From patchwork Wed Oct 23 13:29:22 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xiao Guangrong X-Patchwork-Id: 3088761 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 81515BF924 for ; Wed, 23 Oct 2013 13:34:51 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 562DA203AF for ; Wed, 23 Oct 2013 13:34:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 24EB3203C4 for ; Wed, 23 Oct 2013 13:34:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754589Ab3JWNea (ORCPT ); Wed, 23 Oct 2013 09:34:30 -0400 Received: from e28smtp02.in.ibm.com ([122.248.162.2]:60046 "EHLO e28smtp02.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753688Ab3JWN35 (ORCPT ); Wed, 23 Oct 2013 09:29:57 -0400 Received: from /spool/local by e28smtp02.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Wed, 23 Oct 2013 18:59:52 +0530 Received: from d28relay03.in.ibm.com (d28relay03.in.ibm.com [9.184.220.60]) by d28dlp01.in.ibm.com (Postfix) with ESMTP id 740DBE0056; Wed, 23 Oct 2013 19:01:24 +0530 (IST) Received: from d28av01.in.ibm.com (d28av01.in.ibm.com [9.184.220.63]) by d28relay03.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r9NDWhfr39256260; Wed, 23 Oct 2013 19:02:43 +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 r9NDTpAD025156; Wed, 23 Oct 2013 18:59:51 +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 r9NDTodl025129; Wed, 23 Oct 2013 18:59:51 +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 04/15] KVM: MMU: flush tlb out of mmu lock when write-protect the sptes Date: Wed, 23 Oct 2013 21:29:22 +0800 Message-Id: <1382534973-13197-5-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: 13102313-5816-0000-0000-00000A8A956E 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 Now we can flush all the TLBs out of the mmu lock without TLB corruption when write-proect the sptes, it is because: - we have marked large sptes readonly instead of dropping them that means we just change the spte from writable to readonly so that we only need to care the case of changing spte from present to present (changing the spte from present to nonpresent will flush all the TLBs immediately), in other words, the only case we need to care is mmu_spte_update() - in mmu_spte_update(), we haved checked SPTE_HOST_WRITEABLE | PTE_MMU_WRITEABLE instead of PT_WRITABLE_MASK, that means it does not depend on PT_WRITABLE_MASK anymore Signed-off-by: Xiao Guangrong --- arch/x86/kvm/mmu.c | 18 ++++++++++++++---- arch/x86/kvm/x86.c | 9 +++++++-- 2 files changed, 21 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 62f18ec..337d173 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -4273,15 +4273,25 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot) if (*rmapp) __rmap_write_protect(kvm, rmapp, false); - if (need_resched() || spin_needbreak(&kvm->mmu_lock)) { - kvm_flush_remote_tlbs(kvm); + if (need_resched() || spin_needbreak(&kvm->mmu_lock)) cond_resched_lock(&kvm->mmu_lock); - } } } - kvm_flush_remote_tlbs(kvm); spin_unlock(&kvm->mmu_lock); + + /* + * We can flush all the TLBs out of the mmu lock without TLB + * corruption since we just change the spte from writable to + * readonly so that we only need to care the case of changing + * spte from present to present (changing the spte from present + * to nonpresent will flush all the TLBs immediately), in other + * words, the only case we care is mmu_spte_update() where we + * haved checked SPTE_HOST_WRITEABLE | SPTE_MMU_WRITEABLE + * instead of PT_WRITABLE_MASK, that means it does not depend + * on PT_WRITABLE_MASK anymore. + */ + kvm_flush_remote_tlbs(kvm); } #define BATCH_ZAP_PAGES 10 diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b3aa650..573c6b3 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3571,11 +3571,16 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log) offset = i * BITS_PER_LONG; kvm_mmu_write_protect_pt_masked(kvm, memslot, offset, mask); } - if (is_dirty) - kvm_flush_remote_tlbs(kvm); spin_unlock(&kvm->mmu_lock); + /* + * All the TLBs can be flushed out of mmu lock, see the comments in + * kvm_mmu_slot_remove_write_access(). + */ + if (is_dirty) + kvm_flush_remote_tlbs(kvm); + r = -EFAULT; if (copy_to_user(log->dirty_bitmap, dirty_bitmap_buffer, n)) goto out;