On Thu, May 15, 2025, Dapeng Mi wrote: > On 5/15/2025 8:41 AM, Sean Christopherson wrote: > >> + if (kvm_mediated_pmu_enabled(vcpu) && kvm_pmu_has_perf_global_ctrl(pmu) && > > Just require the guest to have PERF_GLOBAL_CTRL, I don't see any reason to support > > v1 PMUs. It adds complexity and weirdness, and I can't imagine there's a use case. I take that back, there absolutely are use cases, especially for AMD. Any VM shape that exists today should be compatible with the mediated PMU. And I was dead wrong about adding complexity; KVM already needs to intercept GLOBAL_CTRL if the guest has fewer PMCs than hardware, so incorporating this check is all of two lines of code.
