On Wed, Aug 16, 2023, Kai Huang wrote: > > diff --git a/arch/x86/kvm/governed_features.h b/arch/x86/kvm/governed_features.h > > new file mode 100644 > > index 000000000000..40ce8e6608cd > > --- /dev/null > > +++ b/arch/x86/kvm/governed_features.h > > @@ -0,0 +1,9 @@ > > +/* SPDX-License-Identifier: GPL-2.0 */ > > +#if !defined(KVM_GOVERNED_FEATURE) || defined(KVM_GOVERNED_X86_FEATURE) > > +BUILD_BUG() > > +#endif > > + > > +#define KVM_GOVERNED_X86_FEATURE(x) KVM_GOVERNED_FEATURE(X86_FEATURE_##x) > > + > > +#undef KVM_GOVERNED_X86_FEATURE > > +#undef KVM_GOVERNED_FEATURE > > Nit: > > Do you want to move the very last > > #undef KVM_GOVERNED_FEATURE > > out of "governed_features.h", but to the place(s) where the macro is defined? > > Yes there will be multiple: > > #define KVM_GOVERNED_FEATURE(x) ... > #include "governed_features.h" > #undef KVM_GOVERNED_FEATURE > > But this looks clearer to me. I agree the symmetry looks better, but doing the #undef in governed_features.h is much more robust. E.g. having the #undef in the header makes it all but impossible to have a bug where we forget to #undef KVM_GOVERNED_FEATURE. Or worse, have two bugs where we forget to #undef and then also forget to #define in a later include and consume the stale #define. And I also want to follow the pattern used by kvm-x86-ops.h.
