i386/pc: factor out device_memory base/size to helper

Move obtaining hole64_start from device_memory memory region base/size
into an helper alongside correspondent getters in pc_memory_init() when
the hotplug range is unitialized. While doing that remove the memory
region based logic from this newly added helper.

This is the final step that allows pc_pci_hole64_start() to be callable
at the beginning of pc_memory_init() before any memory regions are
initialized.

Cc: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Acked-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20220719170014.27028-9-joao.m.martins@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/i386/pc.c

@@ -825,15 +825,36 @@ static hwaddr pc_above_4g_end(PCMachineState *pcms)
     return x86ms->above_4g_mem_start + x86ms->above_4g_mem_size;
 }
 
-static uint64_t pc_get_cxl_range_start(PCMachineState *pcms)
+static void pc_get_device_memory_range(PCMachineState *pcms,
+                                       hwaddr *base,
+                                       ram_addr_t *device_mem_size)
 {
     PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
     MachineState *machine = MACHINE(pcms);
+    ram_addr_t size;
+    hwaddr addr;
+
+    size = machine->maxram_size - machine->ram_size;
+    addr = ROUND_UP(pc_above_4g_end(pcms), 1 * GiB);
+
+    if (pcmc->enforce_aligned_dimm) {
+        /* size device region assuming 1G page max alignment per slot */
+        size += (1 * GiB) * machine->ram_slots;
+    }
+
+    *base = addr;
+    *device_mem_size = size;
+}
+
+static uint64_t pc_get_cxl_range_start(PCMachineState *pcms)
+{
+    PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
     hwaddr cxl_base;
+    ram_addr_t size;
 
-    if (pcmc->has_reserved_memory && machine->device_memory->base) {
-        cxl_base = machine->device_memory->base
-            + memory_region_size(&machine->device_memory->mr);
+    if (pcmc->has_reserved_memory) {
+        pc_get_device_memory_range(pcms, &cxl_base, &size);
+        cxl_base += size;
     } else {
         cxl_base = pc_above_4g_end(pcms);
     }
@@ -920,7 +941,7 @@ void pc_memory_init(PCMachineState *pcms,
     /* initialize device memory address space */
     if (pcmc->has_reserved_memory &&
         (machine->ram_size < machine->maxram_size)) {
-        ram_addr_t device_mem_size = machine->maxram_size - machine->ram_size;
+        ram_addr_t device_mem_size;
 
         if (machine->ram_slots > ACPI_MAX_RAM_SLOTS) {
             error_report("unsupported amount of memory slots: %"PRIu64,
@@ -935,13 +956,7 @@ void pc_memory_init(PCMachineState *pcms,
             exit(EXIT_FAILURE);
         }
 
-        machine->device_memory->base =
-            ROUND_UP(pc_above_4g_end(pcms), 1 * GiB);
-
-        if (pcmc->enforce_aligned_dimm) {
-            /* size device region assuming 1G page max alignment per slot */
-            device_mem_size += (1 * GiB) * machine->ram_slots;
-        }
+        pc_get_device_memory_range(pcms, &machine->device_memory->base, &device_mem_size);
 
         if ((machine->device_memory->base + device_mem_size) <
             device_mem_size) {
@@ -1046,13 +1061,14 @@ uint64_t pc_pci_hole64_start(void)
     PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
     MachineState *ms = MACHINE(pcms);
     uint64_t hole64_start = 0;
+    ram_addr_t size = 0;
 
     if (pcms->cxl_devices_state.is_enabled) {
         hole64_start = pc_get_cxl_range_end(pcms);
-    } else if (pcmc->has_reserved_memory && ms->device_memory->base) {
-        hole64_start = ms->device_memory->base;
+    } else if (pcmc->has_reserved_memory && (ms->ram_size < ms->maxram_size)) {
+        pc_get_device_memory_range(pcms, &hole64_start, &size);
         if (!pcmc->broken_reserved_end) {
-            hole64_start += memory_region_size(&ms->device_memory->mr);
+            hole64_start += size;
         }
     } else {
         hole64_start = pc_above_4g_end(pcms);