Re: [Xen-devel] [PATCH v2] x86: show remote CPU state upon fatal NMI or unknown MCE

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 16/06/16 12:26, Jan Beulich wrote:
> @@ -570,6 +589,15 @@ void fatal_trap(const struct cpu_user_re
>              printk("Faulting linear address: %p\n", _p(cr2));
>              show_page_walk(cr2);
>          }
> +        if ( show_remote )
> +        {
> +            cpumask_andnot(&show_state_mask, &cpu_online_map,
> +                           cpumask_of(smp_processor_id()));
> +            set_nmi_callback(nmi_show_execution_state);
> +            smp_send_nmi_allbutself();
> +            while ( !cpumask_empty(&show_state_mask) )
> +                cpu_relax();

Sorry about not noticing this before.  We need a maximum timeout here,
just like the nmi shootdown, in case one of the other cpus is already
stuck in an NMI handler, so we block the reboot/kexec.

With that fixed, Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

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