linux-kernel - Re: [PATCH 2/2] KVM: x86/mmu: Don't step down in the TDP iterator when zapping all SPTEs

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Message-ID: <928be04d-e60e-924c-1f3a-cb5fef8b0042@redhat.com>
Date:   Thu, 12 Aug 2021 19:15:01 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Ben Gardon <bgardon@...gle.com>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm <kvm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] KVM: x86/mmu: Don't step down in the TDP iterator
 when zapping all SPTEs

On 12/08/21 19:07, Sean Christopherson wrote:
> Yeah, I was/am on the fence too, I almost included a blurb in the cover letter
> saying as much.  I'll do that for v2 and let Paolo decide.

I think it makes sense to have it.  You can even use the ternary operator

	/*
	 * When zapping everything, all entries at the top level
	 * ultimately go away, and the levels below go down with them.
	 * So do not bother iterating all the way down to the leaves.
	 */
	int min_level = zap_all ? root->role.level : PG_LEVEL_4K;

Paolo