Date:   Wed, 1 Dec 2021 03:08:29 +0000
From:   Sean Christopherson <seanjc@google.com>
To:     "Maciej S. Szmigiero" <mail@maciej.szmigiero.name>
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        Igor Mammedov <imammedo@redhat.com>,
        Marc Zyngier <maz@kernel.org>,
        James Morse <james.morse@arm.com>,
        Julien Thierry <julien.thierry.kdev@gmail.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Huacai Chen <chenhuacai@kernel.org>,
        Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
        Paul Mackerras <paulus@ozlabs.org>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Janosch Frank <frankja@linux.ibm.com>,
        David Hildenbrand <david@redhat.com>,
        Cornelia Huck <cohuck@redhat.com>,
        Claudio Imbrenda <imbrenda@linux.ibm.com>,
        Anup Patel <anup.patel@wdc.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Alexandru Elisei <alexandru.elisei@arm.com>,
        Atish Patra <atish.patra@wdc.com>,
        Ben Gardon <bgardon@google.com>, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 27/29] KVM: Optimize overlapping memslots check
Message-ID: <YabnLaz3QBbsxLl0@google.com>
References: <cover.1638304315.git.maciej.szmigiero@oracle.com>
 <9698a99ccd1938a36dd0c7399262f888dcdf01ac.1638304316.git.maciej.szmigiero@oracle.com>
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On Tue, Nov 30, 2021, Maciej S. Szmigiero wrote:
> From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>
> 
> Do a quick lookup for possibly overlapping gfns when creating or moving
> a memslot instead of performing a linear scan of the whole memslot set.
> 
> Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
> [sean: tweaked params to avoid churn in future cleanup]
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
>  virt/kvm/kvm_main.c | 35 +++++++++++++++++++++--------------
>  1 file changed, 21 insertions(+), 14 deletions(-)
> 
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 086f18969bc3..52117f65bc5b 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1817,6 +1817,18 @@ static int kvm_set_memslot(struct kvm *kvm,
>  	return 0;
>  }
>  
> +static bool kvm_check_memslot_overlap(struct kvm_memslots *slots, int id,
> +				      gfn_t start, gfn_t end)
> +{
> +	struct kvm_memslot_iter iter;
> +
> +	kvm_for_each_memslot_in_gfn_range(&iter, slots, start, end)

The for loop needs curly braces, per coding-style.rst:

Also, use braces when a loop contains more than a single simple statement:

.. code-block:: c

        while (condition) {
                if (test)
                        do_something();
        }

With that,

Reviewed-by: Sean Christopherson <seanjc@google.com>