Re: [PATCH 8/9] xen/smp/pvhvm: Don't initialize IRQ_WORKER as we areusing the native one.

From: Konrad Rzeszutek Wilk
Date: Mon Apr 29 2013 - 14:34:19 EST


On Fri, Apr 26, 2013 at 05:27:20PM +0100, Stefano Stabellini wrote:
> On Tue, 16 Apr 2013, Konrad Rzeszutek Wilk wrote:
> > There is no need to use the PV version of the IRQ_WORKER mechanism
> > as under PVHVM we are using the native version. The native
> > version is using the SMP API.
> >
> > They just sit around unused:
> >
> > 69: 0 0 xen-percpu-ipi irqwork0
> > 83: 0 0 xen-percpu-ipi irqwork1
> >
> > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
>
> Might be worth trying to make it work instead?
> Is it just because we don't set the apic->send_IPI_* functions to the
> xen specific version on PVHVM?
>

Right. We use the baremetal mechanism to do it. And it works fine.

>
> > arch/x86/xen/smp.c | 13 ++++++++++++-
> > 1 file changed, 12 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
> > index 22c800a..415694c 100644
> > --- a/arch/x86/xen/smp.c
> > +++ b/arch/x86/xen/smp.c
> > @@ -144,6 +144,13 @@ static int xen_smp_intr_init(unsigned int cpu)
> > goto fail;
> > per_cpu(xen_callfuncsingle_irq, cpu) = rc;
> >
> > + /*
> > + * The IRQ worker on PVHVM goes through the native path and uses the
> > + * IPI mechanism.
> > + */
> > + if (xen_hvm_domain())
> > + return 0;
> > +
> > callfunc_name = kasprintf(GFP_KERNEL, "irqwork%d", cpu);
> > rc = bind_ipi_to_irqhandler(XEN_IRQ_WORK_VECTOR,
> > cpu,
> > @@ -167,6 +174,9 @@ static int xen_smp_intr_init(unsigned int cpu)
> > if (per_cpu(xen_callfuncsingle_irq, cpu) >= 0)
> > unbind_from_irqhandler(per_cpu(xen_callfuncsingle_irq, cpu),
> > NULL);
> > + if (xen_hvm_domain())
> > + return rc;
> > +
> > if (per_cpu(xen_irq_work, cpu) >= 0)
> > unbind_from_irqhandler(per_cpu(xen_irq_work, cpu), NULL);
> >
> > @@ -661,7 +671,8 @@ static void xen_hvm_cpu_die(unsigned int cpu)
> > unbind_from_irqhandler(per_cpu(xen_callfunc_irq, cpu), NULL);
> > unbind_from_irqhandler(per_cpu(xen_debug_irq, cpu), NULL);
> > unbind_from_irqhandler(per_cpu(xen_callfuncsingle_irq, cpu), NULL);
> > - unbind_from_irqhandler(per_cpu(xen_irq_work, cpu), NULL);
> > + if (!xen_hvm_domain())
> > + unbind_from_irqhandler(per_cpu(xen_irq_work, cpu), NULL);
> > xen_uninit_lock_cpu(cpu);
> > xen_teardown_timer(cpu);
> > native_cpu_die(cpu);
> > --
> > 1.8.1.4
> >
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