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("$FreeBSD$"); 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); 320