xref: /openbmc/qemu/hw/acpi/piix4.c (revision 14a650ec)
1 /*
2  * ACPI implementation
3  *
4  * Copyright (c) 2006 Fabrice Bellard
5  *
6  * This library is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License version 2 as published by the Free Software Foundation.
9  *
10  * This library is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13  * Lesser General Public License for more details.
14  *
15  * You should have received a copy of the GNU Lesser General Public
16  * License along with this library; if not, see <http://www.gnu.org/licenses/>
17  *
18  * Contributions after 2012-01-13 are licensed under the terms of the
19  * GNU GPL, version 2 or (at your option) any later version.
20  */
21 #include "hw/hw.h"
22 #include "hw/i386/pc.h"
23 #include "hw/isa/apm.h"
24 #include "hw/i2c/pm_smbus.h"
25 #include "hw/pci/pci.h"
26 #include "hw/acpi/acpi.h"
27 #include "sysemu/sysemu.h"
28 #include "qemu/range.h"
29 #include "exec/ioport.h"
30 #include "hw/nvram/fw_cfg.h"
31 #include "exec/address-spaces.h"
32 #include "hw/acpi/piix4.h"
33 
34 //#define DEBUG
35 
36 #ifdef DEBUG
37 # define PIIX4_DPRINTF(format, ...)     printf(format, ## __VA_ARGS__)
38 #else
39 # define PIIX4_DPRINTF(format, ...)     do { } while (0)
40 #endif
41 
42 #define GPE_BASE 0xafe0
43 #define GPE_LEN 4
44 
45 #define PCI_HOTPLUG_ADDR 0xae00
46 #define PCI_HOTPLUG_SIZE 0x000f
47 #define PCI_UP_BASE 0xae00
48 #define PCI_DOWN_BASE 0xae04
49 #define PCI_EJ_BASE 0xae08
50 #define PCI_RMV_BASE 0xae0c
51 
52 #define PIIX4_PROC_BASE 0xaf00
53 #define PIIX4_PROC_LEN 32
54 
55 #define PIIX4_PCI_HOTPLUG_STATUS 2
56 #define PIIX4_CPU_HOTPLUG_STATUS 4
57 
58 struct pci_status {
59     uint32_t up; /* deprecated, maintained for migration compatibility */
60     uint32_t down;
61 };
62 
63 typedef struct CPUStatus {
64     uint8_t sts[PIIX4_PROC_LEN];
65 } CPUStatus;
66 
67 typedef struct PIIX4PMState {
68     /*< private >*/
69     PCIDevice parent_obj;
70     /*< public >*/
71 
72     MemoryRegion io;
73     uint32_t io_base;
74 
75     MemoryRegion io_gpe;
76     MemoryRegion io_pci;
77     MemoryRegion io_cpu;
78     ACPIREGS ar;
79 
80     APMState apm;
81 
82     PMSMBus smb;
83     uint32_t smb_io_base;
84 
85     qemu_irq irq;
86     qemu_irq smi_irq;
87     int kvm_enabled;
88     Notifier machine_ready;
89     Notifier powerdown_notifier;
90 
91     /* for pci hotplug */
92     struct pci_status pci0_status;
93     uint32_t pci0_hotplug_enable;
94     uint32_t pci0_slot_device_present;
95 
96     uint8_t disable_s3;
97     uint8_t disable_s4;
98     uint8_t s4_val;
99 
100     CPUStatus gpe_cpu;
101     Notifier cpu_added_notifier;
102 } PIIX4PMState;
103 
104 #define TYPE_PIIX4_PM "PIIX4_PM"
105 
106 #define PIIX4_PM(obj) \
107     OBJECT_CHECK(PIIX4PMState, (obj), TYPE_PIIX4_PM)
108 
109 static void piix4_acpi_system_hot_add_init(MemoryRegion *parent,
110                                            PCIBus *bus, PIIX4PMState *s);
111 
112 #define ACPI_ENABLE 0xf1
113 #define ACPI_DISABLE 0xf0
