Commit 649bccd7 authored by Like Xu's avatar Like Xu Committed by Sean Christopherson
Browse files

KVM: x86/pmu: Rewrite reprogram_counters() to improve performance 



A valid pmc is always tested before using pmu->reprogram_pmi. Eliminate
this part of the redundancy by setting the counter's bitmask directly,
and in addition, trigger KVM_REQ_PMU only once to save more cpu cycles.

Signed-off-by: default avatarLike Xu <likexu@tencent.com>
Link: https://lore.kernel.org/r/20230214050757.9623-4-likexu@tencent.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 8bca8c5c

arch/x86/kvm/vmx/pmu_intel.c

+6 −6
Original line number Diff line number Diff line
@@ -76,13 +76,13 @@ static struct kvm_pmc *intel_pmc_idx_to_pmc(struct kvm_pmu *pmu, int pmc_idx) 
static void reprogram_counters(struct kvm_pmu *pmu, u64 diff)

{

	int bit;

	struct kvm_pmc *pmc;



	for_each_set_bit(bit, (unsigned long *)&diff, X86_PMC_IDX_MAX) {

		pmc = intel_pmc_idx_to_pmc(pmu, bit);

		if (pmc)

			kvm_pmu_request_counter_reprogam(pmc);

	}

	if (!diff)

		return;



	for_each_set_bit(bit, (unsigned long *)&diff, X86_PMC_IDX_MAX)

		set_bit(bit, pmu->reprogram_pmi);

	kvm_make_request(KVM_REQ_PMU, pmu_to_vcpu(pmu));

}



static bool intel_hw_event_available(struct kvm_pmc *pmc)