xref: /openbmc/qemu/hw/pci/pcie.c (revision 14a650ec)
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 
30 //#define DEBUG_PCIE
31 #ifdef DEBUG_PCIE
32 # define PCIE_DPRINTF(fmt, ...)                                         \
33     fprintf(stderr, "%s:%d " fmt, __func__, __LINE__, ## __VA_ARGS__)
34 #else
35 # define PCIE_DPRINTF(fmt, ...) do {} while (0)
36 #endif
37 #define PCIE_DEV_PRINTF(dev, fmt, ...)                                  \
38     PCIE_DPRINTF("%s:%x "fmt, (dev)->name, (dev)->devfn, ## __VA_ARGS__)
39 
40 
41 /***************************************************************************
42  * pci express capability helper functions
43  */
44 int pcie_cap_init(PCIDevice *dev, uint8_t offset, uint8_t type, uint8_t port)
45 {
46     int pos;
47     uint8_t *exp_cap;
48 
49     assert(pci_is_express(dev));
50 
51     pos = pci_add_capability(dev, PCI_CAP_ID_EXP, offset,
52                                  PCI_EXP_VER2_SIZEOF);
53     if (pos < 0) {
54         return pos;
55     }
56     dev->exp.exp_cap = pos;
57     exp_cap = dev->config + pos;
58 
59     /* capability register
60        interrupt message number defaults to 0 */
61     pci_set_word(exp_cap + PCI_EXP_FLAGS,
62                  ((type << PCI_EXP_FLAGS_TYPE_SHIFT) & PCI_EXP_FLAGS_TYPE) |
63                  PCI_EXP_FLAGS_VER2);
64 
65     /* device capability register
66      * table 7-12:
67      * roll based error reporting bit must be set by all
68      * Functions conforming to the ECN, PCI Express Base
69      * Specification, Revision 1.1., or subsequent PCI Express Base
70      * Specification revisions.
71      */
72     pci_set_long(exp_cap + PCI_EXP_DEVCAP, PCI_EXP_DEVCAP_RBER);
73 
74     pci_set_long(exp_cap + PCI_EXP_LNKCAP,
75                  (port << PCI_EXP_LNKCAP_PN_SHIFT) |
76                  PCI_EXP_LNKCAP_ASPMS_0S |
77                  PCI_EXP_LNK_MLW_1 |
78                  PCI_EXP_LNK_LS_25);
79 
80     pci_set_word(exp_cap + PCI_EXP_LNKSTA,
81                  PCI_EXP_LNK_MLW_1 | PCI_EXP_LNK_LS_25);
82 
83     pci_set_long(exp_cap + PCI_EXP_DEVCAP2,
84                  PCI_EXP_DEVCAP2_EFF | PCI_EXP_DEVCAP2_EETLPP);
85 
86     pci_set_word(dev->wmask + pos, PCI_EXP_DEVCTL2_EETLPPB);
87     return pos;
88 }
89 
90 int pcie_endpoint_cap_init(PCIDevice *dev, uint8_t offset)
91 {
92     uint8_t type = PCI_EXP_TYPE_ENDPOINT;
93 
94     /*
95      * Windows guests will report Code 10, device cannot start, if
96      * a regular Endpoint type is exposed on a root complex.  These
97      * should instead be Root Complex Integrated Endpoints.
