[Qemu-devel] [PATCH v4 1/3] machine: show if CLI option '-numa node, mem' is supported in QAPI schema

[Igor Mammedov <imammedo@redhat.com>]

Legacy '-numa node,mem' option has a number of issues and mgmt often
defaults to it. Unfortunately it's no possible to replace it with
an alternative '-numa memdev' without breaking migration compatibility.
What's possible though is to deprecate it, keeping option working with
old machine types only.

In order to help users to find out if being deprecated CLI option
'-numa node,mem' is still supported by particular machine type, add new
"numa-mem-supported" property to MachineInfo description in QAPI schema.

"numa-mem-supported" is set to 'true' for machines that currently support
NUMA, but it will be flipped to 'false' later on, once deprecation period
expires and kept 'true' only for old machine types that used to support
the legacy option so it won't break existing configuration that are using
it.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---

Notes:
    v4:
      * drop idea to use "qom-list-properties" and use MachineInfo instead
        which could be inspected with 'query-machines'

 include/hw/boards.h | 3 +++
 hw/arm/virt.c       | 1 +
 hw/i386/pc.c        | 1 +
 hw/ppc/spapr.c      | 1 +
 qapi/misc.json      | 5 ++++-
 vl.c                | 1 +
 6 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/include/hw/boards.h b/include/hw/boards.h
index 6f7916f..86894b6 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -158,6 +158,8 @@ typedef struct {
  * @kvm_type:
  *    Return the type of KVM corresponding to the kvm-type string option or
  *    computed based on other criteria such as the host kernel capabilities.
+ * @numa_mem_supported:
+ *    true if '--numa node.mem' option is supported and false otherwise
  */
 struct MachineClass {
     /*< private >*/
@@ -210,6 +212,7 @@ struct MachineClass {
     bool ignore_boot_device_suffixes;
     bool smbus_no_migration_support;
     bool nvdimm_supported;
+    bool numa_mem_supported;
 
     HotplugHandler *(*get_hotplug_handler)(MachineState *machine,
                                            DeviceState *dev);
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index bf54f10..481a603 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -1943,6 +1943,7 @@ static void virt_machine_class_init(ObjectClass *oc, void *data)
     assert(!mc->get_hotplug_handler);
     mc->get_hotplug_handler = virt_machine_get_hotplug_handler;
     hc->plug = virt_machine_device_plug_cb;
+    mc->numa_mem_supported = true;
 }
 
 static void virt_instance_init(Object *obj)
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 2632b73..05b8368 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -2747,6 +2747,7 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
     nc->nmi_monitor_handler = x86_nmi;
     mc->default_cpu_type = TARGET_DEFAULT_CPU_TYPE;
     mc->nvdimm_supported = true;
+    mc->numa_mem_supported = true;
 
     object_class_property_add(oc, PC_MACHINE_DEVMEM_REGION_SIZE, "int",
         pc_machine_get_device_memory_region_size, NULL,
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 2ef3ce4..265ecfb 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -4336,6 +4336,7 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data)
      * in which LMBs are represented and hot-added
      */
     mc->numa_mem_align_shift = 28;
+    mc->numa_mem_supported = true;
 
     smc->default_caps.caps[SPAPR_CAP_HTM] = SPAPR_CAP_OFF;
     smc->default_caps.caps[SPAPR_CAP_VSX] = SPAPR_CAP_ON;
diff --git a/qapi/misc.json b/qapi/misc.json
index 8b3ca4f..d0bdccb 100644
--- a/qapi/misc.json
+++ b/qapi/misc.json
@@ -2018,12 +2018,15 @@
 #
 # @hotpluggable-cpus: cpu hotplug via -device is supported (since 2.7.0)
 #
+# @numa-mem-supported: true if '-numa node,mem' option is supported by machine
+#                      type and false otherwise (since 4.1)
+#
 # Since: 1.2.0
 ##
 { 'struct': 'MachineInfo',
   'data': { 'name': 'str', '*alias': 'str',
             '*is-default': 'bool', 'cpu-max': 'int',
-            'hotpluggable-cpus': 'bool'} }
+            'hotpluggable-cpus': 'bool', 'numa-mem-supported': 'bool'} }
 
 ##
 # @query-machines:
diff --git a/vl.c b/vl.c
index 5550bd7..5bf17f5 100644
--- a/vl.c
+++ b/vl.c
@@ -1520,6 +1520,7 @@ MachineInfoList *qmp_query_machines(Error **errp)
         info->name = g_strdup(mc->name);
         info->cpu_max = !mc->max_cpus ? 1 : mc->max_cpus;
         info->hotpluggable_cpus = mc->has_hotpluggable_cpus;
+        info->numa_mem_supported = mc->numa_mem_supported;
 
         entry = g_malloc0(sizeof(*entry));
         entry->value = info;
-- 
2.7.4