1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Xen PCI Frontend
   4 *
   5 * Author: Ryan Wilson <hap9@epoch.ncsc.mil>
   6 */
   7#include <linux/module.h>
   8#include <linux/init.h>
   9#include <linux/mm.h>
  10#include <xen/xenbus.h>
  11#include <xen/events.h>
  12#include <xen/grant_table.h>
  13#include <xen/page.h>
  14#include <linux/spinlock.h>
  15#include <linux/pci.h>
  16#include <linux/msi.h>
  17#include <xen/interface/io/pciif.h>
  18#include <asm/xen/pci.h>
  19#include <linux/interrupt.h>
  20#include <linux/atomic.h>
  21#include <linux/workqueue.h>
  22#include <linux/bitops.h>
  23#include <linux/time.h>
  24#include <linux/ktime.h>
  25#include <xen/platform_pci.h>
  26
  27#include <asm/xen/swiotlb-xen.h>
  28#define INVALID_GRANT_REF (0)
  29#define INVALID_EVTCHN    (-1)
  30
  31struct pci_bus_entry {
  32	struct list_head list;
  33	struct pci_bus *bus;
  34};
  35
  36#define _PDEVB_op_active		(0)
  37#define PDEVB_op_active			(1 << (_PDEVB_op_active))
  38
  39struct pcifront_device {
  40	struct xenbus_device *xdev;
  41	struct list_head root_buses;
  42
  43	int evtchn;
  44	int gnt_ref;
  45
  46	int irq;
  47
  48	/* Lock this when doing any operations in sh_info */
  49	spinlock_t sh_info_lock;
  50	struct xen_pci_sharedinfo *sh_info;
  51	struct work_struct op_work;
  52	unsigned long flags;
  53
  54};
  55
  56struct pcifront_sd {
  57	struct pci_sysdata sd;
  58	struct pcifront_device *pdev;
  59};
  60
  61static inline struct pcifront_device *
  62pcifront_get_pdev(struct pcifront_sd *sd)
  63{
  64	return sd->pdev;
  65}
  66
  67static inline void pcifront_init_sd(struct pcifront_sd *sd,
  68				    unsigned int domain, unsigned int bus,
  69				    struct pcifront_device *pdev)
  70{
  71	/* Because we do not expose that information via XenBus. */
  72	sd->sd.node = first_online_node;
  73	sd->sd.domain = domain;
  74	sd->pdev = pdev;
  75}
  76
  77static DEFINE_SPINLOCK(pcifront_dev_lock);
  78static struct pcifront_device *pcifront_dev;
  79
  80static int verbose_request;
  81module_param(verbose_request, int, 0644);
  82
  83static int errno_to_pcibios_err(int errno)
  84{
  85	switch (errno) {
  86	case XEN_PCI_ERR_success:
  87		return PCIBIOS_SUCCESSFUL;
  88
  89	case XEN_PCI_ERR_dev_not_found:
  90		return PCIBIOS_DEVICE_NOT_FOUND;
  91
  92	case XEN_PCI_ERR_invalid_offset:
  93	case XEN_PCI_ERR_op_failed:
  94		return PCIBIOS_BAD_REGISTER_NUMBER;
  95
  96	case XEN_PCI_ERR_not_implemented:
  97		return PCIBIOS_FUNC_NOT_SUPPORTED;
  98
  99	case XEN_PCI_ERR_access_denied:
 100		return PCIBIOS_SET_FAILED;
 101	}
 102	return errno;
 103}
 104
 105static inline void schedule_pcifront_aer_op(struct pcifront_device *pdev)
 106{
 107	if (test_bit(_XEN_PCIB_active, (unsigned long *)&pdev->sh_info->flags)
 108		&& !test_and_set_bit(_PDEVB_op_active, &pdev->flags)) {
 109		dev_dbg(&pdev->xdev->dev, "schedule aer frontend job\n");
 110		schedule_work(&pdev->op_work);
 111	}
 112}
 113
 114static int do_pci_op(struct pcifront_device *pdev, struct xen_pci_op *op)
 115{
 116	int err = 0;
 117	struct xen_pci_op *active_op = &pdev->sh_info->op;
 118	unsigned long irq_flags;
 119	evtchn_port_t port = pdev->evtchn;
 120	unsigned irq = pdev->irq;
 121	s64 ns, ns_timeout;
 122
 123	spin_lock_irqsave(&pdev->sh_info_lock, irq_flags);
 124
 125	memcpy(active_op, op, sizeof(struct xen_pci_op));
 126
 127	/* Go */
 128	wmb();
 129	set_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags);
 130	notify_remote_via_evtchn(port);
 131
 132	/*
 133	 * We set a poll timeout of 3 seconds but give up on return after
 134	 * 2 seconds. It is better to time out too late rather than too early
 135	 * (in the latter case we end up continually re-executing poll() with a
 136	 * timeout in the past). 1s difference gives plenty of slack for error.
 137	 */
 138	ns_timeout = ktime_get_ns() + 2 * (s64)NSEC_PER_SEC;
 139
 140	xen_clear_irq_pending(irq);
 141
 142	while (test_bit(_XEN_PCIF_active,
 143			(unsigned long *)&pdev->sh_info->flags)) {
 144		xen_poll_irq_timeout(irq, jiffies + 3*HZ);
 145		xen_clear_irq_pending(irq);
 146		ns = ktime_get_ns();
 147		if (ns > ns_timeout) {
 148			dev_err(&pdev->xdev->dev,
 149				"pciback not responding!!!\n");
 150			clear_bit(_XEN_PCIF_active,
 151				  (unsigned long *)&pdev->sh_info->flags);
 152			err = XEN_PCI_ERR_dev_not_found;
 153			goto out;
 154		}
 155	}
 156
 157	/*
 158	* We might lose backend service request since we
 159	* reuse same evtchn with pci_conf backend response. So re-schedule
 160	* aer pcifront service.
