hw/i386/acpi-build: Rely on machine->device_memory when building SRAT

We're already looking at machine->device_memory when calling
build_srat_memory(), so let's simply avoid going via
PC_MACHINE_DEVMEM_REGION_SIZE to get the size and rely on
machine->device_memory directly.

Once machine->device_memory is set, we know that the size > 0. The code now
looks much more similar the hw/arm/virt-acpi-build.c variant.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Eduardo Habkost <eduardo@habkost.net>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20230623124553.400585-8-david@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>

hw/i386/acpi-build.c

@@ -1950,12 +1950,8 @@ build_srat(GArray *table_data, BIOSLinker *linker, MachineState *machine)
     MachineClass *mc = MACHINE_GET_CLASS(machine);
     X86MachineState *x86ms = X86_MACHINE(machine);
     const CPUArchIdList *apic_ids = mc->possible_cpu_arch_ids(machine);
-    PCMachineState *pcms = PC_MACHINE(machine);
     int nb_numa_nodes = machine->numa_state->num_nodes;
     NodeInfo *numa_info = machine->numa_state->nodes;
-    ram_addr_t hotpluggable_address_space_size =
-        object_property_get_int(OBJECT(pcms), PC_MACHINE_DEVMEM_REGION_SIZE,
-                                NULL);
     AcpiTable table = { .sig = "SRAT", .rev = 1, .oem_id = x86ms->oem_id,
                         .oem_table_id = x86ms->oem_table_id };
 
@@ -2071,9 +2067,10 @@ build_srat(GArray *table_data, BIOSLinker *linker, MachineState *machine)
      * Memory devices may override proximity set by this entry,
      * providing _PXM method if necessary.
      */
-    if (hotpluggable_address_space_size) {
+    if (machine->device_memory) {
         build_srat_memory(table_data, machine->device_memory->base,
-                          hotpluggable_address_space_size, nb_numa_nodes - 1,
+                          memory_region_size(&machine->device_memory->mr),
+                          nb_numa_nodes - 1,
                           MEM_AFFINITY_HOTPLUGGABLE | MEM_AFFINITY_ENABLED);
     }