diff --git a/hw/dec_pci.c b/hw/dec_pci.c
index a35f382..1aec066 100644
--- a/hw/dec_pci.c
+++ b/hw/dec_pci.c
@@ -80,16 +80,15 @@
 static int pci_dec_21154_init_device(SysBusDevice *dev)
 {
     DECState *s;
-    int pci_mem_config, pci_mem_data;
 
     s = FROM_SYSBUS(DECState, dev);
 
-    pci_mem_config = pci_host_conf_register_mmio(&s->host_state,
-                                                 DEVICE_LITTLE_ENDIAN);
-    pci_mem_data = pci_host_data_register_mmio(&s->host_state,
-                                               DEVICE_LITTLE_ENDIAN);
-    sysbus_init_mmio(dev, 0x1000, pci_mem_config);
-    sysbus_init_mmio(dev, 0x1000, pci_mem_data);
+    memory_region_init_io(&s->host_state.conf_mem, &pci_host_conf_le_ops,
+                          &s->host_state, "pci-conf-idx", 0x1000);
+    memory_region_init_io(&s->host_state.data_mem, &pci_host_data_le_ops,
+                          &s->host_state, "pci-data-idx", 0x1000);
+    sysbus_init_mmio_region(dev, &s->host_state.conf_mem);
+    sysbus_init_mmio_region(dev, &s->host_state.data_mem);
     return 0;
 }
 
diff --git a/hw/grackle_pci.c b/hw/grackle_pci.c
index 9a823e1..9d3ff7d 100644
--- a/hw/grackle_pci.c
+++ b/hw/grackle_pci.c
@@ -92,16 +92,15 @@
 static int pci_grackle_init_device(SysBusDevice *dev)
 {
     GrackleState *s;
-    int pci_mem_config, pci_mem_data;
 
     s = FROM_SYSBUS(GrackleState, dev);
 
-    pci_mem_config = pci_host_conf_register_mmio(&s->host_state,
-                                                 DEVICE_LITTLE_ENDIAN);
-    pci_mem_data = pci_host_data_register_mmio(&s->host_state,
-                                               DEVICE_LITTLE_ENDIAN);
-    sysbus_init_mmio(dev, 0x1000, pci_mem_config);
-    sysbus_init_mmio(dev, 0x1000, pci_mem_data);
+    memory_region_init_io(&s->host_state.conf_mem, &pci_host_conf_le_ops,
+                          &s->host_state, "pci-conf-idx", 0x1000);
+    memory_region_init_io(&s->host_state.data_mem, &pci_host_data_le_ops,
+                          &s->host_state, "pci-data-idx", 0x1000);
+    sysbus_init_mmio_region(dev, &s->host_state.conf_mem);
+    sysbus_init_mmio_region(dev, &s->host_state.data_mem);
 
     qemu_register_reset(pci_grackle_reset, &s->host_state);
     return 0;
diff --git a/hw/pci_host.c b/hw/pci_host.c
index 2e8a29f..44c6c20 100644
--- a/hw/pci_host.c
+++ b/hw/pci_host.c
@@ -94,82 +94,72 @@
     return val;
 }
 
-static void pci_host_config_write(ReadWriteHandler *handler,
-                                  pcibus_t addr, uint32_t val, int len)
+static void pci_host_config_write(void *opaque, target_phys_addr_t addr,
+                                  uint64_t val, unsigned len)
 {
-    PCIHostState *s = container_of(handler, PCIHostState, conf_handler);
+    PCIHostState *s = opaque;
 
-    PCI_DPRINTF("%s addr %" FMT_PCIBUS " %d val %"PRIx32"\n",
+    PCI_DPRINTF("%s addr " TARGET_FMT_plx " len %d val %"PRIx64"\n",
                 __func__, addr, len, val);
     s->config_reg = val;
 }
 
