s390/topology: alternative topology for topology-less machines

[linux-block.git] / arch / s390 / kernel / topology.c

diff --git a/arch/s390/kernel/topology.c b/arch/s390/kernel/topology.c
index bb47c92476f0d852ded0b9b50f9756e46480e9b9..a0ce9c83f58927c0390b8827ff38fcb8cfea03da 100644 (file)
--- a/arch/s390/kernel/topology.c
+++ b/arch/s390/kernel/topology.c
@@ -29,12 +29,20 @@
 #define PTF_VERTICAL   (1UL)
 #define PTF_CHECK      (2UL)
 
+enum {
+       TOPOLOGY_MODE_HW,
+       TOPOLOGY_MODE_SINGLE,
+       TOPOLOGY_MODE_PACKAGE,
+       TOPOLOGY_MODE_UNINITIALIZED
+};
+
 struct mask_info {
        struct mask_info *next;
        unsigned char id;
        cpumask_t mask;
 };
 
+static int topology_mode = TOPOLOGY_MODE_UNINITIALIZED;
 static void set_topology_timer(void);
 static void topology_work_fn(struct work_struct *work);
 static struct sysinfo_15_1_x *tl_info;
@@ -59,11 +67,26 @@ static cpumask_t cpu_group_map(struct mask_info *info, unsigned int cpu)
        cpumask_t mask;
 
        cpumask_copy(&mask, cpumask_of(cpu));
-       if (!MACHINE_HAS_TOPOLOGY)
-               return mask;
-       for (; info; info = info->next) {
-               if (cpumask_test_cpu(cpu, &info->mask))
-                       return info->mask;
+       switch (topology_mode) {
+       case TOPOLOGY_MODE_HW:
+               while (info) {
+                       if (cpumask_test_cpu(cpu, &info->mask)) {
+                               mask = info->mask;
+                               break;
+                       }
+                       info = info->next;
+               }
+               if (cpumask_empty(&mask))
+                       cpumask_copy(&mask, cpumask_of(cpu));
+               break;
+       case TOPOLOGY_MODE_PACKAGE:
+               cpumask_copy(&mask, cpu_present_mask);
+               break;
+       default:
+               /* fallthrough */
+       case TOPOLOGY_MODE_SINGLE:
+               cpumask_copy(&mask, cpumask_of(cpu));
+               break;
        }
        return mask;
 }
@@ -74,7 +97,7 @@ static cpumask_t cpu_thread_map(unsigned int cpu)
        int i;
 
        cpumask_copy(&mask, cpumask_of(cpu));
-       if (!MACHINE_HAS_TOPOLOGY)
+       if (topology_mode != TOPOLOGY_MODE_HW)
                return mask;
        cpu -= cpu % (smp_cpu_mtid + 1);
        for (i = 0; i <= smp_cpu_mtid; i++)
@@ -223,7 +246,7 @@ int topology_set_cpu_management(int fc)
 static void update_cpu_masks(void)
 {
        struct cpu_topology_s390 *topo;
-       int cpu;
+       int cpu, id;
 
        for_each_possible_cpu(cpu) {
                topo = &cpu_topology[cpu];
@@ -231,12 +254,13 @@ static void update_cpu_masks(void)
                topo->core_mask = cpu_group_map(&socket_info, cpu);
                topo->book_mask = cpu_group_map(&book_info, cpu);
                topo->drawer_mask = cpu_group_map(&drawer_info, cpu);
-               if (!MACHINE_HAS_TOPOLOGY) {
+               if (topology_mode != TOPOLOGY_MODE_HW) {
+                       id = topology_mode == TOPOLOGY_MODE_PACKAGE ? 0 : cpu;
                        topo->thread_id = cpu;
                        topo->core_id = cpu;
-                       topo->socket_id = cpu;
-                       topo->book_id = cpu;
-                       topo->drawer_id = cpu;
+                       topo->socket_id = id;
+                       topo->book_id = id;
+                       topo->drawer_id = id;
                        if (cpu_present(cpu))
                                cpumask_set_cpu(cpu, &cpus_with_topology);
                }
@@ -459,6 +483,12 @@ void __init topology_init_early(void)
        struct sysinfo_15_1_x *info;
 
        set_sched_topology(s390_topology);
+       if (topology_mode == TOPOLOGY_MODE_UNINITIALIZED) {
+               if (MACHINE_HAS_TOPOLOGY)
+                       topology_mode = TOPOLOGY_MODE_HW;
+               else
+                       topology_mode = TOPOLOGY_MODE_SINGLE;
+       }
        if (!MACHINE_HAS_TOPOLOGY)
                goto out;
        tl_info = memblock_virt_alloc(PAGE_SIZE, PAGE_SIZE);
@@ -474,6 +504,26 @@ out:
        __arch_update_cpu_topology();
 }
 
+static inline int topology_get_mode(int enabled)
+{
+       if (!enabled)
+               return TOPOLOGY_MODE_SINGLE;
+       return MACHINE_HAS_TOPOLOGY ? TOPOLOGY_MODE_HW : TOPOLOGY_MODE_PACKAGE;
+}
+
+static int __init topology_setup(char *str)
+{
+       bool enabled;
+       int rc;
+
+       rc = kstrtobool(str, &enabled);
+       if (rc)
+               return rc;
+       topology_mode = topology_get_mode(enabled);
+       return 0;
+}
+early_param("topology", topology_setup);
+
 static int __init topology_init(void)
 {
        if (MACHINE_HAS_TOPOLOGY)