On Fri, Mar 11, 2022 at 12:25:20AM +0000, David Matlack wrote: > Currently KVM only zaps collapsible 4KiB SPTEs in the shadow MMU (i.e. > in the rmap). This is fine for now KVM never creates intermediate huge > pages during dirty logging, i.e. a 1GiB page is never partially split to > a 2MiB page. > > However, this will stop being true once the shadow MMU participates in > eager page splitting, which can in fact leave behind partially split > huge pages. In preparation for that change, change the shadow MMU to > iterate over all necessary levels when zapping collapsible SPTEs. > > No functional change intended. > > Signed-off-by: David Matlack <[email protected]> > --- > arch/x86/kvm/mmu/mmu.c | 26 +++++++++++++++++++------- > 1 file changed, 19 insertions(+), 7 deletions(-) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 89a7a8d7a632..2032be3edd71 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -6142,18 +6142,30 @@ static bool kvm_mmu_zap_collapsible_spte(struct kvm > *kvm, > return need_tlb_flush; > } > > +static void kvm_rmap_zap_collapsible_sptes(struct kvm *kvm, > + const struct kvm_memory_slot *slot) > +{ > + bool flush; > + > + /* > + * Note, use KVM_MAX_HUGEPAGE_LEVEL - 1 since there's no need to zap > + * pages that are already mapped at the maximum possible level. > + */ > + flush = slot_handle_level(kvm, slot, kvm_mmu_zap_collapsible_spte, > + PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL - 1, > + true); > + > + if (flush) > + kvm_arch_flush_remote_tlbs_memslot(kvm, slot); > + > +}
Reviewed-by: Peter Xu <[email protected]> IMHO it looks cleaner to write it in the old way (drop the flush var). Maybe even unwrap the helper? Thanks, -- Peter Xu _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