-static uint32_t pci_host_config_read(ReadWriteHandler *handler,
-                                     pcibus_t addr, int len)
+static uint64_t pci_host_config_read(void *opaque, target_phys_addr_t addr,
+                                     unsigned len)
 {
-    PCIHostState *s = container_of(handler, PCIHostState, conf_handler);
+    PCIHostState *s = opaque;
     uint32_t val = s->config_reg;
 
-    PCI_DPRINTF("%s addr %" FMT_PCIBUS " len %d val %"PRIx32"\n",
+    PCI_DPRINTF("%s addr " TARGET_FMT_plx " len %d val %"PRIx32"\n",
                 __func__, addr, len, val);
     return val;
 }
 
-static void pci_host_data_write(ReadWriteHandler *handler,
-                                pcibus_t addr, uint32_t val, int len)
+static void pci_host_data_write(void *opaque, target_phys_addr_t addr,
+                                uint64_t val, unsigned len)
 {
-    PCIHostState *s = container_of(handler, PCIHostState, data_handler);
-    PCI_DPRINTF("write addr %" FMT_PCIBUS " len %d val %x\n",
-                addr, len, val);
+    PCIHostState *s = opaque;
+    PCI_DPRINTF("write addr " TARGET_FMT_plx " len %d val %x\n",
+                addr, len, (unsigned)val);
     if (s->config_reg & (1u << 31))
         pci_data_write(s->bus, s->config_reg | (addr & 3), val, len);
 }
 
-static uint32_t pci_host_data_read(ReadWriteHandler *handler,
-                                   pcibus_t addr, int len)
+static uint64_t pci_host_data_read(void *opaque,
+                                   target_phys_addr_t addr, unsigned len)
 {
-    PCIHostState *s = container_of(handler, PCIHostState, data_handler);
+    PCIHostState *s = opaque;
     uint32_t val;
     if (!(s->config_reg & (1 << 31)))
         return 0xffffffff;
     val = pci_data_read(s->bus, s->config_reg | (addr & 3), len);
-    PCI_DPRINTF("read addr %" FMT_PCIBUS " len %d val %x\n",
+    PCI_DPRINTF("read addr " TARGET_FMT_plx " len %d val %x\n",
                 addr, len, val);
     return val;
 }
 
-static void pci_host_init(PCIHostState *s)
-{
-    s->conf_handler.write = pci_host_config_write;
-    s->conf_handler.read = pci_host_config_read;
-    s->data_handler.write = pci_host_data_write;
-    s->data_handler.read = pci_host_data_read;
-}
+const MemoryRegionOps pci_host_conf_le_ops = {
+    .read = pci_host_config_read,
+    .write = pci_host_config_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+};
 
-int pci_host_conf_register_mmio(PCIHostState *s, int endian)
-{
-    pci_host_init(s);
-    return cpu_register_io_memory_simple(&s->conf_handler, endian);
-}
+const MemoryRegionOps pci_host_conf_be_ops = {
+    .read = pci_host_config_read,
+    .write = pci_host_config_write,
+    .endianness = DEVICE_BIG_ENDIAN,
+};
 
-void pci_host_conf_register_ioport(pio_addr_t ioport, PCIHostState *s)
-{
-    pci_host_init(s);
-    register_ioport_simple(&s->conf_handler, ioport, 4, 4);
-    sysbus_init_ioports(&s->busdev, ioport, 4);
-}
+const MemoryRegionOps pci_host_data_le_ops = {
+    .read = pci_host_data_read,
+    .write = pci_host_data_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+};
 
-int pci_host_data_register_mmio(PCIHostState *s, int endian)
-{
-    pci_host_init(s);
-    return cpu_register_io_memory_simple(&s->data_handler, endian);
-}
+const MemoryRegionOps pci_host_data_be_ops = {
+    .read = pci_host_data_read,
+    .write = pci_host_data_write,
+    .endianness = DEVICE_BIG_ENDIAN,
+};
 
