From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DF1ABC433DF for ; Tue, 23 Jun 2020 19:36:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BB04D2098B for ; Tue, 23 Jun 2020 19:36:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387588AbgFWTgD (ORCPT ); Tue, 23 Jun 2020 15:36:03 -0400 Received: from mga11.intel.com ([192.55.52.93]:11008 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387502AbgFWTfp (ORCPT ); Tue, 23 Jun 2020 15:35:45 -0400 IronPort-SDR: Q8lFbMZ7xy/EiJM7FIaf9pBZPtH7Qibg9eiEH/x0dP3ijrnUGLhZRKhUOPJoEXnqf0RfhrQocD 7xW6KTslSi7w== X-IronPort-AV: E=McAfee;i="6000,8403,9661"; a="142430971" X-IronPort-AV: E=Sophos;i="5.75,272,1589266800"; d="scan'208";a="142430971" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Jun 2020 12:35:44 -0700 IronPort-SDR: paQmTNzGnJBumOT+MUhvZ2x9BWmJndGmv2BbB6jitFmvWqLuje/y2u830LNVT9ST0JZj0z1O4/ I5V00FXetfBw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,272,1589266800"; d="scan'208";a="263428292" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.152]) by fmsmga007.fm.intel.com with ESMTP; 23 Jun 2020 12:35:43 -0700 From: Sean Christopherson To: Paolo Bonzini Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 2/4] KVM: x86/mmu: Batch zap MMU pages when recycling oldest pages Date: Tue, 23 Jun 2020 12:35:40 -0700 Message-Id: <20200623193542.7554-3-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.26.0 In-Reply-To: <20200623193542.7554-1-sean.j.christopherson@intel.com> References: <20200623193542.7554-1-sean.j.christopherson@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Collect MMU pages for zapping in a loop when making MMU pages available, and skip over active roots when doing so as zapping an active root can never immediately free up a page. Batching the zapping avoids multiple remote TLB flushes and remedies the issue where the loop would bail early if an active root was encountered. Signed-off-by: Sean Christopherson --- arch/x86/kvm/mmu/mmu.c | 58 ++++++++++++++++++++++++++++++------------ 1 file changed, 42 insertions(+), 16 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 8e7df4ed4b55..8c85a3a178f4 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -2838,20 +2838,51 @@ static bool prepare_zap_oldest_mmu_page(struct kvm *kvm, return kvm_mmu_prepare_zap_page(kvm, sp, invalid_list); } +static unsigned long kvm_mmu_zap_oldest_mmu_pages(struct kvm *kvm, + unsigned long nr_to_zap) +{ + unsigned long total_zapped = 0; + struct kvm_mmu_page *sp, *tmp; + LIST_HEAD(invalid_list); + bool unstable; + int nr_zapped; + + if (list_empty(&kvm->arch.active_mmu_pages)) + return 0; + +restart: + list_for_each_entry_safe(sp, tmp, &kvm->arch.active_mmu_pages, link) { + /* + * Don't zap active root pages, the page itself can't be freed + * and zapping it will just force vCPUs to realloc and reload. + */ + if (sp->root_count) + continue; + + unstable = __kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list, + &nr_zapped); + total_zapped += nr_zapped; + if (total_zapped >= nr_to_zap) + break; + + if (unstable) + goto restart; + } + + kvm_mmu_commit_zap_page(kvm, &invalid_list); + + kvm->stat.mmu_recycled += total_zapped; + return total_zapped; +} + static int make_mmu_pages_available(struct kvm_vcpu *vcpu) { - LIST_HEAD(invalid_list); + unsigned long avail = kvm_mmu_available_pages(vcpu->kvm); - if (likely(kvm_mmu_available_pages(vcpu->kvm) >= KVM_MIN_FREE_MMU_PAGES)) + if (likely(avail >= KVM_MIN_FREE_MMU_PAGES)) return 0; - while (kvm_mmu_available_pages(vcpu->kvm) < KVM_REFILL_PAGES) { - if (!prepare_zap_oldest_mmu_page(vcpu->kvm, &invalid_list)) - break; - - ++vcpu->kvm->stat.mmu_recycled; - } - kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list); + kvm_mmu_zap_oldest_mmu_pages(vcpu->kvm, KVM_REFILL_PAGES - avail); if (!kvm_mmu_available_pages(vcpu->kvm)) return -ENOSPC; @@ -2864,17 +2895,12 @@ static int make_mmu_pages_available(struct kvm_vcpu *vcpu) */ void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned long goal_nr_mmu_pages) { - LIST_HEAD(invalid_list); - spin_lock(&kvm->mmu_lock); if (kvm->arch.n_used_mmu_pages > goal_nr_mmu_pages) { - /* Need to free some mmu pages to achieve the goal. */ - while (kvm->arch.n_used_mmu_pages > goal_nr_mmu_pages) - if (!prepare_zap_oldest_mmu_page(kvm, &invalid_list)) - break; + kvm_mmu_zap_oldest_mmu_pages(kvm, kvm->arch.n_used_mmu_pages - + goal_nr_mmu_pages); - kvm_mmu_commit_zap_page(kvm, &invalid_list); goal_nr_mmu_pages = kvm->arch.n_used_mmu_pages; } -- 2.26.0