hw/pci-host/bonito.c: Add PCI mem region mapped at the correct address

Stop using system memory as PCI memory otherwise devices such as VGA
that have regions mapped to PCI memory clash with RAM. Use a separate
memory region for PCI memory and map it to the correct address in
system memory which allows PCI mem regions to show at the correct
address where clients expect them.
Signed-off-by: NBALATON Zoltan <balaton@eik.bme.hu>
Signed-off-by: NAleksandar Markovic <amarkovic@wavecomp.com>
Reviewed-by: NPhilippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: NPhilippe Mathieu-Daudé <philmd@redhat.com>

hw/pci-host/bonito.c

@@ -217,6 +217,7 @@ struct BonitoState {
     PCIHostState parent_obj;
     qemu_irq *pic;
     PCIBonitoState *pci_dev;
+    MemoryRegion pci_mem;
 };
 
 #define TYPE_BONITO_PCI_HOST_BRIDGE "Bonito-pcihost"
@@ -598,11 +599,15 @@ static const VMStateDescription vmstate_bonito = {
 static void bonito_pcihost_realize(DeviceState *dev, Error **errp)
 {
     PCIHostState *phb = PCI_HOST_BRIDGE(dev);
+    BonitoState *bs = BONITO_PCI_HOST_BRIDGE(dev);
 
+    memory_region_init(&bs->pci_mem, OBJECT(dev), "pci.mem", BONITO_PCILO_SIZE);
     phb->bus = pci_register_root_bus(DEVICE(dev), "pci",
                                      pci_bonito_set_irq, pci_bonito_map_irq,
-                                     dev, get_system_memory(), get_system_io(),
+                                     dev, &bs->pci_mem, get_system_io(),
                                      0x28, 32, TYPE_PCI_BUS);
+    memory_region_add_subregion(get_system_memory(), BONITO_PCILO_BASE,
+                                &bs->pci_mem);
 }
 
 static void bonito_realize(PCIDevice *dev, Error **errp)