xref: /openbmc/linux/drivers/pci/xen-pcifront.c (revision f9a38ea5)
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 
29 #define INVALID_EVTCHN    (-1)
30 
31 struct 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 
39 struct pcifront_device {
40 	struct xenbus_device *xdev;
41 	struct list_head root_buses;
42 
43 	int evtchn;
44 	grant_ref_t 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 
56 struct pcifront_sd {
57 	struct pci_sysdata sd;
58 	struct pcifront_device *pdev;
59 };
60 
61 static inline struct pcifront_device *
pcifront_get_pdev(struct pcifront_sd * sd)62 pcifront_get_pdev(struct pcifront_sd *sd)
63 {
64 	return sd->pdev;
65 }
66 
pcifront_init_sd(struct pcifront_sd * sd,unsigned int domain,unsigned int bus,struct pcifront_device * pdev)67 static 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 
77 static DEFINE_SPINLOCK(pcifront_dev_lock);
78 static struct pcifront_device *pcifront_dev;
79 
errno_to_pcibios_err(int errno)80 static int errno_to_pcibios_err(int errno)
81 {
82 	switch (errno) {
83 	case XEN_PCI_ERR_success:
84 		return PCIBIOS_SUCCESSFUL;
85 
86 	case XEN_PCI_ERR_dev_not_found:
87 		return PCIBIOS_DEVICE_NOT_FOUND;
88 
89 	case XEN_PCI_ERR_invalid_offset:
90 	case XEN_PCI_ERR_op_failed:
91 		return PCIBIOS_BAD_REGISTER_NUMBER;
92 
93 	case XEN_PCI_ERR_not_implemented:
94 		return PCIBIOS_FUNC_NOT_SUPPORTED;
95 
96 	case XEN_PCI_ERR_access_denied:
97 		return PCIBIOS_SET_FAILED;
98 	}
99 	return errno;
100 }
101 
schedule_pcifront_aer_op(struct pcifront_device * pdev)102 static inline void schedule_pcifront_aer_op(struct pcifront_device *pdev)
103 {
104 	if (test_bit(_XEN_PCIB_active, (unsigned long *)&pdev->sh_info->flags)
105 		&& !test_and_set_bit(_PDEVB_op_active, &pdev->flags)) {
106 		dev_dbg(&pdev->xdev->dev, "schedule aer frontend job\n");
107 		schedule_work(&pdev->op_work);
108 	}
109 }
110 
do_pci_op(struct pcifront_device * pdev,struct xen_pci_op * op)111 static int do_pci_op(struct pcifront_device *pdev, struct xen_pci_op *op)
112 {
113 	int err = 0;
114 	struct xen_pci_op *active_op = &pdev->sh_info->op;
115 	unsigned long irq_flags;
116 	evtchn_port_t port = pdev->evtchn;
117 	unsigned int irq = pdev->irq;
118 	s64 ns, ns_timeout;
119 
120 	spin_lock_irqsave(&pdev->sh_info_lock, irq_flags);
121 
122 	memcpy(active_op, op, sizeof(struct xen_pci_op));
123 
124 	/* Go */
125 	wmb();
126 	set_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags);
127 	notify_remote_via_evtchn(port);
128 
129 	/*
130 	 * We set a poll timeout of 3 seconds but give up on return after
131 	 * 2 seconds. It is better to time out too late rather than too early
132 	 * (in the latter case we end up continually re-executing poll() with a
133 	 * timeout in the past). 1s difference gives plenty of slack for error.
134 	 */
135 	ns_timeout = ktime_get_ns() + 2 * (s64)NSEC_PER_SEC;
136 
137 	xen_clear_irq_pending(irq);
138 
139 	while (test_bit(_XEN_PCIF_active,
140 			(unsigned long *)&pdev->sh_info->flags)) {
141 		xen_poll_irq_timeout(irq, jiffies + 3*HZ);
142 		xen_clear_irq_pending(irq);
143 		ns = ktime_get_ns();
144 		if (ns > ns_timeout) {
145 			dev_err(&pdev->xdev->dev,
146 				"pciback not responding!!!\n");
147 			clear_bit(_XEN_PCIF_active,
148 				  (unsigned long *)&pdev->sh_info->flags);
149 			err = XEN_PCI_ERR_dev_not_found;
150 			goto out;
151 		}
152 	}
153 
154 	/*
155 	 * We might lose backend service request since we
156 	 * reuse same evtchn with pci_conf backend response. So re-schedule
157 	 * aer pcifront service.
