On Thu, 7 Jan 2021 07:41:25 +0100 Borislav Petkov wrote: > On Thu, Jan 07, 2021 at 12:09:46PM +1300, Kai Huang wrote: > > There's no urgent request to support them for now (and given basic SGX > > virtualization is not in upstream), but I don't know whether they need to be > > supported in the future. > > If that is the case, then wasting a whole leaf for two bits doesn't make > too much sense. And it looks like the kvm reverse lookup can be taught > to deal with composing that leaf dynamically when needed instead. I am not sure changing reverse lookup to handle dynamic would be acceptable. To me it is ugly, and I don't have a first glance on how to do it. KVM can query host CPUID when dealing with SGX w/o X86_FEATURE_SGX1/2, but it is not as straightforward as having X86_FEATURE_SGX1/2. And as Sean pointed out, SGX1 bit is also needed by both SGX driver and init_ia32_feat_ctl(): https://www.spinics.net/lists/kvm/msg231973.html So having it would make things easier. And regarding to other bits of this leaf, to me: 1) we cannot rule out possibility that bit 5 and bit 6 will be supported in the future; 2) I cannot talk more but we cannot rule out the possibility that there will be other bits introduced in the future. Sean, what do you think? > > Thx. > > -- > Regards/Gruss, > Boris. > > https://people.kernel.org/tglx/notes-about-netiquette
