On Sun, May 16, 2021, Maciej S. Szmigiero wrote:
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 8895b95b6a22..3c40c7d32f7e 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -1091,10 +1091,14 @@ bool kvm_arch_irqfd_allowed(struct kvm *kvm, struct kvm_irqfd *args);
> * gfn_to_memslot() itself isn't here as an inline because that would
> * bloat other code too much.
> *
> + * With "approx" set returns the memslot also when the address falls
> + * in a hole. In that case one of the memslots bordering the hole is
> + * returned.
> + *
> * IMPORTANT: Slots are sorted from highest GFN to lowest GFN!
> */
> static inline struct kvm_memory_slot *
> -search_memslots(struct kvm_memslots *slots, gfn_t gfn)
> +search_memslots(struct kvm_memslots *slots, gfn_t gfn, bool approx)
An alternative to modifying the PPC code would be to make the existing
search_memslots() a wrapper to __search_memslots(), with the latter taking
@approx.
We might also want to make this __always_inline to improve the likelihood of the
compiler optimizing away @approx. I doubt it matters in practice...
> {
> int start = 0, end = slots->used_slots;
> int slot = atomic_read(&slots->lru_slot);
> @@ -1116,19 +1120,22 @@ search_memslots(struct kvm_memslots *slots, gfn_t gfn)
> start = slot + 1;
> }
>
> + if (approx && start >= slots->used_slots)
> + return &memslots[slots->used_slots - 1];
> +
> if (start < slots->used_slots && gfn >= memslots[start].base_gfn &&
> gfn < memslots[start].base_gfn + memslots[start].npages) {
> atomic_set(&slots->lru_slot, start);
> return &memslots[start];
> }
>
> - return NULL;
> + return approx ? &memslots[start] : NULL;
> }
>
> static inline struct kvm_memory_slot *
> __gfn_to_memslot(struct kvm_memslots *slots, gfn_t gfn)
> {
> - return search_memslots(slots, gfn);
> + return search_memslots(slots, gfn, false);
> }
>
> static inline unsigned long
