Re: [PATCH v7 00/14] KVM: mm: fd-based approach for supporting KVM guest private memory

Gupta, Pankaj
2022-08-16T11:55:12Z

Hi Chao,

>
> Actually the current version allows you to delay the allocation to a
> later time (e.g. page fault time) if you don't call fallocate() on the
> private fd. fallocate() is necessary in previous versions because we
> treat the existense in the fd as 'private' but in this version we track
> private/shared info in KVM so we don't rely on that fact from memory
> backstores.

Does this also mean reservation of guest physical memory with secure
processor (both for SEV-SNP & TDX) will also happen at page fault time?

Do we plan to keep it this way?

Thanks,
Pankaj
>
> Definitely the page will still be pinned once it's allocated, there is
> no way to swap it out for example just with the current code. That kind
> of support, if desirable, can be extended through MOVABLE flag and some
> other callbacks to let feature-specific code to involve.