From patchwork Sat May 14 21:35:45 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xiao Guangrong X-Patchwork-Id: 785322 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter2.kernel.org (8.14.4/8.14.3) with ESMTP id p4ELYQGM006793 for ; Sat, 14 May 2011 21:34:26 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754792Ab1ENVd7 (ORCPT ); Sat, 14 May 2011 17:33:59 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:55624 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1754540Ab1ENVd6 (ORCPT ); Sat, 14 May 2011 17:33:58 -0400 Received: from tang.cn.fujitsu.com (tang.cn.fujitsu.com [10.167.250.3]) by song.cn.fujitsu.com (Postfix) with ESMTP id C2694170091; Sun, 15 May 2011 05:33:56 +0800 (CST) Received: from mailserver.fnst.cn.fujitsu.com (tang.cn.fujitsu.com [127.0.0.1]) by tang.cn.fujitsu.com (8.14.3/8.13.1) with ESMTP id p4ELXuJv010733; Sun, 15 May 2011 05:33:56 +0800 Received: from eric.localdomain ([10.167.225.99]) by mailserver.fnst.cn.fujitsu.com (Lotus Domino Release 8.5.1FP4) with ESMTP id 2011051505340820-283458 ; Sun, 15 May 2011 05:34:08 +0800 Message-ID: <4DCEF5B1.3050706@cn.fujitsu.com> Date: Sun, 15 May 2011 05:35:45 +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 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 05:34:08, Serialize by Router on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2011-05-15 05:34:08, Serialize complete at 2011-05-15 05:34:08 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.6 (demeter2.kernel.org [140.211.167.43]); Sat, 14 May 2011 21:34:26 +0000 (UTC) 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..d2e5fb8 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -442,6 +442,7 @@ struct kvm_arch { unsigned int n_requested_mmu_pages; unsigned int n_max_mmu_pages; atomic_t invlpg_counter; + atomic_t indirect_shadow_pages; struct hlist_head mmu_page_hash[KVM_NUM_MMU_PAGES]; /* * Hash table of struct kvm_mmu_page. diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 2841805..971e2d2 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; } + atomic_inc(&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); } + atomic_dec(&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 (!atomic_read(&vcpu->kvm->arch.indirect_shadow_pages)) + return; + zap_page = remote_flush = local_flush = false; offset = offset_in_page(gpa);