From mboxrd@z Thu Jan 1 00:00:00 1970 From: Xiao Guangrong Subject: [PATCH v2 4/6] KVM: MMU: don't atomicly set spte if it's not present Date: Fri, 16 Jul 2010 11:27:10 +0800 Message-ID: <4C3FD18E.1010908@cn.fujitsu.com> References: <4C3FCFD7.5070005@cn.fujitsu.com> <4C3FD11D.1060104@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , LKML , KVM list To: Avi Kivity Return-path: In-Reply-To: <4C3FD11D.1060104@cn.fujitsu.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org If the old mapping is not present, the spte.a is not lost, so no need atomic operation to set it Signed-off-by: Xiao Guangrong --- arch/x86/kvm/mmu.c | 5 +++-- 1 files changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index b3896bf..4123e8e 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -307,9 +307,10 @@ static void update_spte(u64 *sptep, u64 new_spte) { u64 old_spte; - if (!shadow_accessed_mask || (new_spte & shadow_accessed_mask)) { + if (!shadow_accessed_mask || (new_spte & shadow_accessed_mask) || + !is_rmap_spte(*sptep)) __set_spte(sptep, new_spte); - } else { + else { old_spte = __xchg_spte(sptep, new_spte); if (old_spte & shadow_accessed_mask) mark_page_accessed(pfn_to_page(spte_to_pfn(old_spte))); -- 1.6.1.2