Re: [PATCH 10/14] KVM: x86: Further clarify the logic and comments for toggling log dirty

Paolo Bonzini
2021-02-18T16:09:20Z

On 13/02/21 01:50, Sean Christopherson wrote:
>
> - * Nothing to do for RO slots or CREATE/MOVE/DELETE of a slot.
> - * See comments below.
> + * Nothing to do for RO slots (which can't be dirtied and can't be made
> + * writable) or CREATE/MOVE/DELETE of a slot. See comments below.
> */
> if ((change != KVM_MR_FLAGS_ONLY) || (new->flags & KVM_MEM_READONLY))
> return;
>
> + /*
> + * READONLY and non-flags changes were filtered out above, and the only
> + * other flag is LOG_DIRTY_PAGES, i.e. something is wrong if dirty
> + * logging isn't being toggled on or off.
> + */
> + if (WARN_ON_ONCE(!((old->flags ^ new->flags) & KVM_MEM_LOG_DIRTY_PAGES)))
> + return;
> +

What about readonly -> readwrite changes?

Paolo