From patchwork Tue Jul 30 13:02:04 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xiao Guangrong X-Patchwork-Id: 2835656 Return-Path: X-Original-To: patchwork-kvm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id EC275C0319 for ; Tue, 30 Jul 2013 13:07:37 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 4295C2038C for ; Tue, 30 Jul 2013 13:07:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 81EEE20377 for ; Tue, 30 Jul 2013 13:07:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755346Ab3G3NHB (ORCPT ); Tue, 30 Jul 2013 09:07:01 -0400 Received: from e28smtp01.in.ibm.com ([122.248.162.1]:50811 "EHLO e28smtp01.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751084Ab3G3NFp (ORCPT ); Tue, 30 Jul 2013 09:05:45 -0400 Received: from /spool/local by e28smtp01.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 30 Jul 2013 18:27:33 +0530 Received: from d28dlp01.in.ibm.com (9.184.220.126) by e28smtp01.in.ibm.com (192.168.1.131) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; Tue, 30 Jul 2013 18:27:30 +0530 Received: from d28relay05.in.ibm.com (d28relay05.in.ibm.com [9.184.220.62]) by d28dlp01.in.ibm.com (Postfix) with ESMTP id 12F74E008E; Tue, 30 Jul 2013 18:35:45 +0530 (IST) Received: from d28av05.in.ibm.com (d28av05.in.ibm.com [9.184.220.67]) by d28relay05.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r6UD5YSV5243010; Tue, 30 Jul 2013 18:35:34 +0530 Received: from d28av05.in.ibm.com (loopback [127.0.0.1]) by d28av05.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r6UD5XSt027227; Tue, 30 Jul 2013 23:05:37 +1000 Received: from localhost (ericxiao.cn.ibm.com [9.111.29.99]) by d28av05.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id r6UD5XOA027162; Tue, 30 Jul 2013 23:05:33 +1000 From: Xiao Guangrong To: gleb@redhat.com Cc: avi.kivity@gmail.com, mtosatti@redhat.com, pbonzini@redhat.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Xiao Guangrong Subject: [PATCH 06/12] KVM: MMU: flush tlb if the spte can be locklessly modified Date: Tue, 30 Jul 2013 21:02:04 +0800 Message-Id: <1375189330-24066-7-git-send-email-xiaoguangrong@linux.vnet.ibm.com> X-Mailer: git-send-email 1.8.1.4 In-Reply-To: <1375189330-24066-1-git-send-email-xiaoguangrong@linux.vnet.ibm.com> References: <1375189330-24066-1-git-send-email-xiaoguangrong@linux.vnet.ibm.com> X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13073012-4790-0000-0000-00000988A53D Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Spam-Status: No, score=-8.4 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Relax the tlb flush condition since we will write-protect the spte out of mmu lock. Note lockless write-protection only marks the writable spte to readonly and the spte can be writable only if both SPTE_HOST_WRITEABLE and SPTE_MMU_WRITEABLE are set (that are tested by spte_is_locklessly_modifiable) This patch is used to avoid this kind of race: VCPU 0 VCPU 1 lockless wirte protection: set spte.w = 0 lock mmu-lock write protection the spte to sync shadow page, see spte.w = 0, then without flush tlb unlock mmu-lock !!! At this point, the shadow page can still be writable due to the corrupt tlb entry Flush all TLB Signed-off-by: Xiao Guangrong --- arch/x86/kvm/mmu.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 58283bf..5a40564 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -600,7 +600,8 @@ static bool mmu_spte_update(u64 *sptep, u64 new_spte) * we always atomicly update it, see the comments in * spte_has_volatile_bits(). */ - if (is_writable_pte(old_spte) && !is_writable_pte(new_spte)) + if (spte_is_locklessly_modifiable(old_spte) && + !is_writable_pte(new_spte)) ret = true; if (!shadow_accessed_mask)