1 files changed, 44 insertions, 0 deletions

diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c
index 2f355d229a58..e5ecd20e72dd 100644
--- a/arch/x86/kernel/pvclock.c
+++ b/arch/x86/kernel/pvclock.c
@@ -141,7 +141,46 @@ void pvclock_read_wallclock(struct pvclock_wall_clock *wall_clock,
         set_normalized_timespec(ts, now.tv_sec, now.tv_nsec);
 }
 
+static struct pvclock_vsyscall_time_info *pvclock_vdso_info;
+
+static struct pvclock_vsyscall_time_info *
+pvclock_get_vsyscall_user_time_info(int cpu)
+{
+        if (!pvclock_vdso_info) {
+                BUG();
+                return NULL;
+        }
+
+        return &pvclock_vdso_info[cpu];
+}
+
+struct pvclock_vcpu_time_info *pvclock_get_vsyscall_time_info(int cpu)
+{
+        return &pvclock_get_vsyscall_user_time_info(cpu)->pvti;
+}
+
 #ifdef CONFIG_X86_64
+static int pvclock_task_migrate(struct notifier_block *nb, unsigned long l,
+                                void *v)
+{
+        struct task_migration_notifier *mn = v;
+        struct pvclock_vsyscall_time_info *pvti;
+
+        pvti = pvclock_get_vsyscall_user_time_info(mn->from_cpu);
+
+        /* this is NULL when pvclock vsyscall is not initialized */
+        if (unlikely(pvti == NULL))
+                return NOTIFY_DONE;
+
+        pvti->migrate_count++;
+
+        return NOTIFY_DONE;
+}
+
+static struct notifier_block pvclock_migrate = {
+        .notifier_call = pvclock_task_migrate,
+};
+
 /*
  * Initialize the generic pvclock vsyscall state.  This will allocate
  * a/some page(s) for the per-vcpu pvclock information, set up a
@@ -155,12 +194,17 @@ int __init pvclock_init_vsyscall(struct pvclock_vsyscall_time_info *i,
 
         WARN_ON (size != PVCLOCK_VSYSCALL_NR_PAGES*PAGE_SIZE);
 
+        pvclock_vdso_info = i;
+
         for (idx = 0; idx <= (PVCLOCK_FIXMAP_END-PVCLOCK_FIXMAP_BEGIN); idx++) {
                 __set_fixmap(PVCLOCK_FIXMAP_BEGIN + idx,
                              __pa(i) + (idx*PAGE_SIZE),
                              PAGE_KERNEL_VVAR);
         }
 
+
+        register_task_migration_notifier(&pvclock_migrate);
+
         return 0;
 }
 #endif