hw/i386/pc: support '-nic' for xen-net-device

The default NIC creation seems a bit hackish to me. I don't understand
why each platform has to call pci_nic_init_nofail() from a point in the
code where it actually has a pointer to the PCI bus, and then we have
the special cases for things like ne2k_isa.

If qmp_device_add() can *find* the appropriate bus and instantiate
the device on it, why can't we just do that from generic code for
creating the default NICs too?

But that isn't a yak I want to shave today. Add a xenbus field to the
PCMachineState so that it can make its way from pc_basic_device_init()
to pc_nic_init() and be handled as a special case like ne2k_isa is.

Now we can launch emulated Xen guests with '-nic user'.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>

4 files changed, 13 insertions, 6 deletions

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 1aef21a..188bc9d 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1261,7 +1261,7 @@ void pc_basic_device_init(struct PCMachineState *pcms,
         if (pcms->bus) {
             pci_create_simple(pcms->bus, -1, "xen-platform");
         }
-        xen_bus_init();
+        pcms->xenbus = xen_bus_init();
         xen_be_init();
     }
 #endif
@@ -1289,7 +1289,8 @@ void pc_basic_device_init(struct PCMachineState *pcms,
                     pcms->vmport != ON_OFF_AUTO_ON);
 }
 
-void pc_nic_init(PCMachineClass *pcmc, ISABus *isa_bus, PCIBus *pci_bus)
+void pc_nic_init(PCMachineClass *pcmc, ISABus *isa_bus, PCIBus *pci_bus,
+                 BusState *xen_bus)
 {
     MachineClass *mc = MACHINE_CLASS(pcmc);
     int i;
@@ -1299,7 +1300,11 @@ void pc_nic_init(PCMachineClass *pcmc, ISABus *isa_bus, PCIBus *pci_bus)
         NICInfo *nd = &nd_table[i];
         const char *model = nd->model ? nd->model : mc->default_nic;
 
-        if (g_str_equal(model, "ne2k_isa")) {
+        if (xen_bus && (!nd->model || g_str_equal(model, "xen-net-device"))) {
+            DeviceState *dev = qdev_new("xen-net-device");
+            qdev_set_nic_properties(dev, nd);
+            qdev_realize_and_unref(dev, xen_bus, &error_fatal);
+        } else if (g_str_equal(model, "ne2k_isa")) {
             pc_init_ne2k_isa(isa_bus, nd);
         } else {
             pci_nic_init_nofail(nd, pci_bus, model, NULL);
diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index 26e161b..eace854 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -342,7 +342,7 @@ static void pc_init1(MachineState *machine,
     pc_basic_device_init(pcms, isa_bus, x86ms->gsi, rtc_state, true,
                          0x4);
 
-    pc_nic_init(pcmc, isa_bus, pci_bus);
+    pc_nic_init(pcmc, isa_bus, pci_bus, pcms->xenbus);
 
     if (pcmc->pci_enabled) {
         pc_cmos_init(pcms, idebus[0], idebus[1], rtc_state);
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 597943f..4f3e541 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -340,7 +340,7 @@ static void pc_q35_init(MachineState *machine)
 
     /* the rest devices to which pci devfn is automatically assigned */
     pc_vga_init(isa_bus, host_bus);
-    pc_nic_init(pcmc, isa_bus, host_bus);
+    pc_nic_init(pcmc, isa_bus, host_bus, pcms->xenbus);
 
     if (machine->nvdimms_state->is_enabled) {
         nvdimm_init_acpi_state(machine->nvdimms_state, system_io,
diff --git a/hw/xen/xen-bus.c b/hw/xen/xen-bus.c
index cc6f1b3..4973e7d 100644
--- a/hw/xen/xen-bus.c
+++ b/hw/xen/xen-bus.c
@@ -1133,11 +1133,13 @@ static void xen_register_types(void)
 
 type_init(xen_register_types)
 
-void xen_bus_init(void)
+BusState *xen_bus_init(void)
 {
     DeviceState *dev = qdev_new(TYPE_XEN_BRIDGE);
     BusState *bus = qbus_new(TYPE_XEN_BUS, dev, NULL);
 
     sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
     qbus_set_bus_hotplug_handler(bus);
+
+    return bus;
 }