hw/acpi/pcihp.c - third_party/qemu - Git at Google

 /*
  * QEMU<->ACPI BIOS PCI hotplug interface
  *
  * QEMU supports PCI hotplug via ACPI. This module
  * implements the interface between QEMU and the ACPI BIOS.
  * Interface specification - see docs/specs/acpi_pci_hotplug.txt
  *
  * Copyright (c) 2013, Red Hat Inc, Michael S. Tsirkin (mst@redhat.com)
  * Copyright (c) 2006 Fabrice Bellard
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License version 2.1 as published by the Free Software Foundation.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with this library; if not, see <http://www.gnu.org/licenses/>
  *
  * Contributions after 2012-01-13 are licensed under the terms of the
  * GNU GPL, version 2 or (at your option) any later version.
  */

 #include "qemu/osdep.h"
 #include "hw/acpi/pcihp.h"

 #include "hw/pci-host/i440fx.h"
 #include "hw/pci/pci.h"
 #include "hw/pci/pci_bridge.h"
 #include "hw/pci/pci_host.h"
 #include "hw/pci/pcie_port.h"
 #include "hw/pci-bridge/xio3130_downstream.h"
 #include "hw/i386/acpi-build.h"
 #include "hw/acpi/acpi.h"
 #include "hw/pci/pci_bus.h"
 #include "migration/vmstate.h"
 #include "qapi/error.h"
 #include "qom/qom-qobject.h"
 #include "trace.h"

 #define ACPI_PCIHP_SIZE 0x0018
 #define PCI_UP_BASE 0x0000
 #define PCI_DOWN_BASE 0x0004
 #define PCI_EJ_BASE 0x0008
 #define PCI_RMV_BASE 0x000c
 #define PCI_SEL_BASE 0x0010
 #define PCI_AIDX_BASE 0x0014

 typedef struct AcpiPciHpFind {
     int bsel;
     PCIBus *bus;
 } AcpiPciHpFind;

 static gint g_cmp_uint32(gconstpointer a, gconstpointer b, gpointer user_data)
 {
     return a - b;
 }

 static GSequence *pci_acpi_index_list(void)
 {
     static GSequence *used_acpi_index_list;

     if (!used_acpi_index_list) {
         used_acpi_index_list = g_sequence_new(NULL);
     }
     return used_acpi_index_list;
 }

 static int acpi_pcihp_get_bsel(PCIBus *bus)
 {
     Error *local_err = NULL;
     uint64_t bsel = object_property_get_uint(OBJECT(bus), ACPI_PCIHP_PROP_BSEL,
                                              &local_err);

     if (local_err || bsel >= ACPI_PCIHP_MAX_HOTPLUG_BUS) {
         if (local_err) {
             error_free(local_err);
         }
         return -1;
     } else {
         return bsel;
     }
 }

 /* Assign BSEL property to all buses.  In the future, this can be changed
  * to only assign to buses that support hotplug.
  */
 static void *acpi_set_bsel(PCIBus *bus, void *opaque)
 {
     unsigned *bsel_alloc = opaque;
     unsigned *bus_bsel;

     if (qbus_is_hotpluggable(BUS(bus))) {
         bus_bsel = g_malloc(sizeof *bus_bsel);

         *bus_bsel = (*bsel_alloc)++;
         object_property_add_uint32_ptr(OBJECT(bus), ACPI_PCIHP_PROP_BSEL,
                                        bus_bsel, OBJ_PROP_FLAG_READ);
     }

     return bsel_alloc;
 }

 static void acpi_set_pci_info(void)
 {
     static bool bsel_is_set;
     Object *host = acpi_get_i386_pci_host();
     PCIBus *bus;
     unsigned bsel_alloc = ACPI_PCIHP_BSEL_DEFAULT;

     if (bsel_is_set) {
         return;
     }
     bsel_is_set = true;

     if (!host) {
         return;
     }

     bus = PCI_HOST_BRIDGE(host)->bus;
     if (bus) {
         /* Scan all PCI buses. Set property to enable acpi based hotplug. */
         pci_for_each_bus_depth_first(bus, acpi_set_bsel, NULL, &bsel_alloc);
     }
 }

 static void acpi_pcihp_disable_root_bus(void)
 {
     Object *host = acpi_get_i386_pci_host();
     PCIBus *bus;

     bus = PCI_HOST_BRIDGE(host)->bus;
     if (bus && qbus_is_hotpluggable(BUS(bus))) {
         /* setting the hotplug handler to NULL makes the bus non-hotpluggable */
         qbus_set_hotplug_handler(BUS(bus), NULL);
     }

     return;
 }

 static void acpi_pcihp_test_hotplug_bus(PCIBus *bus, void *opaque)
 {
     AcpiPciHpFind *find = opaque;
     if (find->bsel == acpi_pcihp_get_bsel(bus)) {
         find->bus = bus;
     }
 }

 static PCIBus *acpi_pcihp_find_hotplug_bus(AcpiPciHpState *s, int bsel)
 {
     AcpiPciHpFind find = { .bsel = bsel, .bus = NULL };

     if (bsel < 0) {
         return NULL;
     }

     pci_for_each_bus(s->root, acpi_pcihp_test_hotplug_bus, &find);