98      */
99     if (pci_bus_is_express(dev->bus) && pci_bus_is_root(dev->bus)) {
100         type = PCI_EXP_TYPE_RC_END;
101     }
102 
103     return pcie_cap_init(dev, offset, type, 0);
104 }
105 
106 void pcie_cap_exit(PCIDevice *dev)
107 {
108     pci_del_capability(dev, PCI_CAP_ID_EXP, PCI_EXP_VER2_SIZEOF);
109 }
110 
111 uint8_t pcie_cap_get_type(const PCIDevice *dev)
112 {
113     uint32_t pos = dev->exp.exp_cap;
114     assert(pos > 0);
115     return (pci_get_word(dev->config + pos + PCI_EXP_FLAGS) &
116             PCI_EXP_FLAGS_TYPE) >> PCI_EXP_FLAGS_TYPE_SHIFT;
117 }
118 
119 /* MSI/MSI-X */
120 /* pci express interrupt message number */
121 /* 7.8.2 PCI Express Capabilities Register: Interrupt Message Number */
122 void pcie_cap_flags_set_vector(PCIDevice *dev, uint8_t vector)
123 {
124     uint8_t *exp_cap = dev->config + dev->exp.exp_cap;
125     assert(vector < 32);
126     pci_word_test_and_clear_mask(exp_cap + PCI_EXP_FLAGS, PCI_EXP_FLAGS_IRQ);
127     pci_word_test_and_set_mask(exp_cap + PCI_EXP_FLAGS,
128                                vector << PCI_EXP_FLAGS_IRQ_SHIFT);
129 }
130 
131 uint8_t pcie_cap_flags_get_vector(PCIDevice *dev)
132 {
133     return (pci_get_word(dev->config + dev->exp.exp_cap + PCI_EXP_FLAGS) &
134             PCI_EXP_FLAGS_IRQ) >> PCI_EXP_FLAGS_IRQ_SHIFT;
135 }
136 
137 void pcie_cap_deverr_init(PCIDevice *dev)
138 {
139     uint32_t pos = dev->exp.exp_cap;
140     pci_long_test_and_set_mask(dev->config + pos + PCI_EXP_DEVCAP,
141                                PCI_EXP_DEVCAP_RBER);
142     pci_long_test_and_set_mask(dev->wmask + pos + PCI_EXP_DEVCTL,
143                                PCI_EXP_DEVCTL_CERE | PCI_EXP_DEVCTL_NFERE |
144                                PCI_EXP_DEVCTL_FERE | PCI_EXP_DEVCTL_URRE);
145     pci_long_test_and_set_mask(dev->w1cmask + pos + PCI_EXP_DEVSTA,
146                                PCI_EXP_DEVSTA_CED | PCI_EXP_DEVSTA_NFED |
147                                PCI_EXP_DEVSTA_URD | PCI_EXP_DEVSTA_URD);
148 }
149 
150 void pcie_cap_deverr_reset(PCIDevice *dev)
151 {
152     uint8_t *devctl = dev->config + dev->exp.exp_cap + PCI_EXP_DEVCTL;
153     pci_long_test_and_clear_mask(devctl,
154                                  PCI_EXP_DEVCTL_CERE | PCI_EXP_DEVCTL_NFERE |
155                                  PCI_EXP_DEVCTL_FERE | PCI_EXP_DEVCTL_URRE);
156 }
157 
158 static void hotplug_event_update_event_status(PCIDevice *dev)
159 {
160     uint32_t pos = dev->exp.exp_cap;
161     uint8_t *exp_cap = dev->config + pos;
162     uint16_t sltctl = pci_get_word(exp_cap + PCI_EXP_SLTCTL);
163     uint16_t sltsta = pci_get_word(exp_cap + PCI_EXP_SLTSTA);
164 
165     dev->exp.hpev_notified = (sltctl & PCI_EXP_SLTCTL_HPIE) &&
166         (sltsta & sltctl & PCI_EXP_HP_EV_SUPPORTED);
167 }
168 
169 static void hotplug_event_notify(PCIDevice *dev)
170 {
171     bool prev = dev->exp.hpev_notified;
172 
173     hotplug_event_update_event_status(dev);
174 
175     if (prev == dev->exp.hpev_notified) {
176         return;
177     }
178 
179     /* Note: the logic above does not take into account whether interrupts
180      * are masked. The result is that interrupt will be sent when it is
181      * subsequently unmasked. This appears to be legal: Section 6.7.3.4:
182      * The Port may optionally send an MSI when there are hot-plug events that
183      * occur while interrupt generation is disabled, and interrupt generation is
184      * subsequently enabled. */
185     if (msix_enabled(dev)) {
186         msix_notify(dev, pcie_cap_flags_get_vector(dev));
187     } else if (msi_enabled(dev)) {
188         msi_notify(dev, pcie_cap_flags_get_vector(dev));
189     } else {
190         pci_set_irq(dev, dev->exp.hpev_notified);
191     }
192 }
193 
194 static void hotplug_event_clear(PCIDevice *dev)
195 {
196     hotplug_event_update_event_status(dev);
197     if (!msix_enabled(dev) && !msi_enabled(dev) && !dev->exp.hpev_notified) {
198         pci_irq_deassert(dev);
199     }
200 }
201 
202 /*
203  * A PCI Express Hot-Plug Event has occurred, so update slot status register
204  * and notify OS of the event if necessary.