-void pci_host_data_register_ioport(pio_addr_t ioport, PCIHostState *s)
-{
-    pci_host_init(s);
-    register_ioport_simple(&s->data_handler, ioport, 4, 1);
-    register_ioport_simple(&s->data_handler, ioport, 4, 2);
-    register_ioport_simple(&s->data_handler, ioport, 4, 4);
-    sysbus_init_ioports(&s->busdev, ioport, 4);
-}
+
diff --git a/hw/pci_host.h b/hw/pci_host.h
index 7f55114..0211086 100644
--- a/hw/pci_host.h
+++ b/hw/pci_host.h
@@ -29,12 +29,11 @@
 #define PCI_HOST_H
 
 #include "sysbus.h"
-#include "rwhandler.h"
 
 struct PCIHostState {
     SysBusDevice busdev;
-    ReadWriteHandler conf_handler;
-    ReadWriteHandler data_handler;
+    MemoryRegion conf_mem;
+    MemoryRegion data_mem;
     MemoryRegion *address_space;
     uint32_t config_reg;
     PCIBus *bus;
@@ -49,12 +48,9 @@
 void pci_data_write(PCIBus *s, uint32_t addr, uint32_t val, int len);
 uint32_t pci_data_read(PCIBus *s, uint32_t addr, int len);
 
-/* for mmio */
-int pci_host_conf_register_mmio(PCIHostState *s, int endian);
-int pci_host_data_register_mmio(PCIHostState *s, int endian);
-
-/* for ioio */
-void pci_host_conf_register_ioport(pio_addr_t ioport, PCIHostState *s);
-void pci_host_data_register_ioport(pio_addr_t ioport, PCIHostState *s);
+extern const MemoryRegionOps pci_host_conf_le_ops;
+extern const MemoryRegionOps pci_host_conf_be_ops;
+extern const MemoryRegionOps pci_host_data_le_ops;
+extern const MemoryRegionOps pci_host_data_be_ops;
 
 #endif /* PCI_HOST_H */
diff --git a/hw/piix_pci.c b/hw/piix_pci.c
index c563c6e..f892994 100644
--- a/hw/piix_pci.c
+++ b/hw/piix_pci.c
@@ -235,9 +235,16 @@
 {
     I440FXState *s = FROM_SYSBUS(I440FXState, dev);
 
-    pci_host_conf_register_ioport(0xcf8, s);
+    memory_region_init_io(&s->conf_mem, &pci_host_conf_le_ops, s,
+                          "pci-conf-idx", 4);
+    sysbus_add_io(dev, 0xcf8, &s->conf_mem);
+    sysbus_init_ioports(&s->busdev, 0xcf8, 4);
 
-    pci_host_data_register_ioport(0xcfc, s);
+    memory_region_init_io(&s->data_mem, &pci_host_data_le_ops, s,
+                          "pci-conf-data", 4);
+    sysbus_add_io(dev, 0xcfc, &s->data_mem);
+    sysbus_init_ioports(&s->busdev, 0xcfc, 4);
+
     return 0;
 }
 
diff --git a/hw/ppc4xx_pci.c b/hw/ppc4xx_pci.c
index 52e2663..339b38e 100644
--- a/hw/ppc4xx_pci.c
+++ b/hw/ppc4xx_pci.c
@@ -368,10 +368,12 @@
     cpu_register_physical_memory(config_space + PCIC0_CFGADDR, 4, index);
 
     /* CFGDATA */
-    index = pci_host_data_register_mmio(&controller->pci_state, 1);
-    if (index < 0)
-        goto free;
-    cpu_register_physical_memory(config_space + PCIC0_CFGDATA, 4, index);
+    memory_region_init_io(&controller->pci_state.data_mem,
+                          &pci_host_data_be_ops,
+                          &controller->pci_state, "pci-conf-data", 4);
+    memory_region_add_subregion(get_system_memory(),
+                                config_space + PCIC0_CFGDATA,
+                                &controller->pci_state.data_mem);
 
