xref: /openbmc/qemu/hw/pci/pcie.c (revision d6032e06)
1 /*
2  * pcie.c
3  *
4  * Copyright (c) 2010 Isaku Yamahata <yamahata at valinux co jp>
5  *                    VA Linux Systems Japan K.K.
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; either version 2 of the License, or
10  * (at your option) any later version.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License along
18  * with this program; if not, see <http://www.gnu.org/licenses/>.
19  */
20 
21 #include "qemu-common.h"
22 #include "hw/pci/pci_bridge.h"
23 #include "hw/pci/pcie.h"
24 #include "hw/pci/msix.h"
25 #include "hw/pci/msi.h"
26 #include "hw/pci/pci_bus.h"
27 #include "hw/pci/pcie_regs.h"
28 #include "qemu/range.h"
29 #include "qapi/qmp/qerror.h"
30 
31 //#define DEBUG_PCIE
32 #ifdef DEBUG_PCIE
33 # define PCIE_DPRINTF(fmt, ...)                                         \
34     fprintf(stderr, "%s:%d " fmt, __func__, __LINE__, ## __VA_ARGS__)
35 #else
36 # define PCIE_DPRINTF(fmt, ...) do {} while (0)
37 #endif
38 #define PCIE_DEV_PRINTF(dev, fmt, ...)                                  \
39     PCIE_DPRINTF("%s:%x "fmt, (dev)->name, (dev)->devfn, ## __VA_ARGS__)
40 
41 
42 /***************************************************************************
43  * pci express capability helper functions
44  */
45 int pcie_cap_init(PCIDevice *dev, uint8_t offset, uint8_t type, uint8_t port)
46 {
47     int pos;
48     uint8_t *exp_cap;
49 
50     assert(pci_is_express(dev));
51 
52     pos = pci_add_capability(dev, PCI_CAP_ID_EXP, offset,
53                                  PCI_EXP_VER2_SIZEOF);
54     if (pos < 0) {
55         return pos;
56     }
57     dev->exp.exp_cap = pos;
58     exp_cap = dev->config + pos;
59 
60     /* capability register
61        interrupt message number defaults to 0 */
62     pci_set_word(exp_cap + PCI_EXP_FLAGS,
63                  ((type << PCI_EXP_FLAGS_TYPE_SHIFT) & PCI_EXP_FLAGS_TYPE) |
64                  PCI_EXP_FLAGS_VER2);
65 
66     /* device capability register
67      * table 7-12:
68      * roll based error reporting bit must be set by all
69      * Functions conforming to the ECN, PCI Express Base
70      * Specification, Revision 1.1., or subsequent PCI Express Base
71      * Specification revisions.
72      */
73     pci_set_long(exp_cap + PCI_EXP_DEVCAP, PCI_EXP_DEVCAP_RBER);
74 
75     pci_set_long(exp_cap + PCI_EXP_LNKCAP,
76                  (port << PCI_EXP_LNKCAP_PN_SHIFT) |
77                  PCI_EXP_LNKCAP_ASPMS_0S |
78                  PCI_EXP_LNK_MLW_1 |
79                  PCI_EXP_LNK_LS_25);
80 
81     pci_set_word(exp_cap + PCI_EXP_LNKSTA,
82                  PCI_EXP_LNK_MLW_1 | PCI_EXP_LNK_LS_25);
83 
84     pci_set_long(exp_cap + PCI_EXP_DEVCAP2,
85                  PCI_EXP_DEVCAP2_EFF | PCI_EXP_DEVCAP2_EETLPP);
86 
87     pci_set_word(dev->wmask + pos, PCI_EXP_DEVCTL2_EETLPPB);
88     return pos;
89 }
90 
91 int pcie_endpoint_cap_init(PCIDevice *dev, uint8_t offset)
92 {
93     uint8_t type = PCI_EXP_TYPE_ENDPOINT;
94 
95     /*
96      * Windows guests will report Code 10, device cannot start, if
97      * a regular Endpoint type is exposed on a root complex.  These
98      * should instead be Root Complex Integrated Endpoints.