158 	 */
159 	if (test_bit(_XEN_PCIB_active,
160 			(unsigned long *)&pdev->sh_info->flags)) {
161 		dev_err(&pdev->xdev->dev,
162 			"schedule aer pcifront service\n");
163 		schedule_pcifront_aer_op(pdev);
164 	}
165 
166 	memcpy(op, active_op, sizeof(struct xen_pci_op));
167 
168 	err = op->err;
169 out:
170 	spin_unlock_irqrestore(&pdev->sh_info_lock, irq_flags);
171 	return err;
172 }
173 
174 /* Access to this function is spinlocked in drivers/pci/access.c */
pcifront_bus_read(struct pci_bus * bus,unsigned int devfn,int where,int size,u32 * val)175 static int pcifront_bus_read(struct pci_bus *bus, unsigned int devfn,
176 			     int where, int size, u32 *val)
177 {
178 	int err = 0;
179 	struct xen_pci_op op = {
180 		.cmd    = XEN_PCI_OP_conf_read,
181 		.domain = pci_domain_nr(bus),
182 		.bus    = bus->number,
183 		.devfn  = devfn,
184 		.offset = where,
185 		.size   = size,
186 	};
187 	struct pcifront_sd *sd = bus->sysdata;
188 	struct pcifront_device *pdev = pcifront_get_pdev(sd);
189 
190 	dev_dbg(&pdev->xdev->dev,
191 		"read dev=%04x:%02x:%02x.%d - offset %x size %d\n",
192 		pci_domain_nr(bus), bus->number, PCI_SLOT(devfn),
193 		PCI_FUNC(devfn), where, size);
194 
195 	err = do_pci_op(pdev, &op);
196 
197 	if (likely(!err)) {
198 		dev_dbg(&pdev->xdev->dev, "read got back value %x\n",
199 			op.value);
200 
201 		*val = op.value;
202 	} else if (err == -ENODEV) {
203 		/* No device here, pretend that it just returned 0 */
204 		err = 0;
205 		*val = 0;
206 	}
207 
208 	return errno_to_pcibios_err(err);
209 }
210 
211 /* Access to this function is spinlocked in drivers/pci/access.c */
pcifront_bus_write(struct pci_bus * bus,unsigned int devfn,int where,int size,u32 val)212 static int pcifront_bus_write(struct pci_bus *bus, unsigned int devfn,
213 			      int where, int size, u32 val)
214 {
215 	struct xen_pci_op op = {
216 		.cmd    = XEN_PCI_OP_conf_write,
217 		.domain = pci_domain_nr(bus),
218 		.bus    = bus->number,
219 		.devfn  = devfn,
220 		.offset = where,
221 		.size   = size,
222 		.value  = val,
223 	};
224 	struct pcifront_sd *sd = bus->sysdata;
225 	struct pcifront_device *pdev = pcifront_get_pdev(sd);
226 
227 	dev_dbg(&pdev->xdev->dev,
228 		"write dev=%04x:%02x:%02x.%d - offset %x size %d val %x\n",
229 		pci_domain_nr(bus), bus->number,
230 		PCI_SLOT(devfn), PCI_FUNC(devfn), where, size, val);
231 
232 	return errno_to_pcibios_err(do_pci_op(pdev, &op));
233 }
234 
235 static struct pci_ops pcifront_bus_ops = {
236 	.read = pcifront_bus_read,
237 	.write = pcifront_bus_write,
238 };
239 
240 #ifdef CONFIG_PCI_MSI
pci_frontend_enable_msix(struct pci_dev * dev,int vector[],int nvec)241 static int pci_frontend_enable_msix(struct pci_dev *dev,
242 				    int vector[], int nvec)
243 {
244 	int err;
245 	int i;
246 	struct xen_pci_op op = {
247 		.cmd    = XEN_PCI_OP_enable_msix,
248 		.domain = pci_domain_nr(dev->bus),
249 		.bus = dev->bus->number,
250 		.devfn = dev->devfn,
251 		.value = nvec,
252 	};
253 	struct pcifront_sd *sd = dev->bus->sysdata;
254 	struct pcifront_device *pdev = pcifront_get_pdev(sd);
255 	struct msi_desc *entry;
256 
257 	if (nvec > SH_INFO_MAX_VEC) {
258 		pci_err(dev, "too many vectors (0x%x) for PCI frontend:"
259 				   " Increase SH_INFO_MAX_VEC\n", nvec);
260 		return -EINVAL;
261 	}
262 
263 	i = 0;
264 	msi_for_each_desc(entry, &dev->dev, MSI_DESC_NOTASSOCIATED) {
265 		op.msix_entries[i].entry = entry->msi_index;
266 		/* Vector is useless at this point. */
267 		op.msix_entries[i].vector = -1;
268 		i++;
269 	}
270 
271 	err = do_pci_op(pdev, &op);
272 
273 	if (likely(!err)) {
274 		if (likely(!op.value)) {
275 			/* we get the result */
276 			for (i = 0; i < nvec; i++) {
277 				if (op.msix_entries[i].vector <= 0) {
278 					pci_warn(dev, "MSI-X entry %d is invalid: %d!\n",
279 						i, op.msix_entries[i].vector);
280 					err = -EINVAL;
281 					vector[i] = -1;
282 					continue;
283 				}
284 				vector[i] = op.msix_entries[i].vector;
285 			}
286 		} else {
287 			pr_info("enable msix get value %x\n", op.value);
288 			err = op.value;
289 		}
290 	} else {
