Re: [Xen-devel] [PATCH 7/9] xen/spinlock: Disable IRQ spinlock (PV) allocation on PVHVM

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Tue, 16 Apr 2013, Konrad Rzeszutek Wilk wrote:
> See git commit f10cd522c5fbfec9ae3cc01967868c9c2401ed23
> (xen: disable PV spinlocks on HVM) for details.
> 
> But we did not disable it everywhere - which means that when
> we boot as PVHVM we end up allocating per-CPU irq line for
> spinlock. This fixes that.
> 
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

Is there any point in calling xen_init_lock_cpu in PVHVM guests?
At that point we might as well remove the call from xen_hvm_cpu_notify.


>  arch/x86/xen/spinlock.c | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
> index 47ae032..8b54603 100644
> --- a/arch/x86/xen/spinlock.c
> +++ b/arch/x86/xen/spinlock.c
> @@ -367,6 +367,13 @@ void __cpuinit xen_init_lock_cpu(int cpu)
>       WARN(per_cpu(lock_kicker_irq, cpu) > 0, "spinlock on CPU%d exists on 
> IRQ%d!\n",
>            cpu, per_cpu(lock_kicker_irq, cpu));
>  
> +     /*
> +      * See git commit f10cd522c5fbfec9ae3cc01967868c9c2401ed23
> +      * (xen: disable PV spinlocks on HVM)
> +      */
> +     if (xen_hvm_domain())
> +             return;
> +
>       name = kasprintf(GFP_KERNEL, "spinlock%d", cpu);
>       irq = bind_ipi_to_irqhandler(XEN_SPIN_UNLOCK_VECTOR,
>                                    cpu,
> @@ -385,12 +392,26 @@ void __cpuinit xen_init_lock_cpu(int cpu)
>  
>  void xen_uninit_lock_cpu(int cpu)
>  {
> +     /*
> +      * See git commit f10cd522c5fbfec9ae3cc01967868c9c2401ed23
> +      * (xen: disable PV spinlocks on HVM)
> +      */
> +     if (xen_hvm_domain())
> +             return;
> +
>       unbind_from_irqhandler(per_cpu(lock_kicker_irq, cpu), NULL);
>       per_cpu(lock_kicker_irq, cpu) = -1;
>  }
>  
>  void __init xen_init_spinlocks(void)
>  {
> +     /*
> +      * See git commit f10cd522c5fbfec9ae3cc01967868c9c2401ed23
> +      * (xen: disable PV spinlocks on HVM)
> +      */
> +     if (xen_hvm_domain())
> +             return;
> +
>       BUILD_BUG_ON(sizeof(struct xen_spinlock) > sizeof(arch_spinlock_t));
>  
>       pv_lock_ops.spin_is_locked = xen_spin_is_locked;
> -- 
> 1.8.1.4
> 

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