99      */
100     if (pci_bus_is_express(dev->bus) && pci_bus_is_root(dev->bus)) {
101         type = PCI_EXP_TYPE_RC_END;
102     }
103 
104     return pcie_cap_init(dev, offset, type, 0);
105 }
106 
107 void pcie_cap_exit(PCIDevice *dev)
108 {
109     pci_del_capability(dev, PCI_CAP_ID_EXP, PCI_EXP_VER2_SIZEOF);
110 }
111 
112 uint8_t pcie_cap_get_type(const PCIDevice *dev)
113 {
114     uint32_t pos = dev->exp.exp_cap;
115     assert(pos > 0);
116     return (pci_get_word(dev->config + pos + PCI_EXP_FLAGS) &
117             PCI_EXP_FLAGS_TYPE) >> PCI_EXP_FLAGS_TYPE_SHIFT;
118 }
119 
120 /* MSI/MSI-X */
121 /* pci express interrupt message number */
122 /* 7.8.2 PCI Express Capabilities Register: Interrupt Message Number */
123 void pcie_cap_flags_set_vector(PCIDevice *dev, uint8_t vector)
124 {
125     uint8_t *exp_cap = dev->config + dev->exp.exp_cap;
126     assert(vector < 32);
127     pci_word_test_and_clear_mask(exp_cap + PCI_EXP_FLAGS, PCI_EXP_FLAGS_IRQ);
128     pci_word_test_and_set_mask(exp_cap + PCI_EXP_FLAGS,
129                                vector << PCI_EXP_FLAGS_IRQ_SHIFT);
130 }
131 
132 uint8_t pcie_cap_flags_get_vector(PCIDevice *dev)
133 {
134     return (pci_get_word(dev->config + dev->exp.exp_cap + PCI_EXP_FLAGS) &
135             PCI_EXP_FLAGS_IRQ) >> PCI_EXP_FLAGS_IRQ_SHIFT;
136 }
137 
138 void pcie_cap_deverr_init(PCIDevice *dev)
139 {
140     uint32_t pos = dev->exp.exp_cap;
141     pci_long_test_and_set_mask(dev->config + pos + PCI_EXP_DEVCAP,
142                                PCI_EXP_DEVCAP_RBER);
143     pci_long_test_and_set_mask(dev->wmask + pos + PCI_EXP_DEVCTL,
144                                PCI_EXP_DEVCTL_CERE | PCI_EXP_DEVCTL_NFERE |
145                                PCI_EXP_DEVCTL_FERE | PCI_EXP_DEVCTL_URRE);
146     pci_long_test_and_set_mask(dev->w1cmask + pos + PCI_EXP_DEVSTA,
147                                PCI_EXP_DEVSTA_CED | PCI_EXP_DEVSTA_NFED |
148                                PCI_EXP_DEVSTA_URD | PCI_EXP_DEVSTA_URD);
149 }
150 
151 void pcie_cap_deverr_reset(PCIDevice *dev)
152 {
153     uint8_t *devctl = dev->config + dev->exp.exp_cap + PCI_EXP_DEVCTL;
154     pci_long_test_and_clear_mask(devctl,
155                                  PCI_EXP_DEVCTL_CERE | PCI_EXP_DEVCTL_NFERE |
156                                  PCI_EXP_DEVCTL_FERE | PCI_EXP_DEVCTL_URRE);
157 }
158 
159 static void hotplug_event_update_event_status(PCIDevice *dev)
160 {
161     uint32_t pos = dev->exp.exp_cap;
162     uint8_t *exp_cap = dev->config + pos;
163     uint16_t sltctl = pci_get_word(exp_cap + PCI_EXP_SLTCTL);
164     uint16_t sltsta = pci_get_word(exp_cap + PCI_EXP_SLTSTA);
165 
166     dev->exp.hpev_notified = (sltctl & PCI_EXP_SLTCTL_HPIE) &&
167         (sltsta & sltctl & PCI_EXP_HP_EV_SUPPORTED);
