1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * xen console driver interface to hvc_console.c 4 * 5 * (c) 2007 Gerd Hoffmann <kraxel@suse.de> 6 */ 7 8 #include <linux/console.h> 9 #include <linux/delay.h> 10 #include <linux/err.h> 11 #include <linux/irq.h> 12 #include <linux/init.h> 13 #include <linux/types.h> 14 #include <linux/list.h> 15 #include <linux/serial_core.h> 16 17 #include <asm/io.h> 18 #include <asm/xen/hypervisor.h> 19 20 #include <xen/xen.h> 21 #include <xen/interface/xen.h> 22 #include <xen/hvm.h> 23 #include <xen/grant_table.h> 24 #include <xen/page.h> 25 #include <xen/events.h> 26 #include <xen/interface/io/console.h> 27 #include <xen/interface/sched.h> 28 #include <xen/hvc-console.h> 29 #include <xen/xenbus.h> 30 31 #include "hvc_console.h" 32 33 #define HVC_COOKIE 0x58656e /* "Xen" in hex */ 34 35 struct xencons_info { 36 struct list_head list; 37 struct xenbus_device *xbdev; 38 struct xencons_interface *intf; 39 unsigned int evtchn; 40 XENCONS_RING_IDX out_cons; 41 unsigned int out_cons_same; 42 struct hvc_struct *hvc; 43 int irq; 44 int vtermno; 45 grant_ref_t gntref; 46 spinlock_t ring_lock; 47 }; 48 49 static LIST_HEAD(xenconsoles); 50 static DEFINE_SPINLOCK(xencons_lock); 51 52 /* ------------------------------------------------------------------ */ 53 54 static struct xencons_info *vtermno_to_xencons(int vtermno) 55 { 56 struct xencons_info *entry, *ret = NULL; 57 unsigned long flags; 58 59 spin_lock_irqsave(&xencons_lock, flags); 60 if (list_empty(&xenconsoles)) { 61 spin_unlock_irqrestore(&xencons_lock, flags); 62 return NULL; 63 } 64 65 list_for_each_entry(entry, &xenconsoles, list) { 66 if (entry->vtermno == vtermno) { 67 ret = entry; 68 break; 69 } 70 } 71 spin_unlock_irqrestore(&xencons_lock, flags); 72 73 return ret; 74 } 75 76 static inline int xenbus_devid_to_vtermno(int devid) 77 { 78 return devid + HVC_COOKIE; 79 } 80 81 static inline void notify_daemon(struct xencons_info *cons) 82 { 83 /* Use evtchn: this is called early, before irq is set up. */ 84 notify_remote_via_evtchn(cons->evtchn); 85 } 86 87 static ssize_t __write_console(struct xencons_info *xencons, 88 const u8 *data, size_t len) 89 { 90 XENCONS_RING_IDX cons, prod; 91 struct xencons_interface *intf = xencons->intf; 92 unsigned long flags; 93 size_t sent = 0; 94 95 spin_lock_irqsave(&xencons->ring_lock, flags); 96 cons = intf->out_cons; 97 prod = intf->out_prod; 98 mb(); /* update queue values before going on */ 99 100 if ((prod - cons) > sizeof(intf->out)) { 101 spin_unlock_irqrestore(&xencons->ring_lock, flags); 102 pr_err_once("xencons: Illegal ring page indices"); 103 return -EINVAL; 104 } 105 106 while ((sent < len) && ((prod - cons) < sizeof(intf->out))) 107 intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++]; 108 109 wmb(); /* write ring before updating pointer */ 110 intf->out_prod = prod; 111 spin_unlock_irqrestore(&xencons->ring_lock, flags); 112 113 if (sent) 114 notify_daemon(xencons); 115 return sent; 116 } 117 118 static ssize_t domU_write_console(uint32_t vtermno, const u8 *data, size_t len) 119 { 120 struct xencons_info *cons = vtermno_to_xencons(vtermno); 121 size_t ret = len; 122 123 if (cons == NULL) 124 return -EINVAL; 125 126 /* 127 * Make sure the whole buffer is emitted, polling if 128 * necessary. We don't ever want to rely on the hvc daemon 129 * because the most interesting console output is when the 130 * kernel is crippled. 