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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 98949C4151A for ; Thu, 7 Feb 2019 14:01:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6020B21920 for ; Thu, 7 Feb 2019 14:01:52 +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="3mJF1Fut" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727118AbfBGOBu (ORCPT ); Thu, 7 Feb 2019 09:01:50 -0500 Received: from merlin.infradead.org ([205.233.59.134]:42238 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726732AbfBGOBu (ORCPT ); Thu, 7 Feb 2019 09:01:50 -0500 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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=AewIT6yEpMwwuUCQuV/zuqKv5UYFpbkS2e0N8nJZ44s=; b=3mJF1FutYd9OY/Ml674OVBDOq E6FItD0VTbHjEqBsNg9qDvAcRpR0Rray5Mjzdt77eevfqCOrbjGu2R26Y54p1DlMWHGEK/SBCP5Er EWoB4wNO20WSw9ZrdOUbGZqUgNb90SqwsaEjsSvXG3I2xTVSkvB2Xh43ZzRfskZc4a/K2F8ZUgCl0 4MBRLnw86cdxahKO9E7CI22CAHfADNMjYQoR7rlw2YBBheOpwq3g/esmfuEEktkn7X7EYj2FcAycO CDP/GXZyoRC3TtVTXg8Zhl0Ip2r6XteQg3ucVoyQRkqZC58Txys1XUGWnj8LxN/WGbbM42IlziYEv 2/NAxhZGg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1grkFA-00050O-W6; Thu, 07 Feb 2019 14:01:33 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id BF944201A1B24; Thu, 7 Feb 2019 15:01:31 +0100 (CET) Date: Thu, 7 Feb 2019 15:01:31 +0100 From: Peter Zijlstra To: Linus Torvalds Cc: Dan Williams , "Luck, Tony" , Ingo Molnar , Linux List Kernel Mailing , Dave Hansen , Andy Lutomirski , Borislav Petkov , Thomas Gleixner , Rik van Riel Subject: Re: [GIT PULL] x86/mm changes for v4.21 Message-ID: <20190207140131.GB32477@hirez.programming.kicks-ass.net> References: <20181224231106.GA27438@gmail.com> <20190207001737.GA32096@agluck-desk> <20190207101846.GB32511@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 07, 2019 at 11:50:52AM +0000, Linus Torvalds wrote: > If you re-generate the canonical address in __cpa_addr(), now we'll > actually have the real virtual address around for a lot of code-paths > (pte lookup etc), which was what people wanted to avoid in the first > place. Note that it's an 'unsigned long' address, not an actual pointer, and (afaict) non of the code paths use it as a pointer. This _should_ avoid the CPU from following said pointer and doing a deref on it. But yes, I didn't go all the way down, maybe I missed some.