168 }
169 
170 static void hotplug_event_notify(PCIDevice *dev)
171 {
172     bool prev = dev->exp.hpev_notified;
173 
174     hotplug_event_update_event_status(dev);
175 
176     if (prev == dev->exp.hpev_notified) {
177         return;
178     }
179 
180     /* Note: the logic above does not take into account whether interrupts
181      * are masked. The result is that interrupt will be sent when it is
182      * subsequently unmasked. This appears to be legal: Section 6.7.3.4:
183      * The Port may optionally send an MSI when there are hot-plug events that
184      * occur while interrupt generation is disabled, and interrupt generation is
185      * subsequently enabled. */
186     if (msix_enabled(dev)) {
187         msix_notify(dev, pcie_cap_flags_get_vector(dev));
188     } else if (msi_enabled(dev)) {
189         msi_notify(dev, pcie_cap_flags_get_vector(dev));
190     } else {
191         pci_set_irq(dev, dev->exp.hpev_notified);
192     }
193 }
194 
195 static void hotplug_event_clear(PCIDevice *dev)
196 {
197     hotplug_event_update_event_status(dev);
198     if (!msix_enabled(dev) && !msi_enabled(dev) && !dev->exp.hpev_notified) {
199         pci_irq_deassert(dev);
200     }
201 }
202 
203 /*
204  * A PCI Express Hot-Plug Event has occurred, so update slot status register
205  * and notify OS of the event if necessary.
206  *
207  * 6.7.3 PCI Express Hot-Plug Events
208  * 6.7.3.4 Software Notification of Hot-Plug Events
209  */
210 static void pcie_cap_slot_event(PCIDevice *dev, PCIExpressHotPlugEvent event)
211 {
212     /* Minor optimization: if nothing changed - no event is needed. */
213     if (pci_word_test_and_set_mask(dev->config + dev->exp.exp_cap +
214                                    PCI_EXP_SLTSTA, event)) {
215         return;
216     }
217     hotplug_event_notify(dev);
218 }
219 
220 static void pcie_cap_slot_hotplug_common(PCIDevice *hotplug_dev,
221                                          DeviceState *dev,
222                                          uint8_t **exp_cap, Error **errp)
223 {
224     PCIDevice *pci_dev = PCI_DEVICE(dev);
225     *exp_cap = hotplug_dev->config + hotplug_dev->exp.exp_cap;
226     uint16_t sltsta = pci_get_word(*exp_cap + PCI_EXP_SLTSTA);
227 
228     PCIE_DEV_PRINTF(pci_dev, "hotplug state: %d\n", state);
229     if (sltsta & PCI_EXP_SLTSTA_EIS) {
230         /* the slot is electromechanically locked.
231          * This error is propagated up to qdev and then to HMP/QMP.
232          */
233         error_setg_errno(errp, -EBUSY, "slot is electromechanically locked");
234     }
235 
236     /* TODO: multifunction hot-plug.
237      * Right now, only a device of function = 0 is allowed to be
238      * hot plugged/unplugged.
