qemu/hw/pci-host/piix.c

/*
 * QEMU i440FX/PIIX3 PCI Bridge Emulation
 *
 * Copyright (c) 2006 Fabrice Bellard
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "hw/hw.h"
#include "hw/i386/pc.h"
#include "hw/pci/pci.h"
#include "hw/pci/pci_host.h"
#include "hw/isa/isa.h"
#include "hw/sysbus.h"
#include "qemu/range.h"
#include "hw/xen/xen.h"
#include "hw/pci-host/pam.h"
#include "sysemu/sysemu.h"
#include "hw/i386/ioapic.h"
#include "qapi/visitor.h"
#include "qemu/error-report.h"

/*
 * I440FX chipset data sheet.
 * http://download.intel.com/design/chipsets/datashts/29054901.pdf
 */

#define I440FX_PCI_HOST_BRIDGE(obj) \
    OBJECT_CHECK(I440FXState, (obj), TYPE_I440FX_PCI_HOST_BRIDGE)

typedef struct I440FXState {
    PCIHostState parent_obj;
    PcPciInfo pci_info;
    uint64_t pci_hole64_size;
    uint32_t short_root_bus;
} I440FXState;

#define PIIX_NUM_PIC_IRQS       16      /* i8259 * 2 */
#define PIIX_NUM_PIRQS          4ULL    /* PIRQ[A-D] */
#define XEN_PIIX_NUM_PIRQS      128ULL
#define PIIX_PIRQC              0x60

/*
 * Reset Control Register: PCI-accessible ISA-Compatible Register at address
 * 0xcf9, provided by the PCI/ISA bridge (PIIX3 PCI function 0, 8086:7000).
 */
#define RCR_IOPORT 0xcf9

typedef struct PIIX3State {
    PCIDevice dev;

    /*
     * bitmap to track pic levels.
     * The pic level is the logical OR of all the PCI irqs mapped to it
     * So one PIC level is tracked by PIIX_NUM_PIRQS bits.
     *
     * PIRQ is mapped to PIC pins, we track it by
     * PIIX_NUM_PIRQS * PIIX_NUM_PIC_IRQS = 64 bits with
     * pic_irq * PIIX_NUM_PIRQS + pirq
     */
#if PIIX_NUM_PIC_IRQS * PIIX_NUM_PIRQS > 64
#error "unable to encode pic state in 64bit in pic_levels."
#endif
    uint64_t pic_levels;

    qemu_irq *pic;

    /* This member isn't used. Just for save/load compatibility */
    int32_t pci_irq_levels_vmstate[PIIX_NUM_PIRQS];

    /* Reset Control Register contents */
    uint8_t rcr;

    /* IO memory region for Reset Control Register (RCR_IOPORT) */
    MemoryRegion rcr_mem;
} PIIX3State;

#define TYPE_PIIX3_PCI_DEVICE "pci-piix3"
#define PIIX3_PCI_DEVICE(obj) \
    OBJECT_CHECK(PIIX3State, (obj), TYPE_PIIX3_PCI_DEVICE)

#define I440FX_PCI_DEVICE(obj) \
    OBJECT_CHECK(PCII440FXState, (obj), TYPE_I440FX_PCI_DEVICE)

struct PCII440FXState {
    /*< private >*/
    PCIDevice parent_obj;
    /*< public >*/

    MemoryRegion *system_memory;
    MemoryRegion *pci_address_space;
    MemoryRegion *ram_memory;
    PAMMemoryRegion pam_regions[13];
    MemoryRegion smram_region;
    MemoryRegion smram, low_smram;
};


#define I440FX_PAM      0x59
#define I440FX_PAM_SIZE 7
#define I440FX_SMRAM    0x72

/* Older coreboot versions (4.0 and older) read a config register that doesn't
 * exist in real hardware, to get the RAM size from QEMU.
 */
#define I440FX_COREBOOT_RAM_SIZE 0x57

static void piix3_set_irq(void *opaque, int pirq, int level);
static PCIINTxRoute piix3_route_intx_pin_to_irq(void *opaque, int pci_intx);
static void piix3_write_config_xen(PCIDevice *dev,
                               uint32_t address, uint32_t val, int len);

