Re: [Xen-devel] [PATCH v2 11/13] x86/PMU: Handle PMU interrupts for PV guests

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 25.09.13 at 17:19, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> wrote:
> On 09/25/2013 10:33 AM, Jan Beulich wrote:
>>>>> On 20.09.13 at 11:42, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> wrote:
>>> Add support for handling PMU interrupts for PV guests, make these interrupts
>>> NMI instead of PMU_APIC_VECTOR vector. Depending on vpmu_mode forward the
>>> interrupts to appropriate guest (mode is VPMU_ON) or to dom0 (VPMU_DOM0).
>> Is using NMIs here a necessity? I guess not, in which case I'd really
>> like this to be a (perhaps even non-default) option controllable via
>> command line option.
> 
> It is not a necessity but using NMIs will allow us to profile code that runs
> with interrupts disabled.

So my request stands to make this optional, default off.

>>> - * This interrupt handles performance counters interrupt
>>> - */
>>> -
>>> -void pmu_apic_interrupt(struct cpu_user_regs *regs)
>>> -{
>>> -    ack_APIC_irq();
>>> -    vpmu_do_interrupt(regs);
>>> -}
>> So this was the only caller of vpmu_do_interrupt(); no new one gets
>> added in this patch afaics, and I don't recall having seen addition of
>> another caller in earlier patches. What's the deal?
> 
> It's in 09/13:
> 
>   
> +int pmu_nmi_interrupt(struct cpu_user_regs *regs, int cpu)
> +{
> +    return vpmu_do_interrupt(regs);
> +}
> +

Ah. Then please try to break up your changes in a way that logically
connected things stay together. The change you quote above can't
make much sense earlier than in patch 11.

Jan


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