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