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 39 #include <sys/param.h> 40 #include <sys/bus.h> 41 #include <sys/kernel.h> 42 #include <sys/lock.h> 43 #include <sys/malloc.h> 44 #include <sys/module.h> 45 #include <sys/sbuf.h> 46 #include <sys/stdarg.h> 47 #include <sys/sysctl.h> 48 #include <sys/syslog.h> 49 #include <sys/systm.h> 50 #include <sys/sx.h> 51 #include <sys/taskqueue.h> 52 53 #include <xen/xen-os.h> 54 #include <xen/gnttab.h> 55 #include <xen/xenbus/xenbusvar.h> 56 #include <xen/xenbus/xenbusb.h> 57 58 /*------------------ Private Device Attachment Functions --------------------*/ 59 /** 60 * \brief Probe for the existence of the XenBus back bus. 61 * 62 * \param dev NewBus device_t for this XenBus back bus instance. 63 * 64 * \return Always returns 0 indicating success. 65 */ 66 static int 67 xenbusb_back_probe(device_t dev) 68 { 69 device_set_desc(dev, "Xen Backend Devices"); 70 71 return (0); 72 } 73 74 /** 75 * \brief Attach the XenBus back bus. 76 * 77 * \param dev NewBus device_t for this XenBus back bus instance. 78 * 79 * \return On success, 0. Otherwise an errno value indicating the 80 * type of failure. 81 */ 82 static int 83 xenbusb_back_attach(device_t dev) 84 { 85 struct xenbusb_softc *xbs; 86 int error; 87 88 xbs = device_get_softc(dev); 89 error = xenbusb_attach(dev, "backend", /*id_components*/2); 90 91 /* 92 * Backend devices operate to serve other domains, 93 * so there is no need to hold up boot processing 94 * while connections to foreign domains are made. 95 */ 96 mtx_lock(&xbs->xbs_lock); 97 if ((xbs->xbs_flags & XBS_ATTACH_CH_ACTIVE) != 0) { 98 xbs->xbs_flags &= ~XBS_ATTACH_CH_ACTIVE; 99 mtx_unlock(&xbs->xbs_lock); 100 config_intrhook_disestablish(&xbs->xbs_attach_ch); 101 } else { 102 mtx_unlock(&xbs->xbs_lock); 103 } 104 105 return (error); 106 } 107 108 /** 109 * \brief Enumerate all devices of the given type on this bus. 110 * 111 * \param dev NewBus device_t for this XenBus backend bus instance. 112 * \param type String indicating the device sub-tree (e.g. "vfb", "vif") 113 * to enumerate. 114 * 115 * \return On success, 0. Otherwise an errno value indicating the 116 * type of failure. 117 * 118 * Devices that are found are entered into the NewBus hierarchy via 119 * xenbusb_add_device(). xenbusb_add_device() ignores duplicate detects 120 * and ignores duplicate devices, so it can be called unconditionally 121 * for any device found in the XenStore. 122 * 123 * The backend XenStore hierarchy has the following format: 124 * 125 * backend/<device type>/<frontend vm id>/<device id> 126 * 127 */ 128 static int 129 xenbusb_back_enumerate_type(device_t dev, const char *type) 130 { 131 struct xenbusb_softc *xbs; 132 const char **vms; 133 u_int vm_idx; 134 u_int vm_count; 135 int error; 136 137 xbs = device_get_softc(dev); 138 error = xs_directory(XST_NIL, xbs->xbs_node, type, &vm_count, &vms); 139 if (error) 140 return (error); 141 for (vm_idx = 0; vm_idx < vm_count; vm_idx++) { 142 struct sbuf *vm_path; 143 const char *vm; 144 const char **devs; 145 u_int dev_idx; 146 u_int dev_count; 147 148 vm = vms[vm_idx]; 149 150 vm_path = xs_join(type, vm); 151 error = xs_directory(XST_NIL, xbs->xbs_node, sbuf_data(vm_path), 152 &dev_count, &devs); 153 sbuf_delete(vm_path); 154 if (error) 155 break; 156 157 for (dev_idx = 0; dev_idx < dev_count; dev_idx++) { 158 const char *dev_num; 159 struct sbuf *id; 160 161 dev_num = devs[dev_idx]; 162 id = xs_join(vm, dev_num); 163 xenbusb_add_device(dev, type, sbuf_data(id)); 164 sbuf_delete(id); 165 } 166 free(devs, M_XENSTORE); 167 } 168 169 free(vms, M_XENSTORE); 170 171 return (0); 172 } 173 174 /** 175 * \brief Determine and store the XenStore path for the other end of 176 * a split device whose local end is represented by ivars. 177 * 178 * \param dev NewBus device_t for this XenBus backend bus instance. 179 * \param ivars Instance variables from the XenBus child device for 180 * which to perform this function. 181 * 182 * \return On success, 0. Otherwise an errno value indicating the 183 * type of failure. 184 * 185 * If successful, the xd_otherend_path field of the child's instance 186 * variables will be updated. 