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 2BA55C432C3 for ; Thu, 14 Nov 2019 19:11:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E76C320718 for ; Thu, 14 Nov 2019 19:11:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Zgv/AkYg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727004AbfKNTLp (ORCPT ); Thu, 14 Nov 2019 14:11:45 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:37405 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726098AbfKNTLo (ORCPT ); Thu, 14 Nov 2019 14:11:44 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1573758703; 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=XB1Zf/ZpUsxeIE2fgo8TYg1AyowvOyj8Umgx+HQXrwQ=; b=Zgv/AkYg8L+1SLA9pLtR76CgeX7qLWw/XkeTWlqBRJUnOoFFzw8oezbm0hoOD0Oovbyk9M xluz42H7wrLOIlFvzg98c/m/O8yqZVK6niFN0unpijzjV/smXMz+JST9vpzOUjwd7wN5H0 GOBuAVKDi3yoTv3NyaaCX4vOm+K9muY= 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-185-HzmppB_UNrGcJATxAeGCAQ-1; Thu, 14 Nov 2019 14:11:39 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 06B9F477; Thu, 14 Nov 2019 19:11:38 +0000 (UTC) Received: from llong.remote.csb (dhcp-17-59.bos.redhat.com [10.18.17.59]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5757B6764C; Thu, 14 Nov 2019 19:11:35 +0000 (UTC) Subject: Re: [PATCH] x86/speculation: Fix incorrect MDS/TAA mitigation status To: Thomas Gleixner Cc: Borislav Petkov , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org, Josh Poimboeuf , Greg Kroah-Hartman , Pawan Gupta , Mark Gross , Tony Luck References: <20191113193350.24511-1-longman@redhat.com> <20191114174553.GC7222@zn.tnic> <8f7e0f4b-5100-67b5-fcb5-f7a968b96110@redhat.com> From: Waiman Long Organization: Red Hat Message-ID: <7f898fcb-3f0d-c754-f75d-213519e0b417@redhat.com> Date: Thu, 14 Nov 2019 14:11:34 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-MC-Unique: HzmppB_UNrGcJATxAeGCAQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/14/19 1:48 PM, Thomas Gleixner wrote: > On Thu, 14 Nov 2019, Waiman Long wrote: >> On 11/14/19 12:45 PM, Borislav Petkov wrote: >>>> -=09/* TAA mitigation is turned off on the cmdline (tsx_async_abort=3D= off) */ >>>> -=09if (taa_mitigation =3D=3D TAA_MITIGATION_OFF) >>>> +=09/* >>>> +=09 * TAA mitigation via VERW is turned off if both >>>> +=09 * tsx_async_abort=3Doff and mds=3Doff are specified. >>>> +=09 */ >>> So this changes the dependency of switches so if anything, it should be >>> properly documented first in all three: >>> >>> Documentation/admin-guide/hw-vuln/tsx_async_abort.rst >>> Documentation/x86/tsx_async_abort.rst >>> Documentation/admin-guide/kernel-parameters.txt >>> >>> However, before we do that, we need to agree on functionality: >> I agree that the documentation needs to be updated. I am going to do >> that once we have a consensus of what is the right thing to do. >>> Will the mitigations be disabled only with *both* =3Doff supplied on th= e >>> command line or should the mitigations be disabled when *any* of the tw= o >>> =3Doff is supplied? >> The mitigation is disabled only with BOTH =3Doff supplied or >> "mitigations=3Doff". This is the current behavior. This patch is just to >> make sure that vulnerabilities files reflect the actual behavior. Of >> course, we can change it to disable mitigation with either =3Doff if thi= s >> is what the consensus turn out to be. > I think the current behaviour is correct. It's just a coincidence that bo= th > issues happen to use the same mitigation technology in the exactly same > places. So if you leave one on then the other gets mitigated as a side > effect and the sysfs file should reflect that. > > Thanks, > > =09tglx > Good to hear that. I will send a v2 patch with document update. Cheers, Longman