diff --git a/hw/lsi53c895a.c b/hw/lsi53c895a.c
index e9904c4..0ab8c78 100644
--- a/hw/lsi53c895a.c
+++ b/hw/lsi53c895a.c
@@ -185,9 +185,9 @@ typedef struct lsi_request {
 
 typedef struct {
     PCIDevice dev;
-    int mmio_io_addr;
-    int ram_io_addr;
-    uint32_t script_ram_base;
+    MemoryRegion mmio_io;
+    MemoryRegion ram_io;
+    MemoryRegion io_io;
 
     int carry; /* ??? Should this be an a visible register somewhere?  */
     int status;
@@ -391,10 +391,9 @@ static inline uint32_t read_dword(LSIState *s, uint32_t addr)
 {
     uint32_t buf;
 
-    /* Optimize reading from SCRIPTS RAM.  */
-    if ((addr & 0xffffe000) == s->script_ram_base) {
-        return s->script_ram[(addr & 0x1fff) >> 2];
-    }
+    /* XXX: an optimization here used to fast-path the read from scripts
+     * memory.  But that bypasses any iommu.
+     */
     cpu_physical_memory_read(addr, (uint8_t *)&buf, 4);
     return cpu_to_le32(buf);
 }
@@ -1899,232 +1898,90 @@ static void lsi_reg_writeb(LSIState *s, int offset, uint8_t val)
 #undef CASE_SET_REG32
 }
 
-static void lsi_mmio_writeb(void *opaque, target_phys_addr_t addr, uint32_t val)
+static void lsi_mmio_write(void *opaque, target_phys_addr_t addr,
+                           uint64_t val, unsigned size)
 {
     LSIState *s = opaque;
 
     lsi_reg_writeb(s, addr & 0xff, val);
 }
 
-static void lsi_mmio_writew(void *opaque, target_phys_addr_t addr, uint32_t val)
-{
-    LSIState *s = opaque;
-
-    addr &= 0xff;
-    lsi_reg_writeb(s, addr, val & 0xff);
-    lsi_reg_writeb(s, addr + 1, (val >> 8) & 0xff);
-}
-
-static void lsi_mmio_writel(void *opaque, target_phys_addr_t addr, uint32_t val)
-{
-    LSIState *s = opaque;
-
-    addr &= 0xff;
-    lsi_reg_writeb(s, addr, val & 0xff);
-    lsi_reg_writeb(s, addr + 1, (val >> 8) & 0xff);
-    lsi_reg_writeb(s, addr + 2, (val >> 16) & 0xff);
-    lsi_reg_writeb(s, addr + 3, (val >> 24) & 0xff);
-}
-
-static uint32_t lsi_mmio_readb(void *opaque, target_phys_addr_t addr)
+static uint64_t lsi_mmio_read(void *opaque, target_phys_addr_t addr,
+                              unsigned size)
 {
     LSIState *s = opaque;
 
     return lsi_reg_readb(s, addr & 0xff);
 }
 
-static uint32_t lsi_mmio_readw(void *opaque, target_phys_addr_t addr)
-{
-    LSIState *s = opaque;
-    uint32_t val;
-
-    addr &= 0xff;
-    val = lsi_reg_readb(s, addr);
-    val |= lsi_reg_readb(s, addr + 1) << 8;
-    return val;
-}
-
-static uint32_t lsi_mmio_readl(void *opaque, target_phys_addr_t addr)
-{
-    LSIState *s = opaque;
-    uint32_t val;
-    addr &= 0xff;
-    val = lsi_reg_readb(s, addr);
-    val |= lsi_reg_readb(s, addr + 1) << 8;
-    val |= lsi_reg_readb(s, addr + 2) << 16;
-    val |= lsi_reg_readb(s, addr + 3) << 24;
-    return val;
-}
-
-static CPUReadMemoryFunc * const lsi_mmio_readfn[3] = {
-    lsi_mmio_readb,
-    lsi_mmio_readw,
-    lsi_mmio_readl,
-};
-
-static CPUWriteMemoryFunc * const lsi_mmio_writefn[3] = {
-    lsi_mmio_writeb,
-    lsi_mmio_writew,
-    lsi_mmio_writel,
+static const MemoryRegionOps lsi_mmio_ops = {
+    .read = lsi_mmio_read,
+    .write = lsi_mmio_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .impl = {
+        .min_access_size = 1,
+        .max_access_size = 1,
+    },
 };
 
-static void lsi_ram_writeb(void *opaque, target_phys_addr_t addr, uint32_t val)
+static void lsi_ram_write(void *opaque, target_phys_addr_t addr,
+                          uint64_t val, unsigned size)
 {
     LSIState *s = opaque;
     uint32_t newval;
+    uint32_t mask;
     int shift;
 
