Re: [PATCH 16/18] KVM: Don't take mmu_lock for range invalidation unless necessary

[Paolo Bonzini]

On 31/03/21 23:22, Sean Christopherson wrote:
> On a related topic, any preference on whether to have an explicit "must_lock"
> flag (what I posted), or derive the logic based on other params?
>
> The helper I posted does:
>
> 	if (range->must_lock &&
> 	    kvm_mmu_lock_and_check_handler(kvm, range, &locked))
> 		goto out_unlock;
>
> but it could be:
>
> 	if (!IS_KVM_NULL_FN(range->on_lock) && !range->may_block &&
> 	    kvm_mmu_lock_and_check_handler(kvm, range, &locked))
> 		goto out_unlock;
>
> The generated code should be nearly identical on a modern compiler, so it's
> purely a question of aesthetics.  I slightly prefer the explicit "must_lock" to
> avoid spreading out the logic too much, but it also feels a bit superfluous.

I do as well, but I hope we don't need any lock after all as in the 
email I've just sent.

Paolo