memhp: don't generate memory hotplug AML if it's not enabled/supported

That reduces DSDT by 910 bytes when memory hotplug
isn't enabled.

While doing so drop intermediate variables/arguments
passing around ACPI_MEMORY_HOTPLUG_IO_LEN and making
it local to memory_hotplug.c, hardcoding it there as
it can't change.

Also don't pass around ACPI_MEMORY_HOTPLUG_BASE through
intermediate variables/arguments where it's not needed.
Instead initialize in module static variable when MMIO
region is mapped and use that within memory_hotplug.c
whenever it's required.
That way MMIO base specified only at one place and AML
with MMIO would always use the same value.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>

hw/acpi/ich9.c

@@ -306,7 +306,8 @@ void ich9_pm_init(PCIDevice *lpc_pci, ICH9LPCPMRegs *pm,
 
     if (pm->acpi_memory_hotplug.is_enabled) {
         acpi_memory_hotplug_init(pci_address_space_io(lpc_pci), OBJECT(lpc_pci),
-                                 &pm->acpi_memory_hotplug);
+                                 &pm->acpi_memory_hotplug,
+                                 ACPI_MEMORY_HOTPLUG_BASE);
     }
 }
 

hw/acpi/memory_hotplug.c

@@ -30,6 +30,9 @@
 #define MEMORY_SLOT_NOTIFY_METHOD    "MTFY"
 #define MEMORY_SLOT_SCAN_METHOD      "MSCN"
 #define MEMORY_HOTPLUG_DEVICE        "MHPD"
+#define MEMORY_HOTPLUG_IO_LEN         24
+
+static uint16_t memhp_io_base;
 
 static ACPIOSTInfo *acpi_memory_device_status(int slot, MemStatus *mdev)
 {
@@ -202,7 +205,7 @@ static const MemoryRegionOps acpi_memory_hotplug_ops = {
 };
 
 void acpi_memory_hotplug_init(MemoryRegion *as, Object *owner,
-                              MemHotplugState *state)
+                              MemHotplugState *state, uint16_t io_base)
 {
     MachineState *machine = MACHINE(qdev_get_machine());
 
@@ -211,10 +214,12 @@ void acpi_memory_hotplug_init(MemoryRegion *as, Object *owner,
         return;
     }
 
+    assert(!memhp_io_base);
+    memhp_io_base = io_base;
     state->devs = g_malloc0(sizeof(*state->devs) * state->dev_count);
     memory_region_init_io(&state->io, owner, &acpi_memory_hotplug_ops, state,
-                          "acpi-mem-hotplug", ACPI_MEMORY_HOTPLUG_IO_LEN);
-    memory_region_add_subregion(as, ACPI_MEMORY_HOTPLUG_BASE, &state->io);
+                          "acpi-mem-hotplug", MEMORY_HOTPLUG_IO_LEN);
+    memory_region_add_subregion(as, memhp_io_base, &state->io);
 }
 
 /**
@@ -332,7 +337,6 @@ const VMStateDescription vmstate_memory_hotplug = {
 };
 
 void build_memory_hotplug_aml(Aml *table, uint32_t nr_mem,
-                              uint16_t io_base, uint16_t io_len,
                               const char *res_root,
                               const char *event_handler_method)
 {
@@ -342,8 +346,13 @@ void build_memory_hotplug_aml(Aml *table, uint32_t nr_mem,
     Aml *sb_scope;
     Aml *mem_ctrl_dev;
     char *scan_path;
-    char *mhp_res_path = g_strdup_printf("%s." MEMORY_HOTPLUG_DEVICE, res_root);
+    char *mhp_res_path;
+
+    if (!memhp_io_base) {
+        return;
+    }
 
