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=-2.2 required=3.0 tests=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 B5890C47255 for ; Mon, 11 May 2020 15:00:32 +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 8EA8420643 for ; Mon, 11 May 2020 15:00:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8EA8420643 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 1jY9uh-0004sr-1i; Mon, 11 May 2020 15:00:15 +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 1jY9ug-0004sm-1p for xen-devel@lists.xenproject.org; Mon, 11 May 2020 15:00:14 +0000 X-Inumbo-ID: 1c57e64c-9398-11ea-a21f-12813bfff9fa Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 1c57e64c-9398-11ea-a21f-12813bfff9fa; Mon, 11 May 2020 15:00:11 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 04F33AD08; Mon, 11 May 2020 15:00:12 +0000 (UTC) Subject: Re: [PATCH 01/16] x86/traps: Drop last_extable_addr To: Andrew Cooper References: <20200501225838.9866-1-andrew.cooper3@citrix.com> <20200501225838.9866-2-andrew.cooper3@citrix.com> <3ec06cb1-6b31-2fde-6de4-23938acab73a@suse.com> <64cb6793-c3a0-e396-c6cc-50f5a36e19a6@citrix.com> From: Jan Beulich Message-ID: Date: Mon, 11 May 2020 17:00:08 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <64cb6793-c3a0-e396-c6cc-50f5a36e19a6@citrix.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit 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 , Wei Liu , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" On 11.05.2020 16:53, Andrew Cooper wrote: > On 04/05/2020 13:44, Jan Beulich wrote: >> On 02.05.2020 00:58, Andrew Cooper wrote: >>> The only user of this facility is dom_crash_sync_extable() by passing 0 into >>> asm_domain_crash_synchronous(). The common error cases are already covered >>> with show_page_walk(), leaving only %ss/%fs selector/segment errors in the >>> compat case. >>> >>> Point at dom_crash_sync_extable in the error message, which is about as good >>> as the error hints from other users of asm_domain_crash_synchronous(), and >>> drop last_extable_addr. >> While I'm not entirely opposed, I'd like you to clarify that you indeed >> mean to (mostly) revert your own improvement from 6 or 7 years back >> (commit 8e0da8c07f4f). I'm also surprised to find this as part of the >> series it's in - in what way does this logic get in the way of CET-SS? > > It was part of the exception_fixup() cleanup.  The first 4 patches not > specifically related to CET-SS. "Cleanup" doesn't mean it's needed as a prereq for the CET-SS, so I'm afraid it's still not really clear to me whether we indeed want to effectively revert the earlier change, which had a reason to be done the way it was done. Jan