291 		pci_err(dev, "enable msix get err %x\n", err);
292 	}
293 	return err;
294 }
295 
pci_frontend_disable_msix(struct pci_dev * dev)296 static void pci_frontend_disable_msix(struct pci_dev *dev)
297 {
298 	int err;
299 	struct xen_pci_op op = {
300 		.cmd    = XEN_PCI_OP_disable_msix,
301 		.domain = pci_domain_nr(dev->bus),
302 		.bus = dev->bus->number,
303 		.devfn = dev->devfn,
304 	};
305 	struct pcifront_sd *sd = dev->bus->sysdata;
306 	struct pcifront_device *pdev = pcifront_get_pdev(sd);
307 
308 	err = do_pci_op(pdev, &op);
309 
310 	/* What should do for error ? */
311 	if (err)
312 		pci_err(dev, "pci_disable_msix get err %x\n", err);
313 }
314 
pci_frontend_enable_msi(struct pci_dev * dev,int vector[])315 static int pci_frontend_enable_msi(struct pci_dev *dev, int vector[])
316 {
317 	int err;
318 	struct xen_pci_op op = {
319 		.cmd    = XEN_PCI_OP_enable_msi,
320 		.domain = pci_domain_nr(dev->bus),
321 		.bus = dev->bus->number,
322 		.devfn = dev->devfn,
323 	};
324 	struct pcifront_sd *sd = dev->bus->sysdata;
325 	struct pcifront_device *pdev = pcifront_get_pdev(sd);
326 
327 	err = do_pci_op(pdev, &op);
328 	if (likely(!err)) {
329 		vector[0] = op.value;
330 		if (op.value <= 0) {
331 			pci_warn(dev, "MSI entry is invalid: %d!\n",
332 				op.value);
333 			err = -EINVAL;
334 			vector[0] = -1;
335 		}
336 	} else {
337 		pci_err(dev, "pci frontend enable msi failed for dev "
338 				    "%x:%x\n", op.bus, op.devfn);
339 		err = -EINVAL;
340 	}
341 	return err;
342 }
343 
pci_frontend_disable_msi(struct pci_dev * dev)344 static void pci_frontend_disable_msi(struct pci_dev *dev)
345 {
346 	int err;
347 	struct xen_pci_op op = {
348 		.cmd    = XEN_PCI_OP_disable_msi,
349 		.domain = pci_domain_nr(dev->bus),
350 		.bus = dev->bus->number,
351 		.devfn = dev->devfn,
352 	};
353 	struct pcifront_sd *sd = dev->bus->sysdata;
354 	struct pcifront_device *pdev = pcifront_get_pdev(sd);
355 
356 	err = do_pci_op(pdev, &op);
357 	if (err == XEN_PCI_ERR_dev_not_found) {
358 		/* XXX No response from backend, what shall we do? */
359 		pr_info("get no response from backend for disable MSI\n");
360 		return;
361 	}
362 	if (err)
363 		/* how can pciback notify us fail? */
364 		pr_info("get fake response from backend\n");
365 }
366 
367 static struct xen_pci_frontend_ops pci_frontend_ops = {
368 	.enable_msi = pci_frontend_enable_msi,
369 	.disable_msi = pci_frontend_disable_msi,
370 	.enable_msix = pci_frontend_enable_msix,
371 	.disable_msix = pci_frontend_disable_msix,
372 };
373 
pci_frontend_registrar(int enable)374 static void pci_frontend_registrar(int enable)
375 {
376 	if (enable)
377 		xen_pci_frontend = &pci_frontend_ops;
378 	else
379 		xen_pci_frontend = NULL;
380 };
381 #else
pci_frontend_registrar(int enable)382 static inline void pci_frontend_registrar(int enable) { };
383 #endif /* CONFIG_PCI_MSI */
384 
385 /* Claim resources for the PCI frontend as-is, backend won't allow changes */
pcifront_claim_resource(struct pci_dev * dev,void * data)386 static int pcifront_claim_resource(struct pci_dev *dev, void *data)
387 {
388 	struct pcifront_device *pdev = data;
389 	int i;
390 	struct resource *r;
391 
392 	pci_dev_for_each_resource(dev, r, i) {
393 		if (!r->parent && r->start && r->flags) {
394 			dev_info(&pdev->xdev->dev, "claiming resource %s/%d\n",
395 				pci_name(dev), i);
396 			if (pci_claim_resource(dev, i)) {
397 				dev_err(&pdev->xdev->dev, "Could not claim resource %s/%d! "
398 					"Device offline. Try using e820_host=1 in the guest config.\n",
399 					pci_name(dev), i);
400 			}
401 		}
402 	}
403 
404 	return 0;
405 }
406 
pcifront_scan_bus(struct pcifront_device * pdev,unsigned int domain,unsigned int bus,struct pci_bus * b)407 static int pcifront_scan_bus(struct pcifront_device *pdev,
408 				unsigned int domain, unsigned int bus,
409 				struct pci_bus *b)
410 {
411 	struct pci_dev *d;
412 	unsigned int devfn;
413 
414 	/*
415 	 * Scan the bus for functions and add.
416 	 * We omit handling of PCI bridge attachment because pciback prevents
417 	 * bridges from being exported.