     /* Make bsel 0 eject root bus if bsel property is not set,
      * for compatibility with non acpi setups.
      * TODO: really needed?
      */
     if (!bsel && !find.bus) {
         find.bus = s->root;
     }

     /*
      * Check if find.bus is actually hotpluggable. If bsel is set to
      * NULL for example on the root bus in order to make it
      * non-hotpluggable, find.bus will match the root bus when bsel
      * is 0. See acpi_pcihp_test_hotplug_bus() above. Since the
      * bus is not hotpluggable however, we should not select the bus.
      * Instead, we should set find.bus to NULL in that case. In the check
      * below, we generalize this case for all buses, not just the root bus.
      * The callers of this function check for a null return value and
      * handle them appropriately.
      */
     if (find.bus && !qbus_is_hotpluggable(BUS(find.bus))) {
         find.bus = NULL;
     }
     return find.bus;
 }

 static bool acpi_pcihp_pc_no_hotplug(AcpiPciHpState *s, PCIDevice *dev)
 {
     PCIDeviceClass *pc = PCI_DEVICE_GET_CLASS(dev);
     DeviceClass *dc = DEVICE_GET_CLASS(dev);
     /*
      * ACPI doesn't allow hotplug of bridge devices.  Don't allow
      * hot-unplug of bridge devices unless they were added by hotplug
      * (and so, not described by acpi).
      */
     return (pc->is_bridge && !dev->qdev.hotplugged) || !dc->hotpluggable;
 }

 static void acpi_pcihp_eject_slot(AcpiPciHpState *s, unsigned bsel, unsigned slots)
 {
     HotplugHandler *hotplug_ctrl;
     BusChild *kid, *next;
     int slot = ctz32(slots);
     PCIBus *bus = acpi_pcihp_find_hotplug_bus(s, bsel);

     trace_acpi_pci_eject_slot(bsel, slot);

     if (!bus || slot > 31) {
         return;
     }

     /* Mark request as complete */
     s->acpi_pcihp_pci_status[bsel].down &= ~(1U << slot);
     s->acpi_pcihp_pci_status[bsel].up &= ~(1U << slot);

     QTAILQ_FOREACH_SAFE(kid, &bus->qbus.children, sibling, next) {
         DeviceState *qdev = kid->child;
         PCIDevice *dev = PCI_DEVICE(qdev);
         if (PCI_SLOT(dev->devfn) == slot) {
             if (!acpi_pcihp_pc_no_hotplug(s, dev)) {
                 /*
                  * partially_hotplugged is used by virtio-net failover:
                  * failover has asked the guest OS to unplug the device
                  * but we need to keep some references to the device
                  * to be able to plug it back in case of failure so
                  * we don't execute hotplug_handler_unplug().
                  */
                 if (dev->partially_hotplugged) {
                     /*
                      * pending_deleted_event is set to true when
                      * virtio-net failover asks to unplug the device,
                      * and set to false here when the operation is done
                      * This is used by the migration loop to detect the
                      * end of the operation and really start the migration.
                      */
                     qdev->pending_deleted_event = false;
                 } else {
                     hotplug_ctrl = qdev_get_hotplug_handler(qdev);
                     hotplug_handler_unplug(hotplug_ctrl, qdev, &error_abort);
                     object_unparent(OBJECT(qdev));
                 }
             }
         }
     }
 }

 static void acpi_pcihp_update_hotplug_bus(AcpiPciHpState *s, int bsel)
 {
     BusChild *kid, *next;
     PCIBus *bus = acpi_pcihp_find_hotplug_bus(s, bsel);

     /* Execute any pending removes during reset */
     while (s->acpi_pcihp_pci_status[bsel].down) {
         acpi_pcihp_eject_slot(s, bsel, s->acpi_pcihp_pci_status[bsel].down);
     }

     s->acpi_pcihp_pci_status[bsel].hotplug_enable = ~0;

     if (!bus) {
         return;
     }
     QTAILQ_FOREACH_SAFE(kid, &bus->qbus.children, sibling, next) {
         DeviceState *qdev = kid->child;
         PCIDevice *pdev = PCI_DEVICE(qdev);
         int slot = PCI_SLOT(pdev->devfn);

         if (acpi_pcihp_pc_no_hotplug(s, pdev)) {
             s->acpi_pcihp_pci_status[bsel].hotplug_enable &= ~(1U << slot);
         }
     }
 }

 static void acpi_pcihp_update(AcpiPciHpState *s)
 {
     int i;

     for (i = 0; i < ACPI_PCIHP_MAX_HOTPLUG_BUS; ++i) {
         acpi_pcihp_update_hotplug_bus(s, i);
     }
 }

 void acpi_pcihp_reset(AcpiPciHpState *s, bool acpihp_root_off)
 {
     if (acpihp_root_off) {
         acpi_pcihp_disable_root_bus();
     }
     acpi_set_pci_info();
     acpi_pcihp_update(s);
 }

 #define ONBOARD_INDEX_MAX (16 * 1024 - 1)

 void acpi_pcihp_device_pre_plug_cb(HotplugHandler *hotplug_dev,
                                    DeviceState *dev, Error **errp)
 {
     PCIDevice *pdev = PCI_DEVICE(dev);