     /* Internal registers */
     index = cpu_register_io_memory(pci_reg_read, pci_reg_write, controller,
diff --git a/hw/ppce500_pci.c b/hw/ppce500_pci.c
index 4390aeb..2db365d 100644
--- a/hw/ppce500_pci.c
+++ b/hw/ppce500_pci.c
@@ -79,8 +79,6 @@
     uint32_t gasket_time;
     qemu_irq irq[4];
     /* mmio maps */
-    int cfgaddr;
-    int cfgdata;
     int reg;
 };
 
@@ -268,18 +266,18 @@
     PCIHostState *h = FROM_SYSBUS(PCIHostState, sysbus_from_qdev(dev));
     PPCE500PCIState *s = DO_UPCAST(PPCE500PCIState, pci_state, h);
 
-    cpu_register_physical_memory(base + PCIE500_CFGADDR, 4, s->cfgaddr);
-    cpu_register_physical_memory(base + PCIE500_CFGDATA, 4, s->cfgdata);
+    sysbus_add_memory(dev, base + PCIE500_CFGADDR, &h->conf_mem);
+    sysbus_add_memory(dev, base + PCIE500_CFGDATA, &h->data_mem);
     cpu_register_physical_memory(base + PCIE500_REG_BASE, PCIE500_REG_SIZE,
                                  s->reg);
 }
 
 static void e500_pci_unmap(SysBusDevice *dev, target_phys_addr_t base)
 {
-    cpu_register_physical_memory(base + PCIE500_CFGADDR, 4,
-                                 IO_MEM_UNASSIGNED);
-    cpu_register_physical_memory(base + PCIE500_CFGDATA, 4,
-                                 IO_MEM_UNASSIGNED);
+    PCIHostState *h = FROM_SYSBUS(PCIHostState, sysbus_from_qdev(dev));
+
+    sysbus_del_memory(dev, &h->conf_mem);
+    sysbus_del_memory(dev, &h->data_mem);
     cpu_register_physical_memory(base + PCIE500_REG_BASE, PCIE500_REG_SIZE,
                                  IO_MEM_UNASSIGNED);
 }
@@ -309,9 +307,10 @@
 
     pci_create_simple(b, 0, "e500-host-bridge");
 
-    s->cfgaddr = pci_host_conf_register_mmio(&s->pci_state, DEVICE_BIG_ENDIAN);
-    s->cfgdata = pci_host_data_register_mmio(&s->pci_state,
-                                             DEVICE_LITTLE_ENDIAN);
+    memory_region_init_io(&h->conf_mem, &pci_host_conf_be_ops, h,
+                          "pci-conf-idx", 4);
+    memory_region_init_io(&h->data_mem, &pci_host_data_le_ops, h,
+                          "pci-conf-data", 4);
     s->reg = cpu_register_io_memory(e500_pci_reg_read, e500_pci_reg_write, s,
                                     DEVICE_BIG_ENDIAN);
     sysbus_init_mmio_cb2(dev, e500_pci_map, e500_pci_unmap);
diff --git a/hw/prep_pci.c b/hw/prep_pci.c
index c36232a..55e4e25 100644
--- a/hw/prep_pci.c
+++ b/hw/prep_pci.c
@@ -125,9 +125,15 @@
                               address_space_io,
                               0, 4);
 
-    pci_host_conf_register_ioport(0xcf8, s);
+    memory_region_init_io(&s->conf_mem, &pci_host_conf_be_ops, s,
+                          "pci-conf-idx", 1);
+    memory_region_add_subregion(address_space_io, 0xcf8, &s->conf_mem);
+    sysbus_init_ioports(&s->busdev, 0xcf8, 1);
 
