linux-kernel - [PATCH V14 1/4] powerpc/vphn: Update CPU topology when VPHN enabled

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Date:   Fri, 8 Sep 2017 15:47:27 -0500
From:   Michael Bringmann <mwb@...ux.vnet.ibm.com>
To:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Cc:     Michael Bringmann <mwb@...ux.vnet.ibm.com>,
        Nathan Fontenot <nfont@...ux.vnet.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        John Allen <jallen@...ux.vnet.ibm.com>
Subject: [PATCH V14 1/4] powerpc/vphn: Update CPU topology when VPHN enabled

powerpc/vphn: On Power systems with shared configurations of CPUs
and memory, there are some issues with the association of additional
CPUs and memory to nodes when hot-adding resources.  This patch
corrects the currently broken capability to set the topology for
shared CPUs in LPARs.  At boot time for shared CPU lpars, the
topology for each CPU was being set to node zero.  Now when
numa_update_cpu_topology() is called appropriately, the Virtual
Processor Home Node (VPHN) capabilities information provided by the
pHyp allows the appropriate node in the shared configuration to be
selected for the CPU.

Signed-off-by: Michael Bringmann <mwb@...ux.vnet.ibm.com>
---
Changes in V14:
  -- Cleanup some duplicate code. Change a trace stmt to debug.
---
 arch/powerpc/mm/numa.c |   22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index b95c584..3ae031d 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -1153,6 +1153,8 @@ struct topology_update_data {
 static int vphn_enabled;
 static int prrn_enabled;
 static void reset_topology_timer(void);
+static int topology_inited;
+static int topology_update_needed;
 
 /*
  * Store the current values of the associativity change counters in the
@@ -1246,6 +1248,10 @@ static long vphn_get_associativity(unsigned long cpu,
 			"hcall_vphn() experienced a hardware fault "
 			"preventing VPHN. Disabling polling...\n");
 		stop_topology_update();
+		break;
+	case H_SUCCESS:
+		dbg("VPHN hcall succeeded. Reset polling...\n");
+		break;
 	}
 
 	return rc;
@@ -1323,8 +1329,11 @@ int numa_update_cpu_topology(bool cpus_locked)
 	struct device *dev;
 	int weight, new_nid, i = 0;
 
-	if (!prrn_enabled && !vphn_enabled)
+	if (!prrn_enabled && !vphn_enabled) {
+		if (!topology_inited)
+			topology_update_needed = 1;
 		return 0;
+	}
 
 	weight = cpumask_weight(&cpu_associativity_changes_mask);
 	if (!weight)
@@ -1363,6 +1372,8 @@ int numa_update_cpu_topology(bool cpus_locked)
 			cpumask_andnot(&cpu_associativity_changes_mask,
 					&cpu_associativity_changes_mask,
 					cpu_sibling_mask(cpu));
+			dbg("Assoc chg gives same node %d for cpu%d\n",
+					new_nid, cpu);
 			cpu = cpu_last_thread_sibling(cpu);
 			continue;
 		}
@@ -1433,6 +1444,7 @@ int numa_update_cpu_topology(bool cpus_locked)
 
 out:
 	kfree(updates);
+	topology_update_needed = 0;
 	return changed;
 }
 
@@ -1613,9 +1625,17 @@ static int topology_update_init(void)
 	if (topology_updates_enabled)
 		start_topology_update();
 
+	if (vphn_enabled)
+		topology_schedule_update();
+
 	if (!proc_create("powerpc/topology_updates", 0644, NULL, &topology_ops))
 		return -ENOMEM;
 
+	topology_inited = 1;
+	if (topology_update_needed)
+		bitmap_fill(cpumask_bits(&cpu_associativity_changes_mask),
+					nr_cpumask_bits);
+
 	return 0;
 }
 device_initcall(topology_update_init);