     /* Only hotplugged devices need the hotplug capability. */
     if (dev->hotplugged &&
         acpi_pcihp_get_bsel(pci_get_bus(pdev)) < 0) {
         error_setg(errp, "Unsupported bus. Bus doesn't have property '"
                    ACPI_PCIHP_PROP_BSEL "' set");
         return;
     }

     /*
      * capped by systemd (see: udev-builtin-net_id.c)
      * as it's the only known user honor it to avoid users
      * misconfigure QEMU and then wonder why acpi-index doesn't work
      */
     if (pdev->acpi_index > ONBOARD_INDEX_MAX) {
         error_setg(errp, "acpi-index should be less or equal to %u",
                    ONBOARD_INDEX_MAX);
         return;
     }

     /*
      * make sure that acpi-index is unique across all present PCI devices
      */
     if (pdev->acpi_index) {
         GSequence *used_indexes = pci_acpi_index_list();

         if (g_sequence_lookup(used_indexes, GINT_TO_POINTER(pdev->acpi_index),
                               g_cmp_uint32, NULL)) {
             error_setg(errp, "a PCI device with acpi-index = %" PRIu32
                        " already exist", pdev->acpi_index);
             return;
         }
         g_sequence_insert_sorted(used_indexes,
                                  GINT_TO_POINTER(pdev->acpi_index),
                                  g_cmp_uint32, NULL);
     }
 }

 void acpi_pcihp_device_plug_cb(HotplugHandler *hotplug_dev, AcpiPciHpState *s,
                                DeviceState *dev, Error **errp)
 {
     PCIDevice *pdev = PCI_DEVICE(dev);
     int slot = PCI_SLOT(pdev->devfn);
     PCIDevice *bridge;
     PCIBus *bus;
     int bsel;

     /* Don't send event when device is enabled during qemu machine creation:
      * it is present on boot, no hotplug event is necessary. We do send an
      * event when the device is disabled later. */
     if (!dev->hotplugged) {
         /*
          * Overwrite the default hotplug handler with the ACPI PCI one
          * for cold plugged bridges only.
          */
         if (!s->legacy_piix &&
             object_dynamic_cast(OBJECT(dev), TYPE_PCI_BRIDGE)) {
             PCIBus *sec = pci_bridge_get_sec_bus(PCI_BRIDGE(pdev));

             /* Remove all hot-plug handlers if hot-plug is disabled on slot */
             if (object_dynamic_cast(OBJECT(dev), TYPE_PCIE_SLOT) &&
                 !PCIE_SLOT(pdev)->hotplug) {
                 qbus_set_hotplug_handler(BUS(sec), NULL);
                 return;
             }

             qbus_set_hotplug_handler(BUS(sec), OBJECT(hotplug_dev));
             /* We don't have to overwrite any other hotplug handler yet */
             assert(QLIST_EMPTY(&sec->child));
         }

         return;
     }

     bus = pci_get_bus(pdev);
     bridge = pci_bridge_get_device(bus);
     if (object_dynamic_cast(OBJECT(bridge), TYPE_PCIE_ROOT_PORT) ||
         object_dynamic_cast(OBJECT(bridge), TYPE_XIO3130_DOWNSTREAM)) {
         pcie_cap_slot_enable_power(bridge);
     }

     bsel = acpi_pcihp_get_bsel(bus);
     g_assert(bsel >= 0);
     s->acpi_pcihp_pci_status[bsel].up |= (1U << slot);
     acpi_send_event(DEVICE(hotplug_dev), ACPI_PCI_HOTPLUG_STATUS);
 }

 void acpi_pcihp_device_unplug_cb(HotplugHandler *hotplug_dev, AcpiPciHpState *s,
                                  DeviceState *dev, Error **errp)
 {
     PCIDevice *pdev = PCI_DEVICE(dev);

     trace_acpi_pci_unplug(PCI_SLOT(pdev->devfn),
                           acpi_pcihp_get_bsel(pci_get_bus(pdev)));

     /*
      * clean up acpi-index so it could reused by another device
      */
     if (pdev->acpi_index) {
         GSequence *used_indexes = pci_acpi_index_list();

         g_sequence_remove(g_sequence_lookup(used_indexes,
                           GINT_TO_POINTER(pdev->acpi_index),
                           g_cmp_uint32, NULL));
     }

     qdev_unrealize(dev);
 }

 void acpi_pcihp_device_unplug_request_cb(HotplugHandler *hotplug_dev,
                                          AcpiPciHpState *s, DeviceState *dev,
                                          Error **errp)
 {
     PCIDevice *pdev = PCI_DEVICE(dev);
     int slot = PCI_SLOT(pdev->devfn);
     int bsel = acpi_pcihp_get_bsel(pci_get_bus(pdev));

     trace_acpi_pci_unplug_request(bsel, slot);

     if (bsel < 0) {
         error_setg(errp, "Unsupported bus. Bus doesn't have property '"
                    ACPI_PCIHP_PROP_BSEL "' set");
         return;
     }