114 
115 static void pm_update_sci(PIIX4PMState *s)
116 {
117     int sci_level, pmsts;
118 
119     pmsts = acpi_pm1_evt_get_sts(&s->ar);
120     sci_level = (((pmsts & s->ar.pm1.evt.en) &
121                   (ACPI_BITMASK_RT_CLOCK_ENABLE |
122                    ACPI_BITMASK_POWER_BUTTON_ENABLE |
123                    ACPI_BITMASK_GLOBAL_LOCK_ENABLE |
124                    ACPI_BITMASK_TIMER_ENABLE)) != 0) ||
125         (((s->ar.gpe.sts[0] & s->ar.gpe.en[0]) &
126           (PIIX4_PCI_HOTPLUG_STATUS | PIIX4_CPU_HOTPLUG_STATUS)) != 0);
127 
128     qemu_set_irq(s->irq, sci_level);
129     /* schedule a timer interruption if needed */
130     acpi_pm_tmr_update(&s->ar, (s->ar.pm1.evt.en & ACPI_BITMASK_TIMER_ENABLE) &&
131                        !(pmsts & ACPI_BITMASK_TIMER_STATUS));
132 }
133 
134 static void pm_tmr_timer(ACPIREGS *ar)
135 {
136     PIIX4PMState *s = container_of(ar, PIIX4PMState, ar);
137     pm_update_sci(s);
138 }
139 
140 static void apm_ctrl_changed(uint32_t val, void *arg)
141 {
142     PIIX4PMState *s = arg;
143     PCIDevice *d = PCI_DEVICE(s);
144 
145     /* ACPI specs 3.0, 4.7.2.5 */
146     acpi_pm1_cnt_update(&s->ar, val == ACPI_ENABLE, val == ACPI_DISABLE);
147 
148     if (d->config[0x5b] & (1 << 1)) {
149         if (s->smi_irq) {
150             qemu_irq_raise(s->smi_irq);
151         }
152     }
153 }
154 
155 static void pm_io_space_update(PIIX4PMState *s)
156 {
157     PCIDevice *d = PCI_DEVICE(s);
158 
159     s->io_base = le32_to_cpu(*(uint32_t *)(d->config + 0x40));
160     s->io_base &= 0xffc0;
161 
162     memory_region_transaction_begin();
163     memory_region_set_enabled(&s->io, d->config[0x80] & 1);
164     memory_region_set_address(&s->io, s->io_base);
165     memory_region_transaction_commit();
166 }
167 
168 static void smbus_io_space_update(PIIX4PMState *s)
169 {
170     PCIDevice *d = PCI_DEVICE(s);
171 
172     s->smb_io_base = le32_to_cpu(*(uint32_t *)(d->config + 0x90));
173     s->smb_io_base &= 0xffc0;
174 
175     memory_region_transaction_begin();
176     memory_region_set_enabled(&s->smb.io, d->config[0xd2] & 1);
177     memory_region_set_address(&s->smb.io, s->smb_io_base);
178     memory_region_transaction_commit();
179 }
180 
181 static void pm_write_config(PCIDevice *d,
182                             uint32_t address, uint32_t val, int len)
183 {
184     pci_default_write_config(d, address, val, len);
185     if (range_covers_byte(address, len, 0x80) ||
186         ranges_overlap(address, len, 0x40, 4)) {
187         pm_io_space_update((PIIX4PMState *)d);
188     }
189     if (range_covers_byte(address, len, 0xd2) ||
190         ranges_overlap(address, len, 0x90, 4)) {
191         smbus_io_space_update((PIIX4PMState *)d);
192     }
193 }
194 
195 static void vmstate_pci_status_pre_save(void *opaque)
196 {
197     struct pci_status *pci0_status = opaque;
198     PIIX4PMState *s = container_of(pci0_status, PIIX4PMState, pci0_status);
199 
200     /* We no longer track up, so build a safe value for migrating
