1 /****************************************************************************** 2 * Talks to Xen Store to figure out what devices we have (backend half). 3 * 4 * Copyright (C) 2005 Rusty Russell, IBM Corporation 5 * Copyright (C) 2005 Mike Wray, Hewlett-Packard 6 * Copyright (C) 2005, 2006 XenSource Ltd 7 * Copyright (C) 2007 Solarflare Communications, Inc. 8 * 9 * This program is free software; you can redistribute it and/or 10 * modify it under the terms of the GNU General Public License version 2 11 * as published by the Free Software Foundation; or, when distributed 12 * separately from the Linux kernel or incorporated into other 13 * software packages, subject to the following license: 14 * 15 * Permission is hereby granted, free of charge, to any person obtaining a copy 16 * of this source file (the "Software"), to deal in the Software without 17 * restriction, including without limitation the rights to use, copy, modify, 18 * merge, publish, distribute, sublicense, and/or sell copies of the Software, 19 * and to permit persons to whom the Software is furnished to do so, subject to 20 * the following conditions: 21 * 22 * The above copyright notice and this permission notice shall be included in 23 * all copies or substantial portions of the Software. 24 * 25 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 26 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 27 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 28 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 29 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 30 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 31 * IN THE SOFTWARE. 32 */ 33 34 #define DPRINTK(fmt, args...) \ 35 pr_debug("xenbus_probe (%s:%d) " fmt ".\n", \ 36 __func__, __LINE__, ##args) 37 38 #include <linux/kernel.h> 39 #include <linux/err.h> 40 #include <linux/string.h> 41 #include <linux/ctype.h> 42 #include <linux/fcntl.h> 43 #include <linux/mm.h> 44 #include <linux/notifier.h> 45 #include <linux/export.h> 46 47 #include <asm/page.h> 48 #include <asm/pgtable.h> 49 #include <asm/xen/hypervisor.h> 50 #include <asm/hypervisor.h> 51 #include <xen/xenbus.h> 52 #include <xen/features.h> 53 54 #include "xenbus_comms.h" 55 #include "xenbus_probe.h" 56 57 /* backend/<type>/<fe-uuid>/<id> => <type>-<fe-domid>-<id> */ 58 static int backend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename) 59 { 60 int domid, err; 61 const char *devid, *type, *frontend; 62 unsigned int typelen; 63 64 type = strchr(nodename, '/'); 65 if (!type) 66 return -EINVAL; 67 type++; 68 typelen = strcspn(type, "/"); 69 if (!typelen || type[typelen] != '/') 70 return -EINVAL; 71 72 devid = strrchr(nodename, '/') + 1; 73 74 err = xenbus_gather(XBT_NIL, nodename, "frontend-id", "%i", &domid, 75 "frontend", NULL, &frontend, 76 NULL); 77 if (err) 78 return err; 79 if (strlen(frontend) == 0) 80 err = -ERANGE; 81 if (!err && !xenbus_exists(XBT_NIL, frontend, "")) 82 err = -ENOENT; 83 kfree(frontend); 84 85 if (err) 86 return err; 87 88 if (snprintf(bus_id, XEN_BUS_ID_SIZE, "%.*s-%i-%s", 89 typelen, type, domid, devid) >= XEN_BUS_ID_SIZE) 90 return -ENOSPC; 91 return 0; 92 } 93 94 static int xenbus_uevent_backend(struct device *dev, 95 struct kobj_uevent_env *env) 96 { 97 struct xenbus_device *xdev; 98 struct xenbus_driver *drv; 99 struct xen_bus_type *bus; 100 101 DPRINTK(""); 102 103 if (dev == NULL) 104 return -ENODEV; 105 106 xdev = to_xenbus_device(dev); 107 bus = container_of(xdev->dev.bus, struct xen_bus_type, bus); 108 109 if (add_uevent_var(env, "MODALIAS=xen-backend:%s", xdev->devicetype)) 110 return -ENOMEM; 111 112 /* stuff we want to pass to /sbin/hotplug */ 113 if (add_uevent_var(env, "XENBUS_TYPE=%s", xdev->devicetype)) 114 return -ENOMEM; 115 116 if (add_uevent_var(env, "XENBUS_PATH=%s", xdev->nodename)) 117 return -ENOMEM; 118 119 if (add_uevent_var(env, "XENBUS_BASE_PATH=%s", bus->root)) 120 return -ENOMEM; 121 122 if (dev->driver) { 123 drv = to_xenbus_driver(dev->driver); 124 if (drv && drv->uevent) 125 return drv->uevent(xdev, env); 126 } 127 128 return 0; 129 } 130 131 /* backend/<typename>/<frontend-uuid>/<name> */ 132 static int xenbus_probe_backend_unit(struct xen_bus_type *bus, 133 const char *dir, 134 const char *type, 135 const char *name) 136 { 137 char *nodename; 138 int err; 139 140 nodename = kasprintf(GFP_KERNEL, "%s/%s", dir, name); 141 if (!nodename) 142 return -ENOMEM; 143 144 DPRINTK("%s\n", nodename); 145 146 err = xenbus_probe_node(bus, type, nodename); 147 kfree(nodename); 148 return err; 149 } 150 151 /* backend/<typename>/<frontend-domid> */ 152 static int xenbus_probe_backend(struct xen_bus_type *bus, const char *type, 153 const char *domid) 154 { 155 char *nodename; 156 int err = 0; 157 char **dir; 158 unsigned int i, dir_n = 0; 159 160 DPRINTK(""); 161 162 nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, domid); 163 if (!nodename) 164 return -ENOMEM; 165 166 dir = xenbus_directory(XBT_NIL, nodename, "", &dir_n); 167 if (IS_ERR(dir)) { 168 kfree(nodename); 169 return PTR_ERR(dir); 170 } 171 172 for (i = 0; i < dir_n; i++) { 173 err = xenbus_probe_backend_unit(bus, nodename, type, dir[i]); 174 if (err) 175 break; 176 } 177 kfree(dir); 178 kfree(nodename); 179 return err; 180 } 181 182 static void frontend_changed(struct xenbus_watch *watch, 183 const char **vec, unsigned int len) 184 { 185 xenbus_otherend_changed(watch, vec, len, 0); 186 } 187 188 static struct xen_bus_type xenbus_backend = { 189 .root = "backend", 190 .levels = 3, /* backend/type/<frontend>/<id> */ 191 .get_bus_id = backend_bus_id, 192 .probe = xenbus_probe_backend, 193 .otherend_changed = frontend_changed, 194 .bus = { 195 .name = "xen-backend", 196 .match = xenbus_match, 197 .uevent = xenbus_uevent_backend, 198 .probe = xenbus_dev_probe, 199 .remove = xenbus_dev_remove, 200 .shutdown = xenbus_dev_shutdown, 201 .dev_attrs = xenbus_dev_attrs, 202 }, 203 }; 204 205 static void backend_changed(struct xenbus_watch *watch, 206 const char **vec, unsigned int len) 207 { 208 DPRINTK(""); 209 210 xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_backend); 211 } 212 213 static struct xenbus_watch be_watch = { 214 .node = "backend", 215 .callback = backend_changed, 216 }; 217 218 static int read_frontend_details(struct xenbus_device *xendev) 219 { 220 return xenbus_read_otherend_details(xendev, "frontend-id", "frontend"); 221 } 222 223 int xenbus_dev_is_online(struct xenbus_device *dev) 224 { 225 int rc, val; 226 227 rc = xenbus_scanf(XBT_NIL, dev->nodename, "online", "%d", &val); 228 if (rc != 1) 229 val = 0; /* no online node present */ 230 231 return val; 232 } 233 EXPORT_SYMBOL_GPL(xenbus_dev_is_online); 234 235 int xenbus_register_backend(struct xenbus_driver *drv) 236 { 237 drv->read_otherend_details = read_frontend_details; 238 239 return xenbus_register_driver_common(drv, &xenbus_backend); 240 } 241 EXPORT_SYMBOL_GPL(xenbus_register_backend); 242 243 static int backend_probe_and_watch(struct notifier_block *notifier, 244 unsigned long event, 245 void *data) 246 { 247 /* Enumerate devices in xenstore and watch for changes. */ 248 xenbus_probe_devices(&xenbus_backend); 249 register_xenbus_watch(&be_watch); 250 251 return NOTIFY_DONE; 252 } 253 254 static int __init xenbus_probe_backend_init(void) 255 { 256 static struct notifier_block xenstore_notifier = { 257 .notifier_call = backend_probe_and_watch 258 }; 259 int err; 260 261 DPRINTK(""); 262 263 /* Register ourselves with the kernel bus subsystem */ 264 err = bus_register(&xenbus_backend.bus); 265 if (err) 266 return err; 267 268 register_xenstore_notifier(&xenstore_notifier); 269 270 return 0; 271 } 272 subsys_initcall(xenbus_probe_backend_init); 273