/* return the global irq number corresponding to a given device irq
   pin. We could also use the bus number to have a more precise
   mapping. */
static int pci_slot_get_pirq(PCIDevice *pci_dev, int pci_intx)
{
    int slot_addend;
    slot_addend = (pci_dev->devfn >> 3) - 1;
    return (pci_intx + slot_addend) & 3;
}

static void i440fx_update_memory_mappings(PCII440FXState *d)
{
    int i;
    PCIDevice *pd = PCI_DEVICE(d);

    memory_region_transaction_begin();
    for (i = 0; i < 13; i++) {
        pam_update(&d->pam_regions[i], i,
                   pd->config[I440FX_PAM + ((i + 1) / 2)]);
    }
    memory_region_set_enabled(&d->smram_region,
                              !(pd->config[I440FX_SMRAM] & SMRAM_D_OPEN));
    memory_region_set_enabled(&d->smram,
                              pd->config[I440FX_SMRAM] & SMRAM_G_SMRAME);
    memory_region_transaction_commit();
}


static void i440fx_write_config(PCIDevice *dev,
                                uint32_t address, uint32_t val, int len)
{
    PCII440FXState *d = I440FX_PCI_DEVICE(dev);

    /* XXX: implement SMRAM.D_LOCK */
    pci_default_write_config(dev, address, val, len);
    if (ranges_overlap(address, len, I440FX_PAM, I440FX_PAM_SIZE) ||
        range_covers_byte(address, len, I440FX_SMRAM)) {
        i440fx_update_memory_mappings(d);
    }
}

static int i440fx_load_old(QEMUFile* f, void *opaque, int version_id)
{
    PCII440FXState *d = opaque;
    PCIDevice *pd = PCI_DEVICE(d);
    int ret, i;
    uint8_t smm_enabled;

    ret = pci_device_load(pd, f);
    if (ret < 0)
        return ret;
    i440fx_update_memory_mappings(d);
    qemu_get_8s(f, &smm_enabled);

    if (version_id == 2) {
        for (i = 0; i < PIIX_NUM_PIRQS; i++) {
            qemu_get_be32(f); /* dummy load for compatibility */
        }
    }

    return 0;
}

static int i440fx_post_load(void *opaque, int version_id)
{
    PCII440FXState *d = opaque;

    i440fx_update_memory_mappings(d);
    return 0;
}

static const VMStateDescription vmstate_i440fx = {
    .name = "I440FX",
    .version_id = 3,
    .minimum_version_id = 3,
    .minimum_version_id_old = 1,
    .load_state_old = i440fx_load_old,
    .post_load = i440fx_post_load,
    .fields = (VMStateField[]) {
        VMSTATE_PCI_DEVICE(parent_obj, PCII440FXState),
        /* Used to be smm_enabled, which was basically always zero because
         * SeaBIOS hardly uses SMM.  SMRAM is now handled by CPU code.
         */
        VMSTATE_UNUSED(1),
        VMSTATE_END_OF_LIST()
    }
};

static void i440fx_pcihost_get_pci_hole_start(Object *obj, Visitor *v,
                                              void *opaque, const char *name,
                                              Error **errp)
{
    I440FXState *s = I440FX_PCI_HOST_BRIDGE(obj);
    uint32_t value = s->pci_info.w32.begin;

    visit_type_uint32(v, &value, name, errp);
}

static void i440fx_pcihost_get_pci_hole_end(Object *obj, Visitor *v,
                                            void *opaque, const char *name,
                                            Error **errp)
{
    I440FXState *s = I440FX_PCI_HOST_BRIDGE(obj);
    uint32_t value = s->pci_info.w32.end;

    visit_type_uint32(v, &value, name, errp);
}

static void i440fx_pcihost_get_pci_hole64_start(Object *obj, Visitor *v,
                                                void *opaque, const char *name,
                                                Error **errp)
{
    PCIHostState *h = PCI_HOST_BRIDGE(obj);
    Range w64;