201      * to a version that still does... of course these might get lost
202      * by an old buggy implementation, but we try. */
203     pci0_status->up = s->pci0_slot_device_present & s->pci0_hotplug_enable;
204 }
205 
206 static int vmstate_acpi_post_load(void *opaque, int version_id)
207 {
208     PIIX4PMState *s = opaque;
209 
210     pm_io_space_update(s);
211     return 0;
212 }
213 
214 #define VMSTATE_GPE_ARRAY(_field, _state)                            \
215  {                                                                   \
216      .name       = (stringify(_field)),                              \
217      .version_id = 0,                                                \
218      .info       = &vmstate_info_uint16,                             \
219      .size       = sizeof(uint16_t),                                 \
220      .flags      = VMS_SINGLE | VMS_POINTER,                         \
221      .offset     = vmstate_offset_pointer(_state, _field, uint8_t),  \
222  }
223 
224 static const VMStateDescription vmstate_gpe = {
225     .name = "gpe",
226     .version_id = 1,
227     .minimum_version_id = 1,
228     .minimum_version_id_old = 1,
229     .fields      = (VMStateField []) {
230         VMSTATE_GPE_ARRAY(sts, ACPIGPE),
231         VMSTATE_GPE_ARRAY(en, ACPIGPE),
232         VMSTATE_END_OF_LIST()
233     }
234 };
235 
236 static const VMStateDescription vmstate_pci_status = {
237     .name = "pci_status",
238     .version_id = 1,
239     .minimum_version_id = 1,
240     .minimum_version_id_old = 1,
241     .pre_save = vmstate_pci_status_pre_save,
242     .fields      = (VMStateField []) {
243         VMSTATE_UINT32(up, struct pci_status),
244         VMSTATE_UINT32(down, struct pci_status),
245         VMSTATE_END_OF_LIST()
246     }
247 };
248 
249 static int acpi_load_old(QEMUFile *f, void *opaque, int version_id)
250 {
251     PIIX4PMState *s = opaque;
252     int ret, i;
253     uint16_t temp;
254 
255     ret = pci_device_load(PCI_DEVICE(s), f);
256     if (ret < 0) {
257         return ret;
258     }
259     qemu_get_be16s(f, &s->ar.pm1.evt.sts);
260     qemu_get_be16s(f, &s->ar.pm1.evt.en);
261     qemu_get_be16s(f, &s->ar.pm1.cnt.cnt);
262 
263     ret = vmstate_load_state(f, &vmstate_apm, &s->apm, 1);
264     if (ret) {
265         return ret;
266     }
267 
268     timer_get(f, s->ar.tmr.timer);
269     qemu_get_sbe64s(f, &s->ar.tmr.overflow_time);
270 
271     qemu_get_be16s(f, (uint16_t *)s->ar.gpe.sts);
272     for (i = 0; i < 3; i++) {
273         qemu_get_be16s(f, &temp);
274     }
275 
276     qemu_get_be16s(f, (uint16_t *)s->ar.gpe.en);
277     for (i = 0; i < 3; i++) {
278         qemu_get_be16s(f, &temp);
279     }
280 
281     ret = vmstate_load_state(f, &vmstate_pci_status, &s->pci0_status, 1);
282     return ret;
283 }
284 
285 /* qemu-kvm 1.2 uses version 3 but advertised as 2
286  * To support incoming qemu-kvm 1.2 migration, change version_id
287  * and minimum_version_id to 2 below (which breaks migration from
288  * qemu 1.2).
