linux-kernel - [PATCH v2 0/6] KVM: x86/pmu: Count two basic events for emulated instructions

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Date:   Tue, 30 Nov 2021 15:42:15 +0800
From:   Like Xu <like.xu.linux@...il.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Like Xu <likexu@...cent.com>
Subject: [PATCH v2 0/6] KVM: x86/pmu: Count two basic events for emulated instructions

Hi,

[ Jim is on holiday, so I'm here to continue this work. ]

Some cloud customers need accurate virtualization of two
basic PMU events on x86 hardware: "instructions retired" and
"branch instructions retired". The existing PMU virtualization code
fails to account for instructions (e.g, CPUID) that are emulated by KVM.

Accurately virtualizing all PMU events for all microarchitectures is a
herculean task, let's just stick to the two events covered by this set.

Eric Hankland wrote this code originally, but his plate is full, so Jim
and I volunteered to shepherd the changes through upstream acceptance.

Thanks,

v1 -> v2 Changelog:
- Include the patch set [1] and drop the intel_find_fixed_event(); [Paolo]
  (we will fix the misleading Intel CPUID events in another patch set)
- Drop checks for pmc->perf_event or event state or event type;
- Increase a counter once its umask bits and the first 8 select bits are matched;
- Rewrite kvm_pmu_incr_counter() with a less invasive approach to the host perf;
- Rename kvm_pmu_record_event to kvm_pmu_trigger_event;
- Add counter enable check for kvm_pmu_trigger_event();
- Add vcpu CPL check for kvm_pmu_trigger_event(); [Jim]

Previous:
https://lore.kernel.org/kvm/20211112235235.1125060-2-jmattson@google.com/

[1] https://lore.kernel.org/kvm/20211119064856.77948-1-likexu@tencent.com/

Jim Mattson (1):
  KVM: x86: Update vPMCs when retiring branch instructions

Like Xu (5):
  KVM: x86/pmu: Setup pmc->eventsel for fixed PMCs
  KVM: x86/pmu: Refactoring find_arch_event() to pmc_perf_hw_id()
  KVM: x86/pmu: Reuse pmc_perf_hw_id() and drop find_fixed_event()
  KVM: x86/pmu: Add pmc->intr to refactor kvm_perf_overflow{_intr}()
  KVM: x86: Update vPMCs when retiring instructions

 arch/x86/include/asm/kvm_host.h |   1 +
 arch/x86/kvm/emulate.c          |  55 ++++++++------
 arch/x86/kvm/kvm_emulate.h      |   1 +
 arch/x86/kvm/pmu.c              | 128 ++++++++++++++++++++++----------
 arch/x86/kvm/pmu.h              |   5 +-
 arch/x86/kvm/svm/pmu.c          |  19 ++---
 arch/x86/kvm/vmx/nested.c       |   7 +-
 arch/x86/kvm/vmx/pmu_intel.c    |  44 ++++++-----
 arch/x86/kvm/x86.c              |   5 ++
 9 files changed, 167 insertions(+), 98 deletions(-)

-- 
2.33.1