Re: [PATCH v5.5 24/30] KVM: Use interval tree to do fast hva lookup in memslots
Sean Christopherson <[email protected]>
| Newsgroups | org.kernel.vger.kvm-ppc,dev.linux.lists.kvmarm,org.infradead.lists.kvm-riscv,org.infradead.lists.linux-arm-kernel,org.infradead.lists.linux-riscv,org.kernel.vger.kvm,org.kernel.vger.linux-kernel,org.kernel.vger.linux-mips |
|---|---|
| Message-ID | <[email protected]> |
On Fri, Nov 12, 2021, Maciej S. Szmigiero wrote:
> On 04.11.2021 01:25, Sean Christopherson wrote:
> > @@ -1262,22 +1274,32 @@ static void kvm_replace_memslot(struct kvm_memslots *slots,
> > struct kvm_memory_slot *new)
> > {
> > /*
> > - * Remove the old memslot from the hash list, copying the node data
> > - * would corrupt the list.
> > + * Remove the old memslot from the hash list and interval tree, copying
> > + * the node data would corrupt the structures.
> > */
> > if (old) {
> > hash_del(&old->id_node);
> > + interval_tree_remove(&old->hva_node, &slots->hva_tree);
> > if (!new)
> > return;
> > }
> > - /* Copy the source *data*, not the pointer, to the destination. */
> > - if (old)
> > + /*
> > + * Copy the source *data*, not the pointer, to the destination. If
> > + * @old is NULL, initialize @new's hva range.
> > + */
> > + if (old) {
> > *new = *old;
> > + } else if (new) {
>
> Unnecessary check - if "new" is NULL then the code will crash anyway
> accessing this pointer unconditionally...
>
> > + new->hva_node.start = new->userspace_addr;
> > + new->hva_node.last = new->userspace_addr +
> > + (new->npages << PAGE_SHIFT) - 1;
> > + }
> > /* (Re)Add the new memslot. */
> > hash_add(slots->id_hash, &new->id_node, new->id);
> > + interval_tree_insert(&new->hva_node, &slots->hva_tree);
>
> ...in these two lines above.
Yep, definitely worthless. I think this was another "plan for the future" idea
that didn't actually add value.