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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 8DE5CC5CFFE for ; Mon, 10 Dec 2018 19:06:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4F7182082F for ; Mon, 10 Dec 2018 19:06:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4F7182082F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729088AbeLJTGD (ORCPT ); Mon, 10 Dec 2018 14:06:03 -0500 Received: from mx1.redhat.com ([209.132.183.28]:34218 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727221AbeLJTGC (ORCPT ); Mon, 10 Dec 2018 14:06:02 -0500 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id AD3B83082E55; Mon, 10 Dec 2018 19:06:02 +0000 (UTC) Received: from localhost (ovpn-116-63.gru2.redhat.com [10.97.116.63]) by smtp.corp.redhat.com (Postfix) with ESMTP id E8E4D5D717; Mon, 10 Dec 2018 19:06:01 +0000 (UTC) Date: Mon, 10 Dec 2018 17:06:00 -0200 From: Eduardo Habkost To: Borislav Petkov Cc: Paolo Bonzini , =?iso-8859-1?Q?J=F6rg_R=F6del?= , Andre Przywara , kvm ML , lkml , Tom Lendacky Subject: Re: kvm: RDTSCP on AMD Message-ID: <20181210190600.GK4669@habkost.net> References: <20181210181328.GA762@zn.tnic> <20181210183730.GJ4669@habkost.net> <20181210184153.GB5482@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181210184153.GB5482@zn.tnic> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Mon, 10 Dec 2018 19:06:02 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 10, 2018 at 07:41:53PM +0100, Borislav Petkov wrote: > On Mon, Dec 10, 2018 at 04:37:30PM -0200, Eduardo Habkost wrote: > > It isn't as simply as reverting commit 33b5e8c03ae7, but we can > > surely re-add RDTSCP on pc-*-4.0 and newer. > > Sure. If you could only point me to an example how to add that to > pc-*-4.0 and newer, I'll gladly cook up a patch and test it. > > > I thought we added documentation mentioning the minimum kernel > > version required by QEMU, but I can't find it. In either case, > > it seems reasonable to require Linux 4.5 or newer on newer > > machine-types. > > When you say "require" does that mean, one puts it in a text file > somewhere in the qemu sources or do we enforce it somehow? I mean documenting it. We already have code that will print warnings if a feature isn't available. See my previous attempt to document the minimum kernel version at . -- Eduardo