3 files changed, 70 insertions, 0 deletions

diff --git a/include/linux/smp.h b/include/linux/smp.h
index eccae4690f41..8e0cb7a0f836 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -196,6 +196,9 @@ extern void arch_enable_nonboot_cpus_end(void);
 
 void smp_setup_processor_id(void);
 
+int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par,
+                    bool phys);
+
 /* SMP core functions */
 int smpcfd_prepare_cpu(unsigned int cpu);
 int smpcfd_dead_cpu(unsigned int cpu);
diff --git a/kernel/smp.c b/kernel/smp.c
index 4274ca5f3bbc..f4f6137941cb 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -725,3 +725,53 @@ void wake_up_all_idle_cpus(void)
         preempt_enable();
 }
 EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);
+
+/**
+ * smp_call_on_cpu - Call a function on a specific cpu
+ *
+ * Used to call a function on a specific cpu and wait for it to return.
+ * Optionally make sure the call is done on a specified physical cpu via vcpu
+ * pinning in order to support virtualized environments.
+ */
+struct smp_call_on_cpu_struct {
+        struct work_struct      work;
+        struct completion       done;
+        int                     (*func)(void *);
+        void                    *data;
+        int                     ret;
+        int                     cpu;
+};
+
+static void smp_call_on_cpu_callback(struct work_struct *work)
+{
+        struct smp_call_on_cpu_struct *sscs;
+
+        sscs = container_of(work, struct smp_call_on_cpu_struct, work);
+        if (sscs->cpu >= 0)
+                hypervisor_pin_vcpu(sscs->cpu);
+        sscs->ret = sscs->func(sscs->data);
+        if (sscs->cpu >= 0)
+                hypervisor_pin_vcpu(-1);
+
+        complete(&sscs->done);
+}
+
+int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys)
+{
+        struct smp_call_on_cpu_struct sscs = {
+                .work = __WORK_INITIALIZER(sscs.work, smp_call_on_cpu_callback),
+                .done = COMPLETION_INITIALIZER_ONSTACK(sscs.done),
+                .func = func,
+                .data = par,
+                .cpu  = phys ? cpu : -1,
+        };
+
+        if (cpu >= nr_cpu_ids || !cpu_online(cpu))
+                return -ENXIO;
+
+        queue_work_on(cpu, system_wq, &sscs.work);
+        wait_for_completion(&sscs.done);
+
+        return sscs.ret;
+}
+EXPORT_SYMBOL_GPL(smp_call_on_cpu);
diff --git a/kernel/up.c b/kernel/up.c
index 3ccee2bd13ba..ee81ac9af4ca 100644
--- a/kernel/up.c
+++ b/kernel/up.c
@@ -83,3 +83,20 @@ void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info),
         preempt_enable();
 }
 EXPORT_SYMBOL(on_each_cpu_cond);
+
+int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys)
+{
+        int ret;
+
+        if (cpu != 0)
+                return -ENXIO;
+
+        if (phys)
+                hypervisor_pin_vcpu(0);
+        ret = func(par);
+        if (phys)
+                hypervisor_pin_vcpu(-1);
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(smp_call_on_cpu);