x86/paravirt: Set up the virt_spin_lock_key after static keys get initialized

Commit:

  9043442b43b1 ("locking/paravirt: Use new static key for controlling call of virt_spin_lock()")

sets the static virt_spin_lock_key to a value before jump_label_init()
has been called, which will result in a WARN().

Reorder the initialization sequence:

 - Move the native_pv_lock_init() into native_smp_prepare_cpus()
 - set the value in xen_init_lock_cpu()

to avoid calling into the not yet initialized static keys subsystem.

Suggested-by: Juergen Gross <jgross@suse.com>
Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Dou Liyang <douly.fnst@cn.fujitsu.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: boris.ostrovsky@oracle.com
Cc: bp@suse.de
Cc: luto@kernel.org
Cc: vkuznets@redhat.com
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1509170804-3813-1-git-send-email-douly.fnst@cn.fujitsu.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 6 insertions, 3 deletions

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 361f91674ce5..198416ddff01 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1358,6 +1358,8 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
         pr_info("CPU0: ");
         print_cpu_info(&cpu_data(0));
 
+        native_pv_lock_init();
+
         uv_system_init();
 
         set_mtrr_aps_delayed_init();
@@ -1385,7 +1387,6 @@ void __init native_smp_prepare_boot_cpu(void)
         /* already set me in cpu_online_mask in boot_cpu_init() */
         cpumask_set_cpu(me, cpu_callout_mask);
         cpu_set_state_online(me);
-        native_pv_lock_init();
 }
 
 void __init native_smp_cpus_done(unsigned int max_cpus)
diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
index e8ab80ad7a6f..1e1462d3d43e 100644
--- a/arch/x86/xen/spinlock.c
+++ b/arch/x86/xen/spinlock.c
@@ -81,8 +81,11 @@ void xen_init_lock_cpu(int cpu)
         int irq;
         char *name;
 
-        if (!xen_pvspin)
+        if (!xen_pvspin) {
+                if (cpu == 0)
+                        static_branch_disable(&virt_spin_lock_key);
                 return;
+        }
 
         WARN(per_cpu(lock_kicker_irq, cpu) >= 0, "spinlock on CPU%d exists on IRQ%d!\n",
              cpu, per_cpu(lock_kicker_irq, cpu));
@@ -130,7 +133,6 @@ void __init xen_init_spinlocks(void)
 
         if (!xen_pvspin) {
                 printk(KERN_DEBUG "xen: PV spinlocks disabled\n");
-                static_branch_disable(&virt_spin_lock_key);
                 return;
         }
         printk(KERN_DEBUG "xen: PV spinlocks enabled\n");