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KVM: vPMU: Fill get_msr MSR_CORE_PERF_GLOBAL_OVF_CTRL w/ 0

Browse source 
SDM section 18.2.3 mentioned that:

  "IA32_PERF_GLOBAL_OVF_CTL MSR allows software to clear overflow indicator(s) of
   any general-purpose or fixed-function counters via a single WRMSR."

It is R/W mentioned by SDM, we read this msr on bare-metal during perf testing,
the value is always 0 for ICX/SKX boxes on hands. Let's fill get_msr
MSR_CORE_PERF_GLOBAL_OVF_CTRL w/ 0 as hardware behavior and drop
global_ovf_ctrl variable.

Tested-by: Like Xu <likexu@tencent.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1634631160-67276-2-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Wanpeng Li 2021-10-19 01:12:39 -07:00 committed by Paolo Bonzini
parent 610265ea3d
commit 540c7abe61
2 changed files with 2 additions and 5 deletions
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1
arch/x86/include/asm/kvm_host.h
View file

@ -499,7 +499,6 @@ struct kvm_pmu {
u64 fixed_ctr_ctrl;
u64 global_ctrl;
u64 global_status;
u64 global_ovf_ctrl;
u64 counter_bitmask[2];
u64 global_ctrl_mask;
u64 global_ovf_ctrl_mask;

6
arch/x86/kvm/vmx/pmu_intel.c
View file

@ -365,7 +365,7 @@ static int intel_pmu_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
msr_info->data = pmu->global_ctrl;
return 0;
case MSR_CORE_PERF_GLOBAL_OVF_CTRL:
msr_info->data = pmu->global_ovf_ctrl;
msr_info->data = 0;
return 0;
default:
if ((pmc = get_gp_pmc(pmu, msr, MSR_IA32_PERFCTR0)) ||
@ -423,7 +423,6 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
if (!(data & pmu->global_ovf_ctrl_mask)) {
if (!msr_info->host_initiated)
pmu->global_status &= ~data;
pmu->global_ovf_ctrl = data;
return 0;
}
break;
@ -588,8 +587,7 @@ static void intel_pmu_reset(struct kvm_vcpu *vcpu)
pmc->counter = 0;
}
pmu->fixed_ctr_ctrl = pmu->global_ctrl = pmu->global_status =
pmu->global_ovf_ctrl = 0;
pmu->fixed_ctr_ctrl = pmu->global_ctrl = pmu->global_status = 0;
intel_pmu_release_guest_lbr_event(vcpu);
}