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 p9_req_put(p9_req); 189 190 return 0; 191 } 192 193 static void p9_xen_response(struct work_struct *work) 194 { 195 struct xen_9pfs_front_priv *priv; 196 struct xen_9pfs_dataring *ring; 197 RING_IDX cons, prod, masked_cons, masked_prod; 198 struct xen_9pfs_header h; 199 struct p9_req_t *req; 200 int status; 201 202 ring = container_of(work, struct xen_9pfs_dataring, work); 203 priv = ring->priv; 204 205 while (1) { 206 cons = ring->intf->in_cons; 207 prod = ring->intf->in_prod; 208 virt_rmb(); 209 210 if (xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE) < 211 sizeof(h)) { 212 notify_remote_via_irq(ring->irq); 213 return; 214 } 215 216 masked_prod = xen_9pfs_mask(prod, XEN_9PFS_RING_SIZE); 217 masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE); 218 219 /* First, read just the header */ 220 xen_9pfs_read_packet(&h, ring->data.in, sizeof(h), 221 masked_prod, &masked_cons, 222 XEN_9PFS_RING_SIZE); 223 224 req = p9_tag_lookup(priv->client, h.tag); 225 if (!req || req->status != REQ_STATUS_SENT) { 226 dev_warn(&priv->dev->dev, "Wrong req tag=%x\n", h.tag); 227 cons += h.size; 228 virt_mb(); 229 ring->intf->in_cons = cons; 230 continue; 231 } 232 233 memcpy(&req->rc, &h, sizeof(h)); 234 req->rc.offset = 0; 235 236 masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE); 237 /* Then, read the whole packet (including the header) */ 238 xen_9pfs_read_packet(req->rc.sdata, ring->data.in, h.size, 239 masked_prod, &masked_cons, 240 XEN_9PFS_RING_SIZE); 241 242 virt_mb(); 243 cons += h.size; 244 ring->intf->in_cons = cons; 245 246 status = (req->status != REQ_STATUS_ERROR) ? 247 REQ_STATUS_RCVD : REQ_STATUS_ERROR; 248 249 p9_client_cb(priv->client, req, status); 250 } 251 } 252 253 static irqreturn_t xen_9pfs_front_event_handler(int irq, void *r) 254 { 255 struct xen_9pfs_dataring *ring = r; 256 257 if (!ring || !ring->priv->client) { 258 /* ignore spurious interrupt */ 259 return IRQ_HANDLED; 260 } 261 262 wake_up_interruptible(&ring->wq); 263 schedule_work(&ring->work); 264 265 return IRQ_HANDLED; 266 } 267 268 static struct p9_trans_module p9_xen_trans = { 269 .name = "xen", 270 .maxsize = 1 << (XEN_9PFS_RING_ORDER + XEN_PAGE_SHIFT), 271 .def = 1, 272 .create = p9_xen_create, 273 .close = p9_xen_close, 274 .request = p9_xen_request, 275 .cancel = p9_xen_cancel, 276 .owner = THIS_MODULE, 277 }; 278 279 static const struct xenbus_device_id xen_9pfs_front_ids[] = { 280 { "9pfs" }, 281 { "" } 282 }; 283 284 static void xen_9pfs_front_free(struct xen_9pfs_front_priv *priv) 285 { 286 int i, j; 287 288 write_lock(&xen_9pfs_lock); 289 list_del(&priv->list); 290 write_unlock(&xen_9pfs_lock); 291 292 for (i = 0; i < priv->num_rings; i++) { 293 if (!priv->rings[i].intf) 294 break; 295 if (priv->rings[i].irq > 0) 296 unbind_from_irqhandler(priv->rings[i].irq, priv->dev); 297 if (priv->rings[i].data.in) { 298 for (j = 0; j < (1 << XEN_9PFS_RING_ORDER); j++) { 299 grant_ref_t ref; 300 301 ref = priv->rings[i].intf->ref[j]; 302 gnttab_end_foreign_access(ref, 0, 0); 303 } 304 free_pages((unsigned long)priv->rings[i].data.in, 305 XEN_9PFS_RING_ORDER - 306 (PAGE_SHIFT - XEN_PAGE_SHIFT)); 307 } 308 gnttab_end_foreign_access(priv->rings[i].ref, 0, 0); 309 free_page((unsigned long)priv->rings[i].intf); 