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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 80B53C433F5 for ; Mon, 3 Sep 2018 17:01:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 42B7A20779 for ; Mon, 3 Sep 2018 17:01:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 42B7A20779 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org 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 S1728592AbeICVWB (ORCPT ); Mon, 3 Sep 2018 17:22:01 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:38638 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728252AbeICVWA (ORCPT ); Mon, 3 Sep 2018 17:22:00 -0400 Received: from localhost (ip-213-127-74-90.ip.prioritytelecom.net [213.127.74.90]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id A0861CFC; Mon, 3 Sep 2018 17:00:59 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, xxxxxx xxxxxx , Christopher Snowhill , Vlastimil Babka , Thomas Gleixner , "H . Peter Anvin" , Linus Torvalds , Andi Kleen , Dave Hansen , Michal Hocko Subject: [PATCH 4.4 54/80] x86/speculation/l1tf: Fix off-by-one error when warning that system has too much RAM Date: Mon, 3 Sep 2018 18:49:32 +0200 Message-Id: <20180903164936.304843147@linuxfoundation.org> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180903164934.171677301@linuxfoundation.org> References: <20180903164934.171677301@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vlastimil Babka commit b0a182f875689647b014bc01d36b340217792852 upstream. Two users have reported [1] that they have an "extremely unlikely" system with more than MAX_PA/2 memory and L1TF mitigation is not effective. In fact it's a CPU with 36bits phys limit (64GB) and 32GB memory, but due to holes in the e820 map, the main region is almost 500MB over the 32GB limit: [ 0.000000] BIOS-e820: [mem 0x0000000100000000-0x000000081effffff] usable Suggestions to use 'mem=32G' to enable the L1TF mitigation while losing the 500MB revealed, that there's an off-by-one error in the check in l1tf_select_mitigation(). l1tf_pfn_limit() returns the last usable pfn (inclusive) and the range check in the mitigation path does not take this into account. Instead of amending the range check, make l1tf_pfn_limit() return the first PFN which is over the limit which is less error prone. Adjust the other users accordingly. [1] https://bugzilla.suse.com/show_bug.cgi?id=1105536 Fixes: 17dbca119312 ("x86/speculation/l1tf: Add sysfs reporting for l1tf") Reported-by: xxxxxx xxxxxx Reported-by: Christopher Snowhill Signed-off-by: Vlastimil Babka Signed-off-by: Thomas Gleixner Cc: "H . Peter Anvin" Cc: Linus Torvalds Cc: Andi Kleen Cc: Dave Hansen Cc: Michal Hocko Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20180823134418.17008-1-vbabka@suse.cz Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/processor.h | 2 +- arch/x86/mm/init.c | 2 +- arch/x86/mm/mmap.c | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-) --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -174,7 +174,7 @@ extern void cpu_detect(struct cpuinfo_x8 static inline unsigned long long l1tf_pfn_limit(void) { - return BIT_ULL(boot_cpu_data.x86_phys_bits - 1 - PAGE_SHIFT) - 1; + return BIT_ULL(boot_cpu_data.x86_phys_bits - 1 - PAGE_SHIFT); } extern void early_cpu_init(void); --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -779,7 +779,7 @@ unsigned long max_swapfile_size(void) if (boot_cpu_has_bug(X86_BUG_L1TF)) { /* Limit the swap file size to MAX_PA/2 for L1TF workaround */ - unsigned long long l1tf_limit = l1tf_pfn_limit() + 1; + unsigned long long l1tf_limit = l1tf_pfn_limit(); /* * We encode swap offsets also with 3 bits below those for pfn * which makes the usable limit higher. --- a/arch/x86/mm/mmap.c +++ b/arch/x86/mm/mmap.c @@ -138,7 +138,7 @@ bool pfn_modify_allowed(unsigned long pf /* If it's real memory always allow */ if (pfn_valid(pfn)) return true; - if (pfn > l1tf_pfn_limit() && !capable(CAP_SYS_ADMIN)) + if (pfn >= l1tf_pfn_limit() && !capable(CAP_SYS_ADMIN)) return false; return true; }