spapr: add spapr_machine_using_legacy_numa() helper

The changes to come to NUMA support are all guest visible. In
theory we could just create a new 5_1 class option flag to
avoid the changes to cascade to 5.1 and under. The reality is that
these changes are only relevant if the machine has more than one
NUMA node. There is no need to change guest behavior that has
been around for years needlesly.

This new helper will be used by the next patches to determine
whether we should retain the (soon to be) legacy NUMA behavior
in the pSeries machine. The new behavior will only be exposed
if:

- machine is pseries-5.2 and newer;
- more than one NUMA node is declared in NUMA state.

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: <20201007172849.302240-2-danielhb413@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 12 insertions, 0 deletions

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 4256794f3b..63315f2d0f 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -294,6 +294,15 @@ static hwaddr spapr_node0_size(MachineState *machine)
     return machine->ram_size;
 }
 
+bool spapr_machine_using_legacy_numa(SpaprMachineState *spapr)
+{
+    MachineState *machine = MACHINE(spapr);
+    SpaprMachineClass *smc = SPAPR_MACHINE_GET_CLASS(machine);
+
+    return smc->pre_5_2_numa_associativity ||
+           machine->numa_state->num_nodes <= 1;
+}
+
 static void add_str(GString *s, const gchar *s1)
 {
     g_string_append_len(s, s1, strlen(s1) + 1);
@@ -4519,8 +4528,11 @@ DEFINE_SPAPR_MACHINE(5_2, "5.2", true);
  */
 static void spapr_machine_5_1_class_options(MachineClass *mc)
 {
+    SpaprMachineClass *smc = SPAPR_MACHINE_CLASS(mc);
+
     spapr_machine_5_2_class_options(mc);
     compat_props_add(mc->compat_props, hw_compat_5_1, hw_compat_5_1_len);
+    smc->pre_5_2_numa_associativity = true;
 }
 
 DEFINE_SPAPR_MACHINE(5_1, "5.1", false);