131 */ 132 while (len) { 133 ssize_t sent = __write_console(cons, data, len); 134 135 if (sent < 0) 136 return sent; 137 138 data += sent; 139 len -= sent; 140 141 if (unlikely(len)) 142 HYPERVISOR_sched_op(SCHEDOP_yield, NULL); 143 } 144 145 return ret; 146 } 147 148 static ssize_t domU_read_console(uint32_t vtermno, u8 *buf, size_t len) 149 { 150 struct xencons_interface *intf; 151 XENCONS_RING_IDX cons, prod; 152 struct xencons_info *xencons = vtermno_to_xencons(vtermno); 153 unsigned int eoiflag = 0; 154 unsigned long flags; 155 size_t recv = 0; 156 157 if (xencons == NULL) 158 return -EINVAL; 159 intf = xencons->intf; 160 161 spin_lock_irqsave(&xencons->ring_lock, flags); 162 cons = intf->in_cons; 163 prod = intf->in_prod; 164 mb(); /* get pointers before reading ring */ 165 166 if ((prod - cons) > sizeof(intf->in)) { 167 spin_unlock_irqrestore(&xencons->ring_lock, flags); 168 pr_err_once("xencons: Illegal ring page indices"); 169 return -EINVAL; 170 } 171 172 while (cons != prod && recv < len) 173 buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++, intf->in)]; 174 175 mb(); /* read ring before consuming */ 176 intf->in_cons = cons; 177 178 /* 179 * When to mark interrupt having been spurious: 180 * - there was no new data to be read, and 181 * - the backend did not consume some output bytes, and 182 * - the previous round with no read data didn't see consumed bytes 183 * (we might have a race with an interrupt being in flight while 184 * updating xencons->out_cons, so account for that by allowing one 185 * round without any visible reason) 186 */ 187 if (intf->out_cons != xencons->out_cons) { 188 xencons->out_cons = intf->out_cons; 189 xencons->out_cons_same = 0; 190 } 191 if (!recv && xencons->out_cons_same++ > 1) { 192 eoiflag = XEN_EOI_FLAG_SPURIOUS; 193 } 194 spin_unlock_irqrestore(&xencons->ring_lock, flags); 195 196 if (recv) { 197 notify_daemon(xencons); 198 } 199 200 xen_irq_lateeoi(xencons->irq, eoiflag); 201 202 return recv; 203 } 204 205 static const struct hv_ops domU_hvc_ops = { 206 .get_chars = domU_read_console, 207 .put_chars = domU_write_console, 208 .notifier_add = notifier_add_irq, 209 .notifier_del = notifier_del_irq, 210 .notifier_hangup = notifier_hangup_irq, 211 }; 212 213 static ssize_t dom0_read_console(uint32_t vtermno, u8 *buf, size_t len) 214 { 215 return HYPERVISOR_console_io(CONSOLEIO_read, len, buf); 216 } 217 218 /* 219 * Either for a dom0 to write to the system console, or a domU with a 220 * debug version of Xen 221 */ 222 static ssize_t dom0_write_console(uint32_t vtermno, const u8 *str, size_t len) 223 { 224 int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (u8 *)str); 225 if (rc < 0) 226 return rc; 227 228 return len; 229 } 230 231 static const struct hv_ops dom0_hvc_ops = { 232 .get_chars = dom0_read_console, 233 .put_chars = dom0_write_console, 234 .notifier_add = notifier_add_irq, 235 .notifier_del = notifier_del_irq, 236 .notifier_hangup = notifier_hangup_irq, 237 }; 238 239 static int xen_hvm_console_init(void) 240 { 241 int r; 242 uint64_t v = 0; 243 unsigned long gfn, flags; 244 struct xencons_info *info; 245 246 if (!xen_hvm_domain()) 247 return -ENODEV; 248 249 info = vtermno_to_xencons(HVC_COOKIE); 250 if (!info) { 251 