spapr_numa: forbid asymmetrical NUMA setups

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>
Message-Id: <20201007172849.302240-3-danielhb413@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

diff --git a/hw/ppc/spapr_numa.c b/hw/ppc/spapr_numa.c
index 64fe567f5db69634a9144feb76021eac12ea6e06..fe395e80a3369ac2f0a17e4e2d5501838388f4c3 100644 (file)
--- 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,