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

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Date:   Fri, 27 Oct 2017 18:52:03 +0200
From:   Boris Petkov <bp@...e.de>
To:     Dou Liyang <douly.fnst@...fujitsu.com>,
        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, luto@...nel.org,
        vkuznets@...hat.com
Subject: Re: [PATCH][tip] x86/paravirt: Make the virt_spin_lock_key setup after jump_label_init()

On October 27, 2017 6:02:00 PM GMT+02:00, Dou Liyang <douly.fnst@...fujitsu.com> wrote:
>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 xx_smp_prepare_cpus(). Make the
>setup later to 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>
>---
> arch/x86/kernel/smpboot.c | 3 ++-
> arch/x86/xen/smp_pv.c     | 2 ++
> arch/x86/xen/spinlock.c   | 6 ++++--
> 3 files changed, 8 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/smp_pv.c b/arch/x86/xen/smp_pv.c
>index 5147140..570b2bc 100644
>--- a/arch/x86/xen/smp_pv.c
>+++ b/arch/x86/xen/smp_pv.c
>@@ -236,6 +236,8 @@ static void __init xen_pv_smp_prepare_cpus(unsigned
>int max_cpus)
> 		xen_raw_printk(m);
> 		panic(m);
> 	}
>+	native_pv_lock_init();
>+
> 	xen_init_lock_cpu(0);
> 
> 	smp_store_boot_cpu_info();
>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);

This is assuming CPU 0 is the boot cpu. I think you want boot_cpu_data.cpu_index here or whatever is used on xen to identify the BSP reliably. 


-- 
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