hw/arm: Use MachineClass->default_nic in the virt machine

Mark the default NIC via the new MachineClass->default_nic setting
so that the machine-defaults code in vl.c can decide whether the
default NIC is usable or not (for example when compiling with the
"--without-default-devices" configure switch).

Message-Id: <20230523110435.1375774-4-thuth@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>

hw/arm/virt.c

@@ -1426,6 +1426,7 @@ static void create_pcie(VirtMachineState *vms)
     int i, ecam_id;
     PCIHostState *pci;
     MachineState *ms = MACHINE(vms);
+    MachineClass *mc = MACHINE_GET_CLASS(ms);
 
     dev = qdev_new(TYPE_GPEX_HOST);
     sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
@@ -1479,7 +1480,7 @@ static void create_pcie(VirtMachineState *vms)
             NICInfo *nd = &nd_table[i];
 
             if (!nd->model) {
-                nd->model = g_strdup("virtio");
+                nd->model = g_strdup(mc->default_nic);
             }
 
             pci_nic_init_nofail(nd, pci->bus, nd->model, NULL);
@@ -3033,6 +3034,7 @@ static void virt_machine_class_init(ObjectClass *oc, void *data)
     mc->auto_enable_numa_with_memhp = true;
     mc->auto_enable_numa_with_memdev = true;
     mc->default_ram_id = "mach-virt.ram";
+    mc->default_nic = "virtio-net-pci";
 
     object_class_property_add(oc, "acpi", "OnOffAuto",
         virt_get_acpi, virt_set_acpi,