Re: [RFC PATCH 09/21] KVM: TDX: Enable 2MB mapping size after TD is RUNNABLE

[Edgecombe, Rick P]

On Tue, 2025-06-17 at 08:52 +0800, Yan Zhao wrote:
> > hopefully is just handling accepting a whole range that is not 2MB aligned.
> > But
> > I think we need to verify this more.
> Ok.

In Linux guest if a memory region is not 2MB aligned the guest will accept the
ends at 4k size. If a memory region is identical to a memslot range this will be
fine. KVM will map the ends at 4k because it won't let huge pages span a
memslot. But if several memory regions are not 2MB aligned and are covered by
one large memslot, the accept will fail on the 4k ends under this proposal. I
don't know if this is a common configuration, but to cover it in the TDX guest
may not be trivial.

So I think this will only work if guests can reasonably "merge" all of the
adjacent accepts. Or of we declare a bunch of memory/memslot layouts illegal.

Kirill, how difficult would it be for TDX Linux guest to merge all 2MB adjacent
accepts?