     /*
      * pending_deleted_event is used by virtio-net failover to detect the
      * end of the unplug operation, the flag is set to false in
      * acpi_pcihp_eject_slot() when the operation is completed.
      */
     pdev->qdev.pending_deleted_event = true;
     s->acpi_pcihp_pci_status[bsel].down |= (1U << slot);
     acpi_send_event(DEVICE(hotplug_dev), ACPI_PCI_HOTPLUG_STATUS);
 }

 static uint64_t pci_read(void *opaque, hwaddr addr, unsigned int size)
 {
     AcpiPciHpState *s = opaque;
     uint32_t val = 0;
     int bsel = s->hotplug_select;

     if (bsel < 0 || bsel >= ACPI_PCIHP_MAX_HOTPLUG_BUS) {
         return 0;
     }

     switch (addr) {
     case PCI_UP_BASE:
         val = s->acpi_pcihp_pci_status[bsel].up;
         if (!s->legacy_piix) {
             s->acpi_pcihp_pci_status[bsel].up = 0;
         }
         trace_acpi_pci_up_read(val);
         break;
     case PCI_DOWN_BASE:
         val = s->acpi_pcihp_pci_status[bsel].down;
         trace_acpi_pci_down_read(val);
         break;
     case PCI_EJ_BASE:
         trace_acpi_pci_features_read(val);
         break;
     case PCI_RMV_BASE:
         val = s->acpi_pcihp_pci_status[bsel].hotplug_enable;
         trace_acpi_pci_rmv_read(val);
         break;
     case PCI_SEL_BASE:
         val = s->hotplug_select;
         trace_acpi_pci_sel_read(val);
         break;
     case PCI_AIDX_BASE:
         val = s->acpi_index;
         s->acpi_index = 0;
         trace_acpi_pci_acpi_index_read(val);
         break;
     default:
         break;
     }

     return val;
 }

 static void pci_write(void *opaque, hwaddr addr, uint64_t data,
                       unsigned int size)
 {
     int slot;
     PCIBus *bus;
     BusChild *kid, *next;
     AcpiPciHpState *s = opaque;

     s->acpi_index = 0;
     switch (addr) {
     case PCI_AIDX_BASE:
         /*
          * fetch acpi-index for specified slot so that follow up read from
          * PCI_AIDX_BASE can return it to guest
          */
         slot = ctz32(data);

         if (s->hotplug_select >= ACPI_PCIHP_MAX_HOTPLUG_BUS) {
             break;
         }

         bus = acpi_pcihp_find_hotplug_bus(s, s->hotplug_select);
         if (!bus) {
             break;
         }
         QTAILQ_FOREACH_SAFE(kid, &bus->qbus.children, sibling, next) {
             Object *o = OBJECT(kid->child);
             PCIDevice *dev = PCI_DEVICE(o);
             if (PCI_SLOT(dev->devfn) == slot) {
                 s->acpi_index = object_property_get_uint(o, "acpi-index", NULL);
                 break;
             }
         }
         trace_acpi_pci_acpi_index_write(s->hotplug_select, slot, s->acpi_index);
         break;
     case PCI_EJ_BASE:
         if (s->hotplug_select >= ACPI_PCIHP_MAX_HOTPLUG_BUS) {
             break;
         }
         acpi_pcihp_eject_slot(s, s->hotplug_select, data);
         trace_acpi_pci_ej_write(addr, data);
         break;
     case PCI_SEL_BASE:
         s->hotplug_select = s->legacy_piix ? ACPI_PCIHP_BSEL_DEFAULT : data;
         trace_acpi_pci_sel_write(addr, data);
     default:
         break;
     }
 }

 static const MemoryRegionOps acpi_pcihp_io_ops = {
     .read = pci_read,
     .write = pci_write,
     .endianness = DEVICE_LITTLE_ENDIAN,
     .valid = {
         .min_access_size = 4,
         .max_access_size = 4,
     },
 };

 void acpi_pcihp_init(Object *owner, AcpiPciHpState *s, PCIBus *root_bus,
                      MemoryRegion *address_space_io, bool bridges_enabled,
                      uint16_t io_base)
 {
     s->io_len = ACPI_PCIHP_SIZE;
     s->io_base = io_base;

     s->root = root_bus;
     s->legacy_piix = !bridges_enabled;

     memory_region_init_io(&s->io, owner, &acpi_pcihp_io_ops, s,
                           "acpi-pci-hotplug", s->io_len);
     memory_region_add_subregion(address_space_io, s->io_base, &s->io);

     object_property_add_uint16_ptr(owner, ACPI_PCIHP_IO_BASE_PROP, &s->io_base,
                                    OBJ_PROP_FLAG_READ);
     object_property_add_uint16_ptr(owner, ACPI_PCIHP_IO_LEN_PROP, &s->io_len,
                                    OBJ_PROP_FLAG_READ);
 }

 bool vmstate_acpi_pcihp_use_acpi_index(void *opaque, int version_id)
 {
      AcpiPciHpState *s = opaque;
      return s->acpi_index;
 }