239      */
240     assert(PCI_FUNC(pci_dev->devfn) == 0);
241 }
242 
243 void pcie_cap_slot_hotplug_cb(HotplugHandler *hotplug_dev, DeviceState *dev,
244                               Error **errp)
245 {
246     uint8_t *exp_cap;
247 
248     pcie_cap_slot_hotplug_common(PCI_DEVICE(hotplug_dev), dev, &exp_cap, errp);
249 
250     /* Don't send event when device is enabled during qemu machine creation:
251      * it is present on boot, no hotplug event is necessary. We do send an
252      * event when the device is disabled later. */
253     if (!dev->hotplugged) {
254         pci_word_test_and_set_mask(exp_cap + PCI_EXP_SLTSTA,
255                                    PCI_EXP_SLTSTA_PDS);
256         return;
257     }
258 
259     pci_word_test_and_set_mask(exp_cap + PCI_EXP_SLTSTA,
260                                PCI_EXP_SLTSTA_PDS);
261     pcie_cap_slot_event(PCI_DEVICE(hotplug_dev), PCI_EXP_HP_EV_PDC);
262 }
263 
264 void pcie_cap_slot_hot_unplug_cb(HotplugHandler *hotplug_dev, DeviceState *dev,
265                                  Error **errp)
266 {
267     uint8_t *exp_cap;
268 
269     pcie_cap_slot_hotplug_common(PCI_DEVICE(hotplug_dev), dev, &exp_cap, errp);
270 
271     object_unparent(OBJECT(dev));
272     pci_word_test_and_clear_mask(exp_cap + PCI_EXP_SLTSTA,
273                                  PCI_EXP_SLTSTA_PDS);
274     pcie_cap_slot_event(PCI_DEVICE(hotplug_dev), PCI_EXP_HP_EV_PDC);
275 }
276 
277 /* pci express slot for pci express root/downstream port
278    PCI express capability slot registers */
279 void pcie_cap_slot_init(PCIDevice *dev, uint16_t slot)
280 {
281     uint32_t pos = dev->exp.exp_cap;
282 
283     pci_word_test_and_set_mask(dev->config + pos + PCI_EXP_FLAGS,
284                                PCI_EXP_FLAGS_SLOT);
285 
286     pci_long_test_and_clear_mask(dev->config + pos + PCI_EXP_SLTCAP,
287                                  ~PCI_EXP_SLTCAP_PSN);
288     pci_long_test_and_set_mask(dev->config + pos + PCI_EXP_SLTCAP,
289                                (slot << PCI_EXP_SLTCAP_PSN_SHIFT) |
290                                PCI_EXP_SLTCAP_EIP |
291                                PCI_EXP_SLTCAP_HPS |
292                                PCI_EXP_SLTCAP_HPC |
293                                PCI_EXP_SLTCAP_PIP |
294                                PCI_EXP_SLTCAP_AIP |
295                                PCI_EXP_SLTCAP_ABP);
296 
297     pci_word_test_and_clear_mask(dev->config + pos + PCI_EXP_SLTCTL,
298                                  PCI_EXP_SLTCTL_PIC |
299                                  PCI_EXP_SLTCTL_AIC);
300     pci_word_test_and_set_mask(dev->config + pos + PCI_EXP_SLTCTL,
301                                PCI_EXP_SLTCTL_PIC_OFF |
302                                PCI_EXP_SLTCTL_AIC_OFF);
303     pci_word_test_and_set_mask(dev->wmask + pos + PCI_EXP_SLTCTL,
304                                PCI_EXP_SLTCTL_PIC |
305                                PCI_EXP_SLTCTL_AIC |
306                                PCI_EXP_SLTCTL_HPIE |
307                                PCI_EXP_SLTCTL_CCIE |
308                                PCI_EXP_SLTCTL_PDCE |
309                                PCI_EXP_SLTCTL_ABPE);
310     /* Although reading PCI_EXP_SLTCTL_EIC returns always 0,
311      * make the bit writable here in order to detect 1b is written.
312      * pcie_cap_slot_write_config() test-and-clear the bit, so
313      * this bit always returns 0 to the guest.
