hw/i386/pc: Remove PCMachineClass::enforce_aligned_dimm

PCMachineClass::enforce_aligned_dimm was only used by the
pc-i440fx-2.1 machine, which got removed. It is now always
true. Remove it, simplifying pc_get_device_memory_range().
Update the comment in Avocado test_phybits_low_pse36().

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20240617071118.60464-14-philmd@linaro.org>

hw/i386/pc.c

@@ -728,7 +728,6 @@ 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;
@@ -736,10 +735,8 @@ static void pc_get_device_memory_range(PCMachineState *pcms,
     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;
-    }
+    /* size device region assuming 1G page max alignment per slot */
+    size += (1 * GiB) * machine->ram_slots;
 
     *base = addr;
     *device_mem_size = size;
@@ -1303,12 +1300,9 @@ void pc_i8259_create(ISABus *isa_bus, qemu_irq *i8259_irqs)
 static void pc_memory_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
                                Error **errp)
 {
-    const PCMachineState *pcms = PC_MACHINE(hotplug_dev);
     const X86MachineState *x86ms = X86_MACHINE(hotplug_dev);
-    const PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
     const MachineState *ms = MACHINE(hotplug_dev);
     const bool is_nvdimm = object_dynamic_cast(OBJECT(dev), TYPE_NVDIMM);
-    const uint64_t legacy_align = TARGET_PAGE_SIZE;
     Error *local_err = NULL;
 
     /*
@@ -1333,8 +1327,7 @@ static void pc_memory_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
         return;
     }
 
-    pc_dimm_pre_plug(PC_DIMM(dev), MACHINE(hotplug_dev),
-                     pcmc->enforce_aligned_dimm ? NULL : &legacy_align, errp);
+    pc_dimm_pre_plug(PC_DIMM(dev), MACHINE(hotplug_dev), NULL, errp);
 }
 
 static void pc_memory_plug(HotplugHandler *hotplug_dev,
@@ -1798,7 +1791,6 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
     pcmc->smbios_defaults = true;
     pcmc->gigabyte_align = true;
     pcmc->has_reserved_memory = true;
-    pcmc->enforce_aligned_dimm = true;
     pcmc->enforce_amd_1tb_hole = true;
     pcmc->isa_bios_alias = true;
     /* BIOS ACPI tables: 128K. Other BIOS datastructures: less than 4K reported

include/hw/i386/pc.h

@@ -74,8 +74,6 @@ typedef struct PCMachineState {
  *
  * Compat fields:
  *
- * @enforce_aligned_dimm: check that DIMM's address/size is aligned by
- *                        backend's alignment value if provided
  * @acpi_data_size: Size of the chunk of memory at the top of RAM
  *                  for the BIOS ACPI tables and other BIOS
  *                  datastructures.
@@ -114,7 +112,6 @@ struct PCMachineClass {
     /* RAM / address space compat: */
     bool gigabyte_align;
     bool has_reserved_memory;
-    bool enforce_aligned_dimm;
     bool broken_reserved_end;
     bool enforce_amd_1tb_hole;
     bool isa_bios_alias;

tests/avocado/mem-addr-space-check.py

@@ -31,11 +31,10 @@ def test_phybits_low_pse36(self):
         at 4 GiB boundary when "above_4g_mem_size" is 0 (this would be true when
         we have 0.5 GiB of VM memory, see pc_q35_init()). This means total
         hotpluggable memory size is 60 GiB. Per slot, we reserve 1 GiB of memory
-        for dimm alignment for all newer machines (see enforce_aligned_dimm
-        property for pc machines and pc_get_device_memory_range()). That leaves
-        total hotpluggable actual memory size of 59 GiB. If the VM is started
-        with 0.5 GiB of memory, maxmem should be set to a maximum value of
-        59.5 GiB to ensure that the processor can address all memory directly.
+        for dimm alignment for all machines. That leaves total hotpluggable
+        actual memory size of 59 GiB. If the VM is started with 0.5 GiB of
+        memory, maxmem should be set to a maximum value of 59.5 GiB to ensure
+        that the processor can address all memory directly.
         Note that 64-bit pci hole size is 0 in this case. If maxmem is set to
         59.6G, QEMU should fail to start with a message "phy-bits are too low".
         If maxmem is set to 59.5G with all other QEMU parameters identical, QEMU