diff mbox series

[v4,2/5] spapr_numa: forbid asymmetrical NUMA setups

Message ID 20201007172849.302240-3-danielhb413@gmail.com
State Superseded
Headers show
Series pseries NUMA distance calculation | expand

Commit Message

Daniel Henrique Barboza Oct. 7, 2020, 5:28 p.m. UTC 
The pSeries machine does not support asymmetrical NUMA
configurations. This doesn't make much of a different
since we're not using user input for pSeries NUMA setup,
but this will change in the next patches.

To avoid breaking existing setups, gate this change by
checking for legacy NUMA support.

Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/ppc/spapr_numa.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)
diff mbox series

Patch

diff --git a/hw/ppc/spapr_numa.c b/hw/ppc/spapr_numa.c
index 64fe567f5d..fe395e80a3 100644
--- a/hw/ppc/spapr_numa.c
+++ b/hw/ppc/spapr_numa.c
@@ -19,6 +19,24 @@ 
 /* Moved from hw/ppc/spapr_pci_nvlink2.c */
 #define SPAPR_GPU_NUMA_ID           (cpu_to_be32(1))
 
+static bool spapr_numa_is_symmetrical(MachineState *ms)
+{
+    int src, dst;
+    int nb_numa_nodes = ms->numa_state->num_nodes;
+    NodeInfo *numa_info = ms->numa_state->nodes;
+
+    for (src = 0; src < nb_numa_nodes; src++) {
+        for (dst = src; dst < nb_numa_nodes; dst++) {
+            if (numa_info[src].distance[dst] !=
+                numa_info[dst].distance[src]) {
+                return false;
+            }
+        }
+    }
+
+    return true;
+}
+
 void spapr_numa_associativity_init(SpaprMachineState *spapr,
                                    MachineState *machine)
 {
@@ -61,6 +79,22 @@  void spapr_numa_associativity_init(SpaprMachineState *spapr,
 
         spapr->numa_assoc_array[i][MAX_DISTANCE_REF_POINTS] = cpu_to_be32(i);
     }
+
+    /*
+     * Legacy NUMA guests (pseries-5.1 and older, or guests with only
+     * 1 NUMA node) will not benefit from anything we're going to do
+     * after this point.
+     */
+    if (spapr_machine_using_legacy_numa(spapr)) {
+        return;
+    }
+
+    if (!spapr_numa_is_symmetrical(machine)) {
+        error_report("Asymmetrical NUMA topologies aren't supported "
+                     "in the pSeries machine");
+        exit(EXIT_FAILURE);
+    }
+
 }
 
 void spapr_numa_write_associativity_dt(SpaprMachineState *spapr, void *fdt,