418 	 */
419 	for (devfn = 0; devfn < 0x100; devfn++) {
420 		d = pci_get_slot(b, devfn);
421 		if (d) {
422 			/* Device is already known. */
423 			pci_dev_put(d);
424 			continue;
425 		}
426 
427 		d = pci_scan_single_device(b, devfn);
428 		if (d)
429 			dev_info(&pdev->xdev->dev, "New device on "
430 				 "%04x:%02x:%02x.%d found.\n", domain, bus,
431 				 PCI_SLOT(devfn), PCI_FUNC(devfn));
432 	}
433 
434 	return 0;
435 }
436 
pcifront_scan_root(struct pcifront_device * pdev,unsigned int domain,unsigned int bus)437 static int pcifront_scan_root(struct pcifront_device *pdev,
438 				 unsigned int domain, unsigned int bus)
439 {
440 	struct pci_bus *b;
441 	LIST_HEAD(resources);
442 	struct pcifront_sd *sd = NULL;
443 	struct pci_bus_entry *bus_entry = NULL;
444 	int err = 0;
445 	static struct resource busn_res = {
446 		.start = 0,
447 		.end = 255,
448 		.flags = IORESOURCE_BUS,
449 	};
450 
451 #ifndef CONFIG_PCI_DOMAINS
452 	if (domain != 0) {
453 		dev_err(&pdev->xdev->dev,
454 			"PCI Root in non-zero PCI Domain! domain=%d\n", domain);
455 		dev_err(&pdev->xdev->dev,
456 			"Please compile with CONFIG_PCI_DOMAINS\n");
457 		err = -EINVAL;
458 		goto err_out;
459 	}
460 #endif
461 
462 	dev_info(&pdev->xdev->dev, "Creating PCI Frontend Bus %04x:%02x\n",
463 		 domain, bus);
464 
465 	bus_entry = kzalloc(sizeof(*bus_entry), GFP_KERNEL);
466 	sd = kzalloc(sizeof(*sd), GFP_KERNEL);
467 	if (!bus_entry || !sd) {
468 		err = -ENOMEM;
469 		goto err_out;
470 	}
471 	pci_add_resource(&resources, &ioport_resource);
472 	pci_add_resource(&resources, &iomem_resource);
473 	pci_add_resource(&resources, &busn_res);
474 	pcifront_init_sd(sd, domain, bus, pdev);
475 
476 	pci_lock_rescan_remove();
477 
478 	b = pci_scan_root_bus(&pdev->xdev->dev, bus,
479 				  &pcifront_bus_ops, sd, &resources);
480 	if (!b) {
481 		dev_err(&pdev->xdev->dev,
482 			"Error creating PCI Frontend Bus!\n");
483 		err = -ENOMEM;
484 		pci_unlock_rescan_remove();
485 		pci_free_resource_list(&resources);
486 		goto err_out;
487 	}
488 
489 	bus_entry->bus = b;
490 
491 	list_add(&bus_entry->list, &pdev->root_buses);
492 
493 	/*
494 	 * pci_scan_root_bus skips devices which do not have a
495 	 * devfn==0. The pcifront_scan_bus enumerates all devfn.
496 	 */
497 	err = pcifront_scan_bus(pdev, domain, bus, b);
498 
499 	/* Claim resources before going "live" with our devices */
500 	pci_walk_bus(b, pcifront_claim_resource, pdev);
501 
502 	/* Create SysFS and notify udev of the devices. Aka: "going live" */
503 	pci_bus_add_devices(b);
504 
505 	pci_unlock_rescan_remove();
506 	return err;
507 
508 err_out:
509 	kfree(bus_entry);
510 	kfree(sd);
511 
512 	return err;
513 }
514 
pcifront_rescan_root(struct pcifront_device * pdev,unsigned int domain,unsigned int bus)515 static int pcifront_rescan_root(struct pcifront_device *pdev,
516 				   unsigned int domain, unsigned int bus)
517 {
518 	int err;
519 	struct pci_bus *b;
520 
521 	b = pci_find_bus(domain, bus);
522 	if (!b)
523 		/* If the bus is unknown, create it. */
524 		return pcifront_scan_root(pdev, domain, bus);
525 
526 	dev_info(&pdev->xdev->dev, "Rescanning PCI Frontend Bus %04x:%02x\n",
527 		 domain, bus);
528 
529 	err = pcifront_scan_bus(pdev, domain, bus, b);
530 
531 	/* Claim resources before going "live" with our devices */
532 	pci_walk_bus(b, pcifront_claim_resource, pdev);
533 
534 	/* Create SysFS and notify udev of the devices. Aka: "going live" */
535 	pci_bus_add_devices(b);
536 
537 	return err;
538 }
539 
free_root_bus_devs(struct pci_bus * bus)540 static void free_root_bus_devs(struct pci_bus *bus)
541 {
542 	struct pci_dev *dev;
543 
544 	while (!list_empty(&bus->devices)) {
545 		dev = container_of(bus->devices.next, struct pci_dev,
546 				   bus_list);
547 		pci_dbg(dev, "removing device\n");
548 		pci_stop_and_remove_bus_device(dev);
549 	}
550 }
551 
pcifront_free_roots(struct pcifront_device * pdev)552 static void pcifront_free_roots(struct pcifront_device *pdev)
