
  316 devclass_t xenbusb_back_devclass; 
  317  
  318 DRIVER_MODULE(xenbusb_back, xenstore, xenbusb_back_driver,
  319               xenbusb_back_devclass, 0, 0);

Cache object: 983becc350f1b110f27a560708ca4f9b


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