    pci_bus_get_w64_range(h->bus, &w64);

    visit_type_uint64(v, &w64.begin, name, errp);
}

static void i440fx_pcihost_get_pci_hole64_end(Object *obj, Visitor *v,
                                              void *opaque, const char *name,
                                              Error **errp)
{
    PCIHostState *h = PCI_HOST_BRIDGE(obj);
    Range w64;

    pci_bus_get_w64_range(h->bus, &w64);

    visit_type_uint64(v, &w64.end, name, errp);
}

static void i440fx_pcihost_initfn(Object *obj)
{
    PCIHostState *s = PCI_HOST_BRIDGE(obj);
    I440FXState *d = I440FX_PCI_HOST_BRIDGE(obj);

    memory_region_init_io(&s->conf_mem, obj, &pci_host_conf_le_ops, s,
                          "pci-conf-idx", 4);
    memory_region_init_io(&s->data_mem, obj, &pci_host_data_le_ops, s,
                          "pci-conf-data", 4);

    object_property_add(obj, PCI_HOST_PROP_PCI_HOLE_START, "int",
                        i440fx_pcihost_get_pci_hole_start,
                        NULL, NULL, NULL, NULL);

    object_property_add(obj, PCI_HOST_PROP_PCI_HOLE_END, "int",
                        i440fx_pcihost_get_pci_hole_end,
                        NULL, NULL, NULL, NULL);

    object_property_add(obj, PCI_HOST_PROP_PCI_HOLE64_START, "int",
                        i440fx_pcihost_get_pci_hole64_start,
                        NULL, NULL, NULL, NULL);

    object_property_add(obj, PCI_HOST_PROP_PCI_HOLE64_END, "int",
                        i440fx_pcihost_get_pci_hole64_end,
                        NULL, NULL, NULL, NULL);

    d->pci_info.w32.end = IO_APIC_DEFAULT_ADDRESS;
}

static void i440fx_pcihost_realize(DeviceState *dev, Error **errp)
{
    PCIHostState *s = PCI_HOST_BRIDGE(dev);
    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);

    sysbus_add_io(sbd, 0xcf8, &s->conf_mem);
    sysbus_init_ioports(sbd, 0xcf8, 4);

    sysbus_add_io(sbd, 0xcfc, &s->data_mem);
    sysbus_init_ioports(sbd, 0xcfc, 4);
}

static void i440fx_realize(PCIDevice *dev, Error **errp)
{
    dev->config[I440FX_SMRAM] = 0x02;

    if (object_property_get_bool(qdev_get_machine(), "iommu", NULL)) {
        error_report("warning: i440fx doesn't support emulated iommu");
    }
}

PCIBus *i440fx_init(const char *host_type, const char *pci_type,
                    PCII440FXState **pi440fx_state,
                    int *piix3_devfn,
                    ISABus **isa_bus, qemu_irq *pic,
                    MemoryRegion *address_space_mem,
                    MemoryRegion *address_space_io,
                    ram_addr_t ram_size,
                    ram_addr_t below_4g_mem_size,
                    ram_addr_t above_4g_mem_size,
                    MemoryRegion *pci_address_space,
                    MemoryRegion *ram_memory)
{
    DeviceState *dev;
    PCIBus *b;
    PCIDevice *d;
    PCIHostState *s;
    PIIX3State *piix3;
    PCII440FXState *f;
    unsigned i;
    I440FXState *i440fx;

    dev = qdev_create(NULL, host_type);
    s = PCI_HOST_BRIDGE(dev);
    b = pci_bus_new(dev, NULL, pci_address_space,
                    address_space_io, 0, TYPE_PCI_BUS);
    s->bus = b;
    object_property_add_child(qdev_get_machine(), "i440fx", OBJECT(dev), NULL);
    qdev_init_nofail(dev);

    d = pci_create_simple(b, 0, pci_type);
    *pi440fx_state = I440FX_PCI_DEVICE(d);
    f = *pi440fx_state;
    f->system_memory = address_space_mem;
    f->pci_address_space = pci_address_space;
    f->ram_memory = ram_memory;

    i440fx = I440FX_PCI_HOST_BRIDGE(dev);
    i440fx->pci_info.w32.begin = below_4g_mem_size;

