1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 /*
28  * Talks to Xen Store to figure out what devices we have.
29  *
30  * Copyright (C) 2005 Rusty Russell, IBM Corporation
31  * Copyright (C) 2005 Mike Wray, Hewlett-Packard
32  * Copyright (C) 2005 XenSource Ltd
33  *
34  * This file may be distributed separately from the Linux kernel, or
35  * incorporated into other software packages, subject to the following license:
36  *
37  * Permission is hereby granted, free of charge, to any person obtaining a copy
38  * of this source file (the "Software"), to deal in the Software without
39  * restriction, including without limitation the rights to use, copy, modify,
40  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
41  * and to permit persons to whom the Software is furnished to do so, subject to
42  * the following conditions:
43  *
44  * The above copyright notice and this permission notice shall be included in
45  * all copies or substantial portions of the Software.
46  *
47  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
48  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
49  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
50  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
51  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
52  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
53  * IN THE SOFTWARE.
54  */
55 
56 #ifdef XPV_HVM_DRIVER
57 #include <sys/xpv_support.h>
58 #endif
59 #include <sys/hypervisor.h>
60 #include <xen/sys/xenbus_impl.h>
61 #include <xen/sys/xenbus_comms.h>
62 #include <xen/public/io/xs_wire.h>
63 
64 static int
read_otherend_details(struct xenbus_device * xendev,char * id_node,char * path_node)65 read_otherend_details(struct xenbus_device *xendev,
66 			char *id_node, char *path_node)
67 {
68 	int err = xenbus_gather(XBT_NULL, xendev->nodename,
69 	    id_node, "%i", &xendev->otherend_id, path_node, NULL,
70 	    &xendev->otherend, NULL);
71 	if (err) {
72 		xenbus_dev_fatal(xendev, err,
73 		    "reading other end details from %s", xendev->nodename);
74 		return (err);
75 	}
76 	if (strlen(xendev->otherend) == 0 ||
77 	    !xenbus_exists_dir(xendev->otherend, "")) {
78 		xenbus_dev_fatal(xendev, X_ENOENT, "missing other end from %s",
79 		    xendev->nodename);
80 		kmem_free((void *)xendev->otherend,
81 		    strlen(xendev->otherend) + 1);
82 		xendev->otherend = NULL;
83 		return (X_ENOENT);
84 	}
85 
86 	return (0);
87 }
88 
89 
90 static int
read_backend_details(struct xenbus_device * xendev)91 read_backend_details(struct xenbus_device *xendev)
92 {
93 	return (read_otherend_details(xendev, "backend-id", "backend"));
94 }
95 
96 
97 static int
read_frontend_details(struct xenbus_device * xendev)98 read_frontend_details(struct xenbus_device *xendev)
99 {
100 	return (read_otherend_details(xendev, "frontend-id", "frontend"));
101 }
102 
103 
104 static void
free_otherend_details(struct xenbus_device * dev)105 free_otherend_details(struct xenbus_device *dev)
106 {
107 	if (dev->otherend != NULL) {
108 		kmem_free((void *)dev->otherend, strlen(dev->otherend) + 1);
109 		dev->otherend = NULL;
110 	}
111 }
112 
113 
114 static void
free_otherend_watch(struct xenbus_device * dev)115 free_otherend_watch(struct xenbus_device *dev)
116 {
117 	if (dev->otherend_watch.node) {
118 		unregister_xenbus_watch(&dev->otherend_watch);
119 		kmem_free((void *)dev->otherend_watch.node,
120 		    strlen(dev->otherend_watch.node) + 1);
121 		dev->otherend_watch.node = NULL;
122 	}
123 }
124 
125 
126 /*ARGSUSED2*/
127 static void
otherend_changed(struct xenbus_watch * watch,const char ** vec,unsigned int len)128 otherend_changed(struct xenbus_watch *watch, const char **vec, unsigned int len)
129 {
130 	struct xenbus_device *dev = watch->dev;
131 	XenbusState state;
132 
133 	/*
134 	 * Protect us against watches firing on old details when the otherend
135 	 * details change, say immediately after a resume.
136 	 */
137 	if (!dev->otherend ||
138 	    strncmp(dev->otherend, vec[XS_WATCH_PATH], strlen(dev->otherend))) {
139 #if 0
140 		printf("Ignoring watch at %s", vec[XS_WATCH_PATH]);
141 #endif
142 		return;
143 	}
144 
145 	state = xenbus_read_driver_state(dev->otherend);
146 
147 #if 0
148 	printf("state is %d, %s, %s",
149 	    state, dev->otherend_watch.node, vec[XS_WATCH_PATH]);
150 #endif
151 	if (dev->otherend_changed)
152 		dev->otherend_changed(dev, state);
153 }
154 
155 
156 int
talk_to_otherend(struct xenbus_device * dev)157 talk_to_otherend(struct xenbus_device *dev)
158 {
159 	int err;
160 
161 	free_otherend_watch(dev);
162 	free_otherend_details(dev);
163 
164 	if (dev->frontend)
165 		err = read_backend_details(dev);
166 	else
167 		err = read_frontend_details(dev);
168 	if (err)
169 		return (err);
170 
171 	dev->otherend_watch.dev = dev;
172 	return (xenbus_watch_path2(dev, dev->otherend, "state",
173 	    &dev->otherend_watch, otherend_changed));
174 }
175 
176 
177 /*
178  * Local variables:
179  *  c-file-style: "solaris"
180  *  indent-tabs-mode: t
181  *  c-indent-level: 8
182  *  c-basic-offset: 8
183  *  tab-width: 8
184  * End:
185  */
186