 const VMStateDescription vmstate_acpi_pcihp_pci_status = {
     .name = "acpi_pcihp_pci_status",
     .version_id = 1,
     .minimum_version_id = 1,
     .fields = (VMStateField[]) {
         VMSTATE_UINT32(up, AcpiPciHpPciStatus),
         VMSTATE_UINT32(down, AcpiPciHpPciStatus),
         VMSTATE_END_OF_LIST()
     }
 };
	/*
	* QEMU<->ACPI BIOS PCI hotplug interface
	*
	* QEMU supports PCI hotplug via ACPI. This module
	* implements the interface between QEMU and the ACPI BIOS.
	* Interface specification - see docs/specs/acpi_pci_hotplug.txt
	*
	* Copyright (c) 2013, Red Hat Inc, Michael S. Tsirkin (mst@redhat.com)
	* Copyright (c) 2006 Fabrice Bellard
	*
	* This library is free software; you can redistribute it and/or
	* modify it under the terms of the GNU Lesser General Public
	* License version 2.1 as published by the Free Software Foundation.
	*
	* This library is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* Lesser General Public License for more details.
	*
	* You should have received a copy of the GNU Lesser General Public
	* License along with this library; if not, see <http://www.gnu.org/licenses/>
	*
	* Contributions after 2012-01-13 are licensed under the terms of the
	* GNU GPL, version 2 or (at your option) any later version.
	*/

	#include "qemu/osdep.h"
	#include "hw/acpi/pcihp.h"

	#include "hw/pci-host/i440fx.h"
	#include "hw/pci/pci.h"
	#include "hw/pci/pci_bridge.h"
	#include "hw/pci/pci_host.h"
	#include "hw/pci/pcie_port.h"
	#include "hw/pci-bridge/xio3130_downstream.h"
	#include "hw/i386/acpi-build.h"
	#include "hw/acpi/acpi.h"
	#include "hw/pci/pci_bus.h"
	#include "migration/vmstate.h"
	#include "qapi/error.h"
	#include "qom/qom-qobject.h"
	#include "trace.h"

	#define ACPI_PCIHP_SIZE 0x0018
	#define PCI_UP_BASE 0x0000
	#define PCI_DOWN_BASE 0x0004
	#define PCI_EJ_BASE 0x0008
	#define PCI_RMV_BASE 0x000c
	#define PCI_SEL_BASE 0x0010
	#define PCI_AIDX_BASE 0x0014

	typedef struct AcpiPciHpFind {
	int bsel;
	PCIBus *bus;
	} AcpiPciHpFind;

	static gint g_cmp_uint32(gconstpointer a, gconstpointer b, gpointer user_data)
	{
	return a - b;
	}

	static GSequence *pci_acpi_index_list(void)
	{
	static GSequence *used_acpi_index_list;

	if (!used_acpi_index_list) {
	used_acpi_index_list = g_sequence_new(NULL);
	}
	return used_acpi_index_list;
	}

	static int acpi_pcihp_get_bsel(PCIBus *bus)
	{
	Error *local_err = NULL;
	uint64_t bsel = object_property_get_uint(OBJECT(bus), ACPI_PCIHP_PROP_BSEL,
	&local_err);

	if (local_err \|\| bsel >= ACPI_PCIHP_MAX_HOTPLUG_BUS) {
	if (local_err) {
	error_free(local_err);
	}
	return -1;
	} else {
	return bsel;
	}
	}

	/* Assign BSEL property to all buses. In the future, this can be changed
	* to only assign to buses that support hotplug.
	*/
	static void acpi_set_bsel(PCIBus bus, void *opaque)
	{
	unsigned *bsel_alloc = opaque;
	unsigned *bus_bsel;

	if (qbus_is_hotpluggable(BUS(bus))) {
	bus_bsel = g_malloc(sizeof *bus_bsel);

	bus_bsel = (bsel_alloc)++;
	object_property_add_uint32_ptr(OBJECT(bus), ACPI_PCIHP_PROP_BSEL,
	bus_bsel, OBJ_PROP_FLAG_READ);
	}

	return bsel_alloc;
	}

	static void acpi_set_pci_info(void)
	{
	static bool bsel_is_set;
	Object *host = acpi_get_i386_pci_host();
	PCIBus *bus;
	unsigned bsel_alloc = ACPI_PCIHP_BSEL_DEFAULT;

	if (bsel_is_set) {
	return;
	}
	bsel_is_set = true;

	if (!host) {
	return;
	}

	bus = PCI_HOST_BRIDGE(host)->bus;
	if (bus) {
	/* Scan all PCI buses. Set property to enable acpi based hotplug. */
	pci_for_each_bus_depth_first(bus, acpi_set_bsel, NULL, &bsel_alloc);
	}
	}

	static void acpi_pcihp_disable_root_bus(void)
	{
	Object *host = acpi_get_i386_pci_host();
	PCIBus *bus;

	bus = PCI_HOST_BRIDGE(host)->bus;
	if (bus && qbus_is_hotpluggable(BUS(bus))) {
	/* setting the hotplug handler to NULL makes the bus non-hotpluggable */
	qbus_set_hotplug_handler(BUS(bus), NULL);
	}

	return;
	}

	static void acpi_pcihp_test_hotplug_bus(PCIBus bus, void opaque)
	{
	AcpiPciHpFind *find = opaque;
	if (find->bsel == acpi_pcihp_get_bsel(bus)) {
	find->bus = bus;
	}
	}

	static PCIBus acpi_pcihp_find_hotplug_bus(AcpiPciHpState s, int bsel)
	{
	AcpiPciHpFind find = { .bsel = bsel, .bus = NULL };

	if (bsel < 0) {
	return NULL;
	}

	pci_for_each_bus(s->root, acpi_pcihp_test_hotplug_bus, &find);

