[Qemu-devel] [PATCH] spapr: ensure that all threads within core are on the same NUMA node

[Igor Mammedov <imammedo@redhat.com>]

Threads within a core shouldn't be on different
NUMA nodes, so if user has misconfgured command
line, fail QEMU at start up to force user fix it.

For now use the first thread on the core as source
of core's node-id. Later when cpu-numa refactoring
lands  it will be switched to core's node-id from
possible_cpus[].

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
Enforcement is necessary to ensure that it would be
possible to map legacy CPU index based CLI mapping
to core based one and replace numa_info[XXX].node_cpu
with possible_cpus[] as storage for mapping info.

CC: qemu-ppc@nongnu.org
CC: lvivier@redhat.com
CC: David Gibson <david@gibson.dropbear.id.au>
CC: thuth@redhat.com
CC: mdroth@linux.vnet.ibm.com
CC: agraf@suse.de
---
 hw/ppc/spapr_cpu_core.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
index 55cd045..1499a8b 100644
--- a/hw/ppc/spapr_cpu_core.c
+++ b/hw/ppc/spapr_cpu_core.c
@@ -50,8 +50,6 @@ static void spapr_cpu_init(sPAPRMachineState *spapr, PowerPCCPU *cpu,
                            Error **errp)
 {
     CPUPPCState *env = &cpu->env;
-    CPUState *cs = CPU(cpu);
-    int i;
 
     /* Set time-base frequency to 512 MHz */
     cpu_ppc_tb_init(env, SPAPR_TIMEBASE_FREQ);
@@ -70,12 +68,6 @@ static void spapr_cpu_init(sPAPRMachineState *spapr, PowerPCCPU *cpu,
         }
     }
 
-    /* Set NUMA node for the added CPUs  */
-    i = numa_get_node_for_cpu(cs->cpu_index);
-    if (i < nb_numa_nodes) {
-            cs->numa_node = i;
-    }
-
     xics_cpu_setup(spapr->xics, cpu);
 
     qemu_register_reset(spapr_cpu_reset, cpu);
@@ -159,11 +151,13 @@ static void spapr_cpu_core_realize(DeviceState *dev, Error **errp)
     const char *typename = object_class_get_name(scc->cpu_class);
     size_t size = object_type_get_instance_size(typename);
     Error *local_err = NULL;
+    int core_node_id = numa_get_node_for_cpu(cc->core_id);;
     void *obj;
     int i, j;
 
     sc->threads = g_malloc0(size * cc->nr_threads);
     for (i = 0; i < cc->nr_threads; i++) {
+        int node_id;
         char id[32];
         CPUState *cs;
 
@@ -172,6 +166,19 @@ static void spapr_cpu_core_realize(DeviceState *dev, Error **errp)
         object_initialize(obj, size, typename);
         cs = CPU(obj);
         cs->cpu_index = cc->core_id + i;
+
+        /* Set NUMA node for the added CPUs  */
+        node_id = numa_get_node_for_cpu(cs->cpu_index);
+        if (node_id != core_node_id) {
+            error_setg(&local_err, "Invalid node-id=%d of thread[cpu-index: %d]"
+                " on CPU[core-id: %d, node-id: %d], node-id must be the same",
+                 node_id, cs->cpu_index, cc->core_id, core_node_id);
+            goto err;
+        }
+        if (node_id < nb_numa_nodes) {
+            cs->numa_node = node_id;
+        }
+
         snprintf(id, sizeof(id), "thread[%d]", i);
         object_property_add_child(OBJECT(sc), id, obj, &local_err);
         if (local_err) {
-- 
2.7.4