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 9 47 #define XEN_9PFS_RING_SIZE(ring) XEN_FLEX_RING_SIZE(ring->intf->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(ring) - 136 xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE(ring)) >= 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(ring) - 171 xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE(ring)) < size) { 172 spin_unlock_irqrestore(&ring->lock, flags); 173 goto again; 174 } 175 176 masked_prod = xen_9pfs_mask(prod, XEN_9PFS_RING_SIZE(ring)); 177 masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE(ring)); 178 179 xen_9pfs_write_packet(ring->data.out, p9_req->tc.sdata, size, 180 &masked_prod, masked_cons, 181 XEN_9PFS_RING_SIZE(ring)); 182 183 p9_req->status = REQ_STATUS_SENT; 184 virt_wmb(); /* write ring before updating pointer */ 185 prod += size; 186 ring->intf->out_prod = prod; 187 spin_unlock_irqrestore(&ring->lock, flags); 188 notify_remote_via_irq(ring->irq); 189 p9_req_put(p9_req); 190 191 return 0; 192 } 193 194 static void p9_xen_response(struct work_struct *work) 195 { 196 struct xen_9pfs_front_priv *priv; 197 struct xen_9pfs_dataring *ring; 198 RING_IDX cons, prod, masked_cons, masked_prod; 199 struct xen_9pfs_header h; 200 struct p9_req_t *req; 201 int status; 202 203 ring = container_of(work, struct xen_9pfs_dataring, work); 204 priv = ring->priv; 205 206 while (1) { 207 cons = ring->intf->in_cons; 208 prod = ring->intf->in_prod; 209 virt_rmb(); 210 211 if (xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE(ring)) < 212 sizeof(h)) { 213 notify_remote_via_irq(ring->irq); 214 return; 215 } 216 217 masked_prod = xen_9pfs_mask(prod, XEN_9PFS_RING_SIZE(ring)); 218 masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE(ring)); 219 220 /* First, read just the header */ 221 xen_9pfs_read_packet(&h, ring->data.in, sizeof(h), 222 masked_prod, &masked_cons, 223 XEN_9PFS_RING_SIZE(ring)); 224 225 req = p9_tag_lookup(priv->client, h.tag); 226 if (!req || req->status != REQ_STATUS_SENT) { 227 dev_warn(&priv->dev->dev, "Wrong req tag=%x\n", h.tag); 228 cons += h.size; 229 virt_mb(); 230 ring->intf->in_cons = cons; 231 continue; 232 } 233 234 memcpy(&req->rc, &h, sizeof(h)); 235 req->rc.offset = 0; 236 237 masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE(ring)); 238 /* Then, read the whole packet (including the header) */ 239 xen_9pfs_read_packet(req->rc.sdata, ring->data.in, h.size, 240 masked_prod, &masked_cons, 241 XEN_9PFS_RING_SIZE(ring)); 242 243 virt_mb(); 244 cons += h.size; 245 ring->intf->in_cons = cons; 246 247 status = (req->status != REQ_STATUS_ERROR) ? 248 REQ_STATUS_RCVD : REQ_STATUS_ERROR; 249 250 p9_client_cb(priv->client, req, status); 251 } 252 } 253 254 static irqreturn_t xen_9pfs_front_event_handler(int irq, void *r) 255 { 256 struct xen_9pfs_dataring *ring = r; 257 258 if (!ring || !ring->priv->client) { 259 /* ignore spurious interrupt */ 260 return IRQ_HANDLED; 261 } 262 263 wake_up_interruptible(&ring->wq); 264 schedule_work(&ring->work); 265 266 return IRQ_HANDLED; 267 } 268 269 static struct p9_trans_module p9_xen_trans = { 270 .name = "xen", 271 .maxsize = 1 << (XEN_9PFS_RING_ORDER + XEN_PAGE_SHIFT - 2), 272 .def = 1, 273 .create = p9_xen_create, 274 .close = p9_xen_close, 275 .request = p9_xen_request, 276 .cancel = p9_xen_cancel, 277 .owner = THIS_MODULE, 278 }; 279 280 static const struct xenbus_device_id xen_9pfs_front_ids[] = { 281 { "9pfs" }, 282 { "" } 283 }; 284 285 static void xen_9pfs_front_free(struct xen_9pfs_front_priv *priv) 286 { 287 int i, j; 288 289 write_lock(&xen_9pfs_lock); 290 list_del(&priv->list); 291 write_unlock(&xen_9pfs_lock); 292 293 for (i = 0; i < priv->num_rings; i++) { 294 if (!priv->rings[i].intf) 295 break; 296 if (priv->rings[i].irq > 0) 297 unbind_from_irqhandler(priv->rings[i].irq, priv->dev); 298 if (priv->rings[i].data.in) { 299 for (j = 0; 300 j < (1 << priv->rings[i].intf->ring_order); 301 j++) { 302 grant_ref_t ref; 303 304 ref = priv->rings[i].intf->ref[j]; 305 gnttab_end_foreign_access(ref, 0, 0); 306 } 307 free_pages((unsigned long)priv->rings[i].data.in, 308 priv->rings[i].intf->ring_order - 309 (PAGE_SHIFT - XEN_PAGE_SHIFT)); 310 } 311 gnttab_end_foreign_access(priv->rings[i].ref, 0, 0); 312 free_page((unsigned long)priv->rings[i].intf); 313 } 314 kfree(priv->rings); 315 kfree(priv->tag); 316 kfree(priv); 317 } 318 319 static int xen_9pfs_front_remove(struct xenbus_device *dev) 320 { 321 struct xen_9pfs_front_priv *priv = dev_get_drvdata(&dev->dev); 322 323 dev_set_drvdata(&dev->dev, NULL); 324 xen_9pfs_front_free(priv); 325 return 0; 326 } 327 328 static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev, 329 struct xen_9pfs_dataring *ring, 330 unsigned int order) 331 { 332 int i = 0; 333 int ret = -ENOMEM; 334 void *bytes = NULL; 335 336 init_waitqueue_head(&ring->wq); 337 spin_lock_init(&ring->lock); 338 INIT_WORK(&ring->work, p9_xen_response); 339 340 ring->intf = (struct xen_9pfs_data_intf *)get_zeroed_page(GFP_KERNEL); 341 if (!ring->intf) 342 return ret; 343 ret = gnttab_grant_foreign_access(dev->otherend_id, 344 virt_to_gfn(ring->intf), 0); 345 if (ret < 0) 346 goto out; 347 ring->ref = ret; 348 bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 349 order - (PAGE_SHIFT - XEN_PAGE_SHIFT)); 350 if (!bytes) { 351 ret = -ENOMEM; 352 goto out; 353 } 354 for (; i < (1 << order); i++) { 355 ret = gnttab_grant_foreign_access( 356 dev->otherend_id, virt_to_gfn(bytes) + i, 0); 357 if (ret < 0) 358 goto out; 359 ring->intf->ref[i] = ret; 360 } 361 ring->intf->ring_order = order; 362 ring->data.in = bytes; 363 ring->data.out = bytes + XEN_FLEX_RING_SIZE(order); 364 365 ret = xenbus_alloc_evtchn(dev, &ring->evtchn); 366 if (ret) 367 goto out; 368 ring->irq = bind_evtchn_to_irqhandler(ring->evtchn, 369 xen_9pfs_front_event_handler, 370 0, "xen_9pfs-frontend", ring); 371 if (ring->irq >= 0) 372 return 0; 373 374 xenbus_free_evtchn(dev, ring->evtchn); 375 ret = ring->irq; 376 out: 377 if (bytes) { 378 for (i--; i >= 0; i--) 379 gnttab_end_foreign_access(ring->intf->ref[i], 0, 0); 380 free_pages((unsigned long)bytes, 381 ring->intf->ring_order - 382 (PAGE_SHIFT - XEN_PAGE_SHIFT)); 383 } 384 gnttab_end_foreign_access(ring->ref, 0, 0); 385 free_page((unsigned long)ring->intf); 386 return ret; 387 } 388 389 static int xen_9pfs_front_probe(struct xenbus_device *dev, 390 const struct xenbus_device_id *id) 391 { 392 int ret, i; 393 struct xenbus_transaction xbt; 394 struct xen_9pfs_front_priv *priv = NULL; 395 char *versions; 396 unsigned int max_rings, max_ring_order, len = 0; 397 398 versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len); 399 if (IS_ERR(versions)) 400 return PTR_ERR(versions); 401 if (strcmp(versions, "1")) { 402 kfree(versions); 403 return -EINVAL; 404 } 405 kfree(versions); 406 max_rings = xenbus_read_unsigned(dev->otherend, "max-rings", 0); 407 if (max_rings < XEN_9PFS_NUM_RINGS) 408 return -EINVAL; 409 max_ring_order = xenbus_read_unsigned(dev->otherend, 410 "max-ring-page-order", 0); 411 if (max_ring_order > XEN_9PFS_RING_ORDER) 412 max_ring_order = XEN_9PFS_RING_ORDER; 413 if (p9_xen_trans.maxsize > XEN_FLEX_RING_SIZE(max_ring_order)) 414 p9_xen_trans.maxsize = XEN_FLEX_RING_SIZE(max_ring_order) / 2; 415 416 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 417 if (!priv) 418 return -ENOMEM; 419 420 priv->dev = dev; 421 priv->num_rings = XEN_9PFS_NUM_RINGS; 422 priv->rings = kcalloc(priv->num_rings, sizeof(*priv->rings), 423 GFP_KERNEL); 424 if (!priv->rings) { 425 kfree(priv); 426 return -ENOMEM; 427 } 428 429 for (i = 0; i < priv->num_rings; i++) { 430 priv->rings[i].priv = priv; 431 ret = xen_9pfs_front_alloc_dataring(dev, &priv->rings[i], 432 max_ring_order); 433 if (ret < 0) 434 goto error; 435 } 436 437 again: 438 ret = xenbus_transaction_start(&xbt); 439 if (ret) { 440 xenbus_dev_fatal(dev, ret, "starting transaction"); 441 goto error; 442 } 443 ret = xenbus_printf(xbt, dev->nodename, "version", "%u", 1); 444 if (ret) 445 goto error_xenbus; 446 ret = xenbus_printf(xbt, dev->nodename, "num-rings", "%u", 447 priv->num_rings); 448 if (ret) 449 goto error_xenbus; 450 for (i = 0; i < priv->num_rings; i++) { 451 char str[16]; 452 453 BUILD_BUG_ON(XEN_9PFS_NUM_RINGS > 9); 454 sprintf(str, "ring-ref%d", i); 455 ret = xenbus_printf(xbt, dev->nodename, str, "%d", 456 priv->rings[i].ref); 457 if (ret) 458 goto error_xenbus; 459 460 sprintf(str, "event-channel-%d", i); 461 ret = xenbus_printf(xbt, dev->nodename, str, "%u", 462 priv->rings[i].evtchn); 463 if (ret) 464 goto error_xenbus; 465 } 466 priv->tag = xenbus_read(xbt, dev->nodename, "tag", NULL); 467 if (IS_ERR(priv->tag)) { 468 ret = PTR_ERR(priv->tag); 469 goto error_xenbus; 470 } 471 ret = xenbus_transaction_end(xbt, 0); 472 if (ret) { 473 if (ret == -EAGAIN) 474 goto again; 475 xenbus_dev_fatal(dev, ret, "completing transaction"); 476 goto error; 477 } 478 479 write_lock(&xen_9pfs_lock); 480 list_add_tail(&priv->list, &xen_9pfs_devs); 481 write_unlock(&xen_9pfs_lock); 482 dev_set_drvdata(&dev->dev, priv); 483 xenbus_switch_state(dev, XenbusStateInitialised); 484 485 return 0; 486 487 error_xenbus: 488 xenbus_transaction_end(xbt, 1); 489 xenbus_dev_fatal(dev, ret, "writing xenstore"); 490 error: 491 dev_set_drvdata(&dev->dev, NULL); 492 xen_9pfs_front_free(priv); 493 return ret; 494 } 495 496 static int xen_9pfs_front_resume(struct xenbus_device *dev) 497 { 498 dev_warn(&dev->dev, "suspend/resume unsupported\n"); 499 return 0; 500 } 501 502 static void xen_9pfs_front_changed(struct xenbus_device *dev, 503 enum xenbus_state backend_state) 504 { 505 switch (backend_state) { 506 case XenbusStateReconfiguring: 507 case XenbusStateReconfigured: 508 case XenbusStateInitialising: 509 case XenbusStateInitialised: 510 case XenbusStateUnknown: 511 break; 512 513 case XenbusStateInitWait: 514 break; 515 516 case XenbusStateConnected: 517 xenbus_switch_state(dev, XenbusStateConnected); 518 break; 519 520 case XenbusStateClosed: 521 if (dev->state == XenbusStateClosed) 522 break; 523 fallthrough; /* Missed the backend's CLOSING state */ 524 case XenbusStateClosing: 525 xenbus_frontend_closed(dev); 526 break; 527 } 528 } 529 530 static struct xenbus_driver xen_9pfs_front_driver = { 531 .ids = xen_9pfs_front_ids, 532 .probe = xen_9pfs_front_probe, 533 .remove = xen_9pfs_front_remove, 534 .resume = xen_9pfs_front_resume, 535 .otherend_changed = xen_9pfs_front_changed, 536 }; 537 538 static int p9_trans_xen_init(void) 539 { 540 int rc; 541 542 if (!xen_domain()) 543 return -ENODEV; 544 545 pr_info("Initialising Xen transport for 9pfs\n"); 546 547 v9fs_register_trans(&p9_xen_trans); 548 rc = xenbus_register_frontend(&xen_9pfs_front_driver); 549 if (rc) 550 v9fs_unregister_trans(&p9_xen_trans); 551 552 return rc; 553 } 554 module_init(p9_trans_xen_init); 555 556 static void p9_trans_xen_exit(void) 557 { 558 v9fs_unregister_trans(&p9_xen_trans); 559 return xenbus_unregister_driver(&xen_9pfs_front_driver); 560 } 561 module_exit(p9_trans_xen_exit); 562 563 MODULE_AUTHOR("Stefano Stabellini <stefano@aporeto.com>"); 564 MODULE_DESCRIPTION("Xen Transport for 9P"); 565 MODULE_LICENSE("GPL"); 566