| 1 | /* $NetBSD: xenbus_client.c,v 1.13 2014/09/21 12:46:15 bouyer Exp $ */ |
| 2 | /****************************************************************************** |
| 3 | * Client-facing interface for the Xenbus driver. In other words, the |
| 4 | * interface between the Xenbus and the device-specific code, be it the |
| 5 | * frontend or the backend of that driver. |
| 6 | * |
| 7 | * Copyright (C) 2005 XenSource Ltd |
| 8 | * |
| 9 | * This file may be distributed separately from the Linux kernel, or |
| 10 | * incorporated into other software packages, subject to the following license: |
| 11 | * |
| 12 | * Permission is hereby granted, free of charge, to any person obtaining a copy |
| 13 | * of this source file (the "Software"), to deal in the Software without |
| 14 | * restriction, including without limitation the rights to use, copy, modify, |
| 15 | * merge, publish, distribute, sublicense, and/or sell copies of the Software, |
| 16 | * and to permit persons to whom the Software is furnished to do so, subject to |
| 17 | * the following conditions: |
| 18 | * |
| 19 | * The above copyright notice and this permission notice shall be included in |
| 20 | * all copies or substantial portions of the Software. |
| 21 | * |
| 22 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| 23 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| 24 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| 25 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| 26 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
| 27 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS |
| 28 | * IN THE SOFTWARE. |
| 29 | */ |
| 30 | |
| 31 | #include <sys/cdefs.h> |
| 32 | __KERNEL_RCSID(0, "$NetBSD: xenbus_client.c,v 1.13 2014/09/21 12:46:15 bouyer Exp $" ); |
| 33 | |
| 34 | #if 0 |
| 35 | #define DPRINTK(fmt, args...) \ |
| 36 | printk("xenbus_client (%s:%d) " fmt ".\n", __func__, __LINE__, ##args) |
| 37 | #else |
| 38 | #define DPRINTK(fmt, args...) ((void)0) |
| 39 | #endif |
| 40 | |
| 41 | #include <sys/types.h> |
| 42 | #include <sys/null.h> |
| 43 | #include <sys/errno.h> |
| 44 | #include <sys/malloc.h> |
| 45 | #include <sys/systm.h> |
| 46 | |
| 47 | #include <xen/xen.h> |
| 48 | #include <xen/hypervisor.h> |
| 49 | #include <xen/evtchn.h> |
| 50 | #include <xen/xenbus.h> |
| 51 | #include <xen/granttables.h> |
| 52 | |
| 53 | |
| 54 | int |
| 55 | xenbus_watch_path(struct xenbus_device *dev, char *path, |
| 56 | struct xenbus_watch *watch, |
| 57 | void (*callback)(struct xenbus_watch *, |
| 58 | const char **, unsigned int)) |
| 59 | { |
| 60 | int err; |
| 61 | |
| 62 | watch->node = path; |
| 63 | watch->xbw_callback = callback; |
| 64 | |
| 65 | err = register_xenbus_watch(watch); |
| 66 | |
| 67 | if (err) { |
| 68 | watch->node = NULL; |
| 69 | watch->xbw_callback = NULL; |
| 70 | xenbus_dev_fatal(dev, err, "adding watch on %s" , path); |
| 71 | } |
| 72 | err = 0; |
| 73 | |
| 74 | return err; |
| 75 | } |
| 76 | |
| 77 | int |
| 78 | xenbus_watch_path2(struct xenbus_device *dev, const char *path, |
