Re: [PATCH 7/9] xen/spinlock: Disable IRQ spinlock (PV) allocationon PVHVM

From: Konrad Rzeszutek Wilk
Date: Mon Apr 29 2013 - 14:35:08 EST


On Fri, Apr 26, 2013 at 05:20:23PM +0100, Stefano Stabellini wrote:
> 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?

I was thinking about it.. but I still have hope that I will be able to
take Jeremy's patches for paravirt locking and redo them a bit.

> 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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