3 files changed, 18 insertions, 7 deletions

diff --git a/arch/mips/include/asm/smp.h b/arch/mips/include/asm/smp.h
index 0c534a03bb36..8bc6c70a4030 100644
--- a/arch/mips/include/asm/smp.h
+++ b/arch/mips/include/asm/smp.h
@@ -23,7 +23,7 @@
 extern int smp_num_siblings;
 extern cpumask_t cpu_sibling_map[];
 extern cpumask_t cpu_core_map[];
-extern cpumask_t cpu_foreign_map;
+extern cpumask_t cpu_foreign_map[];
 
 #define raw_smp_processor_id() (current_thread_info()->cpu)
 
diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
index 783d5f50ab9d..f95f094f36e4 100644
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -72,7 +72,7 @@ EXPORT_SYMBOL(cpu_core_map);
  * A logcal cpu mask containing only one VPE per core to
  * reduce the number of IPIs on large MT systems.
  */
-cpumask_t cpu_foreign_map __read_mostly;
+cpumask_t cpu_foreign_map[NR_CPUS] __read_mostly;
 EXPORT_SYMBOL(cpu_foreign_map);
 
 /* representing cpus for which sibling maps can be computed */
@@ -141,7 +141,9 @@ void calculate_cpu_foreign_map(void)
                         cpumask_set_cpu(i, &temp_foreign_map);
         }
 
-        cpumask_copy(&cpu_foreign_map, &temp_foreign_map);
+        for_each_online_cpu(i)
+                cpumask_andnot(&cpu_foreign_map[i],
+                               &temp_foreign_map, &cpu_sibling_map[i]);
 }
 
 struct plat_smp_ops *mp_ops;
diff --git a/arch/mips/mm/c-r4k.c b/arch/mips/mm/c-r4k.c
index 2a4bb5057ebc..57374f0c33f2 100644
--- a/arch/mips/mm/c-r4k.c
+++ b/arch/mips/mm/c-r4k.c
@@ -56,7 +56,9 @@
  * @type:       Type of cache operations (R4K_HIT or R4K_INDEX).
  *
  * Decides whether a cache op needs to be performed on every core in the system.
- * This may change depending on the @type of cache operation.
+ * This may change depending on the @type of cache operation, as well as the set
+ * of online CPUs, so preemption should be disabled by the caller to prevent CPU
+ * hotplug from changing the result.
  *
  * Returns:     1 if the cache operation @type should be done on every core in
  *              the system.
@@ -71,9 +73,15 @@ static inline bool r4k_op_needs_ipi(unsigned int type)
 
         /*
          * Hardware doesn't globalize the required cache ops, so SMP calls may
-         * be needed.
+         * be needed, but only if there are foreign CPUs (non-siblings with
+         * separate caches).
          */
-        return true;
+        /* cpu_foreign_map[] undeclared when !CONFIG_SMP */
+#ifdef CONFIG_SMP
+        return !cpumask_empty(&cpu_foreign_map[0]);
+#else
+        return false;
+#endif
 }
 
 /*
@@ -90,7 +98,8 @@ static inline void r4k_on_each_cpu(unsigned int type,
 {
         preempt_disable();
         if (r4k_op_needs_ipi(type))
-                smp_call_function_many(&cpu_foreign_map, func, info, 1);
+                smp_call_function_many(&cpu_foreign_map[smp_processor_id()],
+                                       func, info, 1);
         func(info);
         preempt_enable();
 }