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=-23.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,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 6DEC6C433B4 for ; Thu, 29 Apr 2021 16:49:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3479961418 for ; Thu, 29 Apr 2021 16:49:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235685AbhD2QuF (ORCPT ); Thu, 29 Apr 2021 12:50:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43514 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232724AbhD2QuE (ORCPT ); Thu, 29 Apr 2021 12:50:04 -0400 Received: from mail-pl1-x636.google.com (mail-pl1-x636.google.com [IPv6:2607:f8b0:4864:20::636]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 12AC7C06138B for ; Thu, 29 Apr 2021 09:49:18 -0700 (PDT) Received: by mail-pl1-x636.google.com with SMTP id e2so30756659plh.8 for ; Thu, 29 Apr 2021 09:49:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=t7wrCkg5HzcpryaSEY8CDFceJToXQ1Z7NajGX4H6Qvs=; b=DVWO+c+DRCdT+xgySkQyrrUeVdkg5lBQIomJGZyyLPXiFiM6g2ZGls9Zvf+QBfamZ9 OUo/OLAWe2ZBkGvQZHyo/qR14GvWrZ9/oH7wEaTqEmtnFHcnF01rsHDHL5CzhsQiGd/v qiamOHcTLEn+gW6uzWCYq5Vb/HvJHs4Fb+IGdM16jfz54KaKFujHv4n2F4TRV4zi26cz zmmtxYxkpVR9T2jnib5zPmGpKfHyns4bKbydHRcf0IrFlo9iXMlAhAvXndAk+A7E1Tcq o1zkUGGQY9b3Cwlfd7CKS8moi5OMkqLHeuslUO1dmapvt9Zqv/dq0wXuZM8uqNoTztUG g03Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=t7wrCkg5HzcpryaSEY8CDFceJToXQ1Z7NajGX4H6Qvs=; b=YlywvcJ0xvtljVSNDucAkTDUGtsy3u368UHjEEm4Rc77xPo0jwsA+RyobxJkLB/DaB /Z4zEze/D6Nf3h0BujqTHJSkIt5KDtJl/vZl4zhhnfsDEKizlJIDH/FZnr7P5C4daHbm fr0sFQUAYggpGKst3YzehgiI0UEK+hb2zOeScoi/sTfmWAVYWdCnLHzzv+G68wFSvt4z stWKxylcREYDBxlA+n2D0mgz+MiXHhZ858OwmwaY6KnGiLN0lA0yBjH89/LdkMLe/YR+ djg5544yBJX4ioZIqkMZjURyGotHqgXXrDDGH+La2ztYQICwIkOmY4sF1eGTE6LUaOW3 aqgA== X-Gm-Message-State: AOAM531pQ6WGCreCFsrsA4p3x5vLykU2MQwo/eunvjVoKNNkdVo9uEOb xDIXiYWiycmu8NXq5Ne4G2/nNu91hECPdQ== X-Google-Smtp-Source: ABdhPJzHQAAP8FLIwNhJZWsPjs5hoRIVnncHAndcMvMe2Z6Y8mNKECypv4RRdm0Mag16K7dAbs5tpg== X-Received: by 2002:a17:902:c3ca:b029:ea:fc69:b6ed with SMTP id j10-20020a170902c3cab02900eafc69b6edmr522207plj.80.1619714957365; Thu, 29 Apr 2021 09:49:17 -0700 (PDT) Received: from google.com (240.111.247.35.bc.googleusercontent.com. [35.247.111.240]) by smtp.gmail.com with ESMTPSA id k4sm423627pgm.73.2021.04.29.09.49.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 29 Apr 2021 09:49:16 -0700 (PDT) Date: Thu, 29 Apr 2021 16:49:13 +0000 From: Sean Christopherson To: "Shahin, Md Shahadat Hossain" Cc: "kvm@vger.kernel.org" , "Szczepanek, Bartosz" , "pbonzini@redhat.com" , "bgardon@google.com" Subject: Re: Subject: [RFC PATCH] kvm/x86: Fix 'lpages' kvm stat for TDM MMU Message-ID: References: <1619700409955.15104@amazon.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1619700409955.15104@amazon.de> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, Apr 29, 2021, Shahin, Md Shahadat Hossain wrote: > Large pages not being created properly may result in increased memory > access time. The 'lpages' kvm stat used to keep track of the current > number of large pages in the system, but with TDP MMU enabled the stat > is not showing the correct number. > > This patch extends the lpages counter to cover the TDP case. > > Signed-off-by: Md Shahadat Hossain Shahin > Cc: Bartosz Szczepanek > --- > arch/x86/kvm/mmu/tdp_mmu.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > index 34207b874886..1e2a3cb33568 100644 > --- a/arch/x86/kvm/mmu/tdp_mmu.c > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > @@ -425,6 +425,12 @@ static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, > > if (old_spte == new_spte) > return; > + > + if (is_large_pte(old_spte)) > + --kvm->stat.lpages; > + > + if (is_large_pte(new_spte)) > + ++kvm->stat.lpages; Hrm, kvm->stat.lpages could get corrupted when __handle_changed_spte() is called under read lock, e.g. if multiple vCPUs are faulting in memory.