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=-5.3 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 995D8C433DF for ; Thu, 23 Jul 2020 15:49:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7118120771 for ; Thu, 23 Jul 2020 15:49:45 +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="alvZyoJ8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728134AbgGWPtp (ORCPT ); Thu, 23 Jul 2020 11:49:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33488 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727108AbgGWPto (ORCPT ); Thu, 23 Jul 2020 11:49:44 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 91660C0619DC; Thu, 23 Jul 2020 08:49:44 -0700 (PDT) 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=LYu+ezmfFFcFKRanzHt9VPcPF2HH2rDVTFxSgTdp7dg=; b=alvZyoJ8DSaI1Us5j3jnl/Ljgo 7S7hzNiPahJhOwpMmvfZiNTjyos5JOZv2Z0LSjLzTC8fqKwLgQC8cvMhStgS7M5YBR/6yVRy20UpI WtGo5RHCbF3WHW9eCY6HXpYgumPbEDb8R7ES/uYrGXURBbamBymu/jd9BOB3y2ekfr1hXMZqhHArJ A0etWtI9yNbA64C66p3z7q+m28NpBiTgJdKQN/pg8XlhfJiIJiqQThFLSNcT5jHqzKzUt4UKJR7ei sIKZHGXmL1I6w5Mu+KqUKaPu/s53OIJqzCouT+OCJtqtfDonGzVVtAtdNddrAU4qbGvguguy0wABm dv/9u6Mw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jydTT-00062q-17; Thu, 23 Jul 2020 15:49:35 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id 5BD82983422; Thu, 23 Jul 2020 17:49:33 +0200 (CEST) Date: Thu, 23 Jul 2020 17:49:33 +0200 From: Peter Zijlstra To: Alex Belits Cc: "tglx@linutronix.de" , "frederic@kernel.org" , "rostedt@goodmis.org" , "mingo@kernel.org" , Prasun Kapoor , "linux-api@vger.kernel.org" , "linux-arch@vger.kernel.org" , "catalin.marinas@arm.com" , "will@kernel.org" , "linux-arm-kernel@lists.infradead.org" , "davem@davemloft.net" , "linux-kernel@vger.kernel.org" , "netdev@vger.kernel.org" Subject: Re: [PATCH v4 00/13] "Task_isolation" mode Message-ID: <20200723154933.GB709@worktop.programming.kicks-ass.net> References: <04be044c1bcd76b7438b7563edc35383417f12c8.camel@marvell.com> <87imeextf3.fsf@nanos.tec.linutronix.de> <831e023422aa0e4cb3da37ceef6fdcd5bc854682.camel@marvell.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <831e023422aa0e4cb3da37ceef6fdcd5bc854682.camel@marvell.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-api-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Thu, Jul 23, 2020 at 03:18:42PM +0000, Alex Belits wrote: > On Thu, 2020-07-23 at 15:17 +0200, Thomas Gleixner wrote: > > > > Without going into details of the individual patches, let me give you a > > high level view of this series: > > > > 1) Entry code handling: > > > > That's completely broken vs. the careful ordering and instrumentation > > protection of the entry code. You can't just slap stuff randomly > > into places which you think are safe w/o actually trying to understand > > why this code is ordered in the way it is. > > > > This clearly was never built and tested with any of the relevant > > debug options enabled. Both build and boot would have told you. > > This is intended to avoid a race condition when entry or exit from isolation > happens at the same time as an event that requires synchronization. The idea > is, it is possible to insulate the core from all events while it is running > isolated task in userspace, it will receive those calls normally after > breaking isolation and entering kernel, and it will synchronize itself on > kernel entry. 'What does noinstr mean? and why do we have it" -- don't dare touch the entry code until you can answer that.