553 {
554 	struct pci_bus_entry *bus_entry, *t;
555 
556 	dev_dbg(&pdev->xdev->dev, "cleaning up root buses\n");
557 
558 	pci_lock_rescan_remove();
559 	list_for_each_entry_safe(bus_entry, t, &pdev->root_buses, list) {
560 		list_del(&bus_entry->list);
561 
562 		free_root_bus_devs(bus_entry->bus);
563 
564 		kfree(bus_entry->bus->sysdata);
565 
566 		device_unregister(bus_entry->bus->bridge);
567 		pci_remove_bus(bus_entry->bus);
568 
569 		kfree(bus_entry);
570 	}
571 	pci_unlock_rescan_remove();
572 }
573 
pcifront_common_process(int cmd,struct pcifront_device * pdev,pci_channel_state_t state)574 static pci_ers_result_t pcifront_common_process(int cmd,
575 						struct pcifront_device *pdev,
576 						pci_channel_state_t state)
577 {
578 	struct pci_driver *pdrv;
579 	int bus = pdev->sh_info->aer_op.bus;
580 	int devfn = pdev->sh_info->aer_op.devfn;
581 	int domain = pdev->sh_info->aer_op.domain;
582 	struct pci_dev *pcidev;
583 
584 	dev_dbg(&pdev->xdev->dev,
585 		"pcifront AER process: cmd %x (bus:%x, devfn%x)",
586 		cmd, bus, devfn);
587 
588 	pcidev = pci_get_domain_bus_and_slot(domain, bus, devfn);
589 	if (!pcidev || !pcidev->dev.driver) {
590 		dev_err(&pdev->xdev->dev, "device or AER driver is NULL\n");
591 		pci_dev_put(pcidev);
592 		return PCI_ERS_RESULT_NONE;
593 	}
594 	pdrv = to_pci_driver(pcidev->dev.driver);
595 
596 	if (pdrv->err_handler && pdrv->err_handler->error_detected) {
597 		pci_dbg(pcidev, "trying to call AER service\n");
598 		switch (cmd) {
599 		case XEN_PCI_OP_aer_detected:
600 			return pdrv->err_handler->error_detected(pcidev, state);
601 		case XEN_PCI_OP_aer_mmio:
602 			return pdrv->err_handler->mmio_enabled(pcidev);
603 		case XEN_PCI_OP_aer_slotreset:
604 			return pdrv->err_handler->slot_reset(pcidev);
605 		case XEN_PCI_OP_aer_resume:
606 			pdrv->err_handler->resume(pcidev);
607 			return PCI_ERS_RESULT_NONE;
608 		default:
609 			dev_err(&pdev->xdev->dev,
610 				"bad request in aer recovery operation!\n");
611 		}
612 	}
613 
614 	return PCI_ERS_RESULT_NONE;
615 }
616 
617 
pcifront_do_aer(struct work_struct * data)618 static void pcifront_do_aer(struct work_struct *data)
619 {
620 	struct pcifront_device *pdev =
621 		container_of(data, struct pcifront_device, op_work);
622 	int cmd = pdev->sh_info->aer_op.cmd;
623 	pci_channel_state_t state =
624 		(pci_channel_state_t)pdev->sh_info->aer_op.err;
625 
626 	/*
627 	 * If a pci_conf op is in progress, we have to wait until it is done
628 	 * before service aer op
629 	 */
630 	dev_dbg(&pdev->xdev->dev,
631 		"pcifront service aer bus %x devfn %x\n",
632 		pdev->sh_info->aer_op.bus, pdev->sh_info->aer_op.devfn);
633 
634 	pdev->sh_info->aer_op.err = pcifront_common_process(cmd, pdev, state);
635 
636 	/* Post the operation to the guest. */
637 	wmb();
638 	clear_bit(_XEN_PCIB_active, (unsigned long *)&pdev->sh_info->flags);
639 	notify_remote_via_evtchn(pdev->evtchn);
640 
641 	/*in case of we lost an aer request in four lines time_window*/
642 	smp_mb__before_atomic();
643 	clear_bit(_PDEVB_op_active, &pdev->flags);
644 	smp_mb__after_atomic();
645 
646 	schedule_pcifront_aer_op(pdev);
647 
648 }
649 
pcifront_handler_aer(int irq,void * dev)650 static irqreturn_t pcifront_handler_aer(int irq, void *dev)
651 {
652 	struct pcifront_device *pdev = dev;
653 
654 	schedule_pcifront_aer_op(pdev);
655 	return IRQ_HANDLED;
656 }
pcifront_connect_and_init_dma(struct pcifront_device * pdev)657 static int pcifront_connect_and_init_dma(struct pcifront_device *pdev)
658 {
659 	int err = 0;
660 
661 	spin_lock(&pcifront_dev_lock);
662 
663 	if (!pcifront_dev) {
664 		dev_info(&pdev->xdev->dev, "Installing PCI frontend\n");
665 		pcifront_dev = pdev;
666 	} else
667 		err = -EEXIST;
668 
669 	spin_unlock(&pcifront_dev_lock);
670 
671 	return err;
672 }
673 
pcifront_disconnect(struct pcifront_device * pdev)674 static void pcifront_disconnect(struct pcifront_device *pdev)
675 {
