hw/i386/pc: Restrict CXL to PCI-based machines

CXL is based on PCIe. In is pointless to initialize
its context on non-PCI machines.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Message-ID: <20240327161642.33574-1-philmd@linaro.org>

hw/i386/pc.c

@@ -1738,7 +1738,9 @@ static void pc_machine_initfn(Object *obj)
     pcms->pcspk = isa_new(TYPE_PC_SPEAKER);
     object_property_add_alias(OBJECT(pcms), "pcspk-audiodev",
                               OBJECT(pcms->pcspk), "audiodev");
-    cxl_machine_init(obj, &pcms->cxl_devices_state);
+    if (pcmc->pci_enabled) {
+        cxl_machine_init(obj, &pcms->cxl_devices_state);
+    }
 
     pcms->machine_done.notify = pc_machine_done;
     qemu_add_machine_init_done_notifier(&pcms->machine_done);