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