Re: [Xen-devel] [Bugfix] x86/apic: Fix xen IRQ allocation failure caused by commit b81975eade8c

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Wed, Jan 07, 2015 at 11:37:52PM +0800, Jiang Liu wrote:
> On 2015/1/7 22:50, Konrad Rzeszutek Wilk wrote:
> > On Wed, Jan 07, 2015 at 02:13:49PM +0800, Jiang Liu wrote:
> >> Commit b81975eade8c ("x86, irq: Clean up irqdomain transition code")
> >> breaks xen IRQ allocation because xen_smp_prepare_cpus() doesn't invoke
> >> setup_IO_APIC(), so no irqdomains created for IOAPICs and
> >> mp_map_pin_to_irq() fails at the very beginning.
> >> --- a/arch/x86/kernel/apic/io_apic.c
> >> +++ b/arch/x86/kernel/apic/io_apic.c
> >> @@ -2369,31 +2369,29 @@ static void ioapic_destroy_irqdomain(int idx)
> >>    ioapics[idx].pin_info = NULL;
> >>  }
> >>  
> >> -void __init setup_IO_APIC(void)
> >> +void __init setup_IO_APIC(bool xen_smp)
> >>  {
> >>    int ioapic;
> >>  
> >> -  /*
> >> -   * calling enable_IO_APIC() is moved to setup_local_APIC for BP
> >> -   */
> >> -  io_apic_irqs = nr_legacy_irqs() ? ~PIC_IRQS : ~0UL;
> >> +  if (!xen_smp) {
> >> +          apic_printk(APIC_VERBOSE, "ENABLING IO-APIC IRQs\n");
> >> +          io_apic_irqs = nr_legacy_irqs() ? ~PIC_IRQS : ~0UL;
> >> +
> >> +          /* Set up IO-APIC IRQ routing. */
> >> +          x86_init.mpparse.setup_ioapic_ids();
> >> +          sync_Arb_IDs();
> >> +  }
> > 
> > 
> > Is there a specific reason that this cannot run in all cases?
> > 
> > What I am asking is why are we doing a special case here? The description
> > at the top implied that we were just missing an call to
> > setup_IO_APIC.. 
> Hi Konrad,
>       I'm not very familiar with Xen IRQ yet, so I just enabled the
> code to create irqdomains for IOAPICs and keep other part as is. I will
> try to check whether we could enable other part all together:)

If you want you can (privately) send me (or Sander) and patch that I would
be happy to test out. It is quite amusing that I have not used the power
button for quite a while  - I always rebooting the machine to install
a new kernel :-)

> Regards!
> Gerry
> 
> > 
> >>  
> >> -  apic_printk(APIC_VERBOSE, "ENABLING IO-APIC IRQs\n");
> >>    for_each_ioapic(ioapic)
> >>            BUG_ON(mp_irqdomain_create(ioapic));
> >> -
> >> -  /*
> >> -         * Set up IO-APIC IRQ routing.
> >> -         */
> >> -  x86_init.mpparse.setup_ioapic_ids();
> >> -
> >> -  sync_Arb_IDs();
> >>    setup_IO_APIC_irqs();
> >> -  init_IO_APIC_traps();
> >> -  if (nr_legacy_irqs())
> >> -          check_timer();
> >> -
> >>    ioapic_initialized = 1;
> >> +
> >> +  if (!xen_smp) {
> >> +          init_IO_APIC_traps();
> >> +          if (nr_legacy_irqs())
> >> +                  check_timer();
> >> +  }
> >>  }
> >>  
> >>  /*
> >> diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
> >> index 4c071aeb8417..7eb0283901fa 100644
> >> --- a/arch/x86/xen/smp.c
> >> +++ b/arch/x86/xen/smp.c
> >> @@ -326,7 +326,10 @@ static void __init xen_smp_prepare_cpus(unsigned int 
> >> max_cpus)
> >>  
> >>            xen_raw_printk(m);
> >>            panic(m);
> >> +  } else {
> >> +          setup_IO_APIC(true);
> >>    }
> >> +
> >>    xen_init_lock_cpu(0);
> >>  
> >>    smp_store_boot_cpu_info();
> >> -- 
> >> 1.7.10.4
> >>
> > --
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