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=-5.2 required=3.0 tests=BAYES_00, 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 E437CC43457 for ; Mon, 19 Oct 2020 18:49:00 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 535FF223BF for ; Mon, 19 Oct 2020 18:49:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 535FF223BF Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9C9B06B005D; Mon, 19 Oct 2020 14:48:59 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 97A596B0062; Mon, 19 Oct 2020 14:48:59 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 81B9E6B0068; Mon, 19 Oct 2020 14:48:59 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0036.hostedemail.com [216.40.44.36]) by kanga.kvack.org (Postfix) with ESMTP id 549EC6B005D for ; Mon, 19 Oct 2020 14:48:59 -0400 (EDT) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id E14CC180AD802 for ; Mon, 19 Oct 2020 18:48:58 +0000 (UTC) X-FDA: 77389561956.07.pain59_500c07127239 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin07.hostedemail.com (Postfix) with ESMTP id BBD211803F9A8 for ; Mon, 19 Oct 2020 18:48:58 +0000 (UTC) X-HE-Tag: pain59_500c07127239 X-Filterd-Recvd-Size: 3400 Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) by imf15.hostedemail.com (Postfix) with ESMTP for ; Mon, 19 Oct 2020 18:48:57 +0000 (UTC) IronPort-SDR: gXaWVd+wyVjWS0eVFnPQiHuASqIo3dHis6Qw5ZF5KdS+H8A4uIbT/F4v7bUiADA8yLh4f5Nwhu U8W/vOaDJ5Qw== X-IronPort-AV: E=McAfee;i="6000,8403,9779"; a="228720940" X-IronPort-AV: E=Sophos;i="5.77,395,1596524400"; d="scan'208";a="228720940" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Oct 2020 11:48:51 -0700 IronPort-SDR: 9Q6lfeqmVXf8xJoZpKKEiMAlLaNRA4+210TknTwmbYMu5RiGfjwSmlxLQWJuXLP/L8JCdm8vZJ yjNckI9qdKrw== X-IronPort-AV: E=Sophos;i="5.77,395,1596524400"; d="scan'208";a="301476541" Received: from iweiny-desk2.sc.intel.com (HELO localhost) ([10.3.52.147]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Oct 2020 11:48:49 -0700 Date: Mon, 19 Oct 2020 11:48:49 -0700 From: Ira Weiny To: Peter Zijlstra Cc: Dave Hansen , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Andy Lutomirski , Fenghua Yu , x86@kernel.org, Dave Hansen , Dan Williams , Andrew Morton , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH RFC V3 4/9] x86/pks: Preserve the PKRS MSR on context switch Message-ID: <20201019184849.GC3713473@iweiny-DESK2.sc.intel.com> References: <20201009194258.3207172-1-ira.weiny@intel.com> <20201009194258.3207172-5-ira.weiny@intel.com> <429789d3-ab5b-49c3-65c3-f0fc30a12516@intel.com> <20201016111226.GN2611@hirez.programming.kicks-ass.net> <20201017051410.GW2046448@iweiny-DESK2.sc.intel.com> <20201019093714.GI2628@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201019093714.GI2628@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.11.1 (2018-12-01) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Oct 19, 2020 at 11:37:14AM +0200, Peter Zijlstra wrote: > On Fri, Oct 16, 2020 at 10:14:10PM -0700, Ira Weiny wrote: > > > so it either needs to > > > explicitly do so, or have an assertion that preemption is indeed > > > disabled. > > > > However, I don't think I understand clearly. Doesn't [get|put]_cpu_ptr() > > handle the preempt_disable() for us? > > It does. > > > Is it not sufficient to rely on that? > > It is. > > > Dave's comment seems to be the opposite where we need to eliminate preempt > > disable before calling write_pkrs(). > > > > FWIW I think I'm mistaken in my response to Dave regarding the > > preempt_disable() in pks_update_protection(). > > Dave's concern is that we're calling with with preemption already > disabled so disabling it again is superfluous. Ok, thanks, and after getting my head straight I think I agree with him, and you. Thanks I've reworked the code to removed the superfluous calls. Sorry about being so dense... :-D Ira