676 	spin_lock(&pcifront_dev_lock);
677 
678 	if (pdev == pcifront_dev) {
679 		dev_info(&pdev->xdev->dev,
680 			 "Disconnecting PCI Frontend Buses\n");
681 		pcifront_dev = NULL;
682 	}
683 
684 	spin_unlock(&pcifront_dev_lock);
685 }
alloc_pdev(struct xenbus_device * xdev)686 static struct pcifront_device *alloc_pdev(struct xenbus_device *xdev)
687 {
688 	struct pcifront_device *pdev;
689 
690 	pdev = kzalloc(sizeof(struct pcifront_device), GFP_KERNEL);
691 	if (pdev == NULL)
692 		goto out;
693 
694 	if (xenbus_setup_ring(xdev, GFP_KERNEL, (void **)&pdev->sh_info, 1,
695 			      &pdev->gnt_ref)) {
696 		kfree(pdev);
697 		pdev = NULL;
698 		goto out;
699 	}
700 	pdev->sh_info->flags = 0;
701 
702 	/*Flag for registering PV AER handler*/
703 	set_bit(_XEN_PCIB_AERHANDLER, (void *)&pdev->sh_info->flags);
704 
705 	dev_set_drvdata(&xdev->dev, pdev);
706 	pdev->xdev = xdev;
707 
708 	INIT_LIST_HEAD(&pdev->root_buses);
709 
710 	spin_lock_init(&pdev->sh_info_lock);
711 
712 	pdev->evtchn = INVALID_EVTCHN;
713 	pdev->irq = -1;
714 
715 	INIT_WORK(&pdev->op_work, pcifront_do_aer);
716 
717 	dev_dbg(&xdev->dev, "Allocated pdev @ 0x%p pdev->sh_info @ 0x%p\n",
718 		pdev, pdev->sh_info);
719 out:
720 	return pdev;
721 }
722 
free_pdev(struct pcifront_device * pdev)723 static void free_pdev(struct pcifront_device *pdev)
724 {
725 	dev_dbg(&pdev->xdev->dev, "freeing pdev @ 0x%p\n", pdev);
726 
727 	pcifront_free_roots(pdev);
728 
729 	cancel_work_sync(&pdev->op_work);
730 
731 	if (pdev->irq >= 0)
732 		unbind_from_irqhandler(pdev->irq, pdev);
733 
734 	if (pdev->evtchn != INVALID_EVTCHN)
735 		xenbus_free_evtchn(pdev->xdev, pdev->evtchn);
736 
737 	xenbus_teardown_ring((void **)&pdev->sh_info, 1, &pdev->gnt_ref);
738 
739 	dev_set_drvdata(&pdev->xdev->dev, NULL);
740 
741 	kfree(pdev);
742 }
743 
pcifront_publish_info(struct pcifront_device * pdev)744 static int pcifront_publish_info(struct pcifront_device *pdev)
745 {
746 	int err = 0;
747 	struct xenbus_transaction trans;
748 
749 	err = xenbus_alloc_evtchn(pdev->xdev, &pdev->evtchn);
750 	if (err)
751 		goto out;
752 
753 	err = bind_evtchn_to_irqhandler(pdev->evtchn, pcifront_handler_aer,
754 		0, "pcifront", pdev);
755 
756 	if (err < 0)
757 		return err;
758 
759 	pdev->irq = err;
760 
761 do_publish:
762 	err = xenbus_transaction_start(&trans);
763 	if (err) {
764 		xenbus_dev_fatal(pdev->xdev, err,
765 				 "Error writing configuration for backend "
766 				 "(start transaction)");
767 		goto out;
768 	}
769 
770 	err = xenbus_printf(trans, pdev->xdev->nodename,
771 			    "pci-op-ref", "%u", pdev->gnt_ref);
772 	if (!err)
773 		err = xenbus_printf(trans, pdev->xdev->nodename,
774 				    "event-channel", "%u", pdev->evtchn);
775 	if (!err)
776 		err = xenbus_printf(trans, pdev->xdev->nodename,
777 				    "magic", XEN_PCI_MAGIC);
778 
779 	if (err) {
780 		xenbus_transaction_end(trans, 1);
781 		xenbus_dev_fatal(pdev->xdev, err,
782 				 "Error writing configuration for backend");
783 		goto out;
784 	} else {
785 		err = xenbus_transaction_end(trans, 0);
786 		if (err == -EAGAIN)
787 			goto do_publish;
788 		else if (err) {
789 			xenbus_dev_fatal(pdev->xdev, err,
790 					 "Error completing transaction "
791 					 "for backend");
792 			goto out;
793 		}
794 	}
795 
796 	xenbus_switch_state(pdev->xdev, XenbusStateInitialised);
797 
798 	dev_dbg(&pdev->xdev->dev, "publishing successful!\n");
799 
800 out:
801 	return err;
802 }
803 
pcifront_connect(struct pcifront_device * pdev)804 static void pcifront_connect(struct pcifront_device *pdev)
805 {
806 	int err;
807 	int i, num_roots, len;
808 	char str[64];
809 	unsigned int domain, bus;
810 
811 	err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend,
812 			   "root_num", "%d", &num_roots);
813 	if (err == -ENOENT) {
814 		xenbus_dev_error(pdev->xdev, err,
815 				 "No PCI Roots found, trying 0000:00");
816 		err = pcifront_rescan_root(pdev, 0, 0);
817 		if (err) {
