From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH] KVM: x86: MMU: Use clear_page() instead of init_shadow_page_table() Date: Fri, 18 Dec 2015 19:08:30 +0100 Message-ID: <56744B9E.6000607@redhat.com> References: <20151218185449.3ba700d079a21ab9ff1508bb@lab.ntt.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org To: Takuya Yoshikawa Return-path: In-Reply-To: <20151218185449.3ba700d079a21ab9ff1508bb@lab.ntt.co.jp> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org 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 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; > } >