310 } 311 kfree(priv->rings); 312 kfree(priv->tag); 313 kfree(priv); 314 } 315 316 static int xen_9pfs_front_remove(struct xenbus_device *dev) 317 { 318 struct xen_9pfs_front_priv *priv = dev_get_drvdata(&dev->dev); 319 320 dev_set_drvdata(&dev->dev, NULL); 321 xen_9pfs_front_free(priv); 322 return 0; 323 } 324 325 static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev, 326 struct xen_9pfs_dataring *ring) 327 { 328 int i = 0; 329 int ret = -ENOMEM; 330 void *bytes = NULL; 331 332 init_waitqueue_head(&ring->wq); 333 spin_lock_init(&ring->lock); 334 INIT_WORK(&ring->work, p9_xen_response); 335 336 ring->intf = (struct xen_9pfs_data_intf *)get_zeroed_page(GFP_KERNEL); 337 if (!ring->intf) 338 return ret; 339 ret = gnttab_grant_foreign_access(dev->otherend_id, 340 virt_to_gfn(ring->intf), 0); 341 if (ret < 0) 342 goto out; 343 ring->ref = ret; 344 bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 345 XEN_9PFS_RING_ORDER - (PAGE_SHIFT - XEN_PAGE_SHIFT)); 346 if (!bytes) { 347 ret = -ENOMEM; 348 goto out; 349 } 350 for (; i < (1 << XEN_9PFS_RING_ORDER); i++) { 351 ret = gnttab_grant_foreign_access( 352 dev->otherend_id, virt_to_gfn(bytes) + i, 0); 353 if (ret < 0) 354 goto out; 355 ring->intf->ref[i] = ret; 356 } 357 ring->intf->ring_order = XEN_9PFS_RING_ORDER; 358 ring->data.in = bytes; 359 ring->data.out = bytes + XEN_9PFS_RING_SIZE; 360 361 ret = xenbus_alloc_evtchn(dev, &ring->evtchn); 362 if (ret) 363 goto out; 364 ring->irq = bind_evtchn_to_irqhandler(ring->evtchn, 365 xen_9pfs_front_event_handler, 366 0, "xen_9pfs-frontend", ring); 367 if (ring->irq >= 0) 368 return 0; 369 370 xenbus_free_evtchn(dev, ring->evtchn); 371 ret = ring->irq; 372 out: 373 if (bytes) { 374 for (i--; i >= 0; i--) 375 gnttab_end_foreign_access(ring->intf->ref[i], 0, 0); 376 free_pages((unsigned long)bytes, 377 XEN_9PFS_RING_ORDER - 378 (PAGE_SHIFT - XEN_PAGE_SHIFT)); 379 } 380 gnttab_end_foreign_access(ring->ref, 0, 0); 381 free_page((unsigned long)ring->intf); 382 return ret; 383 } 384 385 static int xen_9pfs_front_probe(struct xenbus_device *dev, 386 const struct xenbus_device_id *id) 387 { 388 int ret, i; 389 struct xenbus_transaction xbt; 390 struct xen_9pfs_front_priv *priv = NULL; 391 char *versions; 392 unsigned int max_rings, max_ring_order, len = 0; 393 394 versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len); 395 if (IS_ERR(versions)) 396 return PTR_ERR(versions); 397 if (strcmp(versions, "1")) { 398 kfree(versions); 399 return -EINVAL; 400 } 401 kfree(versions); 402 max_rings = xenbus_read_unsigned(dev->otherend, "max-rings", 0); 403 if (max_rings < XEN_9PFS_NUM_RINGS) 404 return -EINVAL; 405 max_ring_order = xenbus_read_unsigned(dev->otherend, 406 "max-ring-page-order", 0); 407 if (max_ring_order < XEN_9PFS_RING_ORDER) 408 return -EINVAL; 409 410 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 411 if (!priv) 412 return -ENOMEM; 413 414 priv->dev = dev; 415 priv->num_rings = XEN_9PFS_NUM_RINGS; 416 priv->rings = kcalloc(priv->num_rings, sizeof(*priv->rings), 417 GFP_KERNEL); 418 if (!priv->rings) { 419 kfree(priv); 420 return -ENOMEM; 421 } 422 423 for (i = 0; i < priv->num_rings; i++) { 424 priv->rings[i].priv = priv; 425 ret = xen_9pfs_front_alloc_dataring(dev, &priv->rings[i]); 426 if (ret < 0) 427 goto error; 428 } 429 