On Thu, Nov 03, 2022 at 12:14:04AM +0300, Kirill A. Shutemov wrote:

On Mon, Oct 31, 2022 at 12:47:38PM -0500, Michael Roth wrote:

quoted

In v8 there was some discussion about potentially passing the page/folio
and order as part of the invalidation callback, I ended up needing
something similar for SEV-SNP, and think it might make sense for other
platforms. This main reasoning is:

  1) restoring kernel directmap:

     Currently SNP (and I believe TDX) need to either split or remove kernel
     direct mappings for restricted PFNs, since there is no guarantee that
     other PFNs within a 2MB range won't be used for non-restricted
     (which will cause an RMP #PF in the case of SNP since the 2MB
     mapping overlaps with guest-owned pages)

That's news to me. Where the restriction for SNP comes from? There's no
such limitation on TDX side AFAIK?

Could you point me to relevant documentation if there's any?

I could be mistaken, I haven't looked into the specific documentation and was
going off of this discussion from a ways back:

  https://lore.kernel.org/all/YWb8WG6Ravbs1nbx@google.com/ (local)

Sean, is my read of that correct? Do you happen to know where there's
some documentation on that for the TDX side?

Thanks,

Mike

-- 
  Kiryl Shutsemau / Kirill A. Shutemov