289  *
290  */
291 static const VMStateDescription vmstate_acpi = {
292     .name = "piix4_pm",
293     .version_id = 3,
294     .minimum_version_id = 3,
295     .minimum_version_id_old = 1,
296     .load_state_old = acpi_load_old,
297     .post_load = vmstate_acpi_post_load,
298     .fields      = (VMStateField []) {
299         VMSTATE_PCI_DEVICE(parent_obj, PIIX4PMState),
300         VMSTATE_UINT16(ar.pm1.evt.sts, PIIX4PMState),
301         VMSTATE_UINT16(ar.pm1.evt.en, PIIX4PMState),
302         VMSTATE_UINT16(ar.pm1.cnt.cnt, PIIX4PMState),
303         VMSTATE_STRUCT(apm, PIIX4PMState, 0, vmstate_apm, APMState),
304         VMSTATE_TIMER(ar.tmr.timer, PIIX4PMState),
305         VMSTATE_INT64(ar.tmr.overflow_time, PIIX4PMState),
306         VMSTATE_STRUCT(ar.gpe, PIIX4PMState, 2, vmstate_gpe, ACPIGPE),
307         VMSTATE_STRUCT(pci0_status, PIIX4PMState, 2, vmstate_pci_status,
308                        struct pci_status),
309         VMSTATE_END_OF_LIST()
310     }
311 };
312 
313 static void acpi_piix_eject_slot(PIIX4PMState *s, unsigned slots)
314 {
315     BusChild *kid, *next;
316     BusState *bus = qdev_get_parent_bus(DEVICE(s));
317     int slot = ffs(slots) - 1;
318     bool slot_free = true;
319 
320     /* Mark request as complete */
321     s->pci0_status.down &= ~(1U << slot);
322 
323     QTAILQ_FOREACH_SAFE(kid, &bus->children, sibling, next) {
324         DeviceState *qdev = kid->child;
325         PCIDevice *dev = PCI_DEVICE(qdev);
326         PCIDeviceClass *pc = PCI_DEVICE_GET_CLASS(dev);
327         if (PCI_SLOT(dev->devfn) == slot) {
328             if (pc->no_hotplug) {
329                 slot_free = false;
330             } else {
331                 object_unparent(OBJECT(qdev));
332             }
333         }
334     }
335     if (slot_free) {
336         s->pci0_slot_device_present &= ~(1U << slot);
337     }
338 }
339 
340 static void piix4_update_hotplug(PIIX4PMState *s)
341 {
342     BusState *bus = qdev_get_parent_bus(DEVICE(s));
343     BusChild *kid, *next;
344 
345     /* Execute any pending removes during reset */
346     while (s->pci0_status.down) {
347         acpi_piix_eject_slot(s, s->pci0_status.down);
348     }
349 
350     s->pci0_hotplug_enable = ~0;
351     s->pci0_slot_device_present = 0;
352 
353     QTAILQ_FOREACH_SAFE(kid, &bus->children, sibling, next) {
354         DeviceState *qdev = kid->child;
355         PCIDevice *pdev = PCI_DEVICE(qdev);
356         PCIDeviceClass *pc = PCI_DEVICE_GET_CLASS(pdev);
357         int slot = PCI_SLOT(pdev->devfn);
358 
359         if (pc->no_hotplug) {
360             s->pci0_hotplug_enable &= ~(1U << slot);
361         }
362 
363         s->pci0_slot_device_present |= (1U << slot);
364     }
365 }
366 
367 static void piix4_reset(void *opaque)
368 {
369     PIIX4PMState *s = opaque;
370     PCIDevice *d = PCI_DEVICE(s);
371     uint8_t *pci_conf = d->config;
372 
373     pci_conf[0x58] = 0;
374     pci_conf[0x59] = 0;
375     pci_conf[0x5a] = 0;
376     pci_conf[0x5b] = 0;
377 
378     pci_conf[0x40] = 0x01; /* PM io base read only bit */
379     pci_conf[0x80] = 0;
380 
381     if (s->kvm_enabled) {
382         /* Mark SMM as already inited (until KVM supports SMM). */
383         pci_conf[0x5B] = 0x02;
384     }
385     pm_io_space_update(s);
386     piix4_update_hotplug(s);
