On Fri, Jun 21, 2024 at 09:25:10AM +0000, Quentin Perret wrote: > On Friday 21 Jun 2024 at 10:02:08 (+0200), David Hildenbrand wrote: > > Sure, there might be cases like "pKVM can handle access to private pages in > > user page mappings", "AMD-SNP will not crash the host if writing to private > > pages" but there are not factors that really make a difference for a common > > solution. > > Sure, there isn't much value in differentiating on these things. One > might argue that we could save one mmap() on the private->shared > conversion path by keeping all of guest_memfd mapped in userspace > including private memory, but that's most probably not worth the > effort of re-designing the whole thing just for that, so let's forget > that. > > The ability to handle stage-2 faults in the kernel has implications in > other places however. It means we don't need to punch holes in the > kernel linear map when donating memory to a guest for example, even with > 'crazy' access patterns like load_unaligned_zeropad(). So that's good. > The ability to handle stage-2 faults in the kernel is something that's specific to arm64 pKVM though. We do want to punch holes in the linear map for Gunyah case. I don't think this is blocking issue. I only want to point out we can't totally ignore the linear map. Thanks, Elliot