818 			xenbus_dev_fatal(pdev->xdev, err,
819 					 "Error scanning PCI root 0000:00");
820 			return;
821 		}
822 		num_roots = 0;
823 	} else if (err != 1) {
824 		xenbus_dev_fatal(pdev->xdev, err >= 0 ? -EINVAL : err,
825 				 "Error reading number of PCI roots");
826 		return;
827 	}
828 
829 	for (i = 0; i < num_roots; i++) {
830 		len = snprintf(str, sizeof(str), "root-%d", i);
831 		if (unlikely(len >= (sizeof(str) - 1)))
832 			return;
833 
834 		err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend, str,
835 				   "%x:%x", &domain, &bus);
836 		if (err != 2) {
837 			xenbus_dev_fatal(pdev->xdev, err >= 0 ? -EINVAL : err,
838 					 "Error reading PCI root %d", i);
839 			return;
840 		}
841 
842 		err = pcifront_rescan_root(pdev, domain, bus);
843 		if (err) {
844 			xenbus_dev_fatal(pdev->xdev, err,
845 					 "Error scanning PCI root %04x:%02x",
846 					 domain, bus);
847 			return;
848 		}
849 	}
850 
851 	xenbus_switch_state(pdev->xdev, XenbusStateConnected);
852 }
853 
pcifront_try_connect(struct pcifront_device * pdev)854 static void pcifront_try_connect(struct pcifront_device *pdev)
855 {
856 	int err;
857 
858 	/* Only connect once */
859 	if (xenbus_read_driver_state(pdev->xdev->nodename) !=
860 	    XenbusStateInitialised)
861 		return;
862 
863 	err = pcifront_connect_and_init_dma(pdev);
864 	if (err && err != -EEXIST) {
865 		xenbus_dev_fatal(pdev->xdev, err,
866 				 "Error setting up PCI Frontend");
867 		return;
868 	}
869 
870 	pcifront_connect(pdev);
871 }
872 
pcifront_try_disconnect(struct pcifront_device * pdev)873 static int pcifront_try_disconnect(struct pcifront_device *pdev)
874 {
875 	int err = 0;
876 	enum xenbus_state prev_state;
877 
878 
879 	prev_state = xenbus_read_driver_state(pdev->xdev->nodename);
880 
881 	if (prev_state >= XenbusStateClosing)
882 		goto out;
883 
884 	if (prev_state == XenbusStateConnected) {
885 		pcifront_free_roots(pdev);
886 		pcifront_disconnect(pdev);
887 	}
888 
889 	err = xenbus_switch_state(pdev->xdev, XenbusStateClosed);
890 
891 out:
892 
893 	return err;
894 }
895 
pcifront_attach_devices(struct pcifront_device * pdev)896 static void pcifront_attach_devices(struct pcifront_device *pdev)
897 {
898 	if (xenbus_read_driver_state(pdev->xdev->nodename) ==
899 	    XenbusStateReconfiguring)
900 		pcifront_connect(pdev);
901 }
902 
pcifront_detach_devices(struct pcifront_device * pdev)903 static int pcifront_detach_devices(struct pcifront_device *pdev)
904 {
905 	int err = 0;
906 	int i, num_devs;
907 	enum xenbus_state state;
908 	unsigned int domain, bus, slot, func;
909 	struct pci_dev *pci_dev;
910 	char str[64];
911 
912 	state = xenbus_read_driver_state(pdev->xdev->nodename);
913 	if (state == XenbusStateInitialised) {
914 		dev_dbg(&pdev->xdev->dev, "Handle skipped connect.\n");
915 		/* We missed Connected and need to initialize. */
916 		err = pcifront_connect_and_init_dma(pdev);
917 		if (err && err != -EEXIST) {
918 			xenbus_dev_fatal(pdev->xdev, err,
919 					 "Error setting up PCI Frontend");
920 			goto out;
921 		}
922 
923 		goto out_switch_state;
924 	} else if (state != XenbusStateConnected) {
925 		goto out;
926 	}
927 
928 	err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend, "num_devs", "%d",
929 			   &num_devs);
930 	if (err != 1) {
931 		if (err >= 0)
932 			err = -EINVAL;
933 		xenbus_dev_fatal(pdev->xdev, err,
934 				 "Error reading number of PCI devices");
935 		goto out;
936 	}
937 
938 	/* Find devices being detached and remove them. */
939 	for (i = 0; i < num_devs; i++) {
940 		int l, state;
941 
942 		l = snprintf(str, sizeof(str), "state-%d", i);
943 		if (unlikely(l >= (sizeof(str) - 1))) {
944 			err = -ENOMEM;
945 			goto out;
946 		}
947 		state = xenbus_read_unsigned(pdev->xdev->otherend, str,
948 					     XenbusStateUnknown);
949 
950 		if (state != XenbusStateClosing)
951 			continue;
952 
953 		/* Remove device. */
954 		l = snprintf(str, sizeof(str), "vdev-%d", i);