387 }
388 
389 static void piix4_pm_powerdown_req(Notifier *n, void *opaque)
390 {
391     PIIX4PMState *s = container_of(n, PIIX4PMState, powerdown_notifier);
392 
393     assert(s != NULL);
394     acpi_pm1_evt_power_down(&s->ar);
395 }
396 
397 static void piix4_pm_machine_ready(Notifier *n, void *opaque)
398 {
399     PIIX4PMState *s = container_of(n, PIIX4PMState, machine_ready);
400     PCIDevice *d = PCI_DEVICE(s);
401     MemoryRegion *io_as = pci_address_space_io(d);
402     uint8_t *pci_conf;
403 
404     pci_conf = d->config;
405     pci_conf[0x5f] = 0x10 |
406         (memory_region_present(io_as, 0x378) ? 0x80 : 0);
407     pci_conf[0x63] = 0x60;
408     pci_conf[0x67] = (memory_region_present(io_as, 0x3f8) ? 0x08 : 0) |
409         (memory_region_present(io_as, 0x2f8) ? 0x90 : 0);
410 }
411 
412 static void piix4_pm_add_propeties(PIIX4PMState *s)
413 {
414     static const uint8_t acpi_enable_cmd = ACPI_ENABLE;
415     static const uint8_t acpi_disable_cmd = ACPI_DISABLE;
416     static const uint32_t gpe0_blk = GPE_BASE;
417     static const uint32_t gpe0_blk_len = GPE_LEN;
418     static const uint16_t sci_int = 9;
419 
420     object_property_add_uint8_ptr(OBJECT(s), ACPI_PM_PROP_ACPI_ENABLE_CMD,
421                                   &acpi_enable_cmd, NULL);
422     object_property_add_uint8_ptr(OBJECT(s), ACPI_PM_PROP_ACPI_DISABLE_CMD,
423                                   &acpi_disable_cmd, NULL);
424     object_property_add_uint32_ptr(OBJECT(s), ACPI_PM_PROP_GPE0_BLK,
425                                   &gpe0_blk, NULL);
426     object_property_add_uint32_ptr(OBJECT(s), ACPI_PM_PROP_GPE0_BLK_LEN,
427                                   &gpe0_blk_len, NULL);
428     object_property_add_uint16_ptr(OBJECT(s), ACPI_PM_PROP_SCI_INT,
429                                   &sci_int, NULL);
430     object_property_add_uint32_ptr(OBJECT(s), ACPI_PM_PROP_PM_IO_BASE,
431                                   &s->io_base, NULL);
432 }
433 
434 static int piix4_pm_initfn(PCIDevice *dev)
435 {
436     PIIX4PMState *s = PIIX4_PM(dev);
437     uint8_t *pci_conf;
438 
439     pci_conf = dev->config;
440     pci_conf[0x06] = 0x80;
441     pci_conf[0x07] = 0x02;
442     pci_conf[0x09] = 0x00;
443     pci_conf[0x3d] = 0x01; // interrupt pin 1
444 
445     /* APM */
446     apm_init(dev, &s->apm, apm_ctrl_changed, s);
447 
448     if (s->kvm_enabled) {
449         /* Mark SMM as already inited to prevent SMM from running.  KVM does not
450          * support SMM mode. */
451         pci_conf[0x5B] = 0x02;
452     }
453 
454     /* XXX: which specification is used ? The i82731AB has different
455        mappings */
456     pci_conf[0x90] = s->smb_io_base | 1;
457     pci_conf[0x91] = s->smb_io_base >> 8;
458     pci_conf[0xd2] = 0x09;
459     pm_smbus_init(DEVICE(dev), &s->smb);
460     memory_region_set_enabled(&s->smb.io, pci_conf[0xd2] & 1);
461     memory_region_add_subregion(pci_address_space_io(dev),
462                                 s->smb_io_base, &s->smb.io);
463 
464     memory_region_init(&s->io, OBJECT(s), "piix4-pm", 64);
465     memory_region_set_enabled(&s->io, false);
466     memory_region_add_subregion(pci_address_space_io(dev),
467                                 0, &s->io);
468 
469     acpi_pm_tmr_init(&s->ar, pm_tmr_timer, &s->io);
