hw/i386/cxl: ensure maxram is greater than ram size for calculating c…

…xl range

pc_get_device_memory_range() finds the device memory size by calculating the
difference between maxram and ram sizes. This calculation makes sense only when
maxram is greater than the ram size. Make sure we check for that before calling
pc_get_device_memory_range().

Signed-off-by: Ani Sinha <anisinha@redhat.com>
Message-Id: <20231011105335.42296-1-anisinha@redhat.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/i386/pc.c

@@ -781,10 +781,12 @@ static void pc_get_device_memory_range(PCMachineState *pcms,
 static uint64_t pc_get_cxl_range_start(PCMachineState *pcms)
 {
     PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
+    MachineState *ms = MACHINE(pcms);
     hwaddr cxl_base;
     ram_addr_t size;
 
-    if (pcmc->has_reserved_memory) {
+    if (pcmc->has_reserved_memory &&
+        (ms->ram_size < ms->maxram_size)) {
         pc_get_device_memory_range(pcms, &cxl_base, &size);
         cxl_base += size;
     } else {