 161	*/
 162	if (test_bit(_XEN_PCIB_active,
 163			(unsigned long *)&pdev->sh_info->flags)) {
 164		dev_err(&pdev->xdev->dev,
 165			"schedule aer pcifront service\n");
 166		schedule_pcifront_aer_op(pdev);
 167	}
 168
 169	memcpy(op, active_op, sizeof(struct xen_pci_op));
 170
 171	err = op->err;
 172out:
 173	spin_unlock_irqrestore(&pdev->sh_info_lock, irq_flags);
 174	return err;
 175}
 176
 177/* Access to this function is spinlocked in drivers/pci/access.c */
 178static int pcifront_bus_read(struct pci_bus *bus, unsigned int devfn,
 179			     int where, int size, u32 *val)
 180{
 181	int err = 0;
 182	struct xen_pci_op op = {
 183		.cmd    = XEN_PCI_OP_conf_read,
 184		.domain = pci_domain_nr(bus),
 185		.bus    = bus->number,
 186		.devfn  = devfn,
 187		.offset = where,
 188		.size   = size,
 189	};
 190	struct pcifront_sd *sd = bus->sysdata;
 191	struct pcifront_device *pdev = pcifront_get_pdev(sd);
 192
 193	if (verbose_request)
 194		dev_info(&pdev->xdev->dev,
 195			 "read dev=%04x:%02x:%02x.%d - offset %x size %d\n",
 196			 pci_domain_nr(bus), bus->number, PCI_SLOT(devfn),
 197			 PCI_FUNC(devfn), where, size);
 198
 199	err = do_pci_op(pdev, &op);
 200
 201	if (likely(!err)) {
 202		if (verbose_request)
 203			dev_info(&pdev->xdev->dev, "read got back value %x\n",
 204				 op.value);
 205
 206		*val = op.value;
 207	} else if (err == -ENODEV) {
 208		/* No device here, pretend that it just returned 0 */
 209		err = 0;
 210		*val = 0;
 211	}
 212
 213	return errno_to_pcibios_err(err);
 214}
 215
 216/* Access to this function is spinlocked in drivers/pci/access.c */
 217static int pcifront_bus_write(struct pci_bus *bus, unsigned int devfn,
 218			      int where, int size, u32 val)
 219{
 220	struct xen_pci_op op = {
 221		.cmd    = XEN_PCI_OP_conf_write,
 222		.domain = pci_domain_nr(bus),
 223		.bus    = bus->number,
 224		.devfn  = devfn,
 225		.offset = where,
 226		.size   = size,
 227		.value  = val,
 228	};
 229	struct pcifront_sd *sd = bus->sysdata;
 230	struct pcifront_device *pdev = pcifront_get_pdev(sd);
 231
 232	if (verbose_request)
 233		dev_info(&pdev->xdev->dev,
 234			 "write dev=%04x:%02x:%02x.%d - "
 235			 "offset %x size %d val %x\n",
 236			 pci_domain_nr(bus), bus->number,
 237			 PCI_SLOT(devfn), PCI_FUNC(devfn), where, size, val);
 238
 239	return errno_to_pcibios_err(do_pci_op(pdev, &op));
 240}
 241
 242static struct pci_ops pcifront_bus_ops = {
 243	.read = pcifront_bus_read,
 244	.write = pcifront_bus_write,
 245};
 246
 247#ifdef CONFIG_PCI_MSI
 248static int pci_frontend_enable_msix(struct pci_dev *dev,
 249				    int vector[], int nvec)
 250{
 251	int err;
 252	int i;
 253	struct xen_pci_op op = {
 254		.cmd    = XEN_PCI_OP_enable_msix,
 255		.domain = pci_domain_nr(dev->bus),
 256		.bus = dev->bus->number,
 257		.devfn = dev->devfn,
 258		.value = nvec,
 259	};
 260	struct pcifront_sd *sd = dev->bus->sysdata;
 261	struct pcifront_device *pdev = pcifront_get_pdev(sd);
 262	struct msi_desc *entry;
 263
 264	if (nvec > SH_INFO_MAX_VEC) {
 265		pci_err(dev, "too many vectors (0x%x) for PCI frontend:"
 266				   " Increase SH_INFO_MAX_VEC\n", nvec);
 267		return -EINVAL;
 268	}
 269
 270	i = 0;
 271	for_each_pci_msi_entry(entry, dev) {
 272		op.msix_entries[i].entry = entry->msi_attrib.entry_nr;
 273		/* Vector is useless at this point. */
 274		op.msix_entries[i].vector = -1;
 275		i++;
 276	}
 277
 278	err = do_pci_op(pdev, &op);
 279
 280	if (likely(!err)) {
 281		if (likely(!op.value)) {
 282			/* we get the result */
 283			for (i = 0; i < nvec; i++) {
 284				if (op.msix_entries[i].vector <= 0) {
 285					pci_warn(dev, "MSI-X entry %d is invalid: %d!\n",
 286						i, op.msix_entries[i].vector);
 287					err = -EINVAL;
 288					vector[i] = -1;
 289					continue;
 290				}
 291				vector[i] = op.msix_entries[i].vector;
 292			}
 293		} else {