-    pci_host_data_register_ioport(0xcfc, s);
+    memory_region_init_io(&s->conf_mem, &pci_host_data_be_ops, s,
+                          "pci-conf-data", 1);
+    memory_region_add_subregion(address_space_io, 0xcfc, &s->data_mem);
+    sysbus_init_ioports(&s->busdev, 0xcfc, 1);
 
     PPC_io_memory = cpu_register_io_memory(PPC_PCIIO_read,
                                            PPC_PCIIO_write, s,
diff --git a/hw/unin_pci.c b/hw/unin_pci.c
index f896f8c..600cd1e 100644
--- a/hw/unin_pci.c
+++ b/hw/unin_pci.c
@@ -41,7 +41,6 @@
 typedef struct UNINState {
     SysBusDevice busdev;
     PCIHostState host_state;
-    ReadWriteHandler data_handler;
 } UNINState;
 
 static int pci_unin_map_irq(PCIDevice *pci_dev, int irq_num)
@@ -100,67 +99,70 @@
     return retval;
 }
 
-static void unin_data_write(ReadWriteHandler *handler,
-                            pcibus_t addr, uint32_t val, int len)
+static void unin_data_write(void *opaque, target_phys_addr_t addr,
+                            uint64_t val, unsigned len)
 {
-    UNINState *s = container_of(handler, UNINState, data_handler);
-    UNIN_DPRINTF("write addr %" FMT_PCIBUS " len %d val %x\n", addr, len, val);
+    UNINState *s = opaque;
+    UNIN_DPRINTF("write addr %" TARGET_FMT_plx " len %d val %"PRIx64"\n",
+                 addr, len, val);
     pci_data_write(s->host_state.bus,
                    unin_get_config_reg(s->host_state.config_reg, addr),
                    val, len);
 }
 
-static uint32_t unin_data_read(ReadWriteHandler *handler,
-                               pcibus_t addr, int len)
+static uint64_t unin_data_read(void *opaque, target_phys_addr_t addr,
+                               unsigned len)
 {
-    UNINState *s = container_of(handler, UNINState, data_handler);
+    UNINState *s = opaque;
     uint32_t val;
 
     val = pci_data_read(s->host_state.bus,
                         unin_get_config_reg(s->host_state.config_reg, addr),
                         len);
-    UNIN_DPRINTF("read addr %" FMT_PCIBUS " len %d val %x\n", addr, len, val);
+    UNIN_DPRINTF("read addr %" TARGET_FMT_plx " len %d val %x\n",
+                 addr, len, val);
     return val;
 }
 
+static const MemoryRegionOps unin_data_ops = {
+    .read = unin_data_read,
+    .write = unin_data_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+};
+
 static int pci_unin_main_init_device(SysBusDevice *dev)
 {
     UNINState *s;
-    int pci_mem_config, pci_mem_data;
 
     /* Use values found on a real PowerMac */
     /* Uninorth main bus */
     s = FROM_SYSBUS(UNINState, dev);
 
-    pci_mem_config = pci_host_conf_register_mmio(&s->host_state,
-                                                 DEVICE_LITTLE_ENDIAN);
-    s->data_handler.read = unin_data_read;
-    s->data_handler.write = unin_data_write;
-    pci_mem_data = cpu_register_io_memory_simple(&s->data_handler,
-                                                 DEVICE_LITTLE_ENDIAN);
-    sysbus_init_mmio(dev, 0x1000, pci_mem_config);
-    sysbus_init_mmio(dev, 0x1000, pci_mem_data);
+    memory_region_init_io(&s->host_state.conf_mem, &pci_host_conf_le_ops,
+                          &s->host_state, "pci-conf-idx", 0x1000);
+    memory_region_init_io(&s->host_state.data_mem, &unin_data_ops, s,
+                          "pci-conf-data", 0x1000);
+    sysbus_init_mmio_region(dev, &s->host_state.conf_mem);
+    sysbus_init_mmio_region(dev, &s->host_state.data_mem);
 
     qemu_register_reset(pci_unin_reset, &s->host_state);
     return 0;
 }
 
+
 static int pci_u3_agp_init_device(SysBusDevice *dev)
 {
     UNINState *s;
-    int pci_mem_config, pci_mem_data;
 
