1 /* 2 * linux/fs/9p/trans_xen 3 * 4 * Xen transport layer. 5 * 6 * Copyright (C) 2017 by Stefano Stabellini <stefano@aporeto.com> 7 * 8 * This program is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU General Public License version 2 10 * as published by the Free Software Foundation; or, when distributed 11 * separately from the Linux kernel or incorporated into other 12 * software packages, subject to the following license: 13 * 14 * Permission is hereby granted, free of charge, to any person obtaining a copy 15 * of this source file (the "Software"), to deal in the Software without 16 * restriction, including without limitation the rights to use, copy, modify, 17 * merge, publish, distribute, sublicense, and/or sell copies of the Software, 18 * and to permit persons to whom the Software is furnished to do so, subject to 19 * the following conditions: 20 * 21 * The above copyright notice and this permission notice shall be included in 22 * all copies or substantial portions of the Software. 23 * 24 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 25 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 26 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 27 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 28 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 29 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 30 * IN THE SOFTWARE. 31 */ 32 33 #include <xen/events.h> 34 #include <xen/grant_table.h> 35 #include <xen/xen.h> 36 #include <xen/xenbus.h> 37 #include <xen/interface/io/9pfs.h> 38 39 #include <linux/module.h> 40 #include <linux/spinlock.h> 41 #include <net/9p/9p.h> 42 #include <net/9p/client.h> 43 #include <net/9p/transport.h> 44 45 #define XEN_9PFS_NUM_RINGS 2 46 #define XEN_9PFS_RING_ORDER 6 47 #define XEN_9PFS_RING_SIZE XEN_FLEX_RING_SIZE(XEN_9PFS_RING_ORDER) 48 49 struct xen_9pfs_header { 50 uint32_t size; 51 uint8_t id; 52 uint16_t tag; 53 54 /* uint8_t sdata[]; */ 55 } __attribute__((packed)); 56 57 /* One per ring, more than one per 9pfs share */ 58 struct xen_9pfs_dataring { 59 struct xen_9pfs_front_priv *priv; 60 61 struct xen_9pfs_data_intf *intf; 62 grant_ref_t ref; 63 int evtchn; 64 int irq; 65 /* protect a ring from concurrent accesses */ 66 spinlock_t lock; 67 68 struct xen_9pfs_data data; 69 wait_queue_head_t wq; 70 struct work_struct work; 71 }; 72 73 /* One per 9pfs share */ 74 struct xen_9pfs_front_priv { 75 struct list_head list; 76 struct xenbus_device *dev; 77 char *tag; 78 struct p9_client *client; 79 80 int num_rings; 81 struct xen_9pfs_dataring *rings; 82 }; 83 84 static LIST_HEAD(xen_9pfs_devs); 85 static DEFINE_RWLOCK(xen_9pfs_lock); 86 87 /* We don't currently allow canceling of requests */ 88 static int p9_xen_cancel(struct p9_client *client, struct p9_req_t *req) 89 { 90 return 1; 91 } 92 93 static int p9_xen_create(struct p9_client *client, const char *addr, char *args) 94 { 95 struct xen_9pfs_front_priv *priv; 96 97 if (addr == NULL) 98 return -EINVAL; 99 100 read_lock(&xen_9pfs_lock); 101 