info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL); 252 if (!info) 253 return -ENOMEM; 254 spin_lock_init(&info->ring_lock); 255 } else if (info->intf != NULL) { 256 /* already configured */ 257 return 0; 258 } 259 /* 260 * If the toolstack (or the hypervisor) hasn't set these values, the 261 * default value is 0. Even though gfn = 0 and evtchn = 0 are 262 * theoretically correct values, in practice they never are and they 263 * mean that a legacy toolstack hasn't initialized the pv console correctly. 264 */ 265 r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v); 266 if (r < 0 || v == 0) 267 goto err; 268 info->evtchn = v; 269 v = 0; 270 r = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v); 271 if (r < 0 || v == 0) 272 goto err; 273 gfn = v; 274 info->intf = memremap(gfn << XEN_PAGE_SHIFT, XEN_PAGE_SIZE, MEMREMAP_WB); 275 if (info->intf == NULL) 276 goto err; 277 info->vtermno = HVC_COOKIE; 278 279 spin_lock_irqsave(&xencons_lock, flags); 280 list_add_tail(&info->list, &xenconsoles); 281 spin_unlock_irqrestore(&xencons_lock, flags); 282 283 return 0; 284 err: 285 kfree(info); 286 return -ENODEV; 287 } 288 289 static int xencons_info_pv_init(struct xencons_info *info, int vtermno) 290 { 291 spin_lock_init(&info->ring_lock); 292 info->evtchn = xen_start_info->console.domU.evtchn; 293 /* GFN == MFN for PV guest */ 294 info->intf = gfn_to_virt(xen_start_info->console.domU.mfn); 295 info->vtermno = vtermno; 296 297 list_add_tail(&info->list, &xenconsoles); 298 299 return 0; 300 } 301 302 static int xen_pv_console_init(void) 303 { 304 struct xencons_info *info; 305 unsigned long flags; 306 307 if (!xen_pv_domain()) 308 return -ENODEV; 309 310 if (!xen_start_info->console.domU.evtchn) 311 return -ENODEV; 312 313 info = vtermno_to_xencons(HVC_COOKIE); 314 if (!info) { 315 info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL); 316 if (!info) 317 return -ENOMEM; 318 } else if (info->intf != NULL) { 319 /* already configured */ 320 return 0; 321 } 322 spin_lock_irqsave(&xencons_lock, flags); 323 xencons_info_pv_init(info, HVC_COOKIE); 324 spin_unlock_irqrestore(&xencons_lock, flags); 325 326 return 0; 327 } 328 329 static int xen_initial_domain_console_init(void) 330 { 331 struct xencons_info *info; 332 unsigned long flags; 333 334 if (!xen_initial_domain()) 335 return -ENODEV; 336 337 info = vtermno_to_xencons(HVC_COOKIE); 338 if (!info) { 339 info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL); 340 if (!info) 341 return -ENOMEM; 342 spin_lock_init(&info->ring_lock); 343 } 344 345 info->irq = bind_virq_to_irq(VIRQ_CONSOLE, 0, false); 346 info->vtermno = HVC_COOKIE; 347 348 spin_lock_irqsave(&xencons_lock, flags); 349 list_add_tail(&info->list, &xenconsoles); 350 spin_unlock_irqrestore(&xencons_lock, flags); 351 352 return 0; 353 } 354 355 static void xen_console_update_evtchn(struct xencons_info *info) 356 { 357 if (xen_hvm_domain()) { 358 uint64_t v = 0; 359 int err; 360 361 err = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v); 362 if (!err && v) 363 info->evtchn = v; 364 } else 365 info->evtchn = xen_start_info->console.domU.evtchn; 366 } 367 368 void xen_console_resume(void) 369 { 370 struct xencons_info *info = vtermno_to_xencons(HVC_COOKIE); 371 if (info != NULL && info->irq) { 372 if (!xen_initial_domain()) 373 xen_console_update_evtchn(info); 