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,URIBL_BLOCKED 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 C7B58C433E8 for ; Tue, 14 Jul 2020 08:27:12 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7E9AD21835 for ; Tue, 14 Jul 2020 08:27:12 +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="Qliqg88y" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7E9AD21835 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 2B1576B0003; Tue, 14 Jul 2020 04:27:12 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 23A696B0005; Tue, 14 Jul 2020 04:27:12 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0DAEE6B0006; Tue, 14 Jul 2020 04:27:12 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0080.hostedemail.com [216.40.44.80]) by kanga.kvack.org (Postfix) with ESMTP id E9EAB6B0003 for ; Tue, 14 Jul 2020 04:27:11 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id A6C4E33C4 for ; Tue, 14 Jul 2020 08:27:11 +0000 (UTC) X-FDA: 77036001462.01.wing62_3e09e5e26eef Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin01.hostedemail.com (Postfix) with ESMTP id 5EF692000372DBA5 for ; Tue, 14 Jul 2020 08:27:11 +0000 (UTC) X-HE-Tag: wing62_3e09e5e26eef X-Filterd-Recvd-Size: 3159 Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) by imf05.hostedemail.com (Postfix) with ESMTP for ; Tue, 14 Jul 2020 08:27:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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=A51ag8nDs9zuaekV72PLvRRRTy65GcHBqX/h7vCoPM8=; b=Qliqg88yubr5gTr0CebRm5zHyM VmoSi0W8BiWxbo8q0BQItVbTESnzPp2YQGxipV4dST4DFJUBsJEgrytU7IzP9Ptmtt31ahpakJj6W pvVJgC5LHcsQYfqFGy5fNdrhBWJcuZf7H3SfDGiu09ZMSL4+z0b4A+hAncBX1lLJRahHM4aEJlNXj lWa0NgagAQJSPYr3J9uR3wRQOov3bvouDKlbm6svybYdiMyh2k7P7B7hdk3PoyRtrnU8/ltNHbyf4 4872KPEM7cf358Zm+G7TVXFu4J9ua11eoXXrDYwTVxnobsO9G7E1mpGrwznsBUZ6VolO/a5+BQvvh bjtbmldw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jvGHI-0003qe-0A; Tue, 14 Jul 2020 08:27:04 +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 E72DC305C22; Tue, 14 Jul 2020 10:27:01 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id C5FA120D27C6B; Tue, 14 Jul 2020 10:27:01 +0200 (CEST) Date: Tue, 14 Jul 2020 10:27:01 +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: [RFC PATCH 04/15] x86/pks: Preserve the PKRS MSR on context switch Message-ID: <20200714082701.GO10769@hirez.programming.kicks-ass.net> References: <20200714070220.3500839-1-ira.weiny@intel.com> <20200714070220.3500839-5-ira.weiny@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200714070220.3500839-5-ira.weiny@intel.com> X-Rspamd-Queue-Id: 5EF692000372DBA5 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 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 Tue, Jul 14, 2020 at 12:02:09AM -0700, ira.weiny@intel.com wrote: > From: Ira Weiny > > The PKRS MSR is defined as a per-core register. This isolates memory > access by CPU. Unfortunately, the MSR is not preserved by XSAVE. > Therefore, We must preserve the protections for individual tasks even if > they are context switched out and placed on another cpu later. This is a contradiction and utter trainwreck. We're not going to do more per-core MSRs and pretend they make sense per-task.