| 79 | const char *path2, struct xenbus_watch *watch, |
| 80 | void (*callback)(struct xenbus_watch *, |
| 81 | const char **, unsigned int)) |
| 82 | { |
| 83 | int err; |
| 84 | char *state; |
| 85 | |
| 86 | DPRINTK("xenbus_watch_path2 path %s path2 %s\n" , path, path2); |
| 87 | state = |
| 88 | malloc(strlen(path) + 1 + strlen(path2) + 1, M_DEVBUF, |
| 89 | M_NOWAIT); |
| 90 | if (!state) { |
| 91 | xenbus_dev_fatal(dev, ENOMEM, "allocating path for watch" ); |
| 92 | return ENOMEM; |
| 93 | } |
| 94 | strcpy(state, path); |
| 95 | strcat(state, "/" ); |
| 96 | strcat(state, path2); |
| 97 | |
| 98 | err = xenbus_watch_path(dev, state, watch, callback); |
| 99 | |
| 100 | if (err) { |
| 101 | free(state, M_DEVBUF); |
| 102 | } |
| 103 | return err; |
| 104 | } |
| 105 | |
| 106 | |
| 107 | int |
| 108 | xenbus_switch_state(struct xenbus_device *dev, |
| 109 | struct xenbus_transaction *xbt, |
| 110 | XenbusState state) |
| 111 | { |
| 112 | /* We check whether the state is currently set to the given value, and |
| 113 | if not, then the state is set. We don't want to unconditionally |
| 114 | write the given state, because we don't want to fire watches |
| 115 | unnecessarily. Furthermore, if the node has gone, we don't write |
| 116 | to it, as the device will be tearing down, and we don't want to |
| 117 | resurrect that directory. |
| 118 | */ |
| 119 | |
| 120 | u_long current_state; |
| 121 | |
| 122 | int err = xenbus_read_ul(xbt, dev->xbusd_path, "state" , |
| 123 | ¤t_state, 10); |
| 124 | if (err) |
| 125 | return 0; |
| 126 | |
| 127 | if ((XenbusState)current_state == state) |
| 128 | return 0; |
| 129 | |
| 130 | err = xenbus_printf(xbt, dev->xbusd_path, "state" , "%d" , state); |
| 131 | if (err) { |
| 132 | xenbus_dev_fatal(dev, err, "writing new state" ); |
| 133 | return err; |
| 134 | } |
| 135 | return 0; |
| 136 | } |
| 137 | |
| 138 | /** |
| 139 | * Return the path to the error node for the given device, or NULL on failure. |
| 140 | * If the value returned is non-NULL, then it is the caller's to kfree. |
| 141 | */ |
| 142 | static char * |
| 143 | error_path(struct xenbus_device *dev) |
| 144 | { |
| 145 | char *path_buffer = malloc(strlen("error/" ) + strlen(dev->xbusd_path) + |
| 146 | 1, M_DEVBUF, M_NOWAIT); |
| 147 | if (path_buffer == NULL) { |
| 148 | return NULL; |
| 149 | } |
| 150 | |
| 151 | strcpy(path_buffer, "error/" ); |
| 152 | strcpy(path_buffer + strlen("error/" ), dev->xbusd_path); |
| 153 | |
| 154 | return path_buffer; |
| 155 | } |
| 156 | |
| 157 | |
| 158 | static void |
| 159 | _dev_error(struct xenbus_device *dev, int err, const char *fmt, |
| 160 | va_list ap) |
| 161 | { |
| 162 | int ret __diagused; |
| 163 | unsigned int len; |
| 164 | char *printf_buffer = NULL, *path_buffer = NULL; |
| 165 | |
| 166 | #define PRINTF_BUFFER_SIZE 4096 |
| 167 | printf_buffer = malloc(PRINTF_BUFFER_SIZE, M_DEVBUF, M_NOWAIT); |
| 168 | if (printf_buffer == NULL) |
| 169 | goto fail; |
| 170 | |
| 171 | len = snprintf(printf_buffer, PRINTF_BUFFER_SIZE, "%i " , -err); |