	/* Make bsel 0 eject root bus if bsel property is not set,
	* for compatibility with non acpi setups.
	* TODO: really needed?
	*/
	if (!bsel && !find.bus) {
	find.bus = s->root;
	}

	/*
	* Check if find.bus is actually hotpluggable. If bsel is set to
	* NULL for example on the root bus in order to make it
	* non-hotpluggable, find.bus will match the root bus when bsel
	* is 0. See acpi_pcihp_test_hotplug_bus() above. Since the
	* bus is not hotpluggable however, we should not select the bus.
	* Instead, we should set find.bus to NULL in that case. In the check
	* below, we generalize this case for all buses, not just the root bus.
	* The callers of this function check for a null return value and
	* handle them appropriately.
	*/
	if (find.bus && !qbus_is_hotpluggable(BUS(find.bus))) {
	find.bus = NULL;
	}
	return find.bus;
	}

	static bool acpi_pcihp_pc_no_hotplug(AcpiPciHpState s, PCIDevice dev)
	{
	PCIDeviceClass *pc = PCI_DEVICE_GET_CLASS(dev);
	DeviceClass *dc = DEVICE_GET_CLASS(dev);
	/*
	* ACPI doesn't allow hotplug of bridge devices. Don't allow
	* hot-unplug of bridge devices unless they were added by hotplug
	* (and so, not described by acpi).
	*/
	return (pc->is_bridge && !dev->qdev.hotplugged) \|\| !dc->hotpluggable;
	}

	static void acpi_pcihp_eject_slot(AcpiPciHpState *s, unsigned bsel, unsigned slots)
	{
	HotplugHandler *hotplug_ctrl;
	BusChild kid, next;
	int slot = ctz32(slots);
	PCIBus *bus = acpi_pcihp_find_hotplug_bus(s, bsel);

	trace_acpi_pci_eject_slot(bsel, slot);

	if (!bus \|\| slot > 31) {
	return;
	}

	/* Mark request as complete */
	s->acpi_pcihp_pci_status[bsel].down &= ~(1U << slot);
	s->acpi_pcihp_pci_status[bsel].up &= ~(1U << slot);

	QTAILQ_FOREACH_SAFE(kid, &bus->qbus.children, sibling, next) {
	DeviceState *qdev = kid->child;
	PCIDevice *dev = PCI_DEVICE(qdev);
	if (PCI_SLOT(dev->devfn) == slot) {
	if (!acpi_pcihp_pc_no_hotplug(s, dev)) {
	/*
	* partially_hotplugged is used by virtio-net failover:
	* failover has asked the guest OS to unplug the device
	* but we need to keep some references to the device
	* to be able to plug it back in case of failure so
	* we don't execute hotplug_handler_unplug().
	*/
	if (dev->partially_hotplugged) {
	/*
	* pending_deleted_event is set to true when
	* virtio-net failover asks to unplug the device,
	* and set to false here when the operation is done
	* This is used by the migration loop to detect the
	* end of the operation and really start the migration.
	*/
	qdev->pending_deleted_event = false;
	} else {
	hotplug_ctrl = qdev_get_hotplug_handler(qdev);
	hotplug_handler_unplug(hotplug_ctrl, qdev, &error_abort);
	object_unparent(OBJECT(qdev));
	}
	}
	}
	}
	}

	static void acpi_pcihp_update_hotplug_bus(AcpiPciHpState *s, int bsel)
	{
	BusChild kid, next;
	PCIBus *bus = acpi_pcihp_find_hotplug_bus(s, bsel);

	/* Execute any pending removes during reset */
	while (s->acpi_pcihp_pci_status[bsel].down) {
	acpi_pcihp_eject_slot(s, bsel, s->acpi_pcihp_pci_status[bsel].down);
	}

	s->acpi_pcihp_pci_status[bsel].hotplug_enable = ~0;

	if (!bus) {
	return;
	}
	QTAILQ_FOREACH_SAFE(kid, &bus->qbus.children, sibling, next) {
	DeviceState *qdev = kid->child;
	PCIDevice *pdev = PCI_DEVICE(qdev);
	int slot = PCI_SLOT(pdev->devfn);

	if (acpi_pcihp_pc_no_hotplug(s, pdev)) {
	s->acpi_pcihp_pci_status[bsel].hotplug_enable &= ~(1U << slot);
	}
	}
	}

	static void acpi_pcihp_update(AcpiPciHpState *s)
	{
	int i;

	for (i = 0; i < ACPI_PCIHP_MAX_HOTPLUG_BUS; ++i) {
	acpi_pcihp_update_hotplug_bus(s, i);
	}
	}

	void acpi_pcihp_reset(AcpiPciHpState *s, bool acpihp_root_off)
	{
	if (acpihp_root_off) {
	acpi_pcihp_disable_root_bus();
	}
	acpi_set_pci_info();
	acpi_pcihp_update(s);
	}

	#define ONBOARD_INDEX_MAX (16 * 1024 - 1)

	void acpi_pcihp_device_pre_plug_cb(HotplugHandler *hotplug_dev,
	DeviceState dev, Error *errp)
	{
	PCIDevice *pdev = PCI_DEVICE(dev);

