linux-kernel - Re: [PATCH v3 2/8] KVM: Integrate gfn_to_memslot_approx() into search

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Message-ID: <eb9d336a-67dd-6a31-51c2-cbcd72c49824@redhat.com>
Date:   Thu, 10 Jun 2021 18:17:33 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        "Maciej S. Szmigiero" <mail@...iej.szmigiero.name>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Igor Mammedov <imammedo@...hat.com>,
        Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Huacai Chen <chenhuacai@...nel.org>,
        Aleksandar Markovic <aleksandar.qemu.devel@...il.com>,
        Paul Mackerras <paulus@...abs.org>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        David Hildenbrand <david@...hat.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/8] KVM: Integrate gfn_to_memslot_approx() into
 search_memslots()

On 19/05/21 23:24, Sean Christopherson wrote:
> An alternative to modifying the PPC code would be to make the existing
> search_memslots() a wrapper to __search_memslots(), with the latter taking
> @approx.

Let's just modify PPC to use __gfn_to_memslot instead of search_memslots().

__gfn_to_memslot() has never introduced any functionality over 
search_memslots(), ever since search_memslots() was introduced in 2011.

Paolo

> We might also want to make this __always_inline to improve the likelihood of the
> compiler optimizing away @approx.  I doubt it matters in practice...
>