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
xenbusb_back_probe(device_t dev)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
xenbusb_back_attach(device_t dev)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
xenbusb_back_enumerate_type(device_t dev,const char * type)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
xenbusb_back_get_otherend_node(device_t dev,struct xenbus_device_ivars * ivars)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
xenbusb_back_otherend_changed(device_t bus,device_t child,enum xenbus_state peer_state)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
xenbusb_back_localend_changed(device_t bus,device_t child,const char * path)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