374 rebind_evtchn_irq(info->evtchn, info->irq); 375 } 376 } 377 378 #ifdef CONFIG_HVC_XEN_FRONTEND 379 static void xencons_disconnect_backend(struct xencons_info *info) 380 { 381 if (info->hvc != NULL) 382 hvc_remove(info->hvc); 383 info->hvc = NULL; 384 if (info->irq > 0) { 385 evtchn_put(info->evtchn); 386 info->irq = 0; 387 info->evtchn = 0; 388 } 389 /* evtchn_put() will also close it so this is only an error path */ 390 if (info->evtchn > 0) 391 xenbus_free_evtchn(info->xbdev, info->evtchn); 392 info->evtchn = 0; 393 if (info->gntref > 0) 394 gnttab_free_grant_references(info->gntref); 395 info->gntref = 0; 396 } 397 398 static void xencons_free(struct xencons_info *info) 399 { 400 free_page((unsigned long)info->intf); 401 info->intf = NULL; 402 info->vtermno = 0; 403 kfree(info); 404 } 405 406 static int xen_console_remove(struct xencons_info *info) 407 { 408 unsigned long flags; 409 410 xencons_disconnect_backend(info); 411 spin_lock_irqsave(&xencons_lock, flags); 412 list_del(&info->list); 413 spin_unlock_irqrestore(&xencons_lock, flags); 414 if (info->xbdev != NULL) 415 xencons_free(info); 416 else { 417 if (xen_hvm_domain()) 418 iounmap(info->intf); 419 kfree(info); 420 } 421 return 0; 422 } 423 424 static void xencons_remove(struct xenbus_device *dev) 425 { 426 xen_console_remove(dev_get_drvdata(&dev->dev)); 427 } 428 429 static int xencons_connect_backend(struct xenbus_device *dev, 430 struct xencons_info *info) 431 { 432 int ret, evtchn, devid, ref, irq; 433 struct xenbus_transaction xbt; 434 grant_ref_t gref_head; 435 436 ret = xenbus_alloc_evtchn(dev, &evtchn); 437 if (ret) 438 return ret; 439 info->evtchn = evtchn; 440 irq = bind_evtchn_to_irq_lateeoi(evtchn); 441 if (irq < 0) 442 return irq; 443 info->irq = irq; 444 devid = dev->nodename[strlen(dev->nodename) - 1] - '0'; 445 info->hvc = hvc_alloc(xenbus_devid_to_vtermno(devid), 446 irq, &domU_hvc_ops, 256); 447 if (IS_ERR(info->hvc)) 448 return PTR_ERR(info->hvc); 449 ret = gnttab_alloc_grant_references(1, &gref_head); 450 if (ret < 0) 451 return ret; 452 info->gntref = gref_head; 453 ref = gnttab_claim_grant_reference(&gref_head); 454 if (ref < 0) 455 return ref; 456 gnttab_grant_foreign_access_ref(ref, info->xbdev->otherend_id, 457 virt_to_gfn(info->intf), 0); 458 459 again: 460 ret = xenbus_transaction_start(&xbt); 461 if (ret) { 462 xenbus_dev_fatal(dev, ret, "starting transaction"); 463 return ret; 464 } 465 ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", ref); 466 if (ret) 467 goto error_xenbus; 468 ret = xenbus_printf(xbt, dev->nodename, "port", "%u", 469 evtchn); 470 if (ret) 471 goto error_xenbus; 472 ret = xenbus_transaction_end(xbt, 0); 473 if (ret) { 474 if (ret == -EAGAIN) 475 goto again; 476 xenbus_dev_fatal(dev, ret, "completing transaction"); 477 return ret; 478 } 479 480 xenbus_switch_state(dev, XenbusStateInitialised); 481 return 0; 482 483 error_xenbus: 484 xenbus_transaction_end(xbt, 1); 485 xenbus_dev_fatal(dev, ret, "writing xenstore"); 486 return ret; 487 } 488 489 static int xencons_probe(struct xenbus_device *dev, 490 const struct xenbus_device_id *id) 491 { 492 int ret, devid; 493 struct xencons_info *info; 494 unsigned long flags; 495 496 devid = dev->nodename[strlen(dev->nodename) - 1] - '0'; 497 if (devid == 0) 498 return -ENODEV; 499 500 info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL); 