On Wed, 2022-11-30 at 23:09 +0000, Sean Christopherson wrote: > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -11967,6 +11967,11 @@ int kvm_arch_hardware_enable(void) > bool stable, backwards_tsc = false; > > kvm_user_return_msr_cpu_online(); > + > + ret = kvm_x86_check_processor_compatibility(); > + if (ret) > + return ret; > + > ret = static_call(kvm_x86_hardware_enable)(); > if (ret != 0) > return ret; Thinking more, AFAICT, kvm_x86_vendor_init() so far still does the compatibility check on all online cpus. Since now kvm_arch_hardware_enable() also does the compatibility check, IIUC the compatibility check will be done twice -- one in kvm_x86_vendor_init() and one in hardware_enable_all() when creating the first VM. Do you think it's still worth to do compatibility check in vm_x86_vendor_init()? The behaviour difference should be "KVM module fail to load" vs "failing to create the first VM" IIUC. I don't know whether the former is better than the better, but it seems duplicated compatibility checking isn't needed?
