1 files changed, 135 insertions, 13 deletions

diff --git a/arch/s390/kernel/topology.c b/arch/s390/kernel/topology.c
index bb47c92476f0..ed0bdd220e1a 100644
--- a/arch/s390/kernel/topology.c
+++ b/arch/s390/kernel/topology.c
@@ -8,6 +8,8 @@
 
 #include <linux/workqueue.h>
 #include <linux/bootmem.h>
+#include <linux/uaccess.h>
+#include <linux/sysctl.h>
 #include <linux/cpuset.h>
 #include <linux/device.h>
 #include <linux/export.h>
@@ -29,12 +31,20 @@
 #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 +69,26 @@ 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 +99,7 @@ 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++)
@@ -184,10 +209,8 @@ static void topology_update_polarization_simple(void)
 {
         int cpu;
 
-        mutex_lock(&smp_cpu_state_mutex);
         for_each_possible_cpu(cpu)
                 smp_cpu_set_polarization(cpu, POLARIZATION_HRZ);
-        mutex_unlock(&smp_cpu_state_mutex);
 }
 
 static int ptf(unsigned long fc)
@@ -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);
                 }
@@ -254,6 +278,7 @@ static int __arch_update_cpu_topology(void)
         struct sysinfo_15_1_x *info = tl_info;
         int rc = 0;
 
+        mutex_lock(&smp_cpu_state_mutex);
         cpumask_clear(&cpus_with_topology);
         if (MACHINE_HAS_TOPOLOGY) {
                 rc = 1;
@@ -263,6 +288,7 @@ static int __arch_update_cpu_topology(void)
         update_cpu_masks();
         if (!MACHINE_HAS_TOPOLOGY)
                 topology_update_polarization_simple();
+        mutex_unlock(&smp_cpu_state_mutex);
         return rc;
 }
 
@@ -289,6 +315,11 @@ void topology_schedule_update(void)
         schedule_work(&topology_work);
 }
 
+static void topology_flush_work(void)
+{
+        flush_work(&topology_work);
+}
+
 static void topology_timer_fn(unsigned long ignored)
 {
         if (ptf(PTF_CHECK))
@@ -459,6 +490,12 @@ 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);
@@ -474,12 +511,97 @@ 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 inline int topology_is_enabled(void)
+{
+        return topology_mode != TOPOLOGY_MODE_SINGLE;
+}
+
+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 topology_ctl_handler(struct ctl_table *ctl, int write,
+                                void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+        unsigned int len;
+        int new_mode;
+        char buf[2];
+
+        if (!*lenp || *ppos) {
+                *lenp = 0;
+                return 0;
+        }
+        if (!write) {
+                strncpy(buf, topology_is_enabled() ? "1\n" : "0\n",
+                        ARRAY_SIZE(buf));
+                len = strnlen(buf, ARRAY_SIZE(buf));
+                if (len > *lenp)
+                        len = *lenp;
+                if (copy_to_user(buffer, buf, len))
+                        return -EFAULT;
+                goto out;
+        }
+        len = *lenp;
+        if (copy_from_user(buf, buffer, len > sizeof(buf) ? sizeof(buf) : len))
+                return -EFAULT;
+        if (buf[0] != '0' && buf[0] != '1')
+                return -EINVAL;
+        mutex_lock(&smp_cpu_state_mutex);
+        new_mode = topology_get_mode(buf[0] == '1');
+        if (topology_mode != new_mode) {
+                topology_mode = new_mode;
+                topology_schedule_update();
+        }
+        mutex_unlock(&smp_cpu_state_mutex);
+        topology_flush_work();
+out:
+        *lenp = len;
+        *ppos += len;
+        return 0;
+}
+
+static struct ctl_table topology_ctl_table[] = {
+        {
+                .procname       = "topology",
+                .mode           = 0644,
+                .proc_handler   = topology_ctl_handler,
+        },
+        { },
+};
+
+static struct ctl_table topology_dir_table[] = {
+        {
+                .procname       = "s390",
+                .maxlen         = 0,
+                .mode           = 0555,
+                .child          = topology_ctl_table,
+        },
+        { },
+};
+
 static int __init topology_init(void)
 {
         if (MACHINE_HAS_TOPOLOGY)
                 set_topology_timer();
         else
                 topology_update_polarization_simple();
+        register_sysctl_table(topology_dir_table);
         return device_create_file(cpu_subsys.dev_root, &dev_attr_dispatching);
 }
 device_initcall(topology_init);