From: Paolo Bonzini <pbonzini@redhat.com>
To: Like Xu <like.xu.linux@gmail.com>, Jim Mattson <jmattson@google.com>
Cc: Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/4] KVM: x86/pmu: Reuse find_perf_hw_id() and drop find_fixed_event()
Date: Thu, 18 Nov 2021 16:00:03 +0100 [thread overview]
Message-ID: <85286356-8005-8a4d-927c-c3d70c723161@redhat.com> (raw)
In-Reply-To: <20211116122030.4698-4-likexu@tencent.com>
On 11/16/21 13:20, Like Xu wrote:
> +static inline unsigned int intel_find_fixed_event(int idx)
> +{
> + u32 event;
> + size_t size = ARRAY_SIZE(fixed_pmc_events);
> +
> + if (idx >= size)
> + return PERF_COUNT_HW_MAX;
> +
> + event = fixed_pmc_events[array_index_nospec(idx, size)];
> + return intel_arch_events[event].event_type;
> +}
> +
> +
> static unsigned int intel_find_perf_hw_id(struct kvm_pmc *pmc)
> {
> struct kvm_pmu *pmu = pmc_to_pmu(pmc);
> @@ -75,6 +88,9 @@ static unsigned int intel_find_perf_hw_id(struct kvm_pmc *pmc)
> u8 unit_mask = (pmc->eventsel & ARCH_PERFMON_EVENTSEL_UMASK) >> 8;
> int i;
>
> + if (pmc_is_fixed(pmc))
> + return intel_find_fixed_event(pmc->idx - INTEL_PMC_IDX_FIXED);
Is intel_find_fixed_event needed at all? As you point out in the commit
message, eventsel/unit_mask are valid so you can do
@@ -88,13 +75,11 @@ static unsigned int intel_pmc_perf_hw_id(struct kvm_pmc *pmc)
u8 unit_mask = (pmc->eventsel & ARCH_PERFMON_EVENTSEL_UMASK) >> 8;
int i;
- if (pmc_is_fixed(pmc))
- return intel_find_fixed_event(pmc->idx - INTEL_PMC_IDX_FIXED);
-
for (i = 0; i < ARRAY_SIZE(intel_arch_events); i++)
if (intel_arch_events[i].eventsel == event_select
&& intel_arch_events[i].unit_mask == unit_mask
- && (pmu->available_event_types & (1 << i)))
+ && (pmc_is_fixed(pmc) ||
+ pmu->available_event_types & (1 << i)))
break;
if (i == ARRAY_SIZE(intel_arch_events))
What do you think? It's less efficient but makes fixed/gp more similar.
Can you please resubmit the series based on the review feedback?
Thanks,
next prev parent reply other threads:[~2021-11-18 15:00 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-16 12:20 [PATCH 0/4] KVM: x86/pmu: An insightful refactoring of vPMU code Like Xu
2021-11-16 12:20 ` [PATCH 1/4] KVM: x86/pmu: Setup pmc->eventsel for fixed PMCs Like Xu
2021-11-16 12:20 ` [PATCH 2/4] KVM: x86/pmu: Refactoring find_arch_event() to find_perf_hw_id() Like Xu
2021-11-18 13:29 ` Paolo Bonzini
2021-11-16 12:20 ` [PATCH 3/4] KVM: x86/pmu: Reuse find_perf_hw_id() and drop find_fixed_event() Like Xu
2021-11-18 14:43 ` Paolo Bonzini
2021-11-18 15:00 ` Paolo Bonzini [this message]
2021-11-19 7:16 ` Like Xu
2021-11-19 10:29 ` Paolo Bonzini
2021-11-19 11:10 ` Like Xu
2021-11-16 12:20 ` [PATCH 4/4] KVM: x86/pmu: Refactoring kvm_perf_overflow{_intr}() Like Xu
2021-11-18 14:53 ` Paolo Bonzini
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