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=-7.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 A5D04CA9EC3 for ; Thu, 31 Oct 2019 11:26:25 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 76C7420650 for ; Thu, 31 Oct 2019 11:26:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="hiuX6orS"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="sIphd9o6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 76C7420650 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=aV5RWCrj91JM+tQAMP5MaaKlk1+eqONeFV5NNRk/dJo=; b=hiuX6orSiJfCPg B9hysFqS1y1KHR8Zs7EKlqoSOWICpAwkrFEEamxIh9rfZRE+gmYp6t4Xlx3n3S8PvGlf8ld4j/4qD tdgFij2aUWnBzQ3BD59WzGPTG+BHXNVEi7334E96aovO75j4OoJdiS5tWdgL8NclrG14banDD94Pl A7kWJvB3td1+k39OaQsDlTN302BXmiZ9Es1za/dBr4sWvdIox+2Obo8L2Ut1Ey36iWAUKtc6rqqdN /nsIp5zpyU66x2/qeA44rnJxR3gMQSsfPa9KZsK8bni/OVGd5HajIjSh5gd0ehPKIteKi7pjWkU4k LNmgxDeHzslsWUg9yWUg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iQ8ap-0000mM-J2; Thu, 31 Oct 2019 11:26:19 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iQ8al-0000lU-NY for linux-arm-kernel@lists.infradead.org; Thu, 31 Oct 2019 11:26:17 +0000 Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3325D208E3; Thu, 31 Oct 2019 11:26:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572521175; bh=scynK1w3RbTaGbWJXWwUlo8xZ4qi2RZOr8IV+A7V3JM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=sIphd9o6lhzuPuXTqCp9obiSPG5bi6IZHv2BKfPVmFMkKlg/q7GLTucZrx/ma7wqB alzzktK19yzwsQ++8QXjv4vcgDsYmh3kYN7za7HAk84ISJtbsR8NSmUdoZZDdBMPe9 1Vsv8nmZTrl2NDqcqwnLPHb1yHAIs0mbxiRLQqdo= Date: Thu, 31 Oct 2019 11:26:10 +0000 From: Will Deacon To: Mark Brown Subject: Re: [PATCH v4 0/4] E0PD support Message-ID: <20191031112610.GA26059@willie-the-truck> References: <20191024214207.20588-1-broonie@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191024214207.20588-1-broonie@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191031_042615_787678_9CE72333 X-CRM114-Status: GOOD ( 12.01 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Catalin Marinas , john.garry@huawei.com, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org [+John Garry] Hi Mark, On Thu, Oct 24, 2019 at 10:42:03PM +0100, Mark Brown wrote: > This series adds support for E0PD. We enable E0PD unconditionally where > present on systems where all the CPUs in the system support E0PD and > change to not enabling KPTI by default on systems where we have enabled > E0PD. It also converts the runtime checks for use of non-global mappings > into a variable. Although I welcome the simplification introduced by this patch set, I'm worried that we might be removing a significant optimisation to KASLR boot-time on machines with large memory. John reported issues with this in the past, so I'm looping him in in case he has a chance to test this (branch here [1]). Of course, I could just be missing something since this code was really subtle to begin with. On KASLR systems other than TX1, we should use nG mappings by default so that we can avoid the time-consuming task of rewriting swapper during boot. However, with your patches, I think we defer the decision to use nG mappings to the cpufeature code which means we always end up rewriting swapper in this scenario because of the global mappings installed early on. Have I got that right? Cheers, Will [1] https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git/log/?h=for-next/e0pd _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel