Avi Kivity <avi@xxxxxxxxxx> wrote: > > I have one concern about correctness issue though: > > > > concurrent rmap write protection may not be safe due to > > delayed tlb flush ... cannot happen? > > What do you mean by concurrent rmap write protection? > Not sure, but other codes like: - mmu_sync_children() for_each_sp(pages, sp, parents, i) protected |= rmap_write_protect(vcpu->kvm, sp->gfn); if (protected) kvm_flush_remote_tlbs(vcpu->kvm); - kvm_mmu_get_page() if (rmap_write_protect(vcpu->kvm, gfn)) kvm_flush_remote_tlbs(vcpu->kvm); I just wondered what can happen if GET_DIRTY_LOG is being processed behind these processing? They may find nothing to write protect and won't do kvm_flush_remote_tlbs() if the gfn has been already protected by GET_DIRTY_LOG. But GET_DIRTY_LOG may still be busy write protecting other pages and others can return before. (My code releases mmu_lock to not include __put_user() in the critical section.) I am not still enough familier with these code yet. (maybe empty concern) Takuya -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