    /* setup pci memory mapping */
    pc_pci_as_mapping_init(OBJECT(f), f->system_memory,
                           f->pci_address_space);

    /* if *disabled* show SMRAM to all CPUs */
    memory_region_init_alias(&f->smram_region, OBJECT(d), "smram-region",
                             f->pci_address_space, 0xa0000, 0x20000);
    memory_region_add_subregion_overlap(f->system_memory, 0xa0000,
                                        &f->smram_region, 1);
    memory_region_set_enabled(&f->smram_region, true);

    /* smram, as seen by SMM CPUs */
    memory_region_init(&f->smram, OBJECT(d), "smram", 1ull << 32);
    memory_region_set_enabled(&f->smram, true);
    memory_region_init_alias(&f->low_smram, OBJECT(d), "smram-low",
                             f->ram_memory, 0xa0000, 0x20000);
    memory_region_set_enabled(&f->low_smram, true);
    memory_region_add_subregion(&f->smram, 0xa0000, &f->low_smram);
    object_property_add_const_link(qdev_get_machine(), "smram",
                                   OBJECT(&f->smram), &error_abort);

    init_pam(dev, f->ram_memory, f->system_memory, f->pci_address_space,
             &f->pam_regions[0], PAM_BIOS_BASE, PAM_BIOS_SIZE);
    for (i = 0; i < 12; ++i) {
        init_pam(dev, f->ram_memory, f->system_memory, f->pci_address_space,
                 &f->pam_regions[i+1], PAM_EXPAN_BASE + i * PAM_EXPAN_SIZE,
                 PAM_EXPAN_SIZE);
    }

    /* Xen supports additional interrupt routes from the PCI devices to
     * the IOAPIC: the four pins of each PCI device on the bus are also
     * connected to the IOAPIC directly.
     * These additional routes can be discovered through ACPI. */
    if (xen_enabled()) {
        PCIDevice *pci_dev = pci_create_simple_multifunction(b,
                             -1, true, "PIIX3-xen");
        piix3 = PIIX3_PCI_DEVICE(pci_dev);
        pci_bus_irqs(b, xen_piix3_set_irq, xen_pci_slot_get_pirq,
                piix3, XEN_PIIX_NUM_PIRQS);
    } else {
        PCIDevice *pci_dev = pci_create_simple_multifunction(b,
                             -1, true, "PIIX3");
        piix3 = PIIX3_PCI_DEVICE(pci_dev);
        pci_bus_irqs(b, piix3_set_irq, pci_slot_get_pirq, piix3,
                PIIX_NUM_PIRQS);
        pci_bus_set_route_irq_fn(b, piix3_route_intx_pin_to_irq);
    }
    piix3->pic = pic;
    *isa_bus = ISA_BUS(qdev_get_child_bus(DEVICE(piix3), "isa.0"));

    *piix3_devfn = piix3->dev.devfn;

    ram_size = ram_size / 8 / 1024 / 1024;
    if (ram_size > 255) {
        ram_size = 255;
    }
    d->config[I440FX_COREBOOT_RAM_SIZE] = ram_size;

    i440fx_update_memory_mappings(f);

    return b;
}

PCIBus *find_i440fx(void)
{
    PCIHostState *s = OBJECT_CHECK(PCIHostState,
                                   object_resolve_path("/machine/i440fx", NULL),
                                   TYPE_PCI_HOST_BRIDGE);
    return s ? s->bus : NULL;
}