 294			pr_info("enable msix get value %x\n", op.value);
 
 295			err = op.value;
 296		}
 297	} else {
 298		pci_err(dev, "enable msix get err %x\n", err);
 299	}
 300	return err;
 301}
 302
 303static void pci_frontend_disable_msix(struct pci_dev *dev)
 304{
 305	int err;
 306	struct xen_pci_op op = {
 307		.cmd    = XEN_PCI_OP_disable_msix,
 308		.domain = pci_domain_nr(dev->bus),
 309		.bus = dev->bus->number,
 310		.devfn = dev->devfn,
 311	};
 312	struct pcifront_sd *sd = dev->bus->sysdata;
 313	struct pcifront_device *pdev = pcifront_get_pdev(sd);
 314
 315	err = do_pci_op(pdev, &op);
 316
 317	/* What should do for error ? */
 318	if (err)
 319		pci_err(dev, "pci_disable_msix get err %x\n", err);
 320}
 321
 322static int pci_frontend_enable_msi(struct pci_dev *dev, int vector[])
 323{
 324	int err;
 325	struct xen_pci_op op = {
 326		.cmd    = XEN_PCI_OP_enable_msi,
 327		.domain = pci_domain_nr(dev->bus),
 328		.bus = dev->bus->number,
 329		.devfn = dev->devfn,
 330	};
 331	struct pcifront_sd *sd = dev->bus->sysdata;
 332	struct pcifront_device *pdev = pcifront_get_pdev(sd);
 333
 334	err = do_pci_op(pdev, &op);
 335	if (likely(!err)) {
 336		vector[0] = op.value;
 337		if (op.value <= 0) {
 338			pci_warn(dev, "MSI entry is invalid: %d!\n",
 339				op.value);
 340			err = -EINVAL;
 341			vector[0] = -1;
 342		}
 343	} else {
 344		pci_err(dev, "pci frontend enable msi failed for dev "
 345				    "%x:%x\n", op.bus, op.devfn);
 346		err = -EINVAL;
 347	}
 348	return err;
 349}
 350
 351static void pci_frontend_disable_msi(struct pci_dev *dev)
 352{
 353	int err;
 354	struct xen_pci_op op = {
 355		.cmd    = XEN_PCI_OP_disable_msi,
 356		.domain = pci_domain_nr(dev->bus),
 357		.bus = dev->bus->number,
 358		.devfn = dev->devfn,
 359	};
 360	struct pcifront_sd *sd = dev->bus->sysdata;
 361	struct pcifront_device *pdev = pcifront_get_pdev(sd);
 362
 363	err = do_pci_op(pdev, &op);
 364	if (err == XEN_PCI_ERR_dev_not_found) {
 365		/* XXX No response from backend, what shall we do? */
 366		pr_info("get no response from backend for disable MSI\n");
 367		return;
 368	}
 369	if (err)
 370		/* how can pciback notify us fail? */
 371		pr_info("get fake response from backend\n");
 372}
 373
 374static struct xen_pci_frontend_ops pci_frontend_ops = {
 375	.enable_msi = pci_frontend_enable_msi,
 376	.disable_msi = pci_frontend_disable_msi,
 377	.enable_msix = pci_frontend_enable_msix,
 378	.disable_msix = pci_frontend_disable_msix,
 379};
 380
 381static void pci_frontend_registrar(int enable)
 382{
 383	if (enable)
 384		xen_pci_frontend = &pci_frontend_ops;
 385	else
 386		xen_pci_frontend = NULL;
 387};
 388#else
 389static inline void pci_frontend_registrar(int enable) { };
 390#endif /* CONFIG_PCI_MSI */
 391
 392/* Claim resources for the PCI frontend as-is, backend won't allow changes */
 393static int pcifront_claim_resource(struct pci_dev *dev, void *data)
 394{
 395	struct pcifront_device *pdev = data;
 396	int i;
 397	struct resource *r;
 398
 399	for (i = 0; i < PCI_NUM_RESOURCES; i++) {
 400		r = &dev->resource[i];
 401
 402		if (!r->parent && r->start && r->flags) {
 403			dev_info(&pdev->xdev->dev, "claiming resource %s/%d\n",
 404				pci_name(dev), i);
 405			if (pci_claim_resource(dev, i)) {
 406				dev_err(&pdev->xdev->dev, "Could not claim resource %s/%d! "
 407					"Device offline. Try using e820_host=1 in the guest config.\n",
 408					pci_name(dev), i);
 409			}
 410		}
 411	}
 412
 413	return 0;
 414}
 415
 416static int pcifront_scan_bus(struct pcifront_device *pdev,
 417				unsigned int domain, unsigned int bus,
 418				struct pci_bus *b)
 419{
 420	struct pci_dev *d;
 421	unsigned int devfn;
 422
 423	/* Scan the bus for functions and add.
 424	 * We omit handling of PCI bridge attachment because pciback prevents
 425	 * bridges from being exported.
