Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760045Ab1EOPSm (ORCPT ); Sun, 15 May 2011 11:18:42 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:53781 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1756347Ab1EOPSj (ORCPT ); Sun, 15 May 2011 11:18:39 -0400 Message-ID: <4DCFEF3B.5060806@cn.fujitsu.com> Date: Sun, 15 May 2011 23:20:27 +0800 From: Xiao Guangrong User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.15) Gecko/20110307 Fedora/3.1.9-0.39.b3pre.fc14 Thunderbird/3.1.9 MIME-Version: 1.0 To: Avi Kivity CC: Marcelo Tosatti , LKML , KVM Subject: [PATCH v2 1/7] KVM: MMU: optimize pte write path if don't have protected sp X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2011-05-15 23:18:48, Serialize by Router on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2011-05-15 23:18:48, Serialize complete at 2011-05-15 23:18:48 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2136 Lines: 63 Simply return from kvm_mmu_pte_write path if no shadow page is write-protected, then we can avoid to walk all shadow pages and hold mmu-lock Signed-off-by: Xiao Guangrong --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/mmu.c | 9 +++++++++ 2 files changed, 10 insertions(+), 0 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index d2ac8e2..152601a 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -441,6 +441,7 @@ struct kvm_arch { unsigned int n_used_mmu_pages; unsigned int n_requested_mmu_pages; unsigned int n_max_mmu_pages; + unsigned int indirect_shadow_pages; atomic_t invlpg_counter; struct hlist_head mmu_page_hash[KVM_NUM_MMU_PAGES]; /* diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 2841805..ad520d4 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -498,6 +498,7 @@ static void account_shadowed(struct kvm *kvm, gfn_t gfn) linfo = lpage_info_slot(gfn, slot, i); linfo->write_count += 1; } + kvm->arch.indirect_shadow_pages++; } static void unaccount_shadowed(struct kvm *kvm, gfn_t gfn) @@ -513,6 +514,7 @@ static void unaccount_shadowed(struct kvm *kvm, gfn_t gfn) linfo->write_count -= 1; WARN_ON(linfo->write_count < 0); } + kvm->arch.indirect_shadow_pages--; } static int has_wrprotected_page(struct kvm *kvm, @@ -3233,6 +3235,13 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, int level, npte, invlpg_counter, r, flooded = 0; bool remote_flush, local_flush, zap_page; + /* + * If we don't have indirect shadow pages, it means no page is + * write-protected, so we can exit simply. + */ + if (!ACCESS_ONCE(vcpu->kvm->arch.indirect_shadow_pages)) + return; + zap_page = remote_flush = local_flush = false; offset = offset_in_page(gpa); -- 1.7.4.4 -- 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/