/* PIIX3 PCI to ISA bridge */
static void piix3_set_irq_pic(PIIX3State *piix3, int pic_irq)
{
    qemu_set_irq(piix3->pic[pic_irq],
                 !!(piix3->pic_levels &
                    (((1ULL << PIIX_NUM_PIRQS) - 1) <<
                     (pic_irq * PIIX_NUM_PIRQS))));
}

static void piix3_set_irq_level_internal(PIIX3State *piix3, int pirq, int level)
{
    int pic_irq;
    uint64_t mask;

    pic_irq = piix3->dev.config[PIIX_PIRQC + pirq];
    if (pic_irq >= PIIX_NUM_PIC_IRQS) {
        return;
    }

    mask = 1ULL << ((pic_irq * PIIX_NUM_PIRQS) + pirq);
    piix3->pic_levels &= ~mask;
    piix3->pic_levels |= mask * !!level;
}

static void piix3_set_irq_level(PIIX3State *piix3, int pirq, int level)
{
    int pic_irq;

    pic_irq = piix3->dev.config[PIIX_PIRQC + pirq];
    if (pic_irq >= PIIX_NUM_PIC_IRQS) {
        return;
    }

    piix3_set_irq_level_internal(piix3, pirq, level);

    piix3_set_irq_pic(piix3, pic_irq);
}

static void piix3_set_irq(void *opaque, int pirq, int level)
{
    PIIX3State *piix3 = opaque;
    piix3_set_irq_level(piix3, pirq, level);
}

static PCIINTxRoute piix3_route_intx_pin_to_irq(void *opaque, int pin)
{
    PIIX3State *piix3 = opaque;
    int irq = piix3->dev.config[PIIX_PIRQC + pin];
    PCIINTxRoute route;

    if (irq < PIIX_NUM_PIC_IRQS) {
        route.mode = PCI_INTX_ENABLED;
        route.irq = irq;
    } else {
        route.mode = PCI_INTX_DISABLED;
        route.irq = -1;
    }
    return route;
}

/* irq routing is changed. so rebuild bitmap */
static void piix3_update_irq_levels(PIIX3State *piix3)
{
    int pirq;

    piix3->pic_levels = 0;
    for (pirq = 0; pirq < PIIX_NUM_PIRQS; pirq++) {
        piix3_set_irq_level(piix3, pirq,
                            pci_bus_get_irq_level(piix3->dev.bus, pirq));
    }
}

static void piix3_write_config(PCIDevice *dev,
                               uint32_t address, uint32_t val, int len)
{
    pci_default_write_config(dev, address, val, len);
    if (ranges_overlap(address, len, PIIX_PIRQC, 4)) {
        PIIX3State *piix3 = PIIX3_PCI_DEVICE(dev);
        int pic_irq;

        pci_bus_fire_intx_routing_notifier(piix3->dev.bus);
        piix3_update_irq_levels(piix3);
        for (pic_irq = 0; pic_irq < PIIX_NUM_PIC_IRQS; pic_irq++) {
            piix3_set_irq_pic(piix3, pic_irq);
        }
    }
}

static void piix3_write_config_xen(PCIDevice *dev,
                               uint32_t address, uint32_t val, int len)
{
    xen_piix_pci_write_config_client(address, val, len);
    piix3_write_config(dev, address, val, len);
}

static void piix3_reset(void *opaque)
{
    PIIX3State *d = opaque;
    uint8_t *pci_conf = d->dev.config;