-    addr &= 0x1fff;
     newval = s->script_ram[addr >> 2];
     shift = (addr & 3) * 8;
-    newval &= ~(0xff << shift);
+    mask = ((uint64_t)1 << (size * 8)) - 1;
+    newval &= ~(mask << shift);
     newval |= val << shift;
     s->script_ram[addr >> 2] = newval;
 }
 
-static void lsi_ram_writew(void *opaque, target_phys_addr_t addr, uint32_t val)
-{
-    LSIState *s = opaque;
-    uint32_t newval;
-
-    addr &= 0x1fff;
-    newval = s->script_ram[addr >> 2];
-    if (addr & 2) {
-        newval = (newval & 0xffff) | (val << 16);
-    } else {
-        newval = (newval & 0xffff0000) | val;
-    }
-    s->script_ram[addr >> 2] = newval;
-}
-
-
-static void lsi_ram_writel(void *opaque, target_phys_addr_t addr, uint32_t val)
-{
-    LSIState *s = opaque;
-
-    addr &= 0x1fff;
-    s->script_ram[addr >> 2] = val;
-}
-
-static uint32_t lsi_ram_readb(void *opaque, target_phys_addr_t addr)
+static uint64_t lsi_ram_read(void *opaque, target_phys_addr_t addr,
+                             unsigned size)
 {
     LSIState *s = opaque;
     uint32_t val;
+    uint32_t mask;
 
-    addr &= 0x1fff;
     val = s->script_ram[addr >> 2];
+    mask = ((uint64_t)1 << (size * 8)) - 1;
     val >>= (addr & 3) * 8;
-    return val & 0xff;
-}
-
-static uint32_t lsi_ram_readw(void *opaque, target_phys_addr_t addr)
-{
-    LSIState *s = opaque;
-    uint32_t val;
-
-    addr &= 0x1fff;
-    val = s->script_ram[addr >> 2];
-    if (addr & 2)
-        val >>= 16;
-    return val;
-}
-
-static uint32_t lsi_ram_readl(void *opaque, target_phys_addr_t addr)
-{
-    LSIState *s = opaque;
-
-    addr &= 0x1fff;
-    return s->script_ram[addr >> 2];
+    return val & mask;
 }
 
-static CPUReadMemoryFunc * const lsi_ram_readfn[3] = {
-    lsi_ram_readb,
-    lsi_ram_readw,
-    lsi_ram_readl,
+static const MemoryRegionOps lsi_ram_ops = {
+    .read = lsi_ram_read,
+    .write = lsi_ram_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
 };
 
-static CPUWriteMemoryFunc * const lsi_ram_writefn[3] = {
-    lsi_ram_writeb,
-    lsi_ram_writew,
-    lsi_ram_writel,
-};
-
-static uint32_t lsi_io_readb(void *opaque, uint32_t addr)
+static uint64_t lsi_io_read(void *opaque, target_phys_addr_t addr,
+                            unsigned size)
 {
     LSIState *s = opaque;
     return lsi_reg_readb(s, addr & 0xff);
 }
 
-static uint32_t lsi_io_readw(void *opaque, uint32_t addr)
-{
-    LSIState *s = opaque;
-    uint32_t val;
-    addr &= 0xff;
-    val = lsi_reg_readb(s, addr);
-    val |= lsi_reg_readb(s, addr + 1) << 8;
-    return val;
-}
-
-static uint32_t lsi_io_readl(void *opaque, uint32_t addr)
-{
-    LSIState *s = opaque;
-    uint32_t val;
-    addr &= 0xff;
-    val = lsi_reg_readb(s, addr);
-    val |= lsi_reg_readb(s, addr + 1) << 8;
-    val |= lsi_reg_readb(s, addr + 2) << 16;
-    val |= lsi_reg_readb(s, addr + 3) << 24;
-    return val;
-}
-
-static void lsi_io_writeb(void *opaque, uint32_t addr, uint32_t val)
+static void lsi_io_write(void *opaque, target_phys_addr_t addr,
+                         uint64_t val, unsigned size)
 {
     LSIState *s = opaque;
     lsi_reg_writeb(s, addr & 0xff, val);
 }
 