955 		if (unlikely(l >= (sizeof(str) - 1))) {
956 			err = -ENOMEM;
957 			goto out;
958 		}
959 		err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend, str,
960 				   "%x:%x:%x.%x", &domain, &bus, &slot, &func);
961 		if (err != 4) {
962 			if (err >= 0)
963 				err = -EINVAL;
964 			xenbus_dev_fatal(pdev->xdev, err,
965 					 "Error reading PCI device %d", i);
966 			goto out;
967 		}
968 
969 		pci_dev = pci_get_domain_bus_and_slot(domain, bus,
970 				PCI_DEVFN(slot, func));
971 		if (!pci_dev) {
972 			dev_dbg(&pdev->xdev->dev,
973 				"Cannot get PCI device %04x:%02x:%02x.%d\n",
974 				domain, bus, slot, func);
975 			continue;
976 		}
977 		pci_lock_rescan_remove();
978 		pci_stop_and_remove_bus_device(pci_dev);
979 		pci_dev_put(pci_dev);
980 		pci_unlock_rescan_remove();
981 
982 		dev_dbg(&pdev->xdev->dev,
983 			"PCI device %04x:%02x:%02x.%d removed.\n",
984 			domain, bus, slot, func);
985 	}
986 
987  out_switch_state:
988 	err = xenbus_switch_state(pdev->xdev, XenbusStateReconfiguring);
989 
990 out:
991 	return err;
992 }
993 
pcifront_backend_changed(struct xenbus_device * xdev,enum xenbus_state be_state)994 static void pcifront_backend_changed(struct xenbus_device *xdev,
995 						  enum xenbus_state be_state)
996 {
997 	struct pcifront_device *pdev = dev_get_drvdata(&xdev->dev);
998 
999 	switch (be_state) {
1000 	case XenbusStateUnknown:
1001 	case XenbusStateInitialising:
1002 	case XenbusStateInitWait:
1003 	case XenbusStateInitialised:
1004 		break;
1005 
1006 	case XenbusStateConnected:
1007 		pcifront_try_connect(pdev);
1008 		break;
1009 
1010 	case XenbusStateClosed:
1011 		if (xdev->state == XenbusStateClosed)
1012 			break;
1013 		fallthrough;	/* Missed the backend's CLOSING state */
1014 	case XenbusStateClosing:
1015 		dev_warn(&xdev->dev, "backend going away!\n");
1016 		pcifront_try_disconnect(pdev);
1017 		break;
1018 
1019 	case XenbusStateReconfiguring:
1020 		pcifront_detach_devices(pdev);
1021 		break;
1022 
1023 	case XenbusStateReconfigured:
1024 		pcifront_attach_devices(pdev);
1025 		break;
1026 	}
1027 }
1028 
pcifront_xenbus_probe(struct xenbus_device * xdev,const struct xenbus_device_id * id)1029 static int pcifront_xenbus_probe(struct xenbus_device *xdev,
1030 				 const struct xenbus_device_id *id)
1031 {
1032 	int err = 0;
1033 	struct pcifront_device *pdev = alloc_pdev(xdev);
1034 
1035 	if (pdev == NULL) {
1036 		err = -ENOMEM;
1037 		xenbus_dev_fatal(xdev, err,
1038 				 "Error allocating pcifront_device struct");
1039 		goto out;
1040 	}
1041 
1042 	err = pcifront_publish_info(pdev);
1043 	if (err)
1044 		free_pdev(pdev);
1045 
1046 out:
1047 	return err;
1048 }
1049 
pcifront_xenbus_remove(struct xenbus_device * xdev)1050 static void pcifront_xenbus_remove(struct xenbus_device *xdev)
1051 {
1052 	struct pcifront_device *pdev = dev_get_drvdata(&xdev->dev);
1053 
1054 	if (pdev)
1055 		free_pdev(pdev);
1056 }
1057 
1058 static const struct xenbus_device_id xenpci_ids[] = {
1059 	{"pci"},
1060 	{""},
1061 };
1062 
1063 static struct xenbus_driver xenpci_driver = {
1064 	.name			= "pcifront",
1065 	.ids			= xenpci_ids,
1066 	.probe			= pcifront_xenbus_probe,
1067 	.remove			= pcifront_xenbus_remove,
1068 	.otherend_changed	= pcifront_backend_changed,
1069 };
1070 
pcifront_init(void)1071 static int __init pcifront_init(void)
1072 {
1073 	if (!xen_pv_domain() || xen_initial_domain())
1074 		return -ENODEV;
1075 
1076 	if (!xen_has_pv_devices())
1077 		return -ENODEV;
1078 
1079 	pci_frontend_registrar(1 /* enable */);
1080 
1081 	return xenbus_register_frontend(&xenpci_driver);
1082 }
1083 
pcifront_cleanup(void)1084 static void __exit pcifront_cleanup(void)
1085 {
1086 	xenbus_unregister_driver(&xenpci_driver);
1087 	pci_frontend_registrar(0 /* disable */);
1088 }
1089 module_init(pcifront_init);
1090 module_exit(pcifront_cleanup);
1091 
1092 MODULE_DESCRIPTION("Xen PCI passthrough frontend.");
1093 MODULE_LICENSE("GPL");
1094 MODULE_ALIAS("xen:pci");
1095