501 if (!info) 502 return -ENOMEM; 503 spin_lock_init(&info->ring_lock); 504 dev_set_drvdata(&dev->dev, info); 505 info->xbdev = dev; 506 info->vtermno = xenbus_devid_to_vtermno(devid); 507 info->intf = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO); 508 if (!info->intf) 509 goto error_nomem; 510 511 ret = xencons_connect_backend(dev, info); 512 if (ret < 0) 513 goto error; 514 spin_lock_irqsave(&xencons_lock, flags); 515 list_add_tail(&info->list, &xenconsoles); 516 spin_unlock_irqrestore(&xencons_lock, flags); 517 518 return 0; 519 520 error_nomem: 521 ret = -ENOMEM; 522 xenbus_dev_fatal(dev, ret, "allocating device memory"); 523 error: 524 xencons_disconnect_backend(info); 525 xencons_free(info); 526 return ret; 527 } 528 529 static int xencons_resume(struct xenbus_device *dev) 530 { 531 struct xencons_info *info = dev_get_drvdata(&dev->dev); 532 533 xencons_disconnect_backend(info); 534 memset(info->intf, 0, XEN_PAGE_SIZE); 535 return xencons_connect_backend(dev, info); 536 } 537 538 static void xencons_backend_changed(struct xenbus_device *dev, 539 enum xenbus_state backend_state) 540 { 541 switch (backend_state) { 542 case XenbusStateReconfiguring: 543 case XenbusStateReconfigured: 544 case XenbusStateInitialising: 545 case XenbusStateInitialised: 546 case XenbusStateUnknown: 547 break; 548 549 case XenbusStateInitWait: 550 break; 551 552 case XenbusStateConnected: 553 xenbus_switch_state(dev, XenbusStateConnected); 554 break; 555 556 case XenbusStateClosed: 557 if (dev->state == XenbusStateClosed) 558 break; 559 fallthrough; /* Missed the backend's CLOSING state */ 560 case XenbusStateClosing: { 561 struct xencons_info *info = dev_get_drvdata(&dev->dev);; 562 563 /* 564 * Don't tear down the evtchn and grant ref before the other 565 * end has disconnected, but do stop userspace from trying 566 * to use the device before we allow the backend to close. 567 */ 568 if (info->hvc) { 569 hvc_remove(info->hvc); 570 info->hvc = NULL; 571 } 572 573 xenbus_frontend_closed(dev); 574 break; 575 } 576 } 577 } 578 579 static const struct xenbus_device_id xencons_ids[] = { 580 { "console" }, 581 { "" } 582 }; 583 584 static struct xenbus_driver xencons_driver = { 585 .name = "xenconsole", 586 .ids = xencons_ids, 587 .probe = xencons_probe, 588 .remove = xencons_remove, 589 .resume = xencons_resume, 590 .otherend_changed = xencons_backend_changed, 591 .not_essential = true, 592 }; 593 #endif /* CONFIG_HVC_XEN_FRONTEND */ 594 595 static int __init xen_hvc_init(void) 596 { 597 int r; 598 struct xencons_info *info; 599 const struct hv_ops *ops; 600 601 if (!xen_domain()) 602 return -ENODEV; 603 604 if (xen_initial_domain()) { 605 ops = &dom0_hvc_ops; 606 r = xen_initial_domain_console_init(); 607 if (r < 0) 608 goto register_fe; 609 info = vtermno_to_xencons(HVC_COOKIE); 610 } else { 611 ops = &domU_hvc_ops; 612 if (xen_hvm_domain()) 613 r = xen_hvm_console_init(); 614 else 615 r = xen_pv_console_init(); 616 if (r < 0) 617 goto register_fe; 618 619 info = vtermno_to_xencons(HVC_COOKIE); 620 info->irq = bind_evtchn_to_irq_lateeoi(info->evtchn); 621 } 622 if (info->irq < 0) 623 info->irq = 0; /* NO_IRQ */ 624 else 625 irq_set_noprobe(info->irq); 626 627 info->hvc = hvc_alloc(HVC_COOKIE, info->irq, ops, 256); 628 if (IS_ERR(info->hvc)) { 629 unsigned long flags; 