From patchwork Thu Jan 10 18:07:01 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 10756601 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 0FACC13B4 for ; Thu, 10 Jan 2019 18:07:37 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 01C1729E78 for ; Thu, 10 Jan 2019 18:07:37 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id E9D5A29E80; Thu, 10 Jan 2019 18:07:36 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 880FF29E78 for ; Thu, 10 Jan 2019 18:07:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730858AbfAJSHf (ORCPT ); Thu, 10 Jan 2019 13:07:35 -0500 Received: from mga02.intel.com ([134.134.136.20]:30783 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730811AbfAJSHf (ORCPT ); Thu, 10 Jan 2019 13:07:35 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 10 Jan 2019 10:07:19 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,462,1539673200"; d="scan'208";a="137176434" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.154]) by fmsmga001.fm.intel.com with ESMTP; 10 Jan 2019 10:07:19 -0800 From: Sean Christopherson To: Paolo Bonzini , =?utf-8?b?UmFkaW0gS3LEjW3DocWZ?= Cc: kvm@vger.kernel.org, Xiao Guangrong Subject: [PATCH 09/14] Revert "KVM: MMU: zap pages in batch" Date: Thu, 10 Jan 2019 10:07:01 -0800 Message-Id: <20190110180706.24974-10-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.19.2 In-Reply-To: <20190110180706.24974-1-sean.j.christopherson@intel.com> References: <20190110180706.24974-1-sean.j.christopherson@intel.com> MIME-Version: 1.0 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Unwinding optimizations related to obsolete pages is a step towards removing x86 KVM's fast invalidate mechanism, i.e. this is one part of a revert all patches from the series that introduced the mechanism[1]. This reverts commit e7d11c7a894986a13817c1c001e1e7668c5c4eb4. [1] https://lkml.kernel.org/r/1369960590-14138-1-git-send-email-xiaoguangrong@linux.vnet.ibm.com Cc: Xiao Guangrong Signed-off-by: Sean Christopherson --- arch/x86/kvm/mmu.c | 35 ++++++++++++++++++++++++----------- 1 file changed, 24 insertions(+), 11 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 178b47de011f..431cc545ac92 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -5836,18 +5836,14 @@ void kvm_mmu_slot_set_dirty(struct kvm *kvm, } EXPORT_SYMBOL_GPL(kvm_mmu_slot_set_dirty); -#define BATCH_ZAP_PAGES 10 static void kvm_zap_obsolete_pages(struct kvm *kvm) { struct kvm_mmu_page *sp, *node; LIST_HEAD(invalid_list); - int batch = 0; restart: list_for_each_entry_safe_reverse(sp, node, &kvm->arch.active_mmu_pages, link) { - int ret; - /* * No obsolete page exists before new created page since * active_mmu_pages is the FIFO list. @@ -5856,6 +5852,28 @@ static void kvm_zap_obsolete_pages(struct kvm *kvm) break; /* + * Do not repeatedly zap a root page to avoid unnecessary + * KVM_REQ_MMU_RELOAD, otherwise we may not be able to + * progress: + * vcpu 0 vcpu 1 + * call vcpu_enter_guest(): + * 1): handle KVM_REQ_MMU_RELOAD + * and require mmu-lock to + * load mmu + * repeat: + * 1): zap root page and + * send KVM_REQ_MMU_RELOAD + * + * 2): if (cond_resched_lock(mmu-lock)) + * + * 2): hold mmu-lock and load mmu + * + * 3): see KVM_REQ_MMU_RELOAD bit + * on vcpu->requests is set + * then return 1 to call + * vcpu_enter_guest() again. + * goto repeat; + * * Since we are reversely walking the list and the invalid * list will be moved to the head, skip the invalid page * can help us to avoid the infinity list walking. @@ -5863,18 +5881,13 @@ static void kvm_zap_obsolete_pages(struct kvm *kvm) if (sp->role.invalid) continue; - if (batch >= BATCH_ZAP_PAGES && - (need_resched() || spin_needbreak(&kvm->mmu_lock))) { - batch = 0; + if (need_resched() || spin_needbreak(&kvm->mmu_lock)) { kvm_mmu_commit_zap_page(kvm, &invalid_list); cond_resched_lock(&kvm->mmu_lock); goto restart; } - ret = kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list); - batch += ret; - - if (ret) + if (kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list)) goto restart; }