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Date: Thu, 11 Apr 2024 16:17:05 -0700
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Subject: Re: [RFC PATCH 39/41] KVM: x86/pmu: Implement emulated counter
 increment for passthrough PMU
From: Sean Christopherson <seanjc@google.com>
To: Xiong Zhang <xiong.y.zhang@linux.intel.com>
Cc: pbonzini@redhat.com, peterz@infradead.org, mizhang@google.com, 
	kan.liang@intel.com, zhenyuw@linux.intel.com, dapeng1.mi@linux.intel.com, 
	jmattson@google.com, kvm@vger.kernel.org, linux-perf-users@vger.kernel.org, 
	linux-kernel@vger.kernel.org, zhiyuan.lv@intel.com, eranian@google.com, 
	irogers@google.com, samantha.alt@intel.com, like.xu.linux@gmail.com, 
	chao.gao@intel.com
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On Thu, Apr 11, 2024, Sean Christopherson wrote:
> > +	struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
> > +	int bit;
> > +
> > +	for_each_set_bit(bit, pmu->incremented_pmc_idx, X86_PMC_IDX_MAX) {
> 
> I don't love the "incremented_pmc_idx" name.  It's specifically for emulated
> events, that should ideally be clear in the name.
> 
> And does the tracking the emulated counters actually buy anything?  Iterating
> over all PMCs and checking emulated_counter doesn't seem like it'd be measurably
> slow, especially not when this path is likely writing multiple MSRs.
> 
> Wait, why use that and not reprogram_pmi?

If the name is a sticking point, just rename it to something generic, e.g.
dirty_pmcs or something.