On 05/05/21 05:51, Reiji Watanabe wrote:
--- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -637,7 +637,8 @@ static int __do_cpuid_func_emulated(struct kvm_cpuid_array *array, u32 func) case 7: entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX; entry->eax = 0; - entry->ecx = F(RDPID); + if (kvm_cpu_cap_has(X86_FEATURE_RDTSCP)) + entry->ecx = F(RDPID); ++array->nent; default: break;I'm wondering if entry->ecx should be set to F(RDPID) here even if the CPU supports RDPID natively. (i.e. kvm_cpu_cap_has(X86_FEATURE_RDPID) is true) The document "Documentation/virt/kvm/api.rst" says: --- 4.88 KVM_GET_EMULATED_CPUID --------------------------- <...> Userspace can use the information returned by this ioctl to query which features are emulated by kvm instead of being present natively. ---
Setting it always is consistent with the treatment of MOVBE above. Either way is okay but it should be done for both bits.
Paolo
