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Peter Anvin" , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, Yongwei Ma , Xiong Zhang , Dapeng Mi , Jim Mattson , Sandipan Das , Zide Chen , Eranian Stephane , Shukla Manali , Nikunj Dadhania Content-Type: text/plain; charset="us-ascii" On Mon, Mar 24, 2025, Mingwei Zhang wrote: > + /* > + * Clear hardware selector MSR content and its counter to avoid > + * leakage and also avoid this guest GP counter get accidentally > + * enabled during host running when host enable global ctrl. > + */ > + for (i = 0; i < pmu->nr_arch_gp_counters; i++) { > + pmc = &pmu->gp_counters[i]; > + eventsel_msr = pmc_msr_addr(pmu, pmu->gp_eventsel_base, i); > + counter_msr = pmc_msr_addr(pmu, pmu->gp_counter_base, i); > + > + rdpmcl(i, pmc->counter); > + rdmsrl(eventsel_msr, pmc->eventsel_hw); As pointed out by Dapeng offlist, this RDMSR is unnecessary since event selector MSRs are always intercepted. > + if (pmc->counter) > + wrmsrl(counter_msr, 0); > + if (pmc->eventsel_hw) > + wrmsrl(eventsel_msr, 0); > + } > + > + for (i = 0; i < pmu->nr_arch_fixed_counters; i++) { > + pmc = &pmu->fixed_counters[i]; > + counter_msr = pmc_msr_addr(pmu, pmu->fixed_base, i); > + > + rdpmcl(INTEL_PMC_FIXED_RDPMC_BASE | i, pmc->counter); > + if (pmc->counter) > + wrmsrl(counter_msr, 0); > + } > + > +} > +static void intel_put_guest_context(struct kvm_vcpu *vcpu) > +{ > + struct kvm_pmu *pmu = vcpu_to_pmu(vcpu); > + > + /* Global ctrl register is already saved at VM-exit. */ > + rdmsrl(MSR_CORE_PERF_GLOBAL_STATUS, pmu->global_status); > + > + /* Clear hardware MSR_CORE_PERF_GLOBAL_STATUS MSR, if non-zero. */ > + if (pmu->global_status) > + wrmsrl(MSR_CORE_PERF_GLOBAL_OVF_CTRL, pmu->global_status); > + > + rdmsrl(MSR_CORE_PERF_FIXED_CTR_CTRL, pmu->fixed_ctr_ctrl_hw); And same thing here. Though I'm confused as to why KVM always intercept FIXED_CTR_CTRL. /me rummages around the SDM Ahh, because there are Any Thread bits in there. That absolutely needs to be called out, probably in the interception logic in pmu_intel.c. I'll add a comment.