Re: [edk2-rfc] [edk2-devel] RFC: design review for TDVF in OVMF


Min Xu
 

On June 6, 2021 7:30 PM, Michael Brown Wrote:
On 06/06/2021 03:03, Min Xu wrote:
(11) "Page table should support both 4-level and 5-level page table"

As a general development strategy, I would suggest building TDX
support in small, well-isolated layers. 5-level paging is not enabled
(has never been tested, to my knowledge) with OVMF on QEMU/KVM,
regardless of confidential computing, for starters. If 5-level paging
is a strict requirement for TDX, then it arguably needs to be
implemented independently of TDX, at first. So that the common edk2
architecture be at least testable on QEMU/KVM with 5-level paging
enabled.
Yes, 5-level paging is a strict requirement for TDX. I would wait for
the conclusion of the *one binary*.
The "one binary" decision isn't relevant here, is it? It would make more
sense to implement 5-level paging within the base EDK2 architecture. This
would allow that feature to be tested in isolation from TDX (and
consequently tested more widely), and would reduce the distance between
standard builds and TDX builds.
In our first version of TDVF, a static 5-level page table is used. It is simple and
straight forward. But for *one binary* solution, we have to consider the compatibility
with the current 4-level page table. That's why I said "I would wait for the conclusion
of the *one binary*"

Thanks for the suggestion. We will discuss the it internally first.

Michael

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