	/* Only hotplugged devices need the hotplug capability. */
	if (dev->hotplugged &&
	acpi_pcihp_get_bsel(pci_get_bus(pdev)) < 0) {
	error_setg(errp, "Unsupported bus. Bus doesn't have property '"
	ACPI_PCIHP_PROP_BSEL "' set");
	return;
	}

	/*
	* capped by systemd (see: udev-builtin-net_id.c)
	* as it's the only known user honor it to avoid users
	* misconfigure QEMU and then wonder why acpi-index doesn't work
	*/
	if (pdev->acpi_index > ONBOARD_INDEX_MAX) {
	error_setg(errp, "acpi-index should be less or equal to %u",
	ONBOARD_INDEX_MAX);
	return;
	}

	/*
	* make sure that acpi-index is unique across all present PCI devices
	*/
	if (pdev->acpi_index) {
	GSequence *used_indexes = pci_acpi_index_list();

	if (g_sequence_lookup(used_indexes, GINT_TO_POINTER(pdev->acpi_index),
	g_cmp_uint32, NULL)) {
	error_setg(errp, "a PCI device with acpi-index = %" PRIu32
	" already exist", pdev->acpi_index);
	return;
	}
	g_sequence_insert_sorted(used_indexes,
	GINT_TO_POINTER(pdev->acpi_index),
	g_cmp_uint32, NULL);
	}
	}

	void acpi_pcihp_device_plug_cb(HotplugHandler hotplug_dev, AcpiPciHpState s,
	DeviceState dev, Error *errp)
	{
	PCIDevice *pdev = PCI_DEVICE(dev);
	int slot = PCI_SLOT(pdev->devfn);
	PCIDevice *bridge;
	PCIBus *bus;
	int bsel;

	/* Don't send event when device is enabled during qemu machine creation:
	* it is present on boot, no hotplug event is necessary. We do send an
	* event when the device is disabled later. */
	if (!dev->hotplugged) {
	/*
	* Overwrite the default hotplug handler with the ACPI PCI one
	* for cold plugged bridges only.
	*/
	if (!s->legacy_piix &&
	object_dynamic_cast(OBJECT(dev), TYPE_PCI_BRIDGE)) {
	PCIBus *sec = pci_bridge_get_sec_bus(PCI_BRIDGE(pdev));

	/* Remove all hot-plug handlers if hot-plug is disabled on slot */
	if (object_dynamic_cast(OBJECT(dev), TYPE_PCIE_SLOT) &&
	!PCIE_SLOT(pdev)->hotplug) {
	qbus_set_hotplug_handler(BUS(sec), NULL);
	return;
	}

	qbus_set_hotplug_handler(BUS(sec), OBJECT(hotplug_dev));
	/* We don't have to overwrite any other hotplug handler yet */
	assert(QLIST_EMPTY(&sec->child));
	}

	return;
	}

	bus = pci_get_bus(pdev);
	bridge = pci_bridge_get_device(bus);
	if (object_dynamic_cast(OBJECT(bridge), TYPE_PCIE_ROOT_PORT) \|\|
	object_dynamic_cast(OBJECT(bridge), TYPE_XIO3130_DOWNSTREAM)) {
	pcie_cap_slot_enable_power(bridge);
	}

	bsel = acpi_pcihp_get_bsel(bus);
	g_assert(bsel >= 0);
	s->acpi_pcihp_pci_status[bsel].up \|= (1U << slot);
	acpi_send_event(DEVICE(hotplug_dev), ACPI_PCI_HOTPLUG_STATUS);
	}

	void acpi_pcihp_device_unplug_cb(HotplugHandler hotplug_dev, AcpiPciHpState s,
	DeviceState dev, Error *errp)
	{
	PCIDevice *pdev = PCI_DEVICE(dev);

	trace_acpi_pci_unplug(PCI_SLOT(pdev->devfn),
	acpi_pcihp_get_bsel(pci_get_bus(pdev)));

	/*
	* clean up acpi-index so it could reused by another device
	*/
	if (pdev->acpi_index) {
	GSequence *used_indexes = pci_acpi_index_list();

	g_sequence_remove(g_sequence_lookup(used_indexes,
	GINT_TO_POINTER(pdev->acpi_index),
	g_cmp_uint32, NULL));
	}

	qdev_unrealize(dev);
	}

	void acpi_pcihp_device_unplug_request_cb(HotplugHandler *hotplug_dev,
	AcpiPciHpState s, DeviceState dev,
	Error **errp)
	{
	PCIDevice *pdev = PCI_DEVICE(dev);
	int slot = PCI_SLOT(pdev->devfn);
	int bsel = acpi_pcihp_get_bsel(pci_get_bus(pdev));

	trace_acpi_pci_unplug_request(bsel, slot);

	if (bsel < 0) {
	error_setg(errp, "Unsupported bus. Bus doesn't have property '"
	ACPI_PCIHP_PROP_BSEL "' set");
	return;
	}

