numa: move source of default CPUs to NUMA node mapping into boards

Originally CPU threads were by default assigned in
round-robin fashion. However it was causing issues in
guest since CPU threads from the same socket/core could
be placed on different NUMA nodes.
Commit fb43b73b (pc: fix default VCPU to NUMA node mapping)
fixed it by grouping threads within a socket on the same node
introducing cpu_index_to_socket_id() callback and commit
20bb648d (spapr: Fix default NUMA node allocation for threads)
reused callback to fix similar issues for SPAPR machine
even though socket doesn't make much sense there.

As result QEMU ended up having 3 default distribution rules
used by 3 targets /virt-arm, spapr, pc/.

In effort of moving NUMA mapping for CPUs into possible_cpus,
generalize default mapping in numa.c by making boards decide
on default mapping and let them explicitly tell generic
numa code to which node a CPU thread belongs to by replacing
cpu_index_to_socket_id() with @cpu_index_to_instance_props()
which provides default node_id assigned by board to specified
cpu_index.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <1494415802-227633-2-git-send-email-imammedo@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

1 files changed, 17 insertions, 6 deletions

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index f3b372a18f..01693d54ca 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -2243,12 +2243,14 @@ static void pc_machine_reset(void)
     }
 }
 
-static unsigned pc_cpu_index_to_socket_id(unsigned cpu_index)
+static CpuInstanceProperties
+pc_cpu_index_to_props(MachineState *ms, unsigned cpu_index)
 {
-    X86CPUTopoInfo topo;
-    x86_topo_ids_from_idx(smp_cores, smp_threads, cpu_index,
-                          &topo);
-    return topo.pkg_id;
+    MachineClass *mc = MACHINE_GET_CLASS(ms);
+    const CPUArchIdList *possible_cpus = mc->possible_cpu_arch_ids(ms);
+
+    assert(cpu_index < possible_cpus->len);
+    return possible_cpus->cpus[cpu_index].props;
 }
 
 static const CPUArchIdList *pc_possible_cpu_arch_ids(MachineState *ms)
@@ -2280,6 +2282,15 @@ static const CPUArchIdList *pc_possible_cpu_arch_ids(MachineState *ms)
         ms->possible_cpus->cpus[i].props.core_id = topo.core_id;
         ms->possible_cpus->cpus[i].props.has_thread_id = true;
         ms->possible_cpus->cpus[i].props.thread_id = topo.smt_id;
+
+        /* default distribution of CPUs over NUMA nodes */
+        if (nb_numa_nodes) {
+            /* preset values but do not enable them i.e. 'has_node_id = false',
+             * numa init code will enable them later if manual mapping wasn't
+             * present on CLI */
+            ms->possible_cpus->cpus[i].props.node_id =
+                topo.pkg_id % nb_numa_nodes;
+        }
     }
     return ms->possible_cpus;
 }
@@ -2322,7 +2333,7 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
     pcmc->acpi_data_size = 0x20000 + 0x8000;
     pcmc->save_tsc_khz = true;
     mc->get_hotplug_handler = pc_get_hotpug_handler;
-    mc->cpu_index_to_socket_id = pc_cpu_index_to_socket_id;
+    mc->cpu_index_to_instance_props = pc_cpu_index_to_props;
     mc->possible_cpu_arch_ids = pc_possible_cpu_arch_ids;
     mc->has_hotpluggable_cpus = true;
     mc->default_boot_order = "cad";