On Tue, Aug 06, 2024 at 11:14:15AM -0700, Anish Moorthy wrote: > On Mon, Aug 5, 2024 at 3:51 PM Oliver Upton <oliver.upton@xxxxxxxxx> wrote: > > > > The wording of the cap documentation isn't as relaxed as I'd > > anticipated. Perhaps: > > > > The presence of this capability indicates that KVM_RUN *may* fill > > kvm_run.memory_fault if ... > > > > IOW, userspace is not guaranteed that the structure is filled for every > > 'memory fault'. > > Agreed, I can add a patch to update the docs > > While we're at it, what do we think of removing this disclaimer? > > >Note: Userspaces which attempt to resolve memory faults so that they can retry > > KVM_RUN are encouraged to guard against repeatedly receiving the same > > error/annotated fault. > > I originally added this bit due to my concerns with the idea of > filling kvm_run.memory_fault even for EFAULTs that weren't guaranteed > to be returned by KVM_RUN [1]. This sort of language generally isn't necessary in UAPI descriptions. We cannot exhaustively describe the ways userspace might misuse an interface. > However if I'm interpreting Sean's > response to [2] correctly, I think we're now committed to only > KVM_EXIT_MEMORY_FAULTing for EFAULTs/EHWPOISONs which return from > KVM_RUN. At the very least, that seems to be true of current usages. Yeah, I'd have a similar expectation. No point in a half-attempt at getting out to userspace and subsequently stomping the context. -- Thanks, Oliver