314      */
315     pci_word_test_and_set_mask(dev->wmask + pos + PCI_EXP_SLTCTL,
316                                PCI_EXP_SLTCTL_EIC);
317 
318     pci_word_test_and_set_mask(dev->w1cmask + pos + PCI_EXP_SLTSTA,
319                                PCI_EXP_HP_EV_SUPPORTED);
320 
321     dev->exp.hpev_notified = false;
322 
323     qbus_set_hotplug_handler(BUS(pci_bridge_get_sec_bus(PCI_BRIDGE(dev))),
324                              DEVICE(dev), NULL);
325 }
326 
327 void pcie_cap_slot_reset(PCIDevice *dev)
328 {
329     uint8_t *exp_cap = dev->config + dev->exp.exp_cap;
330 
331     PCIE_DEV_PRINTF(dev, "reset\n");
332 
333     pci_word_test_and_clear_mask(exp_cap + PCI_EXP_SLTCTL,
334                                  PCI_EXP_SLTCTL_EIC |
335                                  PCI_EXP_SLTCTL_PIC |
336                                  PCI_EXP_SLTCTL_AIC |
337                                  PCI_EXP_SLTCTL_HPIE |
338                                  PCI_EXP_SLTCTL_CCIE |
339                                  PCI_EXP_SLTCTL_PDCE |
340                                  PCI_EXP_SLTCTL_ABPE);
341     pci_word_test_and_set_mask(exp_cap + PCI_EXP_SLTCTL,
342                                PCI_EXP_SLTCTL_PIC_OFF |
343                                PCI_EXP_SLTCTL_AIC_OFF);
344 
345     pci_word_test_and_clear_mask(exp_cap + PCI_EXP_SLTSTA,
346                                  PCI_EXP_SLTSTA_EIS |/* on reset,
347                                                         the lock is released */
348                                  PCI_EXP_SLTSTA_CC |
349                                  PCI_EXP_SLTSTA_PDC |
350                                  PCI_EXP_SLTSTA_ABP);
351 
352     hotplug_event_update_event_status(dev);
353 }
354 
355 void pcie_cap_slot_write_config(PCIDevice *dev,
356                                 uint32_t addr, uint32_t val, int len)
357 {
358     uint32_t pos = dev->exp.exp_cap;
359     uint8_t *exp_cap = dev->config + pos;
360     uint16_t sltsta = pci_get_word(exp_cap + PCI_EXP_SLTSTA);
361 
362     if (ranges_overlap(addr, len, pos + PCI_EXP_SLTSTA, 2)) {
363         hotplug_event_clear(dev);
364     }
365 
366     if (!ranges_overlap(addr, len, pos + PCI_EXP_SLTCTL, 2)) {
367         return;
368     }
369 
370     if (pci_word_test_and_clear_mask(exp_cap + PCI_EXP_SLTCTL,
371                                      PCI_EXP_SLTCTL_EIC)) {
372         sltsta ^= PCI_EXP_SLTSTA_EIS; /* toggle PCI_EXP_SLTSTA_EIS bit */
373         pci_set_word(exp_cap + PCI_EXP_SLTSTA, sltsta);
374         PCIE_DEV_PRINTF(dev, "PCI_EXP_SLTCTL_EIC: "
375                         "sltsta -> 0x%02"PRIx16"\n",
376                         sltsta);
377     }
378 
379     hotplug_event_notify(dev);
380 
381     /*
382      * 6.7.3.2 Command Completed Events
383      *
384      * Software issues a command to a hot-plug capable Downstream Port by
385      * issuing a write transaction that targets any portion of the Port’s Slot
386      * Control register. A single write to the Slot Control register is
387      * considered to be a single command, even if the write affects more than
388      * one field in the Slot Control register. In response to this transaction,
389      * the Port must carry out the requested actions and then set the
390      * associated status field for the command completed event. */
391 
392     /* Real hardware might take a while to complete requested command because
393      * physical movement would be involved like locking the electromechanical
394      * lock.  However in our case, command is completed instantaneously above,
395      * so send a command completion event right now.
