On Fri, Jan 26, 2024, Xiong Zhang wrote: > Finally, always propagate enable_passthrough_pmu and perf_capabilities into > kvm->arch for each KVM instance. Why? arch.enable_passthrough_pmu is simply "arch.enable_pmu && enable_passthrough_pmu", I don't see any reason to cache that information on a per-VM basis. Blech, it's also cached in vcpu->pmu.passthrough, which is even more compexity that doesn't add any value. E.g. code that is reachable iff the VM/vCPU has a PMU can simply check the module param. And if we commit to that model (all or nothing), then we can probably end up with cleaner code overall because we bifurcate everything at a module level, e.g. even use static_call() if we had reason to.