list_for_each_entry(priv, &xen_9pfs_devs, list) { 102 if (!strcmp(priv->tag, addr)) { 103 priv->client = client; 104 read_unlock(&xen_9pfs_lock); 105 return 0; 106 } 107 } 108 read_unlock(&xen_9pfs_lock); 109 return -EINVAL; 110 } 111 112 static void p9_xen_close(struct p9_client *client) 113 { 114 struct xen_9pfs_front_priv *priv; 115 116 read_lock(&xen_9pfs_lock); 117 list_for_each_entry(priv, &xen_9pfs_devs, list) { 118 if (priv->client == client) { 119 priv->client = NULL; 120 read_unlock(&xen_9pfs_lock); 121 return; 122 } 123 } 124 read_unlock(&xen_9pfs_lock); 125 } 126 127 static bool p9_xen_write_todo(struct xen_9pfs_dataring *ring, RING_IDX size) 128 { 129 RING_IDX cons, prod; 130 131 cons = ring->intf->out_cons; 132 prod = ring->intf->out_prod; 133 virt_mb(); 134 135 return XEN_9PFS_RING_SIZE - 136 xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE) >= size; 137 } 138 139 static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req) 140 { 141 struct xen_9pfs_front_priv *priv = NULL; 142 RING_IDX cons, prod, masked_cons, masked_prod; 143 unsigned long flags; 144 u32 size = p9_req->tc->size; 145 struct xen_9pfs_dataring *ring; 146 int num; 147 148 read_lock(&xen_9pfs_lock); 149 list_for_each_entry(priv, &xen_9pfs_devs, list) { 150 if (priv->client == client) 151 break; 152 } 153 read_unlock(&xen_9pfs_lock); 154 if (!priv || priv->client != client) 155 return -EINVAL; 156 157 num = p9_req->tc->tag % priv->num_rings; 158 ring = &priv->rings[num]; 159 160 again: 161 while (wait_event_killable(ring->wq, 162 p9_xen_write_todo(ring, size)) != 0) 163 ; 164 165 spin_lock_irqsave(&ring->lock, flags); 166 cons = ring->intf->out_cons; 167 prod = ring->intf->out_prod; 168 virt_mb(); 169 170 if (XEN_9PFS_RING_SIZE - xen_9pfs_queued(prod, cons, 171 XEN_9PFS_RING_SIZE) < size) { 172 spin_unlock_irqrestore(&ring->lock, flags); 173 goto again; 174 } 175 176 masked_prod = xen_9pfs_mask(prod, XEN_9PFS_RING_SIZE); 177 masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE); 178 179 xen_9pfs_write_packet(ring->data.out, p9_req->tc->sdata, size, 180 &masked_prod, masked_cons, XEN_9PFS_RING_SIZE); 181 182 p9_req->status = REQ_STATUS_SENT; 183 virt_wmb(); /* write ring before updating pointer */ 184 prod += size; 185 ring->intf->out_prod = prod; 186 spin_unlock_irqrestore(&ring->lock, flags); 187 notify_remote_via_irq(ring->irq); 188 189 return 0; 190 } 191 192 static void p9_xen_response(struct work_struct *work) 193 { 194 struct xen_9pfs_front_priv *priv; 195 struct xen_9pfs_dataring *ring; 196 RING_IDX cons, prod, masked_cons, masked_prod; 197 struct xen_9pfs_header h; 198 struct p9_req_t *req; 199 int status; 200 201 ring = container_of(work, struct xen_9pfs_dataring, work); 202 priv = ring->priv; 203 204 while (1) { 205 cons = ring->intf->in_cons; 206 prod = ring->intf->in_prod; 207 virt_rmb(); 208 209 if (xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE) < 210 sizeof(h)) { 211 notify_remote_via_irq(ring->irq); 212 return; 213 } 214 215 masked_prod = xen_9pfs_mask(prod, XEN_9PFS_RING_SIZE); 216 masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE); 217 218 /* First, read just the header */ 219 xen_9pfs_read_packet(&h, ring->data.in, sizeof(h), 220 masked_prod, &masked_cons, 221 XEN_9PFS_RING_SIZE); 222 223 req = p9_tag_lookup(priv->client, h.tag); 224 if (!req || req->status != REQ_STATUS_SENT) { 225 dev_warn(&priv->dev->dev, "Wrong req tag=%x\n", h.tag); 226 cons += h.size; 227 virt_mb(); 228 ring->intf->in_cons = cons; 229 continue; 230 } 231 232 memcpy(req->rc, &h, sizeof(h)); 233 req->rc->offset = 0; 234 235 masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE); 236 /* Then, read the whole packet (including the header) */ 237 xen_9pfs_read_packet(req->rc->sdata, ring->data.in, h.size, 238 masked_prod, &masked_cons, 239 XEN_9PFS_RING_SIZE); 240 241 virt_mb(); 242 cons += h.size; 243 ring->intf->in_cons = cons; 244 245 status = (req->status != REQ_STATUS_ERROR) ? 246 REQ_STATUS_RCVD : REQ_STATUS_ERROR; 247 248 p9_client_cb(priv->client, req, status); 249 } 250 } 251 252 static irqreturn_t xen_9pfs_front_event_handler(int irq, void *r) 253 { 254 struct xen_9pfs_dataring *ring = r; 255 256 if (!ring || !ring->priv->client) { 257 /* ignore spurious interrupt */ 258 return IRQ_HANDLED; 259 } 260 261 wake_up_interruptible(&ring->wq); 262 schedule_work(&ring->work); 263 264 return IRQ_HANDLED; 265 } 266 267 static struct p9_trans_module p9_xen_trans = { 268 .name = "xen", 269 .maxsize = 1 << (XEN_9PFS_RING_ORDER + XEN_PAGE_SHIFT), 270 .def = 1, 271 .create = p9_xen_create, 272 .close = p9_xen_close, 273 .request = p9_xen_request, 274 .cancel = p9_xen_cancel, 275 .owner = THIS_MODULE, 276 }; 277 278 static const struct xenbus_device_id xen_9pfs_front_ids[] = { 279 { "9pfs" }, 280 { "" } 281 }; 282 283 static void xen_9pfs_front_free(struct xen_9pfs_front_priv *priv) 284 { 285 int i, j; 286 287 write_lock(&xen_9pfs_lock); 288 list_del(&priv->list); 289 write_unlock(&xen_9pfs_lock); 290 291 for (i = 0; i < priv->num_rings; i++) { 292 if (!priv->rings[i].intf) 293 break; 294 if (priv->rings[i].irq > 0) 295 unbind_from_irqhandler(priv->rings[i].irq, priv->dev); 296 if (priv->rings[i].data.in) { 297 for (j = 0; j < (1 << XEN_9PFS_RING_ORDER); j++) { 298 grant_ref_t ref; 299 300 ref = priv->rings[i].intf->ref[j]; 301 gnttab_end_foreign_access(ref, 0, 0); 302 } 303 free_pages((unsigned long)priv->rings[i].data.in, 304 XEN_9PFS_RING_ORDER - 305 (PAGE_SHIFT - XEN_PAGE_SHIFT)); 306 } 307 gnttab_end_foreign_access(priv->rings[i].ref, 0, 0); 308 free_page((unsigned long)priv->rings[i].intf); 309 } 310 kfree(priv->rings); 311 kfree(priv->tag); 312 kfree(priv); 313 } 314 315 static int xen_9pfs_front_remove(struct xenbus_device *dev) 316 { 317 struct xen_9pfs_front_priv *priv = dev_get_drvdata(&dev->dev); 318 319 dev_set_drvdata(&dev->dev, NULL); 320 xen_9pfs_front_free(priv); 321 return 0; 322 } 323 324 static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev, 325 struct xen_9pfs_dataring *ring) 326 { 327 int i = 0; 328 int ret = -ENOMEM; 329 void *bytes = NULL; 330 331 