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, 21 insertions, 7 deletions

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index bdc31ce56c..2077e4b3c6 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -2981,11 +2981,18 @@ static HotplugHandler *spapr_get_hotplug_handler(MachineState *machine,
     return NULL;
 }
 
-static unsigned spapr_cpu_index_to_socket_id(unsigned cpu_index)
+static CpuInstanceProperties
+spapr_cpu_index_to_props(MachineState *machine, unsigned cpu_index)
 {
-    /* Allocate to NUMA nodes on a "socket" basis (not that concept of
-     * socket means much for the paravirtualized PAPR platform) */
-    return cpu_index / smp_threads / smp_cores;
+    CPUArchId *core_slot;
+    MachineClass *mc = MACHINE_GET_CLASS(machine);
+
+    /* make sure possible_cpu are intialized */
+    mc->possible_cpu_arch_ids(machine);
+    /* get CPU core slot containing thread that matches cpu_index */
+    core_slot = spapr_find_cpu_slot(machine, cpu_index, NULL);
+    assert(core_slot);
+    return core_slot->props;
 }
 
 static const CPUArchIdList *spapr_possible_cpu_arch_ids(MachineState *machine)
@@ -3012,8 +3019,15 @@ static const CPUArchIdList *spapr_possible_cpu_arch_ids(MachineState *machine)
         machine->possible_cpus->cpus[i].arch_id = core_id;
         machine->possible_cpus->cpus[i].props.has_core_id = true;
         machine->possible_cpus->cpus[i].props.core_id = core_id;
-        /* TODO: add 'has_node/node' here to describe
-           to which node core belongs */
+
+        /* 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 */
+            machine->possible_cpus->cpus[i].props.node_id =
+                core_id / smp_threads / smp_cores % nb_numa_nodes;
+        }
     }
     return machine->possible_cpus;
 }
@@ -3138,7 +3152,7 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data)
     hc->pre_plug = spapr_machine_device_pre_plug;
     hc->plug = spapr_machine_device_plug;
     hc->unplug = spapr_machine_device_unplug;
-    mc->cpu_index_to_socket_id = spapr_cpu_index_to_socket_id;
+    mc->cpu_index_to_instance_props = spapr_cpu_index_to_props;
     mc->possible_cpu_arch_ids = spapr_possible_cpu_arch_ids;
     hc->unplug_request = spapr_machine_device_unplug_request;