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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 11D01C433E4 for ; Fri, 17 Jul 2020 09:01:37 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C31B1207F5 for ; Fri, 17 Jul 2020 09:01:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="e8KQste/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C31B1207F5 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 65F978D0025; Fri, 17 Jul 2020 05:01:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5E8A38D0009; Fri, 17 Jul 2020 05:01:36 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4D90F8D0025; Fri, 17 Jul 2020 05:01:36 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0201.hostedemail.com [216.40.44.201]) by kanga.kvack.org (Postfix) with ESMTP id 342C58D0009 for ; Fri, 17 Jul 2020 05:01:36 -0400 (EDT) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id E41353015E for ; Fri, 17 Jul 2020 09:01:35 +0000 (UTC) X-FDA: 77046974550.15.test76_391255d26f09 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin15.hostedemail.com (Postfix) with ESMTP id C08E7180260D9 for ; Fri, 17 Jul 2020 09:00:02 +0000 (UTC) X-HE-Tag: test76_391255d26f09 X-Filterd-Recvd-Size: 3299 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf05.hostedemail.com (Postfix) with ESMTP for ; Fri, 17 Jul 2020 09:00:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=8xT/WVtQE2KY4X7YjP79ChPInUPynkTTYKC9pryceZE=; b=e8KQste/jtn3QrtBaetLpn+930 lo7u3UpKqeat3xIAKeiubE8XcxBOKlbeGR+zBvDcke8mVhn2ZhXIwz/zwSoruuzYOQQnpdCu9VnX7 kPEQ1GdsmNi7kWdwGOU62EL1GI1oq3MhbE3MF5Emma66Ddcf580sU3Uax4jBgNxK6tB5mi9o8UN5l dEky9TUhy29LwKea+f2O3dJtrVwpY6RLv8drTRWYk4uE/aME4kvSRVvTQhQZi19Y+5rjSYthwxVtj 3m5koTs+xwLdLDFypF6fAfbSPUXt7HXH9dhFltXANJc09Slkg5B6GcdVs0+Zs1woD4Yqqt0nwQFQf i6xNaS1w==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jwMDk-0005yy-7T; Fri, 17 Jul 2020 08:59:56 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id D695B304D58; Fri, 17 Jul 2020 10:59:54 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id B702429CF6F79; Fri, 17 Jul 2020 10:59:54 +0200 (CEST) Date: Fri, 17 Jul 2020 10:59:54 +0200 From: Peter Zijlstra To: ira.weiny@intel.com Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Andy Lutomirski , Fenghua Yu , x86@kernel.org, Dave Hansen , Dan Williams , Vishal Verma , 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 V2 04/17] x86/pks: Preserve the PKRS MSR on context switch Message-ID: <20200717085954.GY10769@hirez.programming.kicks-ass.net> References: <20200717072056.73134-1-ira.weiny@intel.com> <20200717072056.73134-5-ira.weiny@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200717072056.73134-5-ira.weiny@intel.com> X-Rspamd-Queue-Id: C08E7180260D9 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 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 Fri, Jul 17, 2020 at 12:20:43AM -0700, ira.weiny@intel.com wrote: > +/* > + * Write the PKey Register Supervisor. This must be run with preemption > + * disabled as it does not guarantee the atomicity of updating the pkrs_cache > + * and MSR on its own. > + */ > +void write_pkrs(u32 pkrs_val) > +{ > + this_cpu_write(pkrs_cache, pkrs_val); > + wrmsrl(MSR_IA32_PKRS, pkrs_val); > +} Should we write that like: void write_pkrs(u32 pkr) { u32 *pkrs = get_cpu_ptr(pkrs_cache); if (*pkrs != pkr) { *pkrs = pkr; wrmsrl(MSR_IA32_PKRS, pkr); } put_cpu_ptrpkrs_cache); } given that we fundamentally need to serialize againt schedule() here.