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 9F04EC43467 for ; Mon, 19 Oct 2020 18:49:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4A561223FD for ; Mon, 19 Oct 2020 18:49:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730871AbgJSSs7 (ORCPT ); Mon, 19 Oct 2020 14:48:59 -0400 Received: from mga03.intel.com ([134.134.136.65]:16370 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727681AbgJSSs7 (ORCPT ); Mon, 19 Oct 2020 14:48:59 -0400 IronPort-SDR: 2Uu/efrXkwcYfZ13Vh1e4bjXBRJyN9t9x+RU4MYsgiXB2tp3pGHkTIYkhFr3Ho6UuJp57RtEiL HnJy6ekHAn/A== X-IronPort-AV: E=McAfee;i="6000,8403,9779"; a="167165415" X-IronPort-AV: E=Sophos;i="5.77,395,1596524400"; d="scan'208";a="167165415" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga103.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) Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org 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