On Thu, May 26, 2022 at 8:52 AM Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > > On 5/26/22 16:30, Peter Xu wrote: > > On Thu, May 26, 2022 at 02:01:43PM +0200, Paolo Bonzini wrote: > >> On 5/26/22 01:09, Ben Gardon wrote: > >>> + WARN_ON(max_mapping_level < iter.level); > >>> + > >>> + /* > >>> + * If this page is already mapped at the highest > >>> + * viable level, there's nothing more to do. > >>> + */ > >>> + if (max_mapping_level == iter.level) > >>> + continue; > >>> + > >>> + /* > >>> + * The page can be remapped at a higher level, so step > >>> + * up to zap the parent SPTE. > >>> + */ > >>> + while (max_mapping_level > iter.level) > >>> + tdp_iter_step_up(&iter); > >>> + > >>> /* Note, a successful atomic zap also does a remote TLB flush. */ > >>> - if (tdp_mmu_zap_spte_atomic(kvm, &iter)) > >>> - goto retry; > >>> + tdp_mmu_zap_spte_atomic(kvm, &iter); > >>> + > >> > >> Can you make this a sparate function (for example > >> tdp_mmu_zap_collapsible_spte_atomic)? Otherwise looks great! > > > > There could be a tiny downside of using a helper in that it'll hide the > > step-up of the iterator, which might not be as obvious as keeping it in the > > loop? > > That's true, my reasoning is that zapping at a higher level can only be > done by first moving the iterator up. Maybe > tdp_mmu_zap_at_level_atomic() is a better Though, I can very well apply > this patch as is. I'd be inclined to apply the patch as-is for a couple reasons: 1. As Peter said, hiding the step up could be confusing. 2. If we want to try the in-place promotion, we'll have to dismantle that helper again anyway or else have a bunch of duplicate code. > > Paolo >
