linux-kernel - Re: [RFC PATCH v2 44/69] KVM: x86/mmu: Refactor shadow walk in __direct

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Date:   Tue, 6 Jul 2021 16:56:30 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     isaku.yamahata@...el.com, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, erdemaktas@...gle.com,
        Connor Kuehl <ckuehl@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     isaku.yamahata@...il.com,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: Re: [RFC PATCH v2 44/69] KVM: x86/mmu: Refactor shadow walk in
 __direct_map() to reduce indentation

On 03/07/21 00:04, isaku.yamahata@...el.com wrote:
> From: Sean Christopherson <sean.j.christopherson@...el.com>
> 
> Employ a 'continue' to reduce the indentation for linking a new shadow
> page during __direct_map() in preparation for linking private pages.
> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> ---
>   arch/x86/kvm/mmu/mmu.c | 19 +++++++++----------
>   1 file changed, 9 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 1c40dfd05979..0259781cee6a 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -2910,16 +2910,15 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
>   			break;
>   
>   		drop_large_spte(vcpu, it.sptep);
> -		if (!is_shadow_present_pte(*it.sptep)) {
> -			sp = __kvm_mmu_get_page(vcpu, base_gfn,
> -						gfn_stolen_bits, it.addr,
> -						it.level - 1, true, ACC_ALL);
> -
> -			link_shadow_page(vcpu, it.sptep, sp);
> -			if (is_tdp && huge_page_disallowed &&
> -			    req_level >= it.level)
> -				account_huge_nx_page(vcpu->kvm, sp);
> -		}
> +		if (is_shadow_present_pte(*it.sptep))
> +			continue;
> +
> +		sp = __kvm_mmu_get_page(vcpu, base_gfn, gfn_stolen_bits,
> +					it.addr, it.level - 1, true, ACC_ALL);
> +
> +		link_shadow_page(vcpu, it.sptep, sp);
> +		if (is_tdp && huge_page_disallowed && req_level >= it.level)
> +			account_huge_nx_page(vcpu->kvm, sp);
>   	}
>   
>   	ret = mmu_set_spte(vcpu, it.sptep, ACC_ALL,
> 

Reviewed-by: Paolo Bonzini <pbonzini@...hat.com>