From: Paolo Bonzini <pbonzini@redhat.com>
To: Jim Mattson <jmattson@google.com>, Like Xu <like.xu.linux@gmail.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,
Like Xu <likexu@tencent.com>
Subject: Re: [PATCH v2 1/6] KVM: x86/pmu: Setup pmc->eventsel for fixed PMCs
Date: Thu, 9 Dec 2021 19:49:18 +0100 [thread overview]
Message-ID: <8ca78cd6-12ad-56c4-ad73-e88757364ba9@redhat.com> (raw)
In-Reply-To: <CALMp9eT05nb56b16KkybvGSTYMhkRusQnNL4aWFU8tsets0O2w@mail.gmail.com>
On 12/6/21 20:57, Jim Mattson wrote:
>> +
>> + for (i = 0; i < pmu->nr_arch_fixed_counters; i++) {
>> + pmc = &pmu->fixed_counters[i];
>> + event = fixed_pmc_events[array_index_nospec(i, size)];
> How do we know that i < size? For example, Ice Lake supports 4 fixed
> counters, but fixed_pmc_events only has three entries.
We don't, and it's a preexisting bug in intel_pmu_refresh. Either we hack around it like
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 1b7456b2177b..6f03c8bf1bc2 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -500,8 +500,9 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
pmu->nr_arch_fixed_counters = 0;
} else {
pmu->nr_arch_fixed_counters =
- min_t(int, edx.split.num_counters_fixed,
- x86_pmu.num_counters_fixed);
+ min3(ARRAY_SIZE(fixed_pmc_events),
+ (size_t) edx.split.num_counters_fixed,
+ (size_t) x86_pmu.num_counters_fixed);
edx.split.bit_width_fixed = min_t(int,
edx.split.bit_width_fixed, x86_pmu.bit_width_fixed);
pmu->counter_bitmask[KVM_PMC_FIXED] =
or we modify find_fixed_event and its caller to support PERF_TYPE_RAW
counters, and then add support for the IceLake TOPDOWN.SLOTS fixed
counter.
What's your preference?
Paolo
next prev parent reply other threads:[~2021-12-09 18:49 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-30 7:42 [PATCH v2 0/6] KVM: x86/pmu: Count two basic events for emulated instructions Like Xu
2021-11-30 7:42 ` [PATCH v2 1/6] KVM: x86/pmu: Setup pmc->eventsel for fixed PMCs Like Xu
2021-12-06 19:57 ` Jim Mattson
2021-12-09 18:49 ` Paolo Bonzini [this message]
2021-12-09 18:53 ` Jim Mattson
2021-12-09 18:57 ` Paolo Bonzini
2021-12-10 10:20 ` Like Xu
[not found] ` <CALMp9eTq8H_bJOVKwi_7j3Kum9RvW6o-G3zCLUFco1A1cvNrkQ@mail.gmail.com>
2021-12-07 6:07 ` Like Xu
2021-12-07 17:42 ` Jim Mattson
2021-11-30 7:42 ` [PATCH v2 2/6] KVM: x86/pmu: Refactoring find_arch_event() to pmc_perf_hw_id() Like Xu
2021-12-09 3:52 ` Jim Mattson
2021-12-09 8:11 ` Like Xu
2021-12-09 19:24 ` Paolo Bonzini
2022-02-05 1:55 ` Jim Mattson
2022-02-09 9:00 ` Like Xu
2022-02-09 19:30 ` Jim Mattson
2022-02-10 11:28 ` Like Xu
2022-02-11 9:56 ` Ravi Bangoria
2022-02-11 18:16 ` Jim Mattson
2022-02-14 10:14 ` Ravi Bangoria
2022-02-16 7:44 ` Like Xu
2022-02-16 11:24 ` Ravi Bangoria
2021-11-30 7:42 ` [PATCH v2 3/6] KVM: x86/pmu: Reuse pmc_perf_hw_id() and drop find_fixed_event() Like Xu
2021-12-09 3:58 ` Jim Mattson
2021-11-30 7:42 ` [PATCH v2 4/6] KVM: x86/pmu: Add pmc->intr to refactor kvm_perf_overflow{_intr}() Like Xu
2021-12-09 4:25 ` Jim Mattson
2021-12-09 8:28 ` Like Xu
2021-12-10 0:54 ` Jim Mattson
2021-12-10 9:35 ` Paolo Bonzini
2021-12-10 10:11 ` Like Xu
2021-12-10 22:55 ` Jim Mattson
2021-12-10 22:59 ` Paolo Bonzini
2021-12-10 23:31 ` Jim Mattson
2021-12-12 4:56 ` Jim Mattson
2021-12-13 6:37 ` Jim Mattson
2021-12-16 9:57 ` Like Xu
2021-12-16 17:52 ` Jim Mattson
2021-11-30 7:42 ` [PATCH v2 5/6] KVM: x86: Update vPMCs when retiring instructions Like Xu
2021-12-09 4:33 ` Jim Mattson
2021-12-09 8:44 ` Like Xu
2021-12-09 9:23 ` Like Xu
2021-11-30 7:42 ` [PATCH v2 6/6] KVM: x86: Update vPMCs when retiring branch instructions Like Xu
2021-12-09 4:40 ` Jim Mattson
2021-12-09 19:30 ` [PATCH v2 0/6] KVM: x86/pmu: Count two basic events for emulated instructions Paolo Bonzini
2021-12-16 10:14 ` Like Xu
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