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, 18 insertions, 2 deletions

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index acc748e..dfd6fd4 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -1539,6 +1539,16 @@ static void virt_set_gic_version(Object *obj, const char *value, Error **errp)
     }
 }
 
+static CpuInstanceProperties
+virt_cpu_index_to_props(MachineState *ms, unsigned cpu_index)
+{
+    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 *virt_possible_cpu_arch_ids(MachineState *ms)
 {
     int n;
@@ -1558,8 +1568,13 @@ static const CPUArchIdList *virt_possible_cpu_arch_ids(MachineState *ms)
         ms->possible_cpus->cpus[n].props.has_thread_id = true;
         ms->possible_cpus->cpus[n].props.thread_id = n;
 
-        /* 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 */
+            ms->possible_cpus->cpus[n].props.node_id = n % nb_numa_nodes;
+        }
     }
     return ms->possible_cpus;
 }
@@ -1581,6 +1596,7 @@ static void virt_machine_class_init(ObjectClass *oc, void *data)
     /* We know we will never create a pre-ARMv7 CPU which needs 1K pages */
     mc->minimum_page_bits = 12;
     mc->possible_cpu_arch_ids = virt_possible_cpu_arch_ids;
+    mc->cpu_index_to_instance_props = virt_cpu_index_to_props;
 }
 
 static const TypeInfo virt_machine_info = {