Re: [PATCH 15/22] kvm: mmu: Support changed pte notifier in tdp MMU

[Paolo Bonzini]

On 25/09/20 23:22, Ben Gardon wrote:
> +		*iter.sptep = 0;
> +		handle_changed_spte(kvm, as_id, iter.gfn, iter.old_spte,
> +				    new_spte, iter.level);
> +

Can you explain why new_spte is passed here instead of 0?

All calls to handle_changed_spte are preceded by "*something = 
new_spte" except this one, so I'm thinking of having a change_spte 
function like

static void change_spte(struct kvm *kvm, int as_id, gfn_t gfn,
                        u64 *sptep, u64 new_spte, int level)
{
        u64 old_spte = *sptep;
        *sptep = new_spte;

        __handle_changed_spte(kvm, as_id, gfn, old_spte, new_spte, level);
        handle_changed_spte_acc_track(old_spte, new_spte, level);
        handle_changed_spte_dirty_log(kvm, as_id, gfn, old_spte, new_spte, level);
}

in addition to the previously-mentioned cleanup of always calling
handle_changed_spte instead of special-casing calls to two of the
three functions.  It would be a nice place to add the
trace_kvm_mmu_set_spte tracepoint, too.

Paolo