> All in all, I think we want this: > > case MSR_TSC_AUX: > if (!boot_cpu_has(X86_FEATURE_RDTSCP)) > return 1; > > if (!msr_info->host_initiated && > !guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP)) > return 1; > > /* > * TSC_AUX is usually changed only during boot and never read > * directly. Intercept TSC_AUX instead of exposing it to the > * guest via direct_access_msrs, and switch it via user return. > */ > preempt_disable(); > r = kvm_set_user_return_msr(TSC_AUX_URET_SLOT, data, -1ull); > preempt_enable(); > if (r) > return 1; > > /* > * Bits 63:32 are dropped by AMD CPUs, but are reserved on > * Intel CPUs. AMD's APM has incomplete and conflicting info > * on the architectural behavior; emulate current hardware as > * doing so ensures migrating from AMD to Intel won't explode. > */ > svm->tsc_aux = (u32)data; > break; Thank you for the explanation. I understand and the code above looks good to me. (I would assume we want to check the msr_info->host_initiated and guest_cpuid_has in svm_get_msr as well) Thanks, Reiji