 426	 */
 427	for (devfn = 0; devfn < 0x100; devfn++) {
 428		d = pci_get_slot(b, devfn);
 429		if (d) {
 430			/* Device is already known. */
 431			pci_dev_put(d);
 432			continue;
 433		}
 434
 435		d = pci_scan_single_device(b, devfn);
 436		if (d)
 437			dev_info(&pdev->xdev->dev, "New device on "
 438				 "%04x:%02x:%02x.%d found.\n", domain, bus,
 439				 PCI_SLOT(devfn), PCI_FUNC(devfn));
 440	}
 441
 442	return 0;
 443}
 444
 445static int pcifront_scan_root(struct pcifront_device *pdev,
 446				 unsigned int domain, unsigned int bus)
 447{
 448	struct pci_bus *b;
 449	LIST_HEAD(resources);
 450	struct pcifront_sd *sd = NULL;
 451	struct pci_bus_entry *bus_entry = NULL;
 452	int err = 0;
 453	static struct resource busn_res = {
 454		.start = 0,
 455		.end = 255,
 456		.flags = IORESOURCE_BUS,
 457	};
 458
 459#ifndef CONFIG_PCI_DOMAINS
 460	if (domain != 0) {
 461		dev_err(&pdev->xdev->dev,
 462			"PCI Root in non-zero PCI Domain! domain=%d\n", domain);
 463		dev_err(&pdev->xdev->dev,
 464			"Please compile with CONFIG_PCI_DOMAINS\n");
 465		err = -EINVAL;
 466		goto err_out;
 467	}
 468#endif
 469
 470	dev_info(&pdev->xdev->dev, "Creating PCI Frontend Bus %04x:%02x\n",
 471		 domain, bus);
 472
 473	bus_entry = kzalloc(sizeof(*bus_entry), GFP_KERNEL);
 474	sd = kzalloc(sizeof(*sd), GFP_KERNEL);
 475	if (!bus_entry || !sd) {
 476		err = -ENOMEM;
 477		goto err_out;
 478	}
 479	pci_add_resource(&resources, &ioport_resource);
 480	pci_add_resource(&resources, &iomem_resource);
 481	pci_add_resource(&resources, &busn_res);
 482	pcifront_init_sd(sd, domain, bus, pdev);
 483
 484	pci_lock_rescan_remove();
 485
 486	b = pci_scan_root_bus(&pdev->xdev->dev, bus,
 487				  &pcifront_bus_ops, sd, &resources);
 488	if (!b) {
 489		dev_err(&pdev->xdev->dev,
 490			"Error creating PCI Frontend Bus!\n");
 491		err = -ENOMEM;
 492		pci_unlock_rescan_remove();
 493		pci_free_resource_list(&resources);
 494		goto err_out;
 495	}
 496
 497	bus_entry->bus = b;
 498
 499	list_add(&bus_entry->list, &pdev->root_buses);
 500
 501	/* pci_scan_root_bus skips devices which do not have a
 502	* devfn==0. The pcifront_scan_bus enumerates all devfn. */
 503	err = pcifront_scan_bus(pdev, domain, bus, b);
 504
 505	/* Claim resources before going "live" with our devices */
 506	pci_walk_bus(b, pcifront_claim_resource, pdev);
 507
 508	/* Create SysFS and notify udev of the devices. Aka: "going live" */
 509	pci_bus_add_devices(b);
 510
 511	pci_unlock_rescan_remove();
 512	return err;
 513
 514err_out:
 515	kfree(bus_entry);
 516	kfree(sd);
 517
 518	return err;
 519}
 520
 521static int pcifront_rescan_root(struct pcifront_device *pdev,
 522				   unsigned int domain, unsigned int bus)
 523{
 524	int err;
 525	struct pci_bus *b;
 526
 527#ifndef CONFIG_PCI_DOMAINS
 528	if (domain != 0) {
 529		dev_err(&pdev->xdev->dev,
 530			"PCI Root in non-zero PCI Domain! domain=%d\n", domain);
 531		dev_err(&pdev->xdev->dev,
 532			"Please compile with CONFIG_PCI_DOMAINS\n");
 533		return -EINVAL;
 534	}
 535#endif
 536
 537	dev_info(&pdev->xdev->dev, "Rescanning PCI Frontend Bus %04x:%02x\n",
 538		 domain, bus);
 539
 540	b = pci_find_bus(domain, bus);
 541	if (!b)
 542		/* If the bus is unknown, create it. */
 543		return pcifront_scan_root(pdev, domain, bus);
 544
 545	err = pcifront_scan_bus(pdev, domain, bus, b);
 546
 547	/* Claim resources before going "live" with our devices */
 548	pci_walk_bus(b, pcifront_claim_resource, pdev);
 549
 550	/* Create SysFS and notify udev of the devices. Aka: "going live" */
 551	pci_bus_add_devices(b);
 552
 553	return err;
 554}
 555
 556static void free_root_bus_devs(struct pci_bus *bus)
 557{
 558	struct pci_dev *dev;
 559
 560	while (!list_empty(&bus->devices)) {
 561		dev = container_of(bus->devices.next, struct pci_dev,
 562				   bus_list);
 563		pci_dbg(dev, "removing device\n");
 564		pci_stop_and_remove_bus_device(dev);
 565	}
 566}
 567
 568static void pcifront_free_roots(struct pcifront_device *pdev)
 569{
 570	struct pci_bus_entry *bus_entry, *t;
 571
 572	dev_dbg(&pdev->xdev->dev, "cleaning up root buses\n");
 573
