On Fri, Dec 01, 2023, Mingwei Zhang wrote: > On Fri, Dec 1, 2023 at 1:30 PM Kalra, Ashish <ashish.kalra@xxxxxxx> wrote: > > For SNP + gmem, where the HVA ranges covered by the MMU notifiers are > > not acting on encrypted pages, we are ignoring MMU invalidation > > notifiers for SNP guests as part of the SNP host patches being posted > > upstream and instead relying on gmem own invalidation stuff to clean > > them up on a per-folio basis. > > > > Thanks, > > Ashish > > oh, I have no question about that. This series only applies to > SEV/SEV-ES type of VMs. > > For SNP + guest_memfd, I don't see the implementation details, but I > doubt you can ignore mmu_notifiers if the request does cover some > encrypted memory in error cases or corner cases. Does the SNP enforce > the usage of guest_memfd? How do we prevent exceptional cases? I am > sure you guys already figured out the answers, so I don't plan to dig > deeper until SNP host pages are accepted. KVM will not allow SNP guests to map VMA-based memory as encrypted/private, full stop. Any invalidations initiated by mmu_notifiers will therefore apply only to shared memory. That approach doesn't work for SEV/SEV-ES because KVM can't prevent the guest from accessing memory as encrypted, i.e. KVM needs the #NPF due to RMP violation to intercept attempts to convert a GFN from shared to private.