| 172 | KASSERT(len < PRINTF_BUFFER_SIZE); |
| 173 | ret = vsnprintf(printf_buffer+len, PRINTF_BUFFER_SIZE-len, fmt, ap); |
| 174 | KASSERT(len + ret < PRINTF_BUFFER_SIZE); |
| 175 | dev->xbusd_has_error = 1; |
| 176 | |
| 177 | path_buffer = error_path(dev); |
| 178 | |
| 179 | if (path_buffer == NULL) { |
| 180 | printk("xenbus: failed to write error node for %s (%s)\n" , |
| 181 | dev->xbusd_path, printf_buffer); |
| 182 | goto fail; |
| 183 | } |
| 184 | |
| 185 | if (xenbus_write(NULL, path_buffer, "error" , printf_buffer) != 0) { |
| 186 | printk("xenbus: failed to write error node for %s (%s)\n" , |
| 187 | dev->xbusd_path, printf_buffer); |
| 188 | goto fail; |
| 189 | } |
| 190 | |
| 191 | fail: |
| 192 | if (printf_buffer) |
| 193 | free(printf_buffer, M_DEVBUF); |
| 194 | if (path_buffer) |
| 195 | free(path_buffer, M_DEVBUF); |
| 196 | } |
| 197 | |
| 198 | |
| 199 | void |
| 200 | xenbus_dev_error(struct xenbus_device *dev, int err, const char *fmt, |
| 201 | ...) |
| 202 | { |
| 203 | va_list ap; |
| 204 | |
| 205 | va_start(ap, fmt); |
| 206 | _dev_error(dev, err, fmt, ap); |
| 207 | va_end(ap); |
| 208 | } |
| 209 | |
| 210 | |
| 211 | void |
| 212 | xenbus_dev_fatal(struct xenbus_device *dev, int err, const char *fmt, |
| 213 | ...) |
| 214 | { |
| 215 | va_list ap; |
| 216 | |
| 217 | va_start(ap, fmt); |
| 218 | _dev_error(dev, err, fmt, ap); |
| 219 | va_end(ap); |
| 220 | |
| 221 | xenbus_switch_state(dev, NULL, XenbusStateClosing); |
| 222 | } |
| 223 | |
| 224 | |
| 225 | int |
| 226 | xenbus_grant_ring(struct xenbus_device *dev, paddr_t ring_pa, |
| 227 | grant_ref_t *entryp) |
| 228 | { |
| 229 | int err = xengnt_grant_access(dev->xbusd_otherend_id, ring_pa, |
| 230 | 0, entryp); |
| 231 | if (err != 0) |
| 232 | xenbus_dev_fatal(dev, err, "granting access to ring page" ); |
| 233 | return err; |
| 234 | } |
| 235 | |
| 236 | |
| 237 | int |
| 238 | xenbus_alloc_evtchn(struct xenbus_device *dev, int *port) |
| 239 | { |
| 240 | evtchn_op_t op = { |
| 241 | .cmd = EVTCHNOP_alloc_unbound, |
| 242 | .u.alloc_unbound = { |
| 243 | .dom = DOMID_SELF, |
| 244 | .remote_dom = dev->xbusd_otherend_id, |
| 245 | .port = 0 |
| 246 | } |
| 247 | }; |
| 248 | |
| 249 | int err = HYPERVISOR_event_channel_op(&op); |
| 250 | if (err) |
| 251 | xenbus_dev_fatal(dev, err, "allocating event channel" ); |
| 252 | else |
| 253 | *port = op.u.alloc_unbound.port; |
| 254 | return err; |
| 255 | } |
| 256 | |
| 257 | |
| 258 | XenbusState |
| 259 | xenbus_read_driver_state(const char *path) |
| 260 | { |
| 261 | u_long result; |
| 262 | |
| 263 | int err = xenbus_read_ul(NULL, path, "state" , &result, 10); |
| 264 | if (err) |
| 265 | result = XenbusStateClosed; |
| 266 | |
| 267 | return result; |
| 268 | } |
| 269 | |
| 270 | |
| 271 | /* |
| 272 | * Local variables: |
| 273 | * c-file-style: "linux" |
| 274 | * indent-tabs-mode: t |
| 275 | * c-indent-level: 8 |
| 276 | * c-basic-offset: 8 |
| 277 | * tab-width: 8 |
| 278 | * End: |
| 279 | */ |
| 280 | |