205  *
206  * 6.7.3 PCI Express Hot-Plug Events
207  * 6.7.3.4 Software Notification of Hot-Plug Events
208  */
209 static void pcie_cap_slot_event(PCIDevice *dev, PCIExpressHotPlugEvent event)
210 {
211     /* Minor optimization: if nothing changed - no event is needed. */
212     if (pci_word_test_and_set_mask(dev->config + dev->exp.exp_cap +
213                                    PCI_EXP_SLTSTA, event)) {
214         return;
215     }
216     hotplug_event_notify(dev);
217 }
218 
219 static int pcie_cap_slot_hotplug(DeviceState *qdev,
220                                  PCIDevice *pci_dev, PCIHotplugState state)
221 {
222     PCIDevice *d = PCI_DEVICE(qdev);
223     uint8_t *exp_cap = d->config + d->exp.exp_cap;
224     uint16_t sltsta = pci_get_word(exp_cap + PCI_EXP_SLTSTA);
225 
226     /* Don't send event when device is enabled during qemu machine creation:
227      * it is present on boot, no hotplug event is necessary. We do send an
228      * event when the device is disabled later. */
229     if (state == PCI_COLDPLUG_ENABLED) {
230         pci_word_test_and_set_mask(exp_cap + PCI_EXP_SLTSTA,
231                                    PCI_EXP_SLTSTA_PDS);
232         return 0;
233     }
234 
235     PCIE_DEV_PRINTF(pci_dev, "hotplug state: %d\n", state);
236     if (sltsta & PCI_EXP_SLTSTA_EIS) {
237         /* the slot is electromechanically locked.
238          * This error is propagated up to qdev and then to HMP/QMP.
239          */
240         return -EBUSY;
241     }
242 
243     /* TODO: multifunction hot-plug.
244      * Right now, only a device of function = 0 is allowed to be
245      * hot plugged/unplugged.
246      */
247     assert(PCI_FUNC(pci_dev->devfn) == 0);
248 
249     if (state == PCI_HOTPLUG_ENABLED) {
250         pci_word_test_and_set_mask(exp_cap + PCI_EXP_SLTSTA,
251                                    PCI_EXP_SLTSTA_PDS);
252         pcie_cap_slot_event(d, PCI_EXP_HP_EV_PDC);
253     } else {
254         object_unparent(OBJECT(pci_dev));
255         pci_word_test_and_clear_mask(exp_cap + PCI_EXP_SLTSTA,
256                                      PCI_EXP_SLTSTA_PDS);
257         pcie_cap_slot_event(d, PCI_EXP_HP_EV_PDC);
258     }
259     return 0;
260 }
261 
262 /* pci express slot for pci express root/downstream port
263    PCI express capability slot registers */
264 void pcie_cap_slot_init(PCIDevice *dev, uint16_t slot)
265 {
266     uint32_t pos = dev->exp.exp_cap;
267 
268     pci_word_test_and_set_mask(dev->config + pos + PCI_EXP_FLAGS,
269                                PCI_EXP_FLAGS_SLOT);
270 
271     pci_long_test_and_clear_mask(dev->config + pos + PCI_EXP_SLTCAP,
272                                  ~PCI_EXP_SLTCAP_PSN);
273     pci_long_test_and_set_mask(dev->config + pos + PCI_EXP_SLTCAP,
274                                (slot << PCI_EXP_SLTCAP_PSN_SHIFT) |
275                                PCI_EXP_SLTCAP_EIP |
276                                PCI_EXP_SLTCAP_HPS |
277                                PCI_EXP_SLTCAP_HPC |
278                                PCI_EXP_SLTCAP_PIP |
279                                PCI_EXP_SLTCAP_AIP |
280                                PCI_EXP_SLTCAP_ABP);
281 
282     pci_word_test_and_clear_mask(dev->config + pos + PCI_EXP_SLTCTL,
283                                  PCI_EXP_SLTCTL_PIC |
284                                  PCI_EXP_SLTCTL_AIC);
285     pci_word_test_and_set_mask(dev->config + pos + PCI_EXP_SLTCTL,
286                                PCI_EXP_SLTCTL_PIC_OFF |
287                                PCI_EXP_SLTCTL_AIC_OFF);
288     pci_word_test_and_set_mask(dev->wmask + pos + PCI_EXP_SLTCTL,
289                                PCI_EXP_SLTCTL_PIC |
290                                PCI_EXP_SLTCTL_AIC |
291                                PCI_EXP_SLTCTL_HPIE |
292                                PCI_EXP_SLTCTL_CCIE |
293                                PCI_EXP_SLTCTL_PDCE |
294                                PCI_EXP_SLTCTL_ABPE);
295     /* Although reading PCI_EXP_SLTCTL_EIC returns always 0,
296      * make the bit writable here in order to detect 1b is written.
