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SubjectRe: [RFC PATCH 34/41] KVM: x86/pmu: Intercept EVENT_SELECT MSR
From
On Fri, Jan 26, 2024, Xiong Zhang wrote:
> From: Xiong Zhang <xiong.y.zhang@intel.com>
>
> Event selectors for GP counters are still intercepted for the purpose of
> security, i.e., preventing guest from using unallowed events to steal
> information or take advantages of any CPU errata.

Heh, so then they shouldn't have been passed through in the first place.

> Signed-off-by: Xiong Zhang <xiong.y.zhang@intel.com>
> Signed-off-by: Mingwei Zhang <mizhang@google.com>
> ---
> arch/x86/kvm/vmx/pmu_intel.c | 1 -
> arch/x86/kvm/vmx/vmx.c | 1 -
> 2 files changed, 2 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
> index 9bbd5084a766..621922005184 100644
> --- a/arch/x86/kvm/vmx/pmu_intel.c
> +++ b/arch/x86/kvm/vmx/pmu_intel.c
> @@ -809,7 +809,6 @@ void intel_passthrough_pmu_msrs(struct kvm_vcpu *vcpu)
> int i;
>
> for (i = 0; i < vcpu_to_pmu(vcpu)->nr_arch_gp_counters; i++) {
> - vmx_set_intercept_for_msr(vcpu, MSR_ARCH_PERFMON_EVENTSEL0 + i, MSR_TYPE_RW, false);
> vmx_set_intercept_for_msr(vcpu, MSR_IA32_PERFCTR0 + i, MSR_TYPE_RW, false);
> if (fw_writes_is_enabled(vcpu))
> vmx_set_intercept_for_msr(vcpu, MSR_IA32_PMC0 + i, MSR_TYPE_RW, false);
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index d28afa87be70..1a518800d154 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -698,7 +698,6 @@ static bool is_valid_passthrough_msr(u32 msr)
> case MSR_LBR_CORE_FROM ... MSR_LBR_CORE_FROM + 8:
> case MSR_LBR_CORE_TO ... MSR_LBR_CORE_TO + 8:
> /* LBR MSRs. These are handled in vmx_update_intercept_for_lbr_msrs() */
> - case MSR_ARCH_PERFMON_EVENTSEL0 ... MSR_ARCH_PERFMON_EVENTSEL0 + 7:
> case MSR_IA32_PMC0 ... MSR_IA32_PMC0 + 7:
> case MSR_IA32_PERFCTR0 ... MSR_IA32_PERFCTR0 + 7:
> case MSR_CORE_PERF_FIXED_CTR_CTRL:
> --
> 2.34.1
>

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