linux-kernel - Re: [PATCH v6 27/29] KVM: Optimize overlapping memslots check

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Date:   Wed, 1 Dec 2021 16:45:39 +0100
From:   "Maciej S. Szmigiero" <mail@...iej.szmigiero.name>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        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>,
        Anup Patel <anup.patel@....com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Atish Patra <atish.patra@....com>,
        Ben Gardon <bgardon@...gle.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 27/29] KVM: Optimize overlapping memslots check

On 01.12.2021 04:08, Sean Christopherson wrote:
> On Tue, Nov 30, 2021, Maciej S. Szmigiero wrote:
>> From: "Maciej S. Szmigiero" <maciej.szmigiero@...cle.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@...cle.com>
>> [sean: tweaked params to avoid churn in future cleanup]
>> Signed-off-by: Sean Christopherson <seanjc@...gle.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@...gle.com>
> 

Will add these braces (and your R-b, too).

Thanks,
Maciej