 574	pci_lock_rescan_remove();
 575	list_for_each_entry_safe(bus_entry, t, &pdev->root_buses, list) {
 576		list_del(&bus_entry->list);
 577
 578		free_root_bus_devs(bus_entry->bus);
 579
 580		kfree(bus_entry->bus->sysdata);
 581
 582		device_unregister(bus_entry->bus->bridge);
 583		pci_remove_bus(bus_entry->bus);
 584
 585		kfree(bus_entry);
 586	}
 587	pci_unlock_rescan_remove();
 588}
 589
 590static pci_ers_result_t pcifront_common_process(int cmd,
 591						struct pcifront_device *pdev,
 592						pci_channel_state_t state)
 593{
 594	pci_ers_result_t result;
 595	struct pci_driver *pdrv;
 596	int bus = pdev->sh_info->aer_op.bus;
 597	int devfn = pdev->sh_info->aer_op.devfn;
 598	int domain = pdev->sh_info->aer_op.domain;
 599	struct pci_dev *pcidev;
 600	int flag = 0;
 601
 602	dev_dbg(&pdev->xdev->dev,
 603		"pcifront AER process: cmd %x (bus:%x, devfn%x)",
 604		cmd, bus, devfn);
 605	result = PCI_ERS_RESULT_NONE;
 606
 607	pcidev = pci_get_domain_bus_and_slot(domain, bus, devfn);
 608	if (!pcidev || !pcidev->driver) {
 609		dev_err(&pdev->xdev->dev, "device or AER driver is NULL\n");
 610		pci_dev_put(pcidev);
 611		return result;
 612	}
 613	pdrv = pcidev->driver;
 614
 615	if (pdrv) {
 616		if (pdrv->err_handler && pdrv->err_handler->error_detected) {
 617			pci_dbg(pcidev, "trying to call AER service\n");
 
 618			if (pcidev) {
 619				flag = 1;
 620				switch (cmd) {
 621				case XEN_PCI_OP_aer_detected:
 622					result = pdrv->err_handler->
 623						 error_detected(pcidev, state);
 624					break;
 625				case XEN_PCI_OP_aer_mmio:
 626					result = pdrv->err_handler->
 627						 mmio_enabled(pcidev);
 628					break;
 629				case XEN_PCI_OP_aer_slotreset:
 630					result = pdrv->err_handler->
 631						 slot_reset(pcidev);
 632					break;
 633				case XEN_PCI_OP_aer_resume:
 634					pdrv->err_handler->resume(pcidev);
 635					break;
 636				default:
 637					dev_err(&pdev->xdev->dev,
 638						"bad request in aer recovery "
 639						"operation!\n");
 640
 641				}
 642			}
 643		}
 644	}
 645	if (!flag)
 646		result = PCI_ERS_RESULT_NONE;
 647
 648	return result;
 649}
 650
 651
 652static void pcifront_do_aer(struct work_struct *data)
 653{
 654	struct pcifront_device *pdev =
 655		container_of(data, struct pcifront_device, op_work);
 656	int cmd = pdev->sh_info->aer_op.cmd;
 657	pci_channel_state_t state =
 658		(pci_channel_state_t)pdev->sh_info->aer_op.err;
 659
 660	/*If a pci_conf op is in progress,
 661		we have to wait until it is done before service aer op*/
 662	dev_dbg(&pdev->xdev->dev,
 663		"pcifront service aer bus %x devfn %x\n",
 664		pdev->sh_info->aer_op.bus, pdev->sh_info->aer_op.devfn);
 665
 666	pdev->sh_info->aer_op.err = pcifront_common_process(cmd, pdev, state);
 667
 668	/* Post the operation to the guest. */
 669	wmb();
 670	clear_bit(_XEN_PCIB_active, (unsigned long *)&pdev->sh_info->flags);
 671	notify_remote_via_evtchn(pdev->evtchn);
 672
 673	/*in case of we lost an aer request in four lines time_window*/
 674	smp_mb__before_atomic();
 675	clear_bit(_PDEVB_op_active, &pdev->flags);
 676	smp_mb__after_atomic();
 677
 678	schedule_pcifront_aer_op(pdev);
 679
 680}
 681
 682static irqreturn_t pcifront_handler_aer(int irq, void *dev)
 683{
 684	struct pcifront_device *pdev = dev;
 685	schedule_pcifront_aer_op(pdev);
 686	return IRQ_HANDLED;
 687}
 688static int pcifront_connect_and_init_dma(struct pcifront_device *pdev)
 689{
 690	int err = 0;
 691
 692	spin_lock(&pcifront_dev_lock);
 693
 694	if (!pcifront_dev) {
 695		dev_info(&pdev->xdev->dev, "Installing PCI frontend\n");
 696		pcifront_dev = pdev;
 697	} else
 698		err = -EEXIST;
 699
 700	spin_unlock(&pcifront_dev_lock);
 701
 702	if (!err && !swiotlb_nr_tbl()) {
 703		err = pci_xen_swiotlb_init_late();
 704		if (err)
 705			dev_err(&pdev->xdev->dev, "Could not setup SWIOTLB!\n");
 706	}
 707	return err;
 708}
 709
 710static void pcifront_disconnect(struct pcifront_device *pdev)
 711{
 712	spin_lock(&pcifront_dev_lock);
 713
 714	if (pdev == pcifront_dev) {
 715		dev_info(&pdev->xdev->dev,
 716			 "Disconnecting PCI Frontend Buses\n");
 717		pcifront_dev = NULL;