187 * 188 */ 189 static int 190 xenbusb_back_get_otherend_node(device_t dev, struct xenbus_device_ivars *ivars) 191 { 192 char *otherend_path; 193 int error; 194 195 if (ivars->xd_otherend_path != NULL) { 196 free(ivars->xd_otherend_path, M_XENBUS); 197 ivars->xd_otherend_path = NULL; 198 } 199 200 error = xs_gather(XST_NIL, ivars->xd_node, 201 "frontend-id", "%i", &ivars->xd_otherend_id, 202 "frontend", NULL, &otherend_path, 203 NULL); 204 205 if (error == 0) { 206 ivars->xd_otherend_path = strdup(otherend_path, M_XENBUS); 207 ivars->xd_otherend_path_len = strlen(otherend_path); 208 free(otherend_path, M_XENSTORE); 209 } 210 return (error); 211 } 212 213 /** 214 * \brief Backend XenBus method implementing responses to peer state changes. 215 * 216 * \param bus The XenBus bus parent of child. 217 * \param child The XenBus child whose peer stat has changed. 218 * \param state The current state of the peer. 219 */ 220 static void 221 xenbusb_back_otherend_changed(device_t bus, device_t child, 222 enum xenbus_state peer_state) 223 { 224 /* Perform default processing of state. */ 225 xenbusb_otherend_changed(bus, child, peer_state); 226 227 /* 228 * "Online" devices are never fully detached in the 229 * newbus sense. Only the front<->back connection is 230 * torn down. If the front returns to the initialising 231 * state after closing a previous connection, signal 232 * our willingness to reconnect and that all necessary 233 * XenStore data for feature negotiation is present. 234 */ 235 if (peer_state == XenbusStateInitialising 236 && xenbus_dev_is_online(child) != 0 237 && xenbus_get_state(child) == XenbusStateClosed) 238 xenbus_set_state(child, XenbusStateInitWait); 239 } 240 241 /** 242 * \brief Backend XenBus method implementing responses to local 243 * XenStore changes. 244 * 245 * \param bus The XenBus bus parent of child. 246 * \param child The XenBus child whose peer stat has changed. 247 * \param_path The tree relative sub-path to the modified node. The empty 248 * string indicates the root of the tree was destroyed. 249 */ 250 static void 251 xenbusb_back_localend_changed(device_t bus, device_t child, const char *path) 252 { 253 254 xenbusb_localend_changed(bus, child, path); 255 256 if (strcmp(path, "/state") != 0 257 && strcmp(path, "/online") != 0) 258 return; 259 260 if (xenbus_get_state(child) != XenbusStateClosed 261 || xenbus_dev_is_online(child) != 0) 262 return; 263 264 /* 265 * Cleanup the hotplug entry in the XenStore if 266 * present. The control domain expects any userland 267 * component associated with this device to destroy 268 * this node in order to signify it is safe to 269 * teardown the device. However, not all backends 270 * rely on userland components, and those that 271 * do should either use a communication channel 272 * other than the XenStore, or ensure the hotplug 273 * data is already cleaned up. 274 * 275 * This removal ensures that no matter what path 276 * is taken to mark a back-end closed, the control 277 * domain will understand that it is closed. 278 */ 279 xs_rm(XST_NIL, xenbus_get_node(child), "hotplug-status"); 280 } 281 282 /*-------------------- Private Device Attachment Data -----------------------*/ 283 static device_method_t xenbusb_back_methods[] = { 284 /* Device interface */ 285 DEVMETHOD(device_identify, xenbusb_identify), 286 DEVMETHOD(device_probe, xenbusb_back_probe), 287 DEVMETHOD(device_attach, xenbusb_back_attach), 288 DEVMETHOD(device_detach, bus_generic_detach), 289 DEVMETHOD(device_shutdown, bus_generic_shutdown), 290 DEVMETHOD(device_suspend, bus_generic_suspend), 291 DEVMETHOD(device_resume, xenbusb_resume), 292 293 /* Bus Interface */ 294 DEVMETHOD(bus_print_child, xenbusb_print_child), 295 DEVMETHOD(bus_read_ivar, xenbusb_read_ivar), 296 DEVMETHOD(bus_write_ivar, xenbusb_write_ivar), 297 DEVMETHOD(bus_alloc_resource, bus_generic_alloc_resource), 298 DEVMETHOD(bus_release_resource, bus_generic_release_resource), 299 DEVMETHOD(bus_activate_resource, bus_generic_activate_resource), 300 DEVMETHOD(bus_deactivate_resource, bus_generic_deactivate_resource), 301 302 /* XenBus Bus Interface */ 303 DEVMETHOD(xenbusb_enumerate_type, xenbusb_back_enumerate_type), 304 DEVMETHOD(xenbusb_get_otherend_node, xenbusb_back_get_otherend_node), 305 DEVMETHOD(xenbusb_otherend_changed, xenbusb_back_otherend_changed), 306 DEVMETHOD(xenbusb_localend_changed, xenbusb_back_localend_changed), 307 308 DEVMETHOD_END 309 }; 310 311 DEFINE_CLASS_0(xenbusb_back, xenbusb_back_driver, xenbusb_back_methods, 312 sizeof(struct xenbusb_softc)); 313 314 DRIVER_MODULE(xenbusb_back, xenstore, xenbusb_back_driver, 0, 0); 315