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=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 3EB94C433E2 for ; Thu, 10 Sep 2020 14:08:53 +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 E909F21941 for ; Thu, 10 Sep 2020 14:08:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E909F21941 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 1kGNFf-00020U-11; Thu, 10 Sep 2020 14:08:39 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kGNFd-00020O-8i for xen-devel@lists.xen.org; Thu, 10 Sep 2020 14:08:37 +0000 X-Inumbo-ID: bbceb021-2eeb-4101-910d-7eccc6064c84 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id bbceb021-2eeb-4101-910d-7eccc6064c84; Thu, 10 Sep 2020 14:08:36 +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 7A141B368; Thu, 10 Sep 2020 14:08:49 +0000 (UTC) Subject: Re: Runstate hypercall and Linux KPTI issues To: Bertrand Marquis Cc: "xen-devel@lists.xen.org" , Julien Grall , Stefano Stabellini , George Dunlap References: <1844689F-814F-48AE-8179-95B0EE4E734C@arm.com> <8b9d8bc8-254e-01db-6ba3-ec41bc9cd2c7@suse.com> <2AD6A14F-AA25-464D-9E9E-6067F2F43F29@arm.com> From: Jan Beulich Message-ID: Date: Thu, 10 Sep 2020 16:08:35 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <2AD6A14F-AA25-464D-9E9E-6067F2F43F29@arm.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: , Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" On 10.09.2020 16:00, Bertrand Marquis wrote: >> On 10 Sep 2020, at 14:56, Jan Beulich wrote: >> On 10.09.2020 15:46, Bertrand Marquis wrote: >>> Some open questions: >>> - should we allow to register an area using both hypercalls or should it be exclusive ? >> >> I thought it was already clarified that to a certain degree both need >> to remain usable at least in sequence, to allow transitioning control >> between entirely independent entities (bootloader -> kernel -> dump- >> kernel, for example). > > Sorry my wording was not clear here > > Should we allow to register 2 areas at the same time using both hypercalls (one with > virtual address and one with physical address) or should they be exclusive ie one or > the other but not both at the same time Ah, okay. Just one area at a time, I would say. >>> - should we backport the support for this hypercall in older kernel releases ? >> >> It's a bug fix to KPTI, and as such ought to be at least eligible for >> considering doing so? > > That will mean also backport in Linux. What should be the scope ? All longterm and stable trees which are affected, as I think is usual. Jan