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=-5.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 358FCC433E0 for ; Fri, 3 Jul 2020 00:18:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0DA3C20772 for ; Fri, 3 Jul 2020 00:18:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="E0nVOexq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726106AbgGCASG (ORCPT ); Thu, 2 Jul 2020 20:18:06 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:50238 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725937AbgGCASG (ORCPT ); Thu, 2 Jul 2020 20:18:06 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1593735484; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=hIQsc7L3mlUnsPjNRq6vMDMF6qPjtCUsaG1+ltKNRpk=; b=E0nVOexq2JH16WWUL3uKxMRBYHCN3xvZs3764D173OT2sEY3HMmwArYaTCHEdV5V197hS3 x1CV7QJNCdI6kzcgSGmoykjlW/+dfAkwF8b3H7fUH2mLt477+IPp/rbY74ynaKCmwbSwUu Wq+bFfB6fRHez97K//dhJNCeXLe4Fbo= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-155-DW0ViCadM4GSoHNNdXZJGg-1; Thu, 02 Jul 2020 20:18:03 -0400 X-MC-Unique: DW0ViCadM4GSoHNNdXZJGg-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D1B22800C60; Fri, 3 Jul 2020 00:18:00 +0000 (UTC) Received: from llong.remote.csb (ovpn-112-121.rdu2.redhat.com [10.10.112.121]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0D9555C1B0; Fri, 3 Jul 2020 00:17:57 +0000 (UTC) Subject: Re: [PATCH v3] x86/speculation/l1tf: Add KConfig for setting the L1D cache flush mode To: Abhishek Bhardwaj , LKML Cc: Anthony Steinhauser , Borislav Petkov , "H. Peter Anvin" , Ingo Molnar , Jim Mattson , Joerg Roedel , Josh Poimboeuf , Mark Gross , Mike Rapoport , Paolo Bonzini , Pawan Gupta , Peter Zijlstra , Sean Christopherson , Thomas Gleixner , Tony Luck , Vitaly Kuznetsov , Wanpeng Li , kvm@vger.kernel.org, x86@kernel.org References: <20200702221237.2517080-1-abhishekbh@google.com> From: Waiman Long Organization: Red Hat Message-ID: Date: Thu, 2 Jul 2020 20:17:57 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <20200702221237.2517080-1-abhishekbh@google.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/2/20 6:12 PM, Abhishek Bhardwaj wrote: > This change adds a new kernel configuration that sets the l1d cache > flush setting at compile time rather than at run time. > > Signed-off-by: Abhishek Bhardwaj Can you explain in the commit log why you need a compile time option whereas the desired mitigation can also be set via a boot command line option? The code looks OK, but the question I have is why. Cheers, Longman