[PATCH 1/6] spapr: add spapr_machine_using_legacy_numa() helper

From: Daniel Henrique Barboza <danielhb413@gmail.com>
To: qemu-devel@nongnu.org
Cc: Daniel Henrique Barboza <danielhb413@gmail.com>,
	qemu-ppc@nongnu.org, david@gibson.dropbear.id.au
Subject: [PATCH 1/6] spapr: add spapr_machine_using_legacy_numa() helper
Date: Wed, 23 Sep 2020 16:34:53 -0300	[thread overview]
Message-ID: <20200923193458.203186-2-danielhb413@gmail.com> (raw)
In-Reply-To: <20200923193458.203186-1-danielhb413@gmail.com>

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: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/ppc/spapr.c         | 12 ++++++++++++
 include/hw/ppc/spapr.h |  2 ++
 2 files changed, 14 insertions(+)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index e813c7cfb9..c5d8910a74 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);
@@ -4522,8 +4531,11 @@ 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);
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 114e819969..d1aae03b97 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -143,6 +143,7 @@ struct SpaprMachineClass {
     bool smp_threads_vsmt; /* set VSMT to smp_threads by default */
     hwaddr rma_limit;          /* clamp the RMA to this size */
     bool pre_5_1_assoc_refpoints;
+    bool pre_5_2_numa_associativity;
 
     void (*phb_placement)(SpaprMachineState *spapr, uint32_t index,
                           uint64_t *buid, hwaddr *pio, 
@@ -860,6 +861,7 @@ int spapr_max_server_number(SpaprMachineState *spapr);
 void spapr_store_hpte(PowerPCCPU *cpu, hwaddr ptex,
                       uint64_t pte0, uint64_t pte1);
 void spapr_mce_req_event(PowerPCCPU *cpu, bool recovered);
+bool spapr_machine_using_legacy_numa(SpaprMachineState *spapr);
 
 /* DRC callbacks. */
 void spapr_core_release(DeviceState *dev);
-- 
2.26.2