    pci_conf[0x04] = 0x07; /* master, memory and I/O */
    pci_conf[0x05] = 0x00;
    pci_conf[0x06] = 0x00;
    pci_conf[0x07] = 0x02; /* PCI_status_devsel_medium */
    pci_conf[0x4c] = 0x4d;
    pci_conf[0x4e] = 0x03;
    pci_conf[0x4f] = 0x00;
    pci_conf[0x60] = 0x80;
    pci_conf[0x61] = 0x80;
    pci_conf[0x62] = 0x80;
    pci_conf[0x63] = 0x80;
    pci_conf[0x69] = 0x02;
    pci_conf[0x70] = 0x80;
    pci_conf[0x76] = 0x0c;
    pci_conf[0x77] = 0x0c;
    pci_conf[0x78] = 0x02;
    pci_conf[0x79] = 0x00;
    pci_conf[0x80] = 0x00;
    pci_conf[0x82] = 0x00;
    pci_conf[0xa0] = 0x08;
    pci_conf[0xa2] = 0x00;
    pci_conf[0xa3] = 0x00;
    pci_conf[0xa4] = 0x00;
    pci_conf[0xa5] = 0x00;
    pci_conf[0xa6] = 0x00;
    pci_conf[0xa7] = 0x00;
    pci_conf[0xa8] = 0x0f;
    pci_conf[0xaa] = 0x00;
    pci_conf[0xab] = 0x00;
    pci_conf[0xac] = 0x00;
    pci_conf[0xae] = 0x00;

    d->pic_levels = 0;
    d->rcr = 0;
}

static int piix3_post_load(void *opaque, int version_id)
{
    PIIX3State *piix3 = opaque;
    int pirq;

    /* Because the i8259 has not been deserialized yet, qemu_irq_raise
     * might bring the system to a different state than the saved one;
     * for example, the interrupt could be masked but the i8259 would
     * not know that yet and would trigger an interrupt in the CPU.
     *
     * Here, we update irq levels without raising the interrupt.
     * Interrupt state will be deserialized separately through the i8259.
     */
    piix3->pic_levels = 0;
    for (pirq = 0; pirq < PIIX_NUM_PIRQS; pirq++) {
        piix3_set_irq_level_internal(piix3, pirq,
                            pci_bus_get_irq_level(piix3->dev.bus, pirq));
    }
    return 0;
}

static void piix3_pre_save(void *opaque)
{
    int i;
    PIIX3State *piix3 = opaque;

    for (i = 0; i < ARRAY_SIZE(piix3->pci_irq_levels_vmstate); i++) {
        piix3->pci_irq_levels_vmstate[i] =
            pci_bus_get_irq_level(piix3->dev.bus, i);
    }
}

static bool piix3_rcr_needed(void *opaque)
{
    PIIX3State *piix3 = opaque;

    return (piix3->rcr != 0);
}

static const VMStateDescription vmstate_piix3_rcr = {
    .name = "PIIX3/rcr",
    .version_id = 1,
    .minimum_version_id = 1,
    .needed = piix3_rcr_needed,
    .fields = (VMStateField[]) {
        VMSTATE_UINT8(rcr, PIIX3State),
        VMSTATE_END_OF_LIST()
    }
};

static const VMStateDescription vmstate_piix3 = {
    .name = "PIIX3",
    .version_id = 3,
    .minimum_version_id = 2,
    .post_load = piix3_post_load,
    .pre_save = piix3_pre_save,
    .fields = (VMStateField[]) {
        VMSTATE_PCI_DEVICE(dev, PIIX3State),
        VMSTATE_INT32_ARRAY_V(pci_irq_levels_vmstate, PIIX3State,
                              PIIX_NUM_PIRQS, 3),
        VMSTATE_END_OF_LIST()
    },
    .subsections = (const VMStateDescription*[]) {
        &vmstate_piix3_rcr,
        NULL
    }
};


static void rcr_write(void *opaque, hwaddr addr, uint64_t val, unsigned len)
{
    PIIX3State *d = opaque;

    if (val & 4) {
        qemu_system_reset_request();
        return;
    }
    d->rcr = val & 2; /* keep System Reset type only */
}

static uint64_t rcr_read(void *opaque, hwaddr addr, unsigned len)
{
    PIIX3State *d = opaque;

    return d->rcr;
}

static const MemoryRegionOps rcr_ops = {
    .read = rcr_read,
    .write = rcr_write,
    .endianness = DEVICE_LITTLE_ENDIAN
};

static void piix3_realize(PCIDevice *dev, Error **errp)
{
    PIIX3State *d = PIIX3_PCI_DEVICE(dev);

    isa_bus_new(DEVICE(d), get_system_memory(),
                pci_address_space_io(dev));