297      * pcie_cap_slot_write_config() test-and-clear the bit, so
298      * this bit always returns 0 to the guest.
299      */
300     pci_word_test_and_set_mask(dev->wmask + pos + PCI_EXP_SLTCTL,
301                                PCI_EXP_SLTCTL_EIC);
302 
303     pci_word_test_and_set_mask(dev->w1cmask + pos + PCI_EXP_SLTSTA,
304                                PCI_EXP_HP_EV_SUPPORTED);
305 
306     dev->exp.hpev_notified = false;
307 
308     pci_bus_hotplug(pci_bridge_get_sec_bus(PCI_BRIDGE(dev)),
309                     pcie_cap_slot_hotplug, &dev->qdev);
310 }
311 
312 void pcie_cap_slot_reset(PCIDevice *dev)
313 {
314     uint8_t *exp_cap = dev->config + dev->exp.exp_cap;
315 
316     PCIE_DEV_PRINTF(dev, "reset\n");
317 
318     pci_word_test_and_clear_mask(exp_cap + PCI_EXP_SLTCTL,
319                                  PCI_EXP_SLTCTL_EIC |
320                                  PCI_EXP_SLTCTL_PIC |
321                                  PCI_EXP_SLTCTL_AIC |
322                                  PCI_EXP_SLTCTL_HPIE |
323                                  PCI_EXP_SLTCTL_CCIE |
324                                  PCI_EXP_SLTCTL_PDCE |
325                                  PCI_EXP_SLTCTL_ABPE);
326     pci_word_test_and_set_mask(exp_cap + PCI_EXP_SLTCTL,
327                                PCI_EXP_SLTCTL_PIC_OFF |
328                                PCI_EXP_SLTCTL_AIC_OFF);
329 
330     pci_word_test_and_clear_mask(exp_cap + PCI_EXP_SLTSTA,
331                                  PCI_EXP_SLTSTA_EIS |/* on reset,
332                                                         the lock is released */
333                                  PCI_EXP_SLTSTA_CC |
334                                  PCI_EXP_SLTSTA_PDC |
335                                  PCI_EXP_SLTSTA_ABP);
336 
337     hotplug_event_update_event_status(dev);
338 }
339 
340 void pcie_cap_slot_write_config(PCIDevice *dev,
341                                 uint32_t addr, uint32_t val, int len)
342 {
343     uint32_t pos = dev->exp.exp_cap;
344     uint8_t *exp_cap = dev->config + pos;
345     uint16_t sltsta = pci_get_word(exp_cap + PCI_EXP_SLTSTA);
346 
347     if (ranges_overlap(addr, len, pos + PCI_EXP_SLTSTA, 2)) {
348         hotplug_event_clear(dev);
349     }
350 
351     if (!ranges_overlap(addr, len, pos + PCI_EXP_SLTCTL, 2)) {
352         return;
353     }
354 
355     if (pci_word_test_and_clear_mask(exp_cap + PCI_EXP_SLTCTL,
356                                      PCI_EXP_SLTCTL_EIC)) {
357         sltsta ^= PCI_EXP_SLTSTA_EIS; /* toggle PCI_EXP_SLTSTA_EIS bit */
358         pci_set_word(exp_cap + PCI_EXP_SLTSTA, sltsta);
359         PCIE_DEV_PRINTF(dev, "PCI_EXP_SLTCTL_EIC: "
360                         "sltsta -> 0x%02"PRIx16"\n",
361                         sltsta);
362     }
363 
364     hotplug_event_notify(dev);
365 
366     /*
367      * 6.7.3.2 Command Completed Events
368      *
369      * Software issues a command to a hot-plug capable Downstream Port by
370      * issuing a write transaction that targets any portion of the Port’s Slot
371      * Control register. A single write to the Slot Control register is
372      * considered to be a single command, even if the write affects more than
373      * one field in the Slot Control register. In response to this transaction,
374      * the Port must carry out the requested actions and then set the
375      * associated status field for the command completed event. */
376 
377     /* Real hardware might take a while to complete requested command because
378      * physical movement would be involved like locking the electromechanical
379      * lock.  However in our case, command is completed instantaneously above,
380      * so send a command completion event right now.