init_waitqueue_head(&ring->wq); 332 spin_lock_init(&ring->lock); 333 INIT_WORK(&ring->work, p9_xen_response); 334 335 ring->intf = (struct xen_9pfs_data_intf *)get_zeroed_page(GFP_KERNEL); 336 if (!ring->intf) 337 return ret; 338 ret = gnttab_grant_foreign_access(dev->otherend_id, 339 virt_to_gfn(ring->intf), 0); 340 if (ret < 0) 341 goto out; 342 ring->ref = ret; 343 bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 344 XEN_9PFS_RING_ORDER - (PAGE_SHIFT - XEN_PAGE_SHIFT)); 345 if (!bytes) { 346 ret = -ENOMEM; 347 goto out; 348 } 349 for (; i < (1 << XEN_9PFS_RING_ORDER); i++) { 350 ret = gnttab_grant_foreign_access( 351 dev->otherend_id, virt_to_gfn(bytes) + i, 0); 352 if (ret < 0) 353 goto out; 354 ring->intf->ref[i] = ret; 355 } 356 ring->intf->ring_order = XEN_9PFS_RING_ORDER; 357 ring->data.in = bytes; 358 ring->data.out = bytes + XEN_9PFS_RING_SIZE; 359 360 ret = xenbus_alloc_evtchn(dev, &ring->evtchn); 361 if (ret) 362 goto out; 363 ring->irq = bind_evtchn_to_irqhandler(ring->evtchn, 364 xen_9pfs_front_event_handler, 365 0, "xen_9pfs-frontend", ring); 366 if (ring->irq >= 0) 367 return 0; 368 369 xenbus_free_evtchn(dev, ring->evtchn); 370 ret = ring->irq; 371 out: 372 if (bytes) { 373 for (i--; i >= 0; i--) 374 gnttab_end_foreign_access(ring->intf->ref[i], 0, 0); 375 free_pages((unsigned long)bytes, 376 XEN_9PFS_RING_ORDER - 377 (PAGE_SHIFT - XEN_PAGE_SHIFT)); 378 } 379 gnttab_end_foreign_access(ring->ref, 0, 0); 380 free_page((unsigned long)ring->intf); 381 return ret; 382 } 383 384 static int xen_9pfs_front_probe(struct xenbus_device *dev, 385 const struct xenbus_device_id *id) 386 { 387 int ret, i; 388 struct xenbus_transaction xbt; 389 struct xen_9pfs_front_priv *priv = NULL; 390 char *versions; 391 unsigned int max_rings, max_ring_order, len = 0; 392 393 versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len); 394 if (!len) 395 return -EINVAL; 396 if (strcmp(versions, "1")) { 397 kfree(versions); 398 return -EINVAL; 399 } 400 kfree(versions); 401 max_rings = xenbus_read_unsigned(dev->otherend, "max-rings", 0); 402 if (max_rings < XEN_9PFS_NUM_RINGS) 403 return -EINVAL; 404 max_ring_order = xenbus_read_unsigned(dev->otherend, 405 "max-ring-page-order", 0); 406 if (max_ring_order < XEN_9PFS_RING_ORDER) 407 return -EINVAL; 408 409 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 410 if (!priv) 411 return -ENOMEM; 412 413 priv->dev = dev; 414 priv->num_rings = XEN_9PFS_NUM_RINGS; 415 priv->rings = kcalloc(priv->num_rings, sizeof(*priv->rings), 416 GFP_KERNEL); 417 if (!priv->rings) { 418 kfree(priv); 419 return -ENOMEM; 420 } 421 422 for (i = 0; i < priv->num_rings; i++) { 423 priv->rings[i].priv = priv; 424 ret = xen_9pfs_front_alloc_dataring(dev, &priv->rings[i]); 425 if (ret < 0) 426 goto error; 427 } 428 429 again: 430 ret = xenbus_transaction_start(&xbt); 431 if (ret) { 432 xenbus_dev_fatal(dev, ret, "starting transaction"); 433 goto error; 434 } 435 ret = xenbus_printf(xbt, dev->nodename, "version", "%u", 1); 436 if (ret) 437 goto error_xenbus; 438 ret = xenbus_printf(xbt, dev->nodename, "num-rings", "%u", 439 priv->num_rings); 440 if (ret) 441 goto error_xenbus; 442 for (i = 0; i < priv->num_rings; i++) { 443 char str[16]; 444 445 BUILD_BUG_ON(XEN_9PFS_NUM_RINGS > 9); 446 sprintf(str, "ring-ref%u", i); 447 ret = xenbus_printf(xbt, dev->nodename, str, "%d", 448 priv->rings[i].ref); 449 if (ret) 450 goto error_xenbus; 451 452 sprintf(str, "event-channel-%u", i); 453 ret = xenbus_printf(xbt, dev->nodename, str, "%u", 454 priv->rings[i].evtchn); 455 if (ret) 456 goto error_xenbus; 457 } 458 priv->tag = xenbus_read(xbt, dev->nodename, "tag", NULL); 459 if (IS_ERR(priv->tag)) { 460 ret = PTR_ERR(priv->tag); 461 goto error_xenbus; 462 } 463 ret = xenbus_transaction_end(xbt, 0); 464 if (ret) { 465 if (ret == -EAGAIN) 466 goto again; 467 xenbus_dev_fatal(dev, ret, "completing transaction"); 468 goto error; 469 } 470 471 write_lock(&xen_9pfs_lock); 472 list_add_tail(&priv->list, &xen_9pfs_devs); 473 write_unlock(&xen_9pfs_lock); 474 dev_set_drvdata(&dev->dev, priv); 475 xenbus_switch_state(dev, XenbusStateInitialised); 476 477 return 0; 478 479 error_xenbus: 480 xenbus_transaction_end(xbt, 1); 481 xenbus_dev_fatal(dev, ret, "writing xenstore"); 482 error: 483 dev_set_drvdata(&dev->dev, NULL); 484 xen_9pfs_front_free(priv); 485 return ret; 486 } 487 488 static int xen_9pfs_front_resume(struct xenbus_device *dev) 489 { 490 dev_warn(&dev->dev, "suspend/resume unsupported\n"); 491 return 0; 492 } 493 494 static void xen_9pfs_front_changed(struct xenbus_device *dev, 495 enum xenbus_state backend_state) 496 { 497 switch (backend_state) { 498 case XenbusStateReconfiguring: 499 case XenbusStateReconfigured: 500 case XenbusStateInitialising: 501 case XenbusStateInitialised: 502 case XenbusStateUnknown: 503 break; 504 505 case XenbusStateInitWait: 506 break; 507 508 case XenbusStateConnected: 509 xenbus_switch_state(dev, XenbusStateConnected); 510 break; 511 512 case XenbusStateClosed: 513 if (dev->state == XenbusStateClosed) 514 break; 515 /* Missed the backend's CLOSING state -- fallthrough */ 516 case XenbusStateClosing: 517 xenbus_frontend_closed(dev); 518 break; 519 } 520 } 521 522 static struct xenbus_driver xen_9pfs_front_driver = { 523 .ids = xen_9pfs_front_ids, 524 .probe = xen_9pfs_front_probe, 525 .remove = xen_9pfs_front_remove, 526 .resume = xen_9pfs_front_resume, 527 .otherend_changed = xen_9pfs_front_changed, 528 }; 529 530 static int p9_trans_xen_init(void) 531 { 532 if (!xen_domain()) 533 return -ENODEV; 534 535 pr_info("Initialising Xen transport for 9pfs\n"); 536 537 v9fs_register_trans(&p9_xen_trans); 538 return xenbus_register_frontend(&xen_9pfs_front_driver); 539 } 540 module_init(p9_trans_xen_init); 541 542 static void p9_trans_xen_exit(void) 543 { 544 v9fs_unregister_trans(&p9_xen_trans); 545 return xenbus_unregister_driver(&xen_9pfs_front_driver); 546 } 547 module_exit(p9_trans_xen_exit); 548 549 MODULE_AUTHOR("Stefano Stabellini <stefano@aporeto.com>"); 550 MODULE_DESCRIPTION("Xen Transport for 9P"); 551 MODULE_LICENSE("GPL"); 552