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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 54B59C64EAD for ; Sat, 29 Sep 2018 21:57:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 169222087A for ; Sat, 29 Sep 2018 21:57:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 169222087A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728836AbeI3E1p (ORCPT ); Sun, 30 Sep 2018 00:27:45 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:51694 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728323AbeI3ES0 (ORCPT ); Sun, 30 Sep 2018 00:18:26 -0400 Received: from [2a02:8011:400e:2:cbab:f00:c93f:614] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1g6N66-0000H7-2z; Sat, 29 Sep 2018 22:48:22 +0100 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1g6N5y-0006wl-Lq; Sat, 29 Sep 2018 22:48:14 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Dave Hansen" , "Thomas Gleixner" , "Josh Poimboeuf" , "Andi Kleen" Date: Sat, 29 Sep 2018 22:43:07 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 098/131] x86/speculation/l1tf: Make sure the first page is always reserved In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:cbab:f00:c93f:614 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.59-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Andi Kleen commit 10a70416e1f067f6c4efda6ffd8ea96002ac4223 upstream. The L1TF workaround doesn't make any attempt to mitigate speculate accesses to the first physical page for zeroed PTEs. Normally it only contains some data from the early real mode BIOS. It's not entirely clear that the first page is reserved in all configurations, so add an extra reservation call to make sure it is really reserved. In most configurations (e.g. with the standard reservations) it's likely a nop. Signed-off-by: Andi Kleen Signed-off-by: Thomas Gleixner Reviewed-by: Josh Poimboeuf Acked-by: Dave Hansen Signed-off-by: Ben Hutchings --- arch/x86/kernel/setup.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -860,6 +860,12 @@ void __init setup_arch(char **cmdline_p) memblock_reserve(__pa_symbol(_text), (unsigned long)__bss_stop - (unsigned long)_text); + /* + * Make sure page 0 is always reserved because on systems with + * L1TF its contents can be leaked to user processes. + */ + memblock_reserve(0, PAGE_SIZE); + early_reserve_initrd(); /*