 718	}
 719
 720	spin_unlock(&pcifront_dev_lock);
 721}
 722static struct pcifront_device *alloc_pdev(struct xenbus_device *xdev)
 723{
 724	struct pcifront_device *pdev;
 725
 726	pdev = kzalloc(sizeof(struct pcifront_device), GFP_KERNEL);
 727	if (pdev == NULL)
 728		goto out;
 729
 730	pdev->sh_info =
 731	    (struct xen_pci_sharedinfo *)__get_free_page(GFP_KERNEL);
 732	if (pdev->sh_info == NULL) {
 733		kfree(pdev);
 734		pdev = NULL;
 735		goto out;
 736	}
 737	pdev->sh_info->flags = 0;
 738
 739	/*Flag for registering PV AER handler*/
 740	set_bit(_XEN_PCIB_AERHANDLER, (void *)&pdev->sh_info->flags);
 741
 742	dev_set_drvdata(&xdev->dev, pdev);
 743	pdev->xdev = xdev;
 744
 745	INIT_LIST_HEAD(&pdev->root_buses);
 746
 747	spin_lock_init(&pdev->sh_info_lock);
 748
 749	pdev->evtchn = INVALID_EVTCHN;
 750	pdev->gnt_ref = INVALID_GRANT_REF;
 751	pdev->irq = -1;
 752
 753	INIT_WORK(&pdev->op_work, pcifront_do_aer);
 754
 755	dev_dbg(&xdev->dev, "Allocated pdev @ 0x%p pdev->sh_info @ 0x%p\n",
 756		pdev, pdev->sh_info);
 757out:
 758	return pdev;
 759}
 760
 761static void free_pdev(struct pcifront_device *pdev)
 762{
 763	dev_dbg(&pdev->xdev->dev, "freeing pdev @ 0x%p\n", pdev);
 764
 765	pcifront_free_roots(pdev);
 766
 767	cancel_work_sync(&pdev->op_work);
 768
 769	if (pdev->irq >= 0)
 770		unbind_from_irqhandler(pdev->irq, pdev);
 771
 772	if (pdev->evtchn != INVALID_EVTCHN)
 773		xenbus_free_evtchn(pdev->xdev, pdev->evtchn);
 774
 775	if (pdev->gnt_ref != INVALID_GRANT_REF)
 776		gnttab_end_foreign_access(pdev->gnt_ref, 0 /* r/w page */,
 777					  (unsigned long)pdev->sh_info);
 778	else
 779		free_page((unsigned long)pdev->sh_info);
 780
 781	dev_set_drvdata(&pdev->xdev->dev, NULL);
 782
 783	kfree(pdev);
 784}
 785
 786static int pcifront_publish_info(struct pcifront_device *pdev)
 787{
 788	int err = 0;
 789	struct xenbus_transaction trans;
 790	grant_ref_t gref;
 791
 792	err = xenbus_grant_ring(pdev->xdev, pdev->sh_info, 1, &gref);
 793	if (err < 0)
 794		goto out;
 795
 796	pdev->gnt_ref = gref;
 797
 798	err = xenbus_alloc_evtchn(pdev->xdev, &pdev->evtchn);
 799	if (err)
 800		goto out;
 801
 802	err = bind_evtchn_to_irqhandler(pdev->evtchn, pcifront_handler_aer,
 803		0, "pcifront", pdev);
 804
 805	if (err < 0)
 806		return err;
 807
 808	pdev->irq = err;
 809
 810do_publish:
 811	err = xenbus_transaction_start(&trans);
 812	if (err) {
 813		xenbus_dev_fatal(pdev->xdev, err,
 814				 "Error writing configuration for backend "
 815				 "(start transaction)");
 816		goto out;
 817	}
 818
 819	err = xenbus_printf(trans, pdev->xdev->nodename,
 820			    "pci-op-ref", "%u", pdev->gnt_ref);
 821	if (!err)
 822		err = xenbus_printf(trans, pdev->xdev->nodename,
 823				    "event-channel", "%u", pdev->evtchn);
 824	if (!err)
 825		err = xenbus_printf(trans, pdev->xdev->nodename,
 826				    "magic", XEN_PCI_MAGIC);
 827
 828	if (err) {
 829		xenbus_transaction_end(trans, 1);
 830		xenbus_dev_fatal(pdev->xdev, err,
 831				 "Error writing configuration for backend");
 832		goto out;
 833	} else {
 834		err = xenbus_transaction_end(trans, 0);
 835		if (err == -EAGAIN)
 836			goto do_publish;
 837		else if (err) {
 838			xenbus_dev_fatal(pdev->xdev, err,
 839					 "Error completing transaction "
 840					 "for backend");
 841			goto out;
 842		}
 843	}
 844
 845	xenbus_switch_state(pdev->xdev, XenbusStateInitialised);
 846
 847	dev_dbg(&pdev->xdev->dev, "publishing successful!\n");
 848
 849out:
 850	return err;
 851}
 852
 853static int pcifront_try_connect(struct pcifront_device *pdev)
 854{
 855	int err = -EFAULT;
 856	int i, num_roots, len;
 857	char str[64];
 858	unsigned int domain, bus;
 859
 860
 861	/* Only connect once */
 862	if (xenbus_read_driver_state(pdev->xdev->nodename) !=
 863	    XenbusStateInitialised)
 864		goto out;
 865
 866	err = pcifront_connect_and_init_dma(pdev);
 867	if (err && err != -EEXIST) {
 868		xenbus_dev_fatal(pdev->xdev, err,
 869				 "Error setting up PCI Frontend");
 870		goto out;
 871	}
 872
 873	err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend,
 874			   "root_num", "%d", &num_roots);
