On Wed, Feb 22, 2023 at 02:54:47PM -0800, Sean Christopherson wrote: > Why? I genuinely don't understand the motivation for bundling all of this stuff > under a single "feature". It is called "sanity". See here: https://lore.kernel.org/r/Y%2B5immKTXCsjSysx@xxxxxxx We support SEV, SEV-ES, SEV-SNP, TDX, HyperV... guests and whatever's coming down the pipe. And all that goes into arch/x86/ kernel proper code. The CC_ATTR stuff is clean-ish in the sense that we have separation by confidential computing platform - AMD's and Intel's. Hyper-V comes along and wants to define a different subset of that. And that's only the SEV-SNP side - there's a TDX patchset too. And then some other hypervisor will come along and say, but but, I wanna have X and Y and a pink pony too. Oh, and there's this other fun with MTRRs where each HV decides to do whatever it wants. So, we have a zoo brewing on the horizon already! If there's no clean definition of what each guest is and requires and that stuff isn't documented properly and if depending on which "feature" I need to check, I need to call a different function or query a different variable, then it won't go anywhere as far as guest support goes. The cc_platform_has() thing gives us a relatively clean way to abstract all those differences away and keep the code sane-ish. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette
