1 files changed, 33 insertions, 14 deletions

diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
index 43514f905916..b6ee26b0939a 100644
--- a/arch/arm64/kernel/topology.c
+++ b/arch/arm64/kernel/topology.c
@@ -20,6 +20,7 @@
 #include <linux/of.h>
 #include <linux/sched.h>
 
+#include <asm/cputype.h>
 #include <asm/topology.h>
 
 static int __init get_cpu_for_node(struct device_node *node)
@@ -188,13 +189,9 @@ static int __init parse_dt_topology(void)
 	 * Check that all cores are in the topology; the SMP code will
 	 * only mark cores described in the DT as possible.
 	 */
-	for_each_possible_cpu(cpu) {
-		if (cpu_topology[cpu].cluster_id == -1) {
-			pr_err("CPU%d: No topology information specified\n",
-			       cpu);
+	for_each_possible_cpu(cpu)
+		if (cpu_topology[cpu].cluster_id == -1)
 			ret = -EINVAL;
-		}
-	}
 
 out_map:
 	of_node_put(map);
@@ -219,14 +216,6 @@ static void update_siblings_masks(unsigned int cpuid)
 	struct cpu_topology *cpu_topo, *cpuid_topo = &cpu_topology[cpuid];
 	int cpu;
 
-	if (cpuid_topo->cluster_id == -1) {
-		/*
-		 * DT does not contain topology information for this cpu.
-		 */
-		pr_debug("CPU%u: No topology information configured\n", cpuid);
-		return;
-	}
-
 	/* update core and thread sibling masks */
 	for_each_possible_cpu(cpu) {
 		cpu_topo = &cpu_topology[cpu];
@@ -249,6 +238,36 @@ static void update_siblings_masks(unsigned int cpuid)
 
 void store_cpu_topology(unsigned int cpuid)
 {
+	struct cpu_topology *cpuid_topo = &cpu_topology[cpuid];
+	u64 mpidr;
+
+	if (cpuid_topo->cluster_id != -1)
+		goto topology_populated;
+
+	mpidr = read_cpuid_mpidr();
+
+	/* Uniprocessor systems can rely on default topology values */
+	if (mpidr & MPIDR_UP_BITMASK)
+		return;
+
+	/* Create cpu topology mapping based on MPIDR. */
+	if (mpidr & MPIDR_MT_BITMASK) {
+		/* Multiprocessor system : Multi-threads per core */
+		cpuid_topo->thread_id  = MPIDR_AFFINITY_LEVEL(mpidr, 0);
+		cpuid_topo->core_id    = MPIDR_AFFINITY_LEVEL(mpidr, 1);
+		cpuid_topo->cluster_id = MPIDR_AFFINITY_LEVEL(mpidr, 2);
+	} else {
+		/* Multiprocessor system : Single-thread per core */
+		cpuid_topo->thread_id  = -1;
+		cpuid_topo->core_id    = MPIDR_AFFINITY_LEVEL(mpidr, 0);
+		cpuid_topo->cluster_id = MPIDR_AFFINITY_LEVEL(mpidr, 1);
+	}
+
+	pr_debug("CPU%u: cluster %d core %d thread %d mpidr %#016llx\n",
+		 cpuid, cpuid_topo->cluster_id, cpuid_topo->core_id,
+		 cpuid_topo->thread_id, mpidr);
+
+topology_populated:
 	update_siblings_masks(cpuid);
 }