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Subject: Re: [PATCH 1/2] KVM: x86/mmu: Make HVA handler retpoline-friendly
To:     "Maciej S. Szmigiero" <mail@maciej.szmigiero.name>
Cc:     Sean Christopherson <seanjc@google.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        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>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        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>,
        Joerg Roedel <joro@8bytes.org>, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <ceb96527b6f7bb662eec813f05b897a551ebd0b2.1612140117.git.maciej.szmigiero@oracle.com>
 <c3f775de-9cb5-5f30-3fbc-a5e80c1654de@redhat.com>
 <771da54d-0601-ccd2-8edf-814086739e53@maciej.szmigiero.name>
From:   Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <7b15ae06-4b56-0259-6950-6781622020ab@redhat.com>
Date:   Wed, 3 Feb 2021 15:43:22 +0100
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On 01/02/21 16:19, Maciej S. Szmigiero wrote:
> On 01.02.2021 09:21, Paolo Bonzini wrote:
>> On 01/02/21 09:13, Maciej S. Szmigiero wrote:
>>>   static int kvm_handle_hva_range(struct kvm *kvm,
>>>                   unsigned long start,
>>>                   unsigned long end,
>>> @@ -1495,8 +1534,9 @@ static int kvm_handle_hva_range(struct kvm *kvm,
>>
>>
>>> -static int kvm_tdp_mmu_handle_hva_range(struct kvm *kvm, unsigned 
>>> long start,
>>> -        unsigned long end, unsigned long data,
>>> -        int (*handler)(struct kvm *kvm, struct kvm_memory_slot *slot,
>>> -                   struct kvm_mmu_page *root, gfn_t start,
>>> -                   gfn_t end, unsigned long data))
>>> -{
>>
>> Can you look into just marking these functions __always_inline?  This 
>> should help the compiler change (*handler)(...) into a regular 
>> function call.
> 
> That looks even better - I see the compiler then turns the indirect call
> into a direct one.
> 
> Will change to __always_inline instead of static dispatch in the next
> version.
> Thanks for the pointer.

Feel free to send this separately as it's a self-contained change.

Thanks,

Paolo