    memory_region_init_io(&d->rcr_mem, OBJECT(dev), &rcr_ops, d,
                          "piix3-reset-control", 1);
    memory_region_add_subregion_overlap(pci_address_space_io(dev), RCR_IOPORT,
                                        &d->rcr_mem, 1);

    qemu_register_reset(piix3_reset, d);
}

static void pci_piix3_class_init(ObjectClass *klass, void *data)
{
    DeviceClass *dc = DEVICE_CLASS(klass);
    PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);

    dc->desc        = "ISA bridge";
    dc->vmsd        = &vmstate_piix3;
    dc->hotpluggable   = false;
    k->realize      = piix3_realize;
    k->vendor_id    = PCI_VENDOR_ID_INTEL;
    /* 82371SB PIIX3 PCI-to-ISA bridge (Step A1) */
    k->device_id    = PCI_DEVICE_ID_INTEL_82371SB_0;
    k->class_id     = PCI_CLASS_BRIDGE_ISA;
    /*
     * Reason: part of PIIX3 southbridge, needs to be wired up by
     * pc_piix.c's pc_init1()
     */
    dc->cannot_instantiate_with_device_add_yet = true;
}

static const TypeInfo piix3_pci_type_info = {
    .name = TYPE_PIIX3_PCI_DEVICE,
    .parent = TYPE_PCI_DEVICE,
    .instance_size = sizeof(PIIX3State),
    .abstract = true,
    .class_init = pci_piix3_class_init,
};

static void piix3_class_init(ObjectClass *klass, void *data)
{
    PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);

    k->config_write = piix3_write_config;
}

static const TypeInfo piix3_info = {
    .name          = "PIIX3",
    .parent        = TYPE_PIIX3_PCI_DEVICE,
    .class_init    = piix3_class_init,
};

static void piix3_xen_class_init(ObjectClass *klass, void *data)
{
    PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);

    k->config_write = piix3_write_config_xen;
};

static const TypeInfo piix3_xen_info = {
    .name          = "PIIX3-xen",
    .parent        = TYPE_PIIX3_PCI_DEVICE,
    .class_init    = piix3_xen_class_init,
};

static void i440fx_class_init(ObjectClass *klass, void *data)
{
    DeviceClass *dc = DEVICE_CLASS(klass);
    PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);

    k->realize = i440fx_realize;
    k->config_write = i440fx_write_config;
    k->vendor_id = PCI_VENDOR_ID_INTEL;
    k->device_id = PCI_DEVICE_ID_INTEL_82441;
    k->revision = 0x02;
    k->class_id = PCI_CLASS_BRIDGE_HOST;
    dc->desc = "Host bridge";
    dc->vmsd = &vmstate_i440fx;
    /*
     * PCI-facing part of the host bridge, not usable without the
     * host-facing part, which can't be device_add'ed, yet.
     */
    dc->cannot_instantiate_with_device_add_yet = true;
    dc->hotpluggable   = false;
}

static const TypeInfo i440fx_info = {
    .name          = TYPE_I440FX_PCI_DEVICE,
    .parent        = TYPE_PCI_DEVICE,
    .instance_size = sizeof(PCII440FXState),
    .class_init    = i440fx_class_init,
};

/* IGD Passthrough Host Bridge. */
typedef struct {
    uint8_t offset;
    uint8_t len;
} IGDHostInfo;

/* Here we just expose minimal host bridge offset subset. */
static const IGDHostInfo igd_host_bridge_infos[] = {
    {0x08, 2},  /* revision id */
    {0x2c, 2},  /* sybsystem vendor id */
    {0x2e, 2},  /* sybsystem id */
    {0x50, 2},  /* SNB: processor graphics control register */
    {0x52, 2},  /* processor graphics control register */
    {0xa4, 4},  /* SNB: graphics base of stolen memory */
    {0xa8, 4},  /* SNB: base of GTT stolen memory */
};