630 631 r = PTR_ERR(info->hvc); 632 spin_lock_irqsave(&xencons_lock, flags); 633 list_del(&info->list); 634 spin_unlock_irqrestore(&xencons_lock, flags); 635 if (info->irq) 636 evtchn_put(info->evtchn); 637 kfree(info); 638 return r; 639 } 640 641 r = 0; 642 register_fe: 643 #ifdef CONFIG_HVC_XEN_FRONTEND 644 r = xenbus_register_frontend(&xencons_driver); 645 #endif 646 return r; 647 } 648 device_initcall(xen_hvc_init); 649 650 static int xen_cons_init(void) 651 { 652 const struct hv_ops *ops; 653 654 if (!xen_domain()) 655 return 0; 656 657 if (xen_initial_domain()) 658 ops = &dom0_hvc_ops; 659 else { 660 int r; 661 ops = &domU_hvc_ops; 662 663 if (xen_hvm_domain()) 664 r = xen_hvm_console_init(); 665 else 666 r = xen_pv_console_init(); 667 if (r < 0) 668 return r; 669 } 670 671 hvc_instantiate(HVC_COOKIE, 0, ops); 672 return 0; 673 } 674 console_initcall(xen_cons_init); 675 676 #ifdef CONFIG_X86 677 static void xen_hvm_early_write(uint32_t vtermno, const char *str, int len) 678 { 679 if (xen_cpuid_base()) 680 outsb(0xe9, str, len); 681 } 682 #else 683 static void xen_hvm_early_write(uint32_t vtermno, const char *str, int len) { } 684 #endif 685 686 #ifdef CONFIG_EARLY_PRINTK 687 static int __init xenboot_console_setup(struct console *console, char *string) 688 { 689 static struct xencons_info xenboot; 690 691 if (xen_initial_domain() || !xen_pv_domain()) 692 return 0; 693 694 return xencons_info_pv_init(&xenboot, 0); 695 } 696 697 static void xenboot_write_console(struct console *console, const char *string, 698 unsigned len) 699 { 700 unsigned int linelen, off = 0; 701 const char *pos; 702 703 if (dom0_write_console(0, string, len) >= 0) 704 return; 705 706 if (!xen_pv_domain()) { 707 xen_hvm_early_write(0, string, len); 708 return; 709 } 710 711 if (domU_write_console(0, "(early) ", 8) < 0) 712 return; 713 while (off < len && NULL != (pos = strchr(string+off, '\n'))) { 714 linelen = pos-string+off; 715 if (off + linelen > len) 716 break; 717 domU_write_console(0, string+off, linelen); 718 domU_write_console(0, "\r\n", 2); 719 off += linelen + 1; 720 } 721 if (off < len) 722 domU_write_console(0, string+off, len-off); 723 } 724 725 struct console xenboot_console = { 726 .name = "xenboot", 727 .write = xenboot_write_console, 728 .setup = xenboot_console_setup, 729 .flags = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME, 730 .index = -1, 731 }; 732 #endif /* CONFIG_EARLY_PRINTK */ 733 734 void xen_raw_console_write(const char *str) 735 { 736 ssize_t len = strlen(str); 737 int rc = 0; 738 739 if (xen_domain()) { 740 rc = dom0_write_console(0, str, len); 741 if (rc != -ENOSYS || !xen_hvm_domain()) 742 return; 743 } 744 xen_hvm_early_write(0, str, len); 745 } 746 747 void xen_raw_printk(const char *fmt, ...) 748 { 749 static char buf[512]; 750 va_list ap; 751 752 va_start(ap, fmt); 753 vsnprintf(buf, sizeof(buf), fmt, ap); 754 va_end(ap); 755 756 xen_raw_console_write(buf); 757 } 758 759 static void xenboot_earlycon_write(struct console *console, 760 const char *string, 761 unsigned len) 762 { 763 dom0_write_console(0, string, len); 764 } 765 766 static int __init xenboot_earlycon_setup(struct earlycon_device *device, 767 const char *opt) 768 { 769 device->con->write = xenboot_earlycon_write; 770 return 0; 771 } 772 EARLYCON_DECLARE(xenboot, xenboot_earlycon_setup); 773