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

Gupta, Pankaj
2022-08-16T13:04:30Z

>>> 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?
>
> If you are talking about accepting memory by the guest, it is initiated by
> the guest and has nothing to do with page fault time vs fallocate()
> allocation of host memory. I mean acceptance happens after host memory
> allocation but they are not in lockstep, acceptance can happen much later.

No, I meant reserving guest physical memory range from hypervisor e.g
with RMPUpdate for SEV-SNP or equivalent at TDX side (PAMTs?).

Thanks,
Pankaj