 875	if (err == -ENOENT) {
 876		xenbus_dev_error(pdev->xdev, err,
 877				 "No PCI Roots found, trying 0000:00");
 878		err = pcifront_scan_root(pdev, 0, 0);
 879		if (err) {
 880			xenbus_dev_fatal(pdev->xdev, err,
 881					 "Error scanning PCI root 0000:00");
 882			goto out;
 883		}
 884		num_roots = 0;
 885	} else if (err != 1) {
 886		if (err == 0)
 887			err = -EINVAL;
 888		xenbus_dev_fatal(pdev->xdev, err,
 889				 "Error reading number of PCI roots");
 890		goto out;
 891	}
 892
 893	for (i = 0; i < num_roots; i++) {
 894		len = snprintf(str, sizeof(str), "root-%d", i);
 895		if (unlikely(len >= (sizeof(str) - 1))) {
 896			err = -ENOMEM;
 897			goto out;
 898		}
 899
 900		err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend, str,
 901				   "%x:%x", &domain, &bus);
 902		if (err != 2) {
 903			if (err >= 0)
 904				err = -EINVAL;
 905			xenbus_dev_fatal(pdev->xdev, err,
 906					 "Error reading PCI root %d", i);
 907			goto out;
 908		}
 909
 910		err = pcifront_scan_root(pdev, domain, bus);
 911		if (err) {
 912			xenbus_dev_fatal(pdev->xdev, err,
 913					 "Error scanning PCI root %04x:%02x",
 914					 domain, bus);
 915			goto out;
 916		}
 917	}
 918
 919	err = xenbus_switch_state(pdev->xdev, XenbusStateConnected);
 920
 921out:
 922	return err;
 923}
 924
 925static int pcifront_try_disconnect(struct pcifront_device *pdev)
 926{
 927	int err = 0;
 928	enum xenbus_state prev_state;
 929
 930
 931	prev_state = xenbus_read_driver_state(pdev->xdev->nodename);
 932
 933	if (prev_state >= XenbusStateClosing)
 934		goto out;
 935
 936	if (prev_state == XenbusStateConnected) {
 937		pcifront_free_roots(pdev);
 938		pcifront_disconnect(pdev);
 939	}
 940
 941	err = xenbus_switch_state(pdev->xdev, XenbusStateClosed);
 942
 943out:
 944
 945	return err;
 946}
 947
 948static int pcifront_attach_devices(struct pcifront_device *pdev)
 949{
 950	int err = -EFAULT;
 951	int i, num_roots, len;
 952	unsigned int domain, bus;
 953	char str[64];
 954
 955	if (xenbus_read_driver_state(pdev->xdev->nodename) !=
 956	    XenbusStateReconfiguring)
 957		goto out;
 958
 959	err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend,
 960			   "root_num", "%d", &num_roots);
 961	if (err == -ENOENT) {
 962		xenbus_dev_error(pdev->xdev, err,
 963				 "No PCI Roots found, trying 0000:00");
 964		err = pcifront_rescan_root(pdev, 0, 0);
 965		if (err) {
 966			xenbus_dev_fatal(pdev->xdev, err,
 967					 "Error scanning PCI root 0000:00");
 968			goto out;
 969		}
 970		num_roots = 0;
 971	} else if (err != 1) {
 972		if (err == 0)
 973			err = -EINVAL;
 974		xenbus_dev_fatal(pdev->xdev, err,
 975				 "Error reading number of PCI roots");
 976		goto out;
 977	}
 978
 979	for (i = 0; i < num_roots; i++) {
 980		len = snprintf(str, sizeof(str), "root-%d", i);
 981		if (unlikely(len >= (sizeof(str) - 1))) {
 982			err = -ENOMEM;
 983			goto out;
 984		}
 985
 986		err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend, str,
 987				   "%x:%x", &domain, &bus);
 988		if (err != 2) {
 989			if (err >= 0)
 990				err = -EINVAL;
 991			xenbus_dev_fatal(pdev->xdev, err,
 992					 "Error reading PCI root %d", i);
 993			goto out;
 994		}
 995
 996		err = pcifront_rescan_root(pdev, domain, bus);
 997		if (err) {
 998			xenbus_dev_fatal(pdev->xdev, err,
 999					 "Error scanning PCI root %04x:%02x",
1000					 domain, bus);
1001			goto out;
1002		}
1003	}
1004
1005	xenbus_switch_state(pdev->xdev, XenbusStateConnected);
1006
1007out:
1008	return err;
1009}
1010
1011static int pcifront_detach_devices(struct pcifront_device *pdev)
1012{
1013	int err = 0;
1014	int i, num_devs;
1015	unsigned int domain, bus, slot, func;
1016	struct pci_dev *pci_dev;
1017	char str[64];
1018
1019	if (xenbus_read_driver_state(pdev->xdev->nodename) !=
1020	    XenbusStateConnected)
1021		goto out;
1022
1023	err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend, "num_devs", "%d",
1024			   &num_devs);
1025	if (err != 1) {
1026		if (err >= 0)
1027			err = -EINVAL;
1028		xenbus_dev_fatal(pdev->xdev, err,
1029				 "Error reading number of PCI devices");
1030		goto out;
1031	}
1032
