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

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

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.

> > - * 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);
+}
+



-boris

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