470     acpi_pm1_evt_init(&s->ar, pm_tmr_timer, &s->io);
471     acpi_pm1_cnt_init(&s->ar, &s->io, s->s4_val);
472     acpi_gpe_init(&s->ar, GPE_LEN);
473 
474     s->powerdown_notifier.notify = piix4_pm_powerdown_req;
475     qemu_register_powerdown_notifier(&s->powerdown_notifier);
476 
477     s->machine_ready.notify = piix4_pm_machine_ready;
478     qemu_add_machine_init_done_notifier(&s->machine_ready);
479     qemu_register_reset(piix4_reset, s);
480 
481     piix4_acpi_system_hot_add_init(pci_address_space_io(dev), dev->bus, s);
482 
483     piix4_pm_add_propeties(s);
484     return 0;
485 }
486 
487 Object *piix4_pm_find(void)
488 {
489     bool ambig;
490     Object *o = object_resolve_path_type("", TYPE_PIIX4_PM, &ambig);
491 
492     if (ambig || !o) {
493         return NULL;
494     }
495     return o;
496 }
497 
498 i2c_bus *piix4_pm_init(PCIBus *bus, int devfn, uint32_t smb_io_base,
499                        qemu_irq sci_irq, qemu_irq smi_irq,
500                        int kvm_enabled, FWCfgState *fw_cfg)
501 {
502     DeviceState *dev;
503     PIIX4PMState *s;
504 
505     dev = DEVICE(pci_create(bus, devfn, TYPE_PIIX4_PM));
506     qdev_prop_set_uint32(dev, "smb_io_base", smb_io_base);
507 
508     s = PIIX4_PM(dev);
509     s->irq = sci_irq;
510     s->smi_irq = smi_irq;
511     s->kvm_enabled = kvm_enabled;
512 
513     qdev_init_nofail(dev);
514 
515     if (fw_cfg) {
516         uint8_t suspend[6] = {128, 0, 0, 129, 128, 128};
517         suspend[3] = 1 | ((!s->disable_s3) << 7);
518         suspend[4] = s->s4_val | ((!s->disable_s4) << 7);
519 
520         fw_cfg_add_file(fw_cfg, "etc/system-states", g_memdup(suspend, 6), 6);
521     }
522 
523     return s->smb.smbus;
524 }
525 
526 static Property piix4_pm_properties[] = {
527     DEFINE_PROP_UINT32("smb_io_base", PIIX4PMState, smb_io_base, 0),
528     DEFINE_PROP_UINT8(ACPI_PM_PROP_S3_DISABLED, PIIX4PMState, disable_s3, 0),
529     DEFINE_PROP_UINT8(ACPI_PM_PROP_S4_DISABLED, PIIX4PMState, disable_s4, 0),
530     DEFINE_PROP_UINT8(ACPI_PM_PROP_S4_VAL, PIIX4PMState, s4_val, 2),
531     DEFINE_PROP_END_OF_LIST(),
532 };
533 
534 static void piix4_pm_class_init(ObjectClass *klass, void *data)
535 {
536     DeviceClass *dc = DEVICE_CLASS(klass);
537     PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
538 
539     k->no_hotplug = 1;
540     k->init = piix4_pm_initfn;
541     k->config_write = pm_write_config;
542     k->vendor_id = PCI_VENDOR_ID_INTEL;
543     k->device_id = PCI_DEVICE_ID_INTEL_82371AB_3;
544     k->revision = 0x03;
545     k->class_id = PCI_CLASS_BRIDGE_OTHER;
546     dc->desc = "PM";
547     dc->no_user = 1;
548     dc->vmsd = &vmstate_acpi;
549     dc->props = piix4_pm_properties;
550 }
551 
552 static const TypeInfo piix4_pm_info = {
553     .name          = TYPE_PIIX4_PM,
554     .parent        = TYPE_PCI_DEVICE,
555     .instance_size = sizeof(PIIX4PMState),
556     .class_init    = piix4_pm_class_init,
557 };
558 
559 static void piix4_pm_register_types(void)
560 {
561     type_register_static(&piix4_pm_info);
562 }
563 
564 type_init(piix4_pm_register_types)
565 
566 static uint64_t gpe_readb(void *opaque, hwaddr addr, unsigned width)
567 {
568     PIIX4PMState *s = opaque;
569     uint32_t val = acpi_gpe_ioport_readb(&s->ar, addr);
570 