381      */
382     pcie_cap_slot_event(dev, PCI_EXP_HP_EV_CCI);
383 }
384 
385 int pcie_cap_slot_post_load(void *opaque, int version_id)
386 {
387     PCIDevice *dev = opaque;
388     hotplug_event_update_event_status(dev);
389     return 0;
390 }
391 
392 void pcie_cap_slot_push_attention_button(PCIDevice *dev)
393 {
394     pcie_cap_slot_event(dev, PCI_EXP_HP_EV_ABP);
395 }
396 
397 /* root control/capabilities/status. PME isn't emulated for now */
398 void pcie_cap_root_init(PCIDevice *dev)
399 {
400     pci_set_word(dev->wmask + dev->exp.exp_cap + PCI_EXP_RTCTL,
401                  PCI_EXP_RTCTL_SECEE | PCI_EXP_RTCTL_SENFEE |
402                  PCI_EXP_RTCTL_SEFEE);
403 }
404 
405 void pcie_cap_root_reset(PCIDevice *dev)
406 {
407     pci_set_word(dev->config + dev->exp.exp_cap + PCI_EXP_RTCTL, 0);
408 }
409 
410 /* function level reset(FLR) */
411 void pcie_cap_flr_init(PCIDevice *dev)
412 {
413     pci_long_test_and_set_mask(dev->config + dev->exp.exp_cap + PCI_EXP_DEVCAP,
414                                PCI_EXP_DEVCAP_FLR);
415 
416     /* Although reading BCR_FLR returns always 0,
417      * the bit is made writable here in order to detect the 1b is written
418      * pcie_cap_flr_write_config() test-and-clear the bit, so
419      * this bit always returns 0 to the guest.
420      */
421     pci_word_test_and_set_mask(dev->wmask + dev->exp.exp_cap + PCI_EXP_DEVCTL,
422                                PCI_EXP_DEVCTL_BCR_FLR);
423 }
424 
425 void pcie_cap_flr_write_config(PCIDevice *dev,
426                                uint32_t addr, uint32_t val, int len)
427 {
428     uint8_t *devctl = dev->config + dev->exp.exp_cap + PCI_EXP_DEVCTL;
429     if (pci_get_word(devctl) & PCI_EXP_DEVCTL_BCR_FLR) {
430         /* Clear PCI_EXP_DEVCTL_BCR_FLR after invoking the reset handler
431            so the handler can detect FLR by looking at this bit. */
432         pci_device_reset(dev);
433         pci_word_test_and_clear_mask(devctl, PCI_EXP_DEVCTL_BCR_FLR);
434     }
435 }
436 
437 /* Alternative Routing-ID Interpretation (ARI) */
438 /* ari forwarding support for down stream port */
439 void pcie_cap_ari_init(PCIDevice *dev)
440 {
441     uint32_t pos = dev->exp.exp_cap;
442     pci_long_test_and_set_mask(dev->config + pos + PCI_EXP_DEVCAP2,
443                                PCI_EXP_DEVCAP2_ARI);
444     pci_long_test_and_set_mask(dev->wmask + pos + PCI_EXP_DEVCTL2,
445                                PCI_EXP_DEVCTL2_ARI);
446 }
447 
448 void pcie_cap_ari_reset(PCIDevice *dev)
449 {
450     uint8_t *devctl2 = dev->config + dev->exp.exp_cap + PCI_EXP_DEVCTL2;
451     pci_long_test_and_clear_mask(devctl2, PCI_EXP_DEVCTL2_ARI);
452 }
453 
454 bool pcie_cap_is_ari_enabled(const PCIDevice *dev)
455 {
456     if (!pci_is_express(dev)) {
457         return false;
458     }
459     if (!dev->exp.exp_cap) {
460         return false;
461     }
462 
463     return pci_get_long(dev->config + dev->exp.exp_cap + PCI_EXP_DEVCTL2) &
464         PCI_EXP_DEVCTL2_ARI;
465 }
466 
467 /**************************************************************************
468  * pci express extended capability allocation functions
469  * uint16_t ext_cap_id (16 bit)
470  * uint8_t cap_ver (4 bit)
471  * uint16_t cap_offset (12 bit)
472  * uint16_t ext_cap_size
473  */
474 
