linux-kernel - Re: [PATCH 18/22] kvm: mmu: Support disabling dirty logging for the tdp MMU

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Message-ID: <44822999-f5dc-6116-db12-a41f5bd80dd8@redhat.com>
Date:   Sat, 26 Sep 2020 03:09:16 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Ben Gardon <bgardon@...gle.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     Cannon Matthews <cannonmatthews@...gle.com>,
        Peter Xu <peterx@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Peter Shier <pshier@...gle.com>,
        Peter Feiner <pfeiner@...gle.com>,
        Junaid Shahid <junaids@...gle.com>,
        Jim Mattson <jmattson@...gle.com>,
        Yulei Zhang <yulei.kernel@...il.com>,
        Wanpeng Li <kernellwp@...il.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Xiao Guangrong <xiaoguangrong.eric@...il.com>
Subject: Re: [PATCH 18/22] kvm: mmu: Support disabling dirty logging for the
 tdp MMU

On 25/09/20 23:22, Ben Gardon wrote:
> +	for_each_tdp_pte_root(iter, root, start, end) {
> +		if (!is_shadow_present_pte(iter.old_spte) ||
> +		    is_last_spte(iter.old_spte, iter.level))
> +			continue;
> +

I'm starting to wonder if another iterator like
for_each_tdp_leaf_pte_root would be clearer, since this idiom repeats
itself quite often.  The tdp_iter_next_leaf function would be easily
implemented as

	while (likely(iter->valid) &&
	       (!is_shadow_present_pte(iter.old_spte) ||
		is_last_spte(iter.old_spte, iter.level))
		tdp_iter_next(iter);

Paolo