Re: [PATCH] KVM: x86: MMU: Use clear_page() instead of init_shadow_page_table()

Path	csiph.com!goblin2!goblin.stu.neva.ru!news.etla.org!aioe.org!bofh.it!news.nic.it!robomod
From	Paolo Bonzini <pbonzini@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] KVM: x86: MMU: Use clear_page() instead of init_shadow_page_table()
Date	Fri, 18 Dec 2015 19:10:02 +0100
Message-ID	<qH7DA-By-3@gated-at.bofh.it> (permalink)
References	<qGZPH-3SO-1@gated-at.bofh.it>
X-Original-To	Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
User-Agent	Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0
MIME-Version	1.0
Content-Type	text/plain; charset=windows-1252
Content-Transfer-Encoding	7bit
X-Scanned-By	MIMEDefang 2.68 on 10.5.11.23
Sender	robomod@news.nic.it
List-ID	<linux-kernel.vger.kernel.org>
X-Mailing-List	linux-kernel@vger.kernel.org
Approved	robomod@news.nic.it
Lines	53
Organization	linux.* mail to news gateway
X-Original-Cc	kvm@vger.kernel.org, linux-kernel@vger.kernel.org
X-Original-Date	Fri, 18 Dec 2015 19:08:30 +0100
X-Original-Message-ID	<56744B9E.6000607@redhat.com>
X-Original-References	<20151218185449.3ba700d079a21ab9ff1508bb@lab.ntt.co.jp>
X-Original-Sender	linux-kernel-owner@vger.kernel.org
Xref	csiph.com linux.kernel:1295082

Show key headers only | View raw


On 18/12/2015 10:54, Takuya Yoshikawa wrote:
> Not just in order to clean up the code, but to make it faster by using
> enhanced instructions: the initialization became 20-30% faster on our
> testing machine.
> 
> Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>

Applied locally, but I'm not sure when it will appear on kernel.org...
it depends on the amount of testing I can do next week before the
holidays.  Anyway, it's not lost. :)

Paolo

> ---
>  arch/x86/kvm/mmu.c | 10 +---------
>  1 file changed, 1 insertion(+), 9 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index a1a3d19..7f5a82b 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -2041,14 +2041,6 @@ static void mmu_sync_children(struct kvm_vcpu *vcpu,
>  	}
>  }
>  
> -static void init_shadow_page_table(struct kvm_mmu_page *sp)
> -{
> -	int i;
> -
> -	for (i = 0; i < PT64_ENT_PER_PAGE; ++i)
> -		sp->spt[i] = 0ull;
> -}
> -
>  static void __clear_sp_write_flooding_count(struct kvm_mmu_page *sp)
>  {
>  	sp->write_flooding_count = 0;
> @@ -2128,7 +2120,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
>  		account_shadowed(vcpu->kvm, sp);
>  	}
>  	sp->mmu_valid_gen = vcpu->kvm->arch.mmu_valid_gen;
> -	init_shadow_page_table(sp);
> +	clear_page(sp->spt);
>  	trace_kvm_mmu_get_page(sp, true);
>  	return sp;
>  }
> 
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

[PATCH] KVM: x86: MMU: Use clear_page() instead of  init_shadow_page_table() Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp> - 2015-12-18 10:50 +0100
  Re: [PATCH] KVM: x86: MMU: Use clear_page() instead of  init_shadow_page_table() Paolo Bonzini <pbonzini@redhat.com> - 2015-12-18 19:10 +0100

csiph-web