396      */
397     pcie_cap_slot_event(dev, PCI_EXP_HP_EV_CCI);
398 }
399 
400 int pcie_cap_slot_post_load(void *opaque, int version_id)
401 {
402     PCIDevice *dev = opaque;
403     hotplug_event_update_event_status(dev);
404     return 0;
405 }
406 
407 void pcie_cap_slot_push_attention_button(PCIDevice *dev)
408 {
409     pcie_cap_slot_event(dev, PCI_EXP_HP_EV_ABP);
410 }
411 
412 /* root control/capabilities/status. PME isn't emulated for now */
413 void pcie_cap_root_init(PCIDevice *dev)
414 {
415     pci_set_word(dev->wmask + dev->exp.exp_cap + PCI_EXP_RTCTL,
416                  PCI_EXP_RTCTL_SECEE | PCI_EXP_RTCTL_SENFEE |
417                  PCI_EXP_RTCTL_SEFEE);
418 }
419 
420 void pcie_cap_root_reset(PCIDevice *dev)
421 {
422     pci_set_word(dev->config + dev->exp.exp_cap + PCI_EXP_RTCTL, 0);
423 }
424 
425 /* function level reset(FLR) */
426 void pcie_cap_flr_init(PCIDevice *dev)
427 {
428     pci_long_test_and_set_mask(dev->config + dev->exp.exp_cap + PCI_EXP_DEVCAP,
429                                PCI_EXP_DEVCAP_FLR);
430 
431     /* Although reading BCR_FLR returns always 0,
432      * the bit is made writable here in order to detect the 1b is written
433      * pcie_cap_flr_write_config() test-and-clear the bit, so
434      * this bit always returns 0 to the guest.
435      */
436     pci_word_test_and_set_mask(dev->wmask + dev->exp.exp_cap + PCI_EXP_DEVCTL,
437                                PCI_EXP_DEVCTL_BCR_FLR);
438 }
439 
440 void pcie_cap_flr_write_config(PCIDevice *dev,
441                                uint32_t addr, uint32_t val, int len)
442 {
443     uint8_t *devctl = dev->config + dev->exp.exp_cap + PCI_EXP_DEVCTL;
444     if (pci_get_word(devctl) & PCI_EXP_DEVCTL_BCR_FLR) {
445         /* Clear PCI_EXP_DEVCTL_BCR_FLR after invoking the reset handler
446            so the handler can detect FLR by looking at this bit. */
447         pci_device_reset(dev);
448         pci_word_test_and_clear_mask(devctl, PCI_EXP_DEVCTL_BCR_FLR);
449     }
450 }
451 
452 /* Alternative Routing-ID Interpretation (ARI) */
453 /* ari forwarding support for down stream port */
454 void pcie_cap_ari_init(PCIDevice *dev)
455 {
456     uint32_t pos = dev->exp.exp_cap;
457     pci_long_test_and_set_mask(dev->config + pos + PCI_EXP_DEVCAP2,
458                                PCI_EXP_DEVCAP2_ARI);
459     pci_long_test_and_set_mask(dev->wmask + pos + PCI_EXP_DEVCTL2,
460                                PCI_EXP_DEVCTL2_ARI);
461 }
462 
463 void pcie_cap_ari_reset(PCIDevice *dev)
464 {
465     uint8_t *devctl2 = dev->config + dev->exp.exp_cap + PCI_EXP_DEVCTL2;
466     pci_long_test_and_clear_mask(devctl2, PCI_EXP_DEVCTL2_ARI);
467 }
468 
469 bool pcie_cap_is_ari_enabled(const PCIDevice *dev)
470 {
471     if (!pci_is_express(dev)) {
472         return false;
473     }
474     if (!dev->exp.exp_cap) {
475         return false;
476     }
477 
478     return pci_get_long(dev->config + dev->exp.exp_cap + PCI_EXP_DEVCTL2) &
479         PCI_EXP_DEVCTL2_ARI;
480 }
481 
482 /**************************************************************************
483  * pci express extended capability allocation functions
484  * uint16_t ext_cap_id (16 bit)
485  * uint8_t cap_ver (4 bit)
486  * uint16_t cap_offset (12 bit)
487  * uint16_t ext_cap_size
488  */
489 
