diff --git a/hw/pci-host/bonito.c b/hw/pci-host/bonito.c
index ee6cb85e97..96bd028671 100644
--- a/hw/pci-host/bonito.c
+++ b/hw/pci-host/bonito.c
@@ -654,10 +654,10 @@ static void bonito_host_realize(DeviceState *dev, Error **errp)
 static void bonito_pci_realize(PCIDevice *dev, Error **errp)
 {
     PCIBonitoState *s = PCI_BONITO(dev);
-    SysBusDevice *sysbus = SYS_BUS_DEVICE(s->pcihost);
     PCIHostState *phb = PCI_HOST_BRIDGE(s->pcihost);
     BonitoState *bs = s->pcihost;
     MemoryRegion *pcimem_alias = g_new(MemoryRegion, 1);
+    MemoryRegion *host_mem = get_system_memory();
 
     /*
      * Bonito North Bridge, built on FPGA,
@@ -668,48 +668,48 @@ static void bonito_pci_realize(PCIDevice *dev, Error **errp)
     /* set the north bridge register mapping */
     memory_region_init_io(&s->iomem, OBJECT(s), &bonito_ops, s,
                           "north-bridge-register", BONITO_INTERNAL_REG_SIZE);
-    sysbus_init_mmio(sysbus, &s->iomem);
-    sysbus_mmio_map(sysbus, 0, BONITO_INTERNAL_REG_BASE);
+    memory_region_add_subregion(host_mem, BONITO_INTERNAL_REG_BASE,
+                                &s->iomem);
 
     /* set the north bridge pci configure  mapping */
     memory_region_init_io(&phb->conf_mem, OBJECT(s), &bonito_pciconf_ops, s,
                           "north-bridge-pci-config", BONITO_PCICONFIG_SIZE);
-    sysbus_init_mmio(sysbus, &phb->conf_mem);
-    sysbus_mmio_map(sysbus, 1, BONITO_PCICONFIG_BASE);
+    memory_region_add_subregion(host_mem, BONITO_PCICONFIG_BASE,
+                                &phb->conf_mem);
 
     /* set the south bridge pci configure  mapping */
     memory_region_init_io(&phb->data_mem, OBJECT(s), &bonito_spciconf_ops, s,
                           "south-bridge-pci-config", BONITO_SPCICONFIG_SIZE);
-    sysbus_init_mmio(sysbus, &phb->data_mem);
-    sysbus_mmio_map(sysbus, 2, BONITO_SPCICONFIG_BASE);
+    memory_region_add_subregion(host_mem, BONITO_SPCICONFIG_BASE,
+                                &phb->data_mem);
 
     create_unimplemented_device("bonito", BONITO_REG_BASE, BONITO_REG_SIZE);
 
     memory_region_init_io(&s->iomem_ldma, OBJECT(s), &bonito_ldma_ops, s,
                           "ldma", 0x100);
-    sysbus_init_mmio(sysbus, &s->iomem_ldma);
-    sysbus_mmio_map(sysbus, 3, 0x1fe00200);
+    memory_region_add_subregion(host_mem, 0x1fe00200,
+                                &s->iomem_ldma);
 
     /* PCI copier */
     memory_region_init_io(&s->iomem_cop, OBJECT(s), &bonito_cop_ops, s,
                           "cop", 0x100);
-    sysbus_init_mmio(sysbus, &s->iomem_cop);
-    sysbus_mmio_map(sysbus, 4, 0x1fe00300);
+    memory_region_add_subregion(host_mem, 0x1fe00300,
+                                &s->iomem_cop);
 
     create_unimplemented_device("ROMCS", BONITO_FLASH_BASE, 60 * MiB);
 
     /* Map PCI IO Space  0x1fd0 0000 - 0x1fd1 0000 */
     memory_region_init_alias(&s->bonito_pciio, OBJECT(s), "isa_mmio",
                              get_system_io(), 0, BONITO_PCIIO_SIZE);
-    sysbus_init_mmio(sysbus, &s->bonito_pciio);
-    sysbus_mmio_map(sysbus, 5, BONITO_PCIIO_BASE);
+    memory_region_add_subregion(host_mem, BONITO_PCIIO_BASE,
+                                &s->bonito_pciio);
 
     /* add pci local io mapping */
 
     memory_region_init_alias(&s->bonito_localio, OBJECT(s), "IOCS[0]",
                              get_system_io(), 0, 256 * KiB);
-    sysbus_init_mmio(sysbus, &s->bonito_localio);
-    sysbus_mmio_map(sysbus, 6, BONITO_DEV_BASE);
+    memory_region_add_subregion(host_mem, BONITO_DEV_BASE,
+                                &s->bonito_localio);
     create_unimplemented_device("IOCS[1]", BONITO_DEV_BASE + 1 * 256 * KiB,
                                 256 * KiB);
     create_unimplemented_device("IOCS[2]", BONITO_DEV_BASE + 2 * 256 * KiB,
@@ -719,7 +719,7 @@ static void bonito_pci_realize(PCIDevice *dev, Error **errp)
 
     memory_region_init_alias(pcimem_alias, NULL, "pci.mem.alias",
                              &bs->pci_mem, 0, BONITO_PCIHI_SIZE);
-    memory_region_add_subregion(get_system_memory(),
+    memory_region_add_subregion(host_mem,
                                 BONITO_PCIHI_BASE, pcimem_alias);
     create_unimplemented_device("PCI_2",
                                 (hwaddr)BONITO_PCIHI_BASE + BONITO_PCIHI_SIZE,
