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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id ke7sm9484812ejc.7.2021.01.26.01.33.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 26 Jan 2021 01:33:11 -0800 (PST) Subject: Re: [RESEND v13 10/10] KVM: vmx/pmu: Release guest LBR event via lazy release mechanism To: Like Xu , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel Cc: Ingo Molnar , Thomas Gleixner , Borislav Petkov , "H . Peter Anvin" , ak@linux.intel.com, wei.w.wang@intel.com, kan.liang@intel.com, x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210108013704.134985-1-like.xu@linux.intel.com> <20210108013704.134985-11-like.xu@linux.intel.com> From: Paolo Bonzini Message-ID: <310d674c-44e7-7b46-064f-7cb88c456d0f@redhat.com> Date: Tue, 26 Jan 2021 10:33:09 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20210108013704.134985-11-like.xu@linux.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/01/21 02:37, Like Xu wrote: > The vPMU uses GUEST_LBR_IN_USE_IDX (bit 58) in 'pmu->pmc_in_use' to > indicate whether a guest LBR event is still needed by the vcpu. If the > vcpu no longer accesses LBR related registers within a scheduling time > slice, and the enable bit of LBR has been unset, vPMU will treat the > guest LBR event as a bland event of a vPMC counter and release it > as usual. Also, the pass-through state of LBR records msrs is cancelled. > > Signed-off-by: Like Xu > Reviewed-by: Andi Kleen > --- > arch/x86/kvm/pmu.c | 7 +++++++ > arch/x86/kvm/pmu.h | 4 ++++ > arch/x86/kvm/vmx/pmu_intel.c | 17 ++++++++++++++++- > 3 files changed, 27 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c > index 405890c723a1..e7c72eea07d4 100644 > --- a/arch/x86/kvm/pmu.c > +++ b/arch/x86/kvm/pmu.c > @@ -463,6 +463,7 @@ void kvm_pmu_cleanup(struct kvm_vcpu *vcpu) > struct kvm_pmc *pmc = NULL; > DECLARE_BITMAP(bitmask, X86_PMC_IDX_MAX); > int i; > + bool extra_cleanup = false; > > pmu->need_cleanup = false; > > @@ -474,8 +475,14 @@ void kvm_pmu_cleanup(struct kvm_vcpu *vcpu) > > if (pmc && pmc->perf_event && !pmc_speculative_in_use(pmc)) > pmc_stop_counter(pmc); > + > + if (i == INTEL_GUEST_LBR_INUSE) > + extra_cleanup = true; > } > > + if (extra_cleanup && kvm_x86_ops.pmu_ops->cleanup) > + kvm_x86_ops.pmu_ops->cleanup(vcpu); > + You can call this function always, it's cleaner than hardcoding INTEL_GUEST_LBR_INUSE. You can also use INTEL_PMC_IDX_FIXED_VLBR directly instead of INTEL_GUEST_LBR_INUSE. Paolo