490 static uint16_t pcie_find_capability_list(PCIDevice *dev, uint16_t cap_id,
491                                           uint16_t *prev_p)
492 {
493     uint16_t prev = 0;
494     uint16_t next;
495     uint32_t header = pci_get_long(dev->config + PCI_CONFIG_SPACE_SIZE);
496 
497     if (!header) {
498         /* no extended capability */
499         next = 0;
500         goto out;
501     }
502     for (next = PCI_CONFIG_SPACE_SIZE; next;
503          prev = next, next = PCI_EXT_CAP_NEXT(header)) {
504 
505         assert(next >= PCI_CONFIG_SPACE_SIZE);
506         assert(next <= PCIE_CONFIG_SPACE_SIZE - 8);
507 
508         header = pci_get_long(dev->config + next);
509         if (PCI_EXT_CAP_ID(header) == cap_id) {
510             break;
511         }
512     }
513 
514 out:
515     if (prev_p) {
516         *prev_p = prev;
517     }
518     return next;
519 }
520 
521 uint16_t pcie_find_capability(PCIDevice *dev, uint16_t cap_id)
522 {
523     return pcie_find_capability_list(dev, cap_id, NULL);
524 }
525 
526 static void pcie_ext_cap_set_next(PCIDevice *dev, uint16_t pos, uint16_t next)
527 {
528     uint32_t header = pci_get_long(dev->config + pos);
529     assert(!(next & (PCI_EXT_CAP_ALIGN - 1)));
530     header = (header & ~PCI_EXT_CAP_NEXT_MASK) |
531         ((next << PCI_EXT_CAP_NEXT_SHIFT) & PCI_EXT_CAP_NEXT_MASK);
532     pci_set_long(dev->config + pos, header);
533 }
534 
535 /*
536  * caller must supply valid (offset, size) * such that the range shouldn't
537  * overlap with other capability or other registers.
538  * This function doesn't check it.
539  */
540 void pcie_add_capability(PCIDevice *dev,
541                          uint16_t cap_id, uint8_t cap_ver,
542                          uint16_t offset, uint16_t size)
543 {
544     uint32_t header;
545     uint16_t next;
546 
547     assert(offset >= PCI_CONFIG_SPACE_SIZE);
548     assert(offset < offset + size);
549     assert(offset + size < PCIE_CONFIG_SPACE_SIZE);
550     assert(size >= 8);
551     assert(pci_is_express(dev));
552 
553     if (offset == PCI_CONFIG_SPACE_SIZE) {
554         header = pci_get_long(dev->config + offset);
555         next = PCI_EXT_CAP_NEXT(header);
556     } else {
557         uint16_t prev;
558 
559         /* 0 is reserved cap id. use internally to find the last capability
560            in the linked list */
561         next = pcie_find_capability_list(dev, 0, &prev);
562 
563         assert(prev >= PCI_CONFIG_SPACE_SIZE);
564         assert(next == 0);
565         pcie_ext_cap_set_next(dev, prev, offset);
566     }
567     pci_set_long(dev->config + offset, PCI_EXT_CAP(cap_id, cap_ver, next));
568 
569     /* Make capability read-only by default */
570     memset(dev->wmask + offset, 0, size);
571     memset(dev->w1cmask + offset, 0, size);
572     /* Check capability by default */
573     memset(dev->cmask + offset, 0xFF, size);
574 }
575 
576 /**************************************************************************
577  * pci express extended capability helper functions
578  */
579 
580 /* ARI */
581 void pcie_ari_init(PCIDevice *dev, uint16_t offset, uint16_t nextfn)
582 {
583     pcie_add_capability(dev, PCI_EXT_CAP_ID_ARI, PCI_ARI_VER,
584                         offset, PCI_ARI_SIZEOF);
585     pci_set_long(dev->config + offset + PCI_ARI_CAP, PCI_ARI_CAP_NFN(nextfn));
586 }
587