1033	/* Find devices being detached and remove them. */
1034	for (i = 0; i < num_devs; i++) {
1035		int l, state;
1036		l = snprintf(str, sizeof(str), "state-%d", i);
1037		if (unlikely(l >= (sizeof(str) - 1))) {
1038			err = -ENOMEM;
1039			goto out;
1040		}
1041		state = xenbus_read_unsigned(pdev->xdev->otherend, str,
1042					     XenbusStateUnknown);
1043
1044		if (state != XenbusStateClosing)
1045			continue;
1046
1047		/* Remove device. */
1048		l = snprintf(str, sizeof(str), "vdev-%d", i);
1049		if (unlikely(l >= (sizeof(str) - 1))) {
1050			err = -ENOMEM;
1051			goto out;
1052		}
1053		err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend, str,
1054				   "%x:%x:%x.%x", &domain, &bus, &slot, &func);
1055		if (err != 4) {
1056			if (err >= 0)
1057				err = -EINVAL;
1058			xenbus_dev_fatal(pdev->xdev, err,
1059					 "Error reading PCI device %d", i);
1060			goto out;
1061		}
1062
1063		pci_dev = pci_get_domain_bus_and_slot(domain, bus,
1064				PCI_DEVFN(slot, func));
1065		if (!pci_dev) {
1066			dev_dbg(&pdev->xdev->dev,
1067				"Cannot get PCI device %04x:%02x:%02x.%d\n",
1068				domain, bus, slot, func);
1069			continue;
1070		}
1071		pci_lock_rescan_remove();
1072		pci_stop_and_remove_bus_device(pci_dev);
1073		pci_dev_put(pci_dev);
1074		pci_unlock_rescan_remove();
1075
1076		dev_dbg(&pdev->xdev->dev,
1077			"PCI device %04x:%02x:%02x.%d removed.\n",
1078			domain, bus, slot, func);
1079	}
1080
1081	err = xenbus_switch_state(pdev->xdev, XenbusStateReconfiguring);
1082
1083out:
1084	return err;
1085}
1086
1087static void __ref pcifront_backend_changed(struct xenbus_device *xdev,
1088						  enum xenbus_state be_state)
1089{
1090	struct pcifront_device *pdev = dev_get_drvdata(&xdev->dev);
1091
1092	switch (be_state) {
1093	case XenbusStateUnknown:
1094	case XenbusStateInitialising:
1095	case XenbusStateInitWait:
1096	case XenbusStateInitialised:
1097		break;
1098
1099	case XenbusStateConnected:
1100		pcifront_try_connect(pdev);
1101		break;
1102
1103	case XenbusStateClosed:
1104		if (xdev->state == XenbusStateClosed)
1105			break;
1106		/* fall through - Missed the backend's CLOSING state. */
1107	case XenbusStateClosing:
1108		dev_warn(&xdev->dev, "backend going away!\n");
1109		pcifront_try_disconnect(pdev);
1110		break;
1111
1112	case XenbusStateReconfiguring:
1113		pcifront_detach_devices(pdev);
1114		break;
1115
1116	case XenbusStateReconfigured:
1117		pcifront_attach_devices(pdev);
1118		break;
1119	}
1120}
1121
1122static int pcifront_xenbus_probe(struct xenbus_device *xdev,
1123				 const struct xenbus_device_id *id)
1124{
1125	int err = 0;
1126	struct pcifront_device *pdev = alloc_pdev(xdev);
1127
1128	if (pdev == NULL) {
1129		err = -ENOMEM;
1130		xenbus_dev_fatal(xdev, err,
1131				 "Error allocating pcifront_device struct");
1132		goto out;
1133	}
1134
1135	err = pcifront_publish_info(pdev);
1136	if (err)
1137		free_pdev(pdev);
1138
1139out:
1140	return err;
1141}
1142
1143static int pcifront_xenbus_remove(struct xenbus_device *xdev)
1144{
1145	struct pcifront_device *pdev = dev_get_drvdata(&xdev->dev);
1146	if (pdev)
1147		free_pdev(pdev);
1148
1149	return 0;
1150}
1151
1152static const struct xenbus_device_id xenpci_ids[] = {
1153	{"pci"},
1154	{""},
1155};
1156
1157static struct xenbus_driver xenpci_driver = {
1158	.name			= "pcifront",
1159	.ids			= xenpci_ids,
1160	.probe			= pcifront_xenbus_probe,
1161	.remove			= pcifront_xenbus_remove,
1162	.otherend_changed	= pcifront_backend_changed,
1163};
1164
1165static int __init pcifront_init(void)
1166{
1167	if (!xen_pv_domain() || xen_initial_domain())
1168		return -ENODEV;
1169
1170	if (!xen_has_pv_devices())
1171		return -ENODEV;
1172
1173	pci_frontend_registrar(1 /* enable */);
1174
1175	return xenbus_register_frontend(&xenpci_driver);
1176}
1177
1178static void __exit pcifront_cleanup(void)
1179{
1180	xenbus_unregister_driver(&xenpci_driver);
1181	pci_frontend_registrar(0 /* disable */);
1182}
1183module_init(pcifront_init);
1184module_exit(pcifront_cleanup);
1185
1186MODULE_DESCRIPTION("Xen PCI passthrough frontend.");
1187MODULE_LICENSE("GPL");
1188MODULE_ALIAS("xen:pci");