[tip:locking/core] x86/paravirt: Set up the virt_spin_lock_key after static keys get initialized

[tip-bot for Dou Liyang]

Commit-ID:  ca5d376e17072c1b60c3fee66f3be58ef018952d
Gitweb:     https://git.kernel.org/tip/ca5d376e17072c1b60c3fee66f3be58ef018952d
Author:     Dou Liyang <douly.fnst@xxxxxxxxxxxxxx>
AuthorDate: Sat, 28 Oct 2017 14:06:44 +0800
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 30 Oct 2017 09:17:29 +0100

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@xxxxxxxx>
Reported-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Dou Liyang <douly.fnst@xxxxxxxxxxxxxx>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
Acked-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: boris.ostrovsky@xxxxxxxxxx
Cc: bp@xxxxxxx
Cc: luto@xxxxxxxxxx
Cc: vkuznets@xxxxxxxxxx
Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1509170804-3813-1-git-send-email-douly.fnst@xxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/kernel/smpboot.c | 3 ++-
 arch/x86/xen/spinlock.c   | 6 ++++--
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 361f916..198416d 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 e8ab80a..1e1462d 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");