KVM: vPMU: Fill get_msr MSR_CORE_PERF_GLOBAL_OVF_CTRL w/ 0

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>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index b4fece3..1c523b5 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -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;

diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 10cc4f6..b8e0d21 100644 (file)
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -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);
 }