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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 79F28C83014 for ; Tue, 1 Dec 2020 15:27:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E7840221EB for ; Tue, 1 Dec 2020 15:27:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="sRWAKCym" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391889AbgLAP0k (ORCPT ); Tue, 1 Dec 2020 10:26:40 -0500 Received: from mail.skyhub.de ([5.9.137.197]:59460 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390228AbgLAP0i (ORCPT ); Tue, 1 Dec 2020 10:26:38 -0500 Received: from zn.tnic (p200300ec2f0e6a009ae7ed3e982f3c10.dip0.t-ipconnect.de [IPv6:2003:ec:2f0e:6a00:9ae7:ed3e:982f:3c10]) (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 5D2381EC04D1; Tue, 1 Dec 2020 16:25:57 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1606836357; 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=EqXvKoYqADEjA6zEZSWiBnqob+NV98aFo9Y3mq5PFt4=; b=sRWAKCymZ83rvJB58riy8B6m+MECl/9WckPjTsJ5afX0hVI58qC0mMjUzEdIJAW4CPpsQe nM4tlaPuU6MbCMUj6oXdFJCJ0gqEyJPfdgI+d8V8X4BWUkAoZPYwfMSbxLfs5JohZnLRS/ 8crj6L0sDIsQ8+pIBkMBTVqKC/V8EOU= Date: Tue, 1 Dec 2020 16:25:52 +0100 From: Borislav Petkov To: Rongwei Wang Cc: catalin.marinas@arm.com, Will Deacon , bjorn.andersson@linaro.org, shawnguo@kernel.org, vkoul@kernel.org, geert+renesas@glider.be, Anson.Huang@nxp.com, michael@walle.cc, krzk@kernel.org, olof@lixom.net, vincenzo.frascino@arm.com, ardb@kernel.org, masahiroy@kernel.org, gshan@redhat.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/3] arm64:msr: Add MSR driver Message-ID: <20201201152552.GD22927@zn.tnic> References: <20201130174833.41315-1-rongwei.wang@linux.alibaba.com> <20201130190331.GI6019@zn.tnic> <8724DF91-5BF0-4265-8091-F9E0C7DC2F1A@linux.alibaba.com> <20201201112647.GA22927@zn.tnic> <20201201145415.GC22927@zn.tnic> <8ED75067-DB02-4502-BA03-45B3519E408A@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <8ED75067-DB02-4502-BA03-45B3519E408A@linux.alibaba.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 01, 2020 at 11:17:39PM +0800, Rongwei Wang wrote: > In ARM, the system registers can only be accessed through msr and mrs, > so the problem created by MSR driver (depend on rdmsr and wrmsr) in > x86 is not necessarily present in ARM, which is very different from > x86. No, the point I'm making is that it doesn't matter what the architecture does or does not, register *writes* from userspace are a bad bad idea for the reasons I described. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette