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=-14.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 25EFAC433DF for ; Tue, 23 Jun 2020 21:15:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EF4E22072E for ; Tue, 23 Jun 2020 21:15:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="moQfH9pC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2393340AbgFWVPM (ORCPT ); Tue, 23 Jun 2020 17:15:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53500 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390878AbgFWU2b (ORCPT ); Tue, 23 Jun 2020 16:28:31 -0400 Received: from mail-io1-xd43.google.com (mail-io1-xd43.google.com [IPv6:2607:f8b0:4864:20::d43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B237FC061755 for ; Tue, 23 Jun 2020 13:28:31 -0700 (PDT) Received: by mail-io1-xd43.google.com with SMTP id i4so22312334iov.11 for ; Tue, 23 Jun 2020 13:28:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=WSPtdAoBezoYzD8XC8jNDB6bATmQyei/lRaAJLxm7dw=; b=moQfH9pCQ4VqWT4Y7KzG1qf3keLcBnZnTHixTqrnDXhSW/qaw5cRXwuGHcN4gOtyP/ WKeIXq96XY/WjRtkkgv5myED1TEeWxWMFI+qkQJS2IOYFbR0uA/03nMHTFStmTUS9nDA VvNG359xj9w56+kyALW0DQH91iR92W2Hf97LceZDtdEKpv/pDsoi4jaRVWo4xI5P5bce Fk0c9VRL8d0tS67VKbGTOU/SfLOyZqY3fYyYMK2uyXONFZJkl0FaKM/k+SU5/KBOOmFY ZYGhNbKn3HNH4s+ZuTFvQn/as8jscuATSlVVbRD3poFI9Taoz5GLt/G2/6V6Zp1FrjTj F/bw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=WSPtdAoBezoYzD8XC8jNDB6bATmQyei/lRaAJLxm7dw=; b=VmXfbc7iT1/EJEdtI1arl4Fs76Fz4vN1JJrQWIorbPVYq0GTg1gIpLPi5QrwNvoglI NKED4Oe52u81wpKBu72cC74H6HASEhBzqYbufFsmihP4xLrbKTIeYdlmApkACtRz2Rm+ XhSzX4uEdDEbNdIDLNyMZ4y85Gw3Kw+QBWKShgEoeGwV7VixDxsnUVryg8/o6gkBj52h +F/67lVUUZKfnuFBx9e6NbT1yXTIs7oZEr3EEvgc7tvxRPv8WqoLERV34vA3AxDYyQXc NP2Gf0d9pASY7XqCLvhE9ec4eUnMWEsvMO35iF3KLTdebqFwGQLpHuoIqeYD9LmIFH2f JjKg== X-Gm-Message-State: AOAM533YEppM0pu8Q4THulACYco6JYIrhhbbyjGMIA3PWgbK0H9hUMNY VeCKjuBHhSC6MFL00COFgOFLKW5fGE66YRC0MVW3kA== X-Google-Smtp-Source: ABdhPJxlYU8JWVYxZvphpJBgmzBHsYDxrytL4SZcIB21fkLOEXFrgJ0/tjn/KsDSq3GAKIklzlj9PiYc0oNBsAH3lBY= X-Received: by 2002:a05:6602:2dca:: with SMTP id l10mr27131901iow.163.1592944110821; Tue, 23 Jun 2020 13:28:30 -0700 (PDT) MIME-Version: 1.0 References: <20200623194027.23135-1-sean.j.christopherson@intel.com> <20200623194027.23135-3-sean.j.christopherson@intel.com> In-Reply-To: <20200623194027.23135-3-sean.j.christopherson@intel.com> From: Jon Cargille Date: Tue, 23 Jun 2020 13:28:18 -0700 Message-ID: Subject: Re: [PATCH 2/2] KVM: x86/mmu: Optimize MMU page cache lookup for fully direct MMUs To: Sean Christopherson Cc: Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Peter Feiner Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org LGTM. Reviewed-By: Jon Cargille On Tue, Jun 23, 2020 at 12:40 PM Sean Christopherson wrote: > > Skip the unsync checks and the write flooding clearing for fully direct > MMUs, which are guaranteed to not have unsync'd or indirect pages (write > flooding detection only applies to indirect pages). For TDP, this > avoids unnecessary memory reads and writes, and for the write flooding > count will also avoid dirtying a cache line (unsync_child_bitmap itself > consumes a cache line, i.e. write_flooding_count is guaranteed to be in > a different cache line than parent_ptes). > > Signed-off-by: Sean Christopherson > --- > arch/x86/kvm/mmu/mmu.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 67f8f82e9783..c568a5c55276 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -2475,6 +2475,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, > int direct, > unsigned int access) > { > + bool direct_mmu = vcpu->arch.mmu->direct_map; > union kvm_mmu_page_role role; > struct hlist_head *sp_list; > unsigned quadrant; > @@ -2490,8 +2491,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, > if (role.direct) > role.gpte_is_8_bytes = true; > role.access = access; > - if (!vcpu->arch.mmu->direct_map > - && vcpu->arch.mmu->root_level <= PT32_ROOT_LEVEL) { > + if (!direct_mmu && vcpu->arch.mmu->root_level <= PT32_ROOT_LEVEL) { > quadrant = gaddr >> (PAGE_SHIFT + (PT64_PT_BITS * level)); > quadrant &= (1 << ((PT32_PT_BITS - PT64_PT_BITS) * level)) - 1; > role.quadrant = quadrant; > @@ -2510,6 +2510,9 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, > if (sp->role.word != role.word) > continue; > > + if (direct_mmu) > + goto trace_get_page; > + > if (sp->unsync) { > /* The page is good, but __kvm_sync_page might still end > * up zapping it. If so, break in order to rebuild it. > @@ -2525,6 +2528,8 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, > kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu); > > __clear_sp_write_flooding_count(sp); > + > +trace_get_page: > trace_kvm_mmu_get_page(sp, false); > goto out; > } > -- > 2.26.0 >