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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 9AC6DC433FF for ; Tue, 13 Aug 2019 08:03:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 635A820665 for ; Tue, 13 Aug 2019 08:03:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="HojvWsnu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727908AbfHMIDc (ORCPT ); Tue, 13 Aug 2019 04:03:32 -0400 Received: from mail.skyhub.de ([5.9.137.197]:48728 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725842AbfHMIDc (ORCPT ); Tue, 13 Aug 2019 04:03:32 -0400 Received: from zn.tnic (p200300EC2F0D240075AA4C13F769B7E7.dip0.t-ipconnect.de [IPv6:2003:ec:2f0d:2400:75aa:4c13:f769:b7e7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id DB4771EC0716; Tue, 13 Aug 2019 10:03:30 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1565683411; 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:in-reply-to:in-reply-to: references:references; bh=wl48/yP8ym+uAxlHWjHE76DYRPjIBsOyJqj9CuF2dDw=; b=HojvWsnu4z3l24NK1FunWmVH/LMCwJ92cMf1vgSxKUSF/ZcwW93/nsIVtHdOrjMXeNkNQK SVIAIhTkIFQhq2NH5Gc/obcuQIpikRgovZtLCpW8k/lCRubfAwIxiJax8kyWD1yudp4dO8 8cqabak02k+wK7M22yAuYYxpNfnznP0= Date: Tue, 13 Aug 2019 10:04:16 +0200 From: Borislav Petkov To: Isaku Yamahata Cc: "Kani, Toshi" , "linux-kernel@vger.kernel.org" , "fei1.li@intel.com" , "x86@kernel.org" Subject: Re: [PATCH 0/3] x86/mtrr, pat: make PAT independent from MTRR Message-ID: <20190813080416.GB16770@zn.tnic> References: <20190809070647.GA2152@zn.tnic> <3355d77da5e094ad1d3149b9236cdd204486fd69.camel@hpe.com> <20190813074920.GA24196@private.email.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190813074920.GA24196@private.email.ne.jp> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 13, 2019 at 12:49:20AM -0700, Isaku Yamahata wrote: > In addition to Xen, KVM+qemu can enable/disable MTRR, PAT independently. > So user may want to disable MTRR to reduce attack surface. No, no "user may want" etc vague formulations. Just because some virt thing "can" do stuff doesn't mean we should change the kernel. What are the clear benefits of your proposal, why should it go upstream and why should it be exposed to everybody? How is going to be used it and what would it bring? Are there any downsides? Thx. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.