571     PIIX4_DPRINTF("gpe read %" HWADDR_PRIx " == %" PRIu32 "\n", addr, val);
572     return val;
573 }
574 
575 static void gpe_writeb(void *opaque, hwaddr addr, uint64_t val,
576                        unsigned width)
577 {
578     PIIX4PMState *s = opaque;
579 
580     acpi_gpe_ioport_writeb(&s->ar, addr, val);
581     pm_update_sci(s);
582 
583     PIIX4_DPRINTF("gpe write %" HWADDR_PRIx " <== %" PRIu64 "\n", addr, val);
584 }
585 
586 static const MemoryRegionOps piix4_gpe_ops = {
587     .read = gpe_readb,
588     .write = gpe_writeb,
589     .valid.min_access_size = 1,
590     .valid.max_access_size = 4,
591     .impl.min_access_size = 1,
592     .impl.max_access_size = 1,
593     .endianness = DEVICE_LITTLE_ENDIAN,
594 };
595 
596 static uint64_t pci_read(void *opaque, hwaddr addr, unsigned int size)
597 {
598     PIIX4PMState *s = opaque;
599     uint32_t val = 0;
600 
601     switch (addr) {
602     case PCI_UP_BASE - PCI_HOTPLUG_ADDR:
603         /* Manufacture an "up" value to cause a device check on any hotplug
604          * slot with a device.  Extra device checks are harmless. */
605         val = s->pci0_slot_device_present & s->pci0_hotplug_enable;
606         PIIX4_DPRINTF("pci_up_read %" PRIu32 "\n", val);
607         break;
608     case PCI_DOWN_BASE - PCI_HOTPLUG_ADDR:
609         val = s->pci0_status.down;
610         PIIX4_DPRINTF("pci_down_read %" PRIu32 "\n", val);
611         break;
612     case PCI_EJ_BASE - PCI_HOTPLUG_ADDR:
613         /* No feature defined yet */
614         PIIX4_DPRINTF("pci_features_read %" PRIu32 "\n", val);
615         break;
616     case PCI_RMV_BASE - PCI_HOTPLUG_ADDR:
617         val = s->pci0_hotplug_enable;
618         break;
619     default:
620         break;
621     }
622 
623     return val;
624 }
625 
626 static void pci_write(void *opaque, hwaddr addr, uint64_t data,
627                       unsigned int size)
628 {
629     switch (addr) {
630     case PCI_EJ_BASE - PCI_HOTPLUG_ADDR:
631         acpi_piix_eject_slot(opaque, (uint32_t)data);
632         PIIX4_DPRINTF("pciej write %" HWADDR_PRIx " <== %" PRIu64 "\n",
633                       addr, data);
634         break;
635     default:
636         break;
637     }
638 }
639 
640 static const MemoryRegionOps piix4_pci_ops = {
641     .read = pci_read,
642     .write = pci_write,
643     .endianness = DEVICE_LITTLE_ENDIAN,
644     .valid = {
645         .min_access_size = 4,
646         .max_access_size = 4,
647     },
648 };
649 
650 static uint64_t cpu_status_read(void *opaque, hwaddr addr, unsigned int size)
651 {
652     PIIX4PMState *s = opaque;
653     CPUStatus *cpus = &s->gpe_cpu;
654     uint64_t val = cpus->sts[addr];
655 
656     return val;
657 }
658 
659 static void cpu_status_write(void *opaque, hwaddr addr, uint64_t data,
660                              unsigned int size)
661 {
662     /* TODO: implement VCPU removal on guest signal that CPU can be removed */
663 }
664 
665 static const MemoryRegionOps cpu_hotplug_ops = {
666     .read = cpu_status_read,
667     .write = cpu_status_write,
668     .endianness = DEVICE_LITTLE_ENDIAN,
669     .valid = {
670         .min_access_size = 1,
671         .max_access_size = 1,
672     },
673 };
674 
675 typedef enum {
676     PLUG,
677     UNPLUG,
678 } HotplugEventType;
679 
680 static void piix4_cpu_hotplug_req(PIIX4PMState *s, CPUState *cpu,