	/*
	* pending_deleted_event is used by virtio-net failover to detect the
	* end of the unplug operation, the flag is set to false in
	* acpi_pcihp_eject_slot() when the operation is completed.
	*/
	pdev->qdev.pending_deleted_event = true;
	s->acpi_pcihp_pci_status[bsel].down \|= (1U << slot);
	acpi_send_event(DEVICE(hotplug_dev), ACPI_PCI_HOTPLUG_STATUS);
	}

	static uint64_t pci_read(void *opaque, hwaddr addr, unsigned int size)
	{
	AcpiPciHpState *s = opaque;
	uint32_t val = 0;
	int bsel = s->hotplug_select;

	if (bsel < 0 \|\| bsel >= ACPI_PCIHP_MAX_HOTPLUG_BUS) {
	return 0;
	}

	switch (addr) {
	case PCI_UP_BASE:
	val = s->acpi_pcihp_pci_status[bsel].up;
	if (!s->legacy_piix) {
	s->acpi_pcihp_pci_status[bsel].up = 0;
	}
	trace_acpi_pci_up_read(val);
	break;
	case PCI_DOWN_BASE:
	val = s->acpi_pcihp_pci_status[bsel].down;
	trace_acpi_pci_down_read(val);
	break;
	case PCI_EJ_BASE:
	trace_acpi_pci_features_read(val);
	break;
	case PCI_RMV_BASE:
	val = s->acpi_pcihp_pci_status[bsel].hotplug_enable;
	trace_acpi_pci_rmv_read(val);
	break;
	case PCI_SEL_BASE:
	val = s->hotplug_select;
	trace_acpi_pci_sel_read(val);
	break;
	case PCI_AIDX_BASE:
	val = s->acpi_index;
	s->acpi_index = 0;
	trace_acpi_pci_acpi_index_read(val);
	break;
	default:
	break;
	}

	return val;
	}

	static void pci_write(void *opaque, hwaddr addr, uint64_t data,
	unsigned int size)
	{
	int slot;
	PCIBus *bus;
	BusChild kid, next;
	AcpiPciHpState *s = opaque;

	s->acpi_index = 0;
	switch (addr) {
	case PCI_AIDX_BASE:
	/*
	* fetch acpi-index for specified slot so that follow up read from
	* PCI_AIDX_BASE can return it to guest
	*/
	slot = ctz32(data);

	if (s->hotplug_select >= ACPI_PCIHP_MAX_HOTPLUG_BUS) {
	break;
	}

	bus = acpi_pcihp_find_hotplug_bus(s, s->hotplug_select);
	if (!bus) {
	break;
	}
	QTAILQ_FOREACH_SAFE(kid, &bus->qbus.children, sibling, next) {
	Object *o = OBJECT(kid->child);
	PCIDevice *dev = PCI_DEVICE(o);
	if (PCI_SLOT(dev->devfn) == slot) {
	s->acpi_index = object_property_get_uint(o, "acpi-index", NULL);
	break;
	}
	}
	trace_acpi_pci_acpi_index_write(s->hotplug_select, slot, s->acpi_index);
	break;
	case PCI_EJ_BASE:
	if (s->hotplug_select >= ACPI_PCIHP_MAX_HOTPLUG_BUS) {
	break;
	}
	acpi_pcihp_eject_slot(s, s->hotplug_select, data);
	trace_acpi_pci_ej_write(addr, data);
	break;
	case PCI_SEL_BASE:
	s->hotplug_select = s->legacy_piix ? ACPI_PCIHP_BSEL_DEFAULT : data;
	trace_acpi_pci_sel_write(addr, data);
	default:
	break;
	}
	}

	static const MemoryRegionOps acpi_pcihp_io_ops = {
	.read = pci_read,
	.write = pci_write,
	.endianness = DEVICE_LITTLE_ENDIAN,
	.valid = {
	.min_access_size = 4,
	.max_access_size = 4,
	},
	};

	void acpi_pcihp_init(Object owner, AcpiPciHpState s, PCIBus *root_bus,
	MemoryRegion *address_space_io, bool bridges_enabled,
	uint16_t io_base)
	{
	s->io_len = ACPI_PCIHP_SIZE;
	s->io_base = io_base;

	s->root = root_bus;
	s->legacy_piix = !bridges_enabled;

	memory_region_init_io(&s->io, owner, &acpi_pcihp_io_ops, s,
	"acpi-pci-hotplug", s->io_len);
	memory_region_add_subregion(address_space_io, s->io_base, &s->io);

	object_property_add_uint16_ptr(owner, ACPI_PCIHP_IO_BASE_PROP, &s->io_base,
	OBJ_PROP_FLAG_READ);
	object_property_add_uint16_ptr(owner, ACPI_PCIHP_IO_LEN_PROP, &s->io_len,
	OBJ_PROP_FLAG_READ);
	}

	bool vmstate_acpi_pcihp_use_acpi_index(void *opaque, int version_id)
	{
	AcpiPciHpState *s = opaque;
	return s->acpi_index;
	}

	const VMStateDescription vmstate_acpi_pcihp_pci_status = {
	.name = "acpi_pcihp_pci_status",
	.version_id = 1,
	.minimum_version_id = 1,
	.fields = (VMStateField[]) {
	VMSTATE_UINT32(up, AcpiPciHpPciStatus),
	VMSTATE_UINT32(down, AcpiPciHpPciStatus),
	VMSTATE_END_OF_LIST()
	}
	};