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