2 files changed, 9 insertions, 1 deletions

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 15939e872db2..f091c80974c4 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1692,7 +1692,6 @@ static int xen_hvm_cpu_notify(struct notifier_block *self, unsigned long action,
         case CPU_UP_PREPARE:
                 xen_vcpu_setup(cpu);
                 if (xen_have_vector_callback) {
-                        xen_init_lock_cpu(cpu);
                         if (xen_feature(XENFEAT_hvm_safe_pvclock))
                                 xen_setup_timer(cpu);
                 }
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index 9235842cd76a..c21b825ed056 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -709,6 +709,15 @@ static int xen_hvm_cpu_up(unsigned int cpu, struct task_struct *tidle)
         WARN_ON(rc);
         if (!rc)
                 rc =  native_cpu_up(cpu, tidle);
+
+        /*
+         * We must initialize the slowpath CPU kicker _after_ the native
+         * path has executed. If we initialized it before none of the
+         * unlocker IPI kicks would reach the booting CPU as the booting
+         * CPU had not set itself 'online' in cpu_online_mask. That mask
+         * is checked when IPIs are sent (on HVM at least).
+         */
+        xen_init_lock_cpu(cpu);
         return rc;
 }