430 again: 431 ret = xenbus_transaction_start(&xbt); 432 if (ret) { 433 xenbus_dev_fatal(dev, ret, "starting transaction"); 434 goto error; 435 } 436 ret = xenbus_printf(xbt, dev->nodename, "version", "%u", 1); 437 if (ret) 438 goto error_xenbus; 439 ret = xenbus_printf(xbt, dev->nodename, "num-rings", "%u", 440 priv->num_rings); 441 if (ret) 442 goto error_xenbus; 443 for (i = 0; i < priv->num_rings; i++) { 444 char str[16]; 445 446 BUILD_BUG_ON(XEN_9PFS_NUM_RINGS > 9); 447 sprintf(str, "ring-ref%u", i); 448 ret = xenbus_printf(xbt, dev->nodename, str, "%d", 449 priv->rings[i].ref); 450 if (ret) 451 goto error_xenbus; 452 453 sprintf(str, "event-channel-%u", i); 454 ret = xenbus_printf(xbt, dev->nodename, str, "%u", 455 priv->rings[i].evtchn); 456 if (ret) 457 goto error_xenbus; 458 } 459 priv->tag = xenbus_read(xbt, dev->nodename, "tag", NULL); 460 if (IS_ERR(priv->tag)) { 461 ret = PTR_ERR(priv->tag); 462 goto error_xenbus; 463 } 464 ret = xenbus_transaction_end(xbt, 0); 465 if (ret) { 466 if (ret == -EAGAIN) 467 goto again; 468 xenbus_dev_fatal(dev, ret, "completing transaction"); 469 goto error; 470 } 471 472 write_lock(&xen_9pfs_lock); 473 list_add_tail(&priv->list, &xen_9pfs_devs); 474 write_unlock(&xen_9pfs_lock); 475 dev_set_drvdata(&dev->dev, priv); 476 xenbus_switch_state(dev, XenbusStateInitialised); 477 478 return 0; 479 480 error_xenbus: 481 xenbus_transaction_end(xbt, 1); 482 xenbus_dev_fatal(dev, ret, "writing xenstore"); 483 error: 484 dev_set_drvdata(&dev->dev, NULL); 485 xen_9pfs_front_free(priv); 486 return ret; 487 } 488 489 static int xen_9pfs_front_resume(struct xenbus_device *dev) 490 { 491 dev_warn(&dev->dev, "suspend/resume unsupported\n"); 492 return 0; 493 } 494 495 static void xen_9pfs_front_changed(struct xenbus_device *dev, 496 enum xenbus_state backend_state) 497 { 498 switch (backend_state) { 499 case XenbusStateReconfiguring: 500 case XenbusStateReconfigured: 501 case XenbusStateInitialising: 502 case XenbusStateInitialised: 503 case XenbusStateUnknown: 504 break; 505 506 case XenbusStateInitWait: 507 break; 508 509 case XenbusStateConnected: 510 xenbus_switch_state(dev, XenbusStateConnected); 511 break; 512 513 case XenbusStateClosed: 514 if (dev->state == XenbusStateClosed) 515 break; 516 /* Missed the backend's CLOSING state -- fallthrough */ 517 case XenbusStateClosing: 518 xenbus_frontend_closed(dev); 519 break; 520 } 521 } 522 523 static struct xenbus_driver xen_9pfs_front_driver = { 524 .ids = xen_9pfs_front_ids, 525 .probe = xen_9pfs_front_probe, 526 .remove = xen_9pfs_front_remove, 527 .resume = xen_9pfs_front_resume, 528 .otherend_changed = xen_9pfs_front_changed, 529 }; 530 531 static int p9_trans_xen_init(void) 532 { 533 if (!xen_domain()) 534 return -ENODEV; 535 536 pr_info("Initialising Xen transport for 9pfs\n"); 537 538 v9fs_register_trans(&p9_xen_trans); 539 return xenbus_register_frontend(&xen_9pfs_front_driver); 540 } 541 module_init(p9_trans_xen_init); 542 543 static void p9_trans_xen_exit(void) 544 { 545 v9fs_unregister_trans(&p9_xen_trans); 546 return xenbus_unregister_driver(&xen_9pfs_front_driver); 547 } 548 module_exit(p9_trans_xen_exit); 549 550 MODULE_AUTHOR("Stefano Stabellini <stefano@aporeto.com>"); 551 MODULE_DESCRIPTION("Xen Transport for 9P"); 552 MODULE_LICENSE("GPL"); 553