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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 6BFB4C433E0 for ; Wed, 1 Jul 2020 12:27:02 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 46E06206CB for ; Wed, 1 Jul 2020 12:27:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 46E06206CB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jqbpC-0006GD-BH; Wed, 01 Jul 2020 12:26:50 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jqbpB-0006G7-FI for xen-devel@lists.xenproject.org; Wed, 01 Jul 2020 12:26:49 +0000 X-Inumbo-ID: 226b6db2-bb96-11ea-bca7-bc764e2007e4 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 226b6db2-bb96-11ea-bca7-bc764e2007e4; Wed, 01 Jul 2020 12:26:49 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 3B361ADE2; Wed, 1 Jul 2020 12:26:48 +0000 (UTC) Subject: Re: [PATCH for-4.14] x86/spec-ctrl: Protect against CALL/JMP straight-line speculation To: Andrew Cooper References: <20200701115842.18583-1-andrew.cooper3@citrix.com> From: Jan Beulich Message-ID: <41b49d79-e0fa-161a-bb27-a9a2ccf361f5@suse.com> Date: Wed, 1 Jul 2020 14:26:49 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <20200701115842.18583-1-andrew.cooper3@citrix.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Xen-devel , Paul Durrant , Wei Liu , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" On 01.07.2020 13:58, Andrew Cooper wrote: > Some x86 CPUs speculatively execute beyond indirect CALL/JMP instructions. > > With CONFIG_INDIRECT_THUNK / Retpolines, indirect CALL/JMP instructions are > converted to direct CALL/JMP's to __x86_indirect_thunk_REG(), leaving just a > handful of indirect JMPs implementing those stubs. > > There is no architectrual execution beyond an indirect JMP, so use INT3 as > recommended by vendors to halt speculative execution. This is shorter than > LFENCE (which would also work fine), but also shows up in logs if we do > unexpected execute them. > > Signed-off-by: Andrew Cooper Reviewed-by: Jan Beulich