static int host_pci_config_read(int pos, int len, uint32_t val)
{
    char path[PATH_MAX];
    int config_fd;
    ssize_t size = sizeof(path);
    /* Access real host bridge. */
    int rc = snprintf(path, size, "/sys/bus/pci/devices/%04x:%02x:%02x.%d/%s",
                      0, 0, 0, 0, "config");
    int ret = 0;

    if (rc >= size || rc < 0) {
        return -ENODEV;
    }

    config_fd = open(path, O_RDWR);
    if (config_fd < 0) {
        return -ENODEV;
    }

    if (lseek(config_fd, pos, SEEK_SET) != pos) {
        ret = -errno;
        goto out;
    }
    do {
        rc = read(config_fd, (uint8_t *)&val, len);
    } while (rc < 0 && (errno == EINTR || errno == EAGAIN));
    if (rc != len) {
        ret = -errno;
    }
out:
    close(config_fd);
    return ret;
}

static int igd_pt_i440fx_initfn(struct PCIDevice *pci_dev)
{
    uint32_t val = 0;
    int rc, i, num;
    int pos, len;

    num = ARRAY_SIZE(igd_host_bridge_infos);
    for (i = 0; i < num; i++) {
        pos = igd_host_bridge_infos[i].offset;
        len = igd_host_bridge_infos[i].len;
        rc = host_pci_config_read(pos, len, val);
        if (rc) {
            return -ENODEV;
        }
        pci_default_write_config(pci_dev, pos, val, len);
    }

    return 0;
}

static void igd_passthrough_i440fx_class_init(ObjectClass *klass, void *data)
{
    DeviceClass *dc = DEVICE_CLASS(klass);
    PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);

    k->init = igd_pt_i440fx_initfn;
    dc->desc = "IGD Passthrough Host bridge";
}

static const TypeInfo igd_passthrough_i440fx_info = {
    .name          = TYPE_IGD_PASSTHROUGH_I440FX_PCI_DEVICE,
    .parent        = TYPE_I440FX_PCI_DEVICE,
    .instance_size = sizeof(PCII440FXState),
    .class_init    = igd_passthrough_i440fx_class_init,
};

static const char *i440fx_pcihost_root_bus_path(PCIHostState *host_bridge,
                                                PCIBus *rootbus)
{
    I440FXState *s = I440FX_PCI_HOST_BRIDGE(host_bridge);

    /* For backwards compat with old device paths */
    if (s->short_root_bus) {
        return "0000";
    }
    return "0000:00";
}

static Property i440fx_props[] = {
    DEFINE_PROP_SIZE(PCI_HOST_PROP_PCI_HOLE64_SIZE, I440FXState,
                     pci_hole64_size, DEFAULT_PCI_HOLE64_SIZE),
    DEFINE_PROP_UINT32("short_root_bus", I440FXState, short_root_bus, 0),
    DEFINE_PROP_END_OF_LIST(),
};

static void i440fx_pcihost_class_init(ObjectClass *klass, void *data)
{
    DeviceClass *dc = DEVICE_CLASS(klass);
    PCIHostBridgeClass *hc = PCI_HOST_BRIDGE_CLASS(klass);

    hc->root_bus_path = i440fx_pcihost_root_bus_path;
    dc->realize = i440fx_pcihost_realize;
    dc->fw_name = "pci";
    dc->props = i440fx_props;
}

static const TypeInfo i440fx_pcihost_info = {
    .name          = TYPE_I440FX_PCI_HOST_BRIDGE,
    .parent        = TYPE_PCI_HOST_BRIDGE,
    .instance_size = sizeof(I440FXState),
    .instance_init = i440fx_pcihost_initfn,
    .class_init    = i440fx_pcihost_class_init,
};

static void i440fx_register_types(void)
{
    type_register_static(&i440fx_info);
    type_register_static(&igd_passthrough_i440fx_info);
    type_register_static(&piix3_pci_type_info);
    type_register_static(&piix3_info);
    type_register_static(&piix3_xen_info);
    type_register_static(&i440fx_pcihost_info);
}

type_init(i440fx_register_types)