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

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);


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