From patchwork Wed Oct 23 13:29:21 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xiao Guangrong X-Patchwork-Id: 3088821 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 74D12BF924 for ; Wed, 23 Oct 2013 13:36:03 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 5A33C203C4 for ; Wed, 23 Oct 2013 13:36:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2BEE4203AF for ; Wed, 23 Oct 2013 13:36:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753230Ab3JWNfN (ORCPT ); Wed, 23 Oct 2013 09:35:13 -0400 Received: from e28smtp03.in.ibm.com ([122.248.162.3]:56076 "EHLO e28smtp03.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751789Ab3JWN3z (ORCPT ); Wed, 23 Oct 2013 09:29:55 -0400 Received: from /spool/local by e28smtp03.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 23 Oct 2013 18:59:53 +0530 Received: from d28dlp03.in.ibm.com (9.184.220.128) by e28smtp03.in.ibm.com (192.168.1.133) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; Wed, 23 Oct 2013 18:59:52 +0530 Received: from d28relay04.in.ibm.com (d28relay04.in.ibm.com [9.184.220.61]) by d28dlp03.in.ibm.com (Postfix) with ESMTP id 21B971258055; Wed, 23 Oct 2013 19:00:25 +0530 (IST) Received: from d28av01.in.ibm.com (d28av01.in.ibm.com [9.184.220.63]) by d28relay04.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r9NDTl6R44695724; Wed, 23 Oct 2013 18:59:47 +0530 Received: from d28av01.in.ibm.com (localhost [127.0.0.1]) by d28av01.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id r9NDTosX025112; Wed, 23 Oct 2013 18:59:50 +0530 Received: from localhost (ericxiao.cn.ibm.com [9.111.29.64]) by d28av01.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVin) with ESMTP id r9NDTnF0025064; Wed, 23 Oct 2013 18:59:50 +0530 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 v3 03/15] KVM: MMU: flush tlb if the spte can be locklessly modified Date: Wed, 23 Oct 2013 21:29:21 +0800 Message-Id: <1382534973-13197-4-git-send-email-xiaoguangrong@linux.vnet.ibm.com> X-Mailer: git-send-email 1.8.1.4 In-Reply-To: <1382534973-13197-1-git-send-email-xiaoguangrong@linux.vnet.ibm.com> References: <1382534973-13197-1-git-send-email-xiaoguangrong@linux.vnet.ibm.com> X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13102313-3864-0000-0000-00000AB58517 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Spam-Status: No, score=-7.3 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 Reviewed-by: Marcelo Tosatti --- 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 8739208..62f18ec 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -595,7 +595,8 @@ 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)