     /* Uninorth U3 AGP bus */
     s = FROM_SYSBUS(UNINState, dev);
 
-    pci_mem_config = pci_host_conf_register_mmio(&s->host_state,
-                                                 DEVICE_LITTLE_ENDIAN);
-    s->data_handler.read = unin_data_read;
-    s->data_handler.write = unin_data_write;
-    pci_mem_data = cpu_register_io_memory_simple(&s->data_handler,
-                                                 DEVICE_LITTLE_ENDIAN);
-    sysbus_init_mmio(dev, 0x1000, pci_mem_config);
-    sysbus_init_mmio(dev, 0x1000, pci_mem_data);
+    memory_region_init_io(&s->host_state.conf_mem, &pci_host_conf_le_ops,
+                          &s->host_state, "pci-conf-idx", 0x1000);
+    memory_region_init_io(&s->host_state.data_mem, &unin_data_ops, s,
+                          "pci-conf-data", 0x1000);
+    sysbus_init_mmio_region(dev, &s->host_state.conf_mem);
+    sysbus_init_mmio_region(dev, &s->host_state.data_mem);
 
     qemu_register_reset(pci_unin_reset, &s->host_state);
 
@@ -170,34 +172,32 @@
 static int pci_unin_agp_init_device(SysBusDevice *dev)
 {
     UNINState *s;
-    int pci_mem_config, pci_mem_data;
 
     /* Uninorth AGP bus */
     s = FROM_SYSBUS(UNINState, dev);
 
-    pci_mem_config = pci_host_conf_register_mmio(&s->host_state,
-                                                 DEVICE_LITTLE_ENDIAN);
-    pci_mem_data = pci_host_data_register_mmio(&s->host_state,
-                                               DEVICE_LITTLE_ENDIAN);
-    sysbus_init_mmio(dev, 0x1000, pci_mem_config);
-    sysbus_init_mmio(dev, 0x1000, pci_mem_data);
+    memory_region_init_io(&s->host_state.conf_mem, &pci_host_conf_le_ops,
+                          &s->host_state, "pci-conf-idx", 0x1000);
+    memory_region_init_io(&s->host_state.data_mem, &pci_host_data_le_ops,
+                          &s->host_state, "pci-conf-data", 0x1000);
+    sysbus_init_mmio_region(dev, &s->host_state.conf_mem);
+    sysbus_init_mmio_region(dev, &s->host_state.data_mem);
     return 0;
 }
 
 static int pci_unin_internal_init_device(SysBusDevice *dev)
 {
     UNINState *s;
-    int pci_mem_config, pci_mem_data;
 
     /* Uninorth internal bus */
     s = FROM_SYSBUS(UNINState, dev);
 
-    pci_mem_config = pci_host_conf_register_mmio(&s->host_state,
-                                                 DEVICE_LITTLE_ENDIAN);
-    pci_mem_data = pci_host_data_register_mmio(&s->host_state,
-                                               DEVICE_LITTLE_ENDIAN);
-    sysbus_init_mmio(dev, 0x1000, pci_mem_config);
-    sysbus_init_mmio(dev, 0x1000, pci_mem_data);
+    memory_region_init_io(&s->host_state.conf_mem, &pci_host_conf_le_ops,
+                          &s->host_state, "pci-conf-idx", 0x1000);
+    memory_region_init_io(&s->host_state.data_mem, &pci_host_data_le_ops,
+                          &s->host_state, "pci-conf-data", 0x1000);
+    sysbus_init_mmio_region(dev, &s->host_state.conf_mem);
+    sysbus_init_mmio_region(dev, &s->host_state.data_mem);
     return 0;
 }