linux-kernel - [PATCH tip v2] x86/paravirt: Make the virt_spin_lock_key setup after jump_label

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Date:   Sat, 28 Oct 2017 14:06:44 +0800
From:   Dou Liyang <douly.fnst@...fujitsu.com>
To:     <linux-kernel@...r.kernel.org>, <x86@...nel.org>,
        <xen-devel@...ts.xenproject.org>
CC:     <tglx@...utronix.de>, <mingo@...hat.com>, <hpa@...or.com>,
        <jgross@...e.com>, <boris.ostrovsky@...cle.com>, <bp@...e.de>,
        <luto@...nel.org>, <vkuznets@...hat.com>,
        Dou Liyang <douly.fnst@...fujitsu.com>
Subject: [PATCH tip v2] x86/paravirt: Make the virt_spin_lock_key setup after jump_label_init()

Commit:

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

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

Move the native_pv_lock_init() into native_smp_prepare_cpus(), and set
the value in xen_init_lock_cpu() to make the setup later and avoid the
WARN().

Reported-by: Juergen Gross <jgross@...e.com>
Suggested-by: Juergen Gross <jgross@...e.com>
Signed-off-by: Dou Liyang <douly.fnst@...fujitsu.com>
Reviewed-by: Juergen Gross <jgross@...e.com>
---
changelog:
  v1-->v2: remove the native_pv_lock_init() from xen_pv_smp_prepare_cpus(),
  It is redundant, suggested by Juergen.

---
 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 aed1460..6b1335a 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1323,6 +1323,8 @@ 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();
@@ -1350,7 +1352,6 @@ 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");
-- 
2.5.5