Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935588Ab0GPDeT (ORCPT ); Thu, 15 Jul 2010 23:34:19 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:55849 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S935497Ab0GPDeS (ORCPT ); Thu, 15 Jul 2010 23:34:18 -0400 Message-ID: <4C3FD24A.9020605@cn.fujitsu.com> Date: Fri, 16 Jul 2010 11:30:18 +0800 From: Xiao Guangrong User-Agent: Thunderbird 2.0.0.24 (Windows/20100228) MIME-Version: 1.0 To: Avi Kivity CC: Marcelo Tosatti , LKML , KVM list Subject: [PATCH v2 6/6] KVM: MMU: using __xchg_spte more smarter References: <4C3FCFD7.5070005@cn.fujitsu.com> <4C3FD1C9.5010909@cn.fujitsu.com> In-Reply-To: <4C3FD1C9.5010909@cn.fujitsu.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1255 Lines: 41 Sometimes, atomically set spte is not needed, this patch call __xchg_spte() more smartly Note: if the old mapping's access bit is already set, we no need atomic operation since the access bit is not lost Signed-off-by: Xiao Guangrong --- arch/x86/kvm/mmu.c | 9 +++++++-- 1 files changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index fb3ae54..71e9268 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -682,9 +682,14 @@ static void rmap_remove(struct kvm *kvm, u64 *spte) static void set_spte_track_bits(u64 *sptep, u64 new_spte) { pfn_t pfn; - u64 old_spte; + u64 old_spte = *sptep; + + if (!shadow_accessed_mask || !is_shadow_present_pte(old_spte) || + old_spte & shadow_accessed_mask) { + __set_spte(sptep, new_spte); + } else + old_spte = __xchg_spte(sptep, new_spte); - old_spte = __xchg_spte(sptep, new_spte); if (!is_rmap_spte(old_spte)) return; pfn = spte_to_pfn(old_spte); -- 1.6.1.2 -- 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/