+    mhp_res_path = g_strdup_printf("%s." MEMORY_HOTPLUG_DEVICE, res_root);
     mem_ctrl_dev = aml_device("%s", mhp_res_path);
     {
         Aml *crs;
@@ -367,13 +376,14 @@ void build_memory_hotplug_aml(Aml *table, uint32_t nr_mem,
 
         crs = aml_resource_template();
         aml_append(crs,
-            aml_io(AML_DECODE16, io_base, io_base, 0, io_len)
+            aml_io(AML_DECODE16, memhp_io_base, memhp_io_base, 0,
+                   MEMORY_HOTPLUG_IO_LEN)
         );
         aml_append(mem_ctrl_dev, aml_name_decl("_CRS", crs));
 
         aml_append(mem_ctrl_dev, aml_operation_region(
             MEMORY_HOTPLUG_IO_REGION, AML_SYSTEM_IO,
-            aml_int(io_base), io_len)
+            aml_int(memhp_io_base), MEMORY_HOTPLUG_IO_LEN)
         );
 
         field = aml_field(MEMORY_HOTPLUG_IO_REGION, AML_DWORD_ACC,

hw/acpi/piix4.c

@@ -644,7 +644,8 @@ static void piix4_acpi_system_hot_add_init(MemoryRegion *parent,
                                  PIIX4_CPU_HOTPLUG_IO_BASE);
 
     if (s->acpi_memory_hotplug.is_enabled) {
-        acpi_memory_hotplug_init(parent, OBJECT(s), &s->acpi_memory_hotplug);
+        acpi_memory_hotplug_init(parent, OBJECT(s), &s->acpi_memory_hotplug,
+                                 ACPI_MEMORY_HOTPLUG_BASE);
     }
 }
 

hw/i386/acpi-build.c

@@ -101,8 +101,6 @@ typedef struct AcpiPmInfo {
     uint32_t gpe0_blk_len;
     uint32_t io_base;
     uint16_t cpu_hp_io_base;
-    uint16_t mem_hp_io_base;
-    uint16_t mem_hp_io_len;
     uint16_t pcihp_io_base;
     uint16_t pcihp_io_len;
 } AcpiPmInfo;
@@ -148,9 +146,6 @@ static void acpi_get_pm_info(AcpiPmInfo *pm)
     }
     assert(obj);
 
-    pm->mem_hp_io_base = ACPI_MEMORY_HOTPLUG_BASE;
-    pm->mem_hp_io_len = ACPI_MEMORY_HOTPLUG_IO_LEN;
-
     /* Fill in optional s3/s4 related properties */
     o = object_property_get_qobject(obj, ACPI_PM_PROP_S3_DISABLED, NULL);
     if (o) {
@@ -1925,9 +1920,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
         build_cpus_aml(dsdt, machine, opts, pm->cpu_hp_io_base,
                        "\\_SB.PCI0", "\\_GPE._E02");
     }
-    build_memory_hotplug_aml(dsdt, nr_mem, pm->mem_hp_io_base,
-                             pm->mem_hp_io_len,
-                             "\\_SB.PCI0", "\\_GPE._E03");
+    build_memory_hotplug_aml(dsdt, nr_mem, "\\_SB.PCI0", "\\_GPE._E03");
 
     scope =  aml_scope("_GPE");
     {

include/hw/acpi/memory_hotplug.h

@@ -30,7 +30,7 @@ typedef struct MemHotplugState {
 } MemHotplugState;
 
 void acpi_memory_hotplug_init(MemoryRegion *as, Object *owner,
-                              MemHotplugState *state);
+                              MemHotplugState *state, uint16_t io_base);
 
 void acpi_memory_plug_cb(HotplugHandler *hotplug_dev, MemHotplugState *mem_st,
                          DeviceState *dev, Error **errp);
@@ -48,7 +48,6 @@ extern const VMStateDescription vmstate_memory_hotplug;
 void acpi_memory_ospm_status(MemHotplugState *mem_st, ACPIOSTInfoList ***list);
 
 void build_memory_hotplug_aml(Aml *table, uint32_t nr_mem,
-                              uint16_t io_base, uint16_t io_len,
                               const char *res_root,
                               const char *event_handler_method);
 #endif

include/hw/acpi/pc-hotplug.h

@@ -29,7 +29,6 @@
 #define PIIX4_CPU_HOTPLUG_IO_BASE 0xaf00
 #define CPU_HOTPLUG_RESOURCE_DEVICE PRES
 
-#define ACPI_MEMORY_HOTPLUG_IO_LEN 24
 #define ACPI_MEMORY_HOTPLUG_BASE 0x0a00
 
 #endif