475 static uint16_t pcie_find_capability_list(PCIDevice *dev, uint16_t cap_id,
476                                           uint16_t *prev_p)
477 {
478     uint16_t prev = 0;
479     uint16_t next;
480     uint32_t header = pci_get_long(dev->config + PCI_CONFIG_SPACE_SIZE);
481 
482     if (!header) {
483         /* no extended capability */
484         next = 0;
485         goto out;
486     }
487     for (next = PCI_CONFIG_SPACE_SIZE; next;
488          prev = next, next = PCI_EXT_CAP_NEXT(header)) {
489 
490         assert(next >= PCI_CONFIG_SPACE_SIZE);
491         assert(next <= PCIE_CONFIG_SPACE_SIZE - 8);
492 
493         header = pci_get_long(dev->config + next);
494         if (PCI_EXT_CAP_ID(header) == cap_id) {
495             break;
496         }
497     }
498 
499 out:
500     if (prev_p) {
501         *prev_p = prev;
502     }
503     return next;
504 }
505 
506 uint16_t pcie_find_capability(PCIDevice *dev, uint16_t cap_id)
507 {
508     return pcie_find_capability_list(dev, cap_id, NULL);
509 }
510 
511 static void pcie_ext_cap_set_next(PCIDevice *dev, uint16_t pos, uint16_t next)
512 {
513     uint32_t header = pci_get_long(dev->config + pos);
514     assert(!(next & (PCI_EXT_CAP_ALIGN - 1)));
515     header = (header & ~PCI_EXT_CAP_NEXT_MASK) |
516         ((next << PCI_EXT_CAP_NEXT_SHIFT) & PCI_EXT_CAP_NEXT_MASK);
517     pci_set_long(dev->config + pos, header);
518 }
519 
520 /*
521  * caller must supply valid (offset, size) * such that the range shouldn't
522  * overlap with other capability or other registers.
523  * This function doesn't check it.
524  */
525 void pcie_add_capability(PCIDevice *dev,
526                          uint16_t cap_id, uint8_t cap_ver,
527                          uint16_t offset, uint16_t size)
528 {
529     uint32_t header;
530     uint16_t next;
531 
532     assert(offset >= PCI_CONFIG_SPACE_SIZE);
533     assert(offset < offset + size);
534     assert(offset + size < PCIE_CONFIG_SPACE_SIZE);
535     assert(size >= 8);
536     assert(pci_is_express(dev));
537 
538     if (offset == PCI_CONFIG_SPACE_SIZE) {
539         header = pci_get_long(dev->config + offset);
540         next = PCI_EXT_CAP_NEXT(header);
541     } else {
542         uint16_t prev;
543 
544         /* 0 is reserved cap id. use internally to find the last capability
545            in the linked list */
546         next = pcie_find_capability_list(dev, 0, &prev);
547 
548         assert(prev >= PCI_CONFIG_SPACE_SIZE);
549         assert(next == 0);
550         pcie_ext_cap_set_next(dev, prev, offset);
551     }
552     pci_set_long(dev->config + offset, PCI_EXT_CAP(cap_id, cap_ver, next));
553 
554     /* Make capability read-only by default */
555     memset(dev->wmask + offset, 0, size);
556     memset(dev->w1cmask + offset, 0, size);
557     /* Check capability by default */
558     memset(dev->cmask + offset, 0xFF, size);
559 }
560 
561 /**************************************************************************
562  * pci express extended capability helper functions
563  */
564 
565 /* ARI */
566 void pcie_ari_init(PCIDevice *dev, uint16_t offset, uint16_t nextfn)
567 {
568     pcie_add_capability(dev, PCI_EXT_CAP_ID_ARI, PCI_ARI_VER,
569                         offset, PCI_ARI_SIZEOF);
570     pci_set_long(dev->config + offset + PCI_ARI_CAP, PCI_ARI_CAP_NFN(nextfn));
571 }
572