-static void lsi_io_writew(void *opaque, uint32_t addr, uint32_t val)
-{
-    LSIState *s = opaque;
-    addr &= 0xff;
-    lsi_reg_writeb(s, addr, val & 0xff);
-    lsi_reg_writeb(s, addr + 1, (val >> 8) & 0xff);
-}
-
-static void lsi_io_writel(void *opaque, uint32_t addr, uint32_t val)
-{
-    LSIState *s = opaque;
-    addr &= 0xff;
-    lsi_reg_writeb(s, addr, val & 0xff);
-    lsi_reg_writeb(s, addr + 1, (val >> 8) & 0xff);
-    lsi_reg_writeb(s, addr + 2, (val >> 16) & 0xff);
-    lsi_reg_writeb(s, addr + 3, (val >> 24) & 0xff);
-}
-
-static void lsi_io_mapfunc(PCIDevice *pci_dev, int region_num,
-                           pcibus_t addr, pcibus_t size, int type)
-{
-    LSIState *s = DO_UPCAST(LSIState, dev, pci_dev);
-
-    DPRINTF("Mapping IO at %08"FMT_PCIBUS"\n", addr);
-
-    register_ioport_write(addr, 256, 1, lsi_io_writeb, s);
-    register_ioport_read(addr, 256, 1, lsi_io_readb, s);
-    register_ioport_write(addr, 256, 2, lsi_io_writew, s);
-    register_ioport_read(addr, 256, 2, lsi_io_readw, s);
-    register_ioport_write(addr, 256, 4, lsi_io_writel, s);
-    register_ioport_read(addr, 256, 4, lsi_io_readl, s);
-}
-
-static void lsi_ram_mapfunc(PCIDevice *pci_dev, int region_num,
-                            pcibus_t addr, pcibus_t size, int type)
-{
-    LSIState *s = DO_UPCAST(LSIState, dev, pci_dev);
-
-    DPRINTF("Mapping ram at %08"FMT_PCIBUS"\n", addr);
-    s->script_ram_base = addr;
-    cpu_register_physical_memory(addr + 0, 0x2000, s->ram_io_addr);
-}
+static const MemoryRegionOps lsi_io_ops = {
+    .read = lsi_io_read,
+    .write = lsi_io_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .impl = {
+        .min_access_size = 1,
+        .max_access_size = 1,
+    },
+};
 
 static void lsi_scsi_reset(DeviceState *dev)
 {
@@ -2231,8 +2088,9 @@ static int lsi_scsi_uninit(PCIDevice *d)
 {
     LSIState *s = DO_UPCAST(LSIState, dev, d);
 
-    cpu_unregister_io_memory(s->mmio_io_addr);
-    cpu_unregister_io_memory(s->ram_io_addr);
+    memory_region_destroy(&s->mmio_io);
+    memory_region_destroy(&s->ram_io);
+    memory_region_destroy(&s->io_io);
 
     return 0;
 }
@@ -2256,18 +2114,14 @@ static int lsi_scsi_init(PCIDevice *dev)
     /* Interrupt pin 1 */
     pci_conf[PCI_INTERRUPT_PIN] = 0x01;
 
-    s->mmio_io_addr = cpu_register_io_memory(lsi_mmio_readfn,
-                                             lsi_mmio_writefn, s,
-                                             DEVICE_NATIVE_ENDIAN);
-    s->ram_io_addr = cpu_register_io_memory(lsi_ram_readfn,
-                                            lsi_ram_writefn, s,
-                                            DEVICE_NATIVE_ENDIAN);
-
-    pci_register_bar(&s->dev, 0, 256,
-                           PCI_BASE_ADDRESS_SPACE_IO, lsi_io_mapfunc);
-    pci_register_bar_simple(&s->dev, 1, 0x400, 0, s->mmio_io_addr);
-    pci_register_bar(&s->dev, 2, 0x2000,
-                           PCI_BASE_ADDRESS_SPACE_MEMORY, lsi_ram_mapfunc);
+    memory_region_init_io(&s->mmio_io, &lsi_mmio_ops, s, "lsi-mmio", 0x400);
+    memory_region_init_io(&s->ram_io, &lsi_ram_ops, s, "lsi-ram", 0x2000);
+    memory_region_init_io(&s->io_io, &lsi_io_ops, s, "lsi-io", 256);
+
+    pci_register_bar_region(&s->dev, 0, PCI_BASE_ADDRESS_SPACE_IO, &s->io_io);
+    pci_register_bar_region(&s->dev, 1, 0, &s->mmio_io);
+    pci_register_bar_region(&s->dev, 2, PCI_BASE_ADDRESS_SPACE_MEMORY,
+                            &s->ram_io);
     QTAILQ_INIT(&s->queue);
 
     scsi_bus_new(&s->bus, &dev->qdev, 1, LSI_MAX_DEVS, &lsi_scsi_ops);