681                                   HotplugEventType action)
682 {
683     CPUStatus *g = &s->gpe_cpu;
684     ACPIGPE *gpe = &s->ar.gpe;
685     CPUClass *k = CPU_GET_CLASS(cpu);
686     int64_t cpu_id;
687 
688     assert(s != NULL);
689 
690     *gpe->sts = *gpe->sts | PIIX4_CPU_HOTPLUG_STATUS;
691     cpu_id = k->get_arch_id(CPU(cpu));
692     if (action == PLUG) {
693         g->sts[cpu_id / 8] |= (1 << (cpu_id % 8));
694     } else {
695         g->sts[cpu_id / 8] &= ~(1 << (cpu_id % 8));
696     }
697     pm_update_sci(s);
698 }
699 
700 static void piix4_cpu_added_req(Notifier *n, void *opaque)
701 {
702     PIIX4PMState *s = container_of(n, PIIX4PMState, cpu_added_notifier);
703 
704     piix4_cpu_hotplug_req(s, CPU(opaque), PLUG);
705 }
706 
707 static int piix4_device_hotplug(DeviceState *qdev, PCIDevice *dev,
708                                 PCIHotplugState state);
709 
710 static void piix4_acpi_system_hot_add_init(MemoryRegion *parent,
711                                            PCIBus *bus, PIIX4PMState *s)
712 {
713     CPUState *cpu;
714 
715     memory_region_init_io(&s->io_gpe, OBJECT(s), &piix4_gpe_ops, s,
716                           "acpi-gpe0", GPE_LEN);
717     memory_region_add_subregion(parent, GPE_BASE, &s->io_gpe);
718 
719     memory_region_init_io(&s->io_pci, OBJECT(s), &piix4_pci_ops, s,
720                           "acpi-pci-hotplug", PCI_HOTPLUG_SIZE);
721     memory_region_add_subregion(parent, PCI_HOTPLUG_ADDR,
722                                 &s->io_pci);
723     pci_bus_hotplug(bus, piix4_device_hotplug, DEVICE(s));
724 
725     CPU_FOREACH(cpu) {
726         CPUClass *cc = CPU_GET_CLASS(cpu);
727         int64_t id = cc->get_arch_id(cpu);
728 
729         g_assert((id / 8) < PIIX4_PROC_LEN);
730         s->gpe_cpu.sts[id / 8] |= (1 << (id % 8));
731     }
732     memory_region_init_io(&s->io_cpu, OBJECT(s), &cpu_hotplug_ops, s,
733                           "acpi-cpu-hotplug", PIIX4_PROC_LEN);
734     memory_region_add_subregion(parent, PIIX4_PROC_BASE, &s->io_cpu);
735     s->cpu_added_notifier.notify = piix4_cpu_added_req;
736     qemu_register_cpu_added_notifier(&s->cpu_added_notifier);
737 }
738 
739 static void enable_device(PIIX4PMState *s, int slot)
740 {
741     s->ar.gpe.sts[0] |= PIIX4_PCI_HOTPLUG_STATUS;
742     s->pci0_slot_device_present |= (1U << slot);
743 }
744 
745 static void disable_device(PIIX4PMState *s, int slot)
746 {
747     s->ar.gpe.sts[0] |= PIIX4_PCI_HOTPLUG_STATUS;
748     s->pci0_status.down |= (1U << slot);
749 }
750 
751 static int piix4_device_hotplug(DeviceState *qdev, PCIDevice *dev,
752 				PCIHotplugState state)
753 {
754     int slot = PCI_SLOT(dev->devfn);
755     PIIX4PMState *s = PIIX4_PM(qdev);
756 
757     /* Don't send event when device is enabled during qemu machine creation:
758      * it is present on boot, no hotplug event is necessary. We do send an
759      * event when the device is disabled later. */
760     if (state == PCI_COLDPLUG_ENABLED) {
761         s->pci0_slot_device_present |= (1U << slot);
762         return 0;
763     }
764 
765     if (state == PCI_HOTPLUG_ENABLED) {
766         enable_device(s, slot);
767     } else {
768         disable_device(s, slot);
769     }
770 
771     pm_update_sci(s);
772 
773     return 0;
774 }
775