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=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,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 C303DC4321D for ; Mon, 20 Aug 2018 10:49:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 71D6F20693 for ; Mon, 20 Aug 2018 10:49:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 71D6F20693 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-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726144AbeHTOEl (ORCPT ); Mon, 20 Aug 2018 10:04:41 -0400 Received: from mx2.suse.de ([195.135.220.15]:36944 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725948AbeHTOEl (ORCPT ); Mon, 20 Aug 2018 10:04:41 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 585E6ADDD; Mon, 20 Aug 2018 10:49:33 +0000 (UTC) Date: Mon, 20 Aug 2018 12:49:32 +0200 From: Michal Hocko To: Vlastimil Babka Cc: Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds , Andi Kleen , Dave Hansen , stable@vger.kernel.org, Adrian Schroeter , Dominique Leuenberger Subject: Re: [PATCH] x86/speculation/l1tf: fix overflow on l1tf_pfn_limit() on 32bit Message-ID: <20180820104932.GI29735@dhcp22.suse.cz> References: <20180820095835.5298-1-vbabka@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180820095835.5298-1-vbabka@suse.cz> 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 Mon 20-08-18 11:58:35, Vlastimil Babka wrote: > On 32bit PAE kernels on 64bit hardware with enough physical bits, > l1tf_pfn_limit() will overflow unsigned long. This in turn affects > max_swapfile_size() and can lead to swapon returning -EINVAL. This has been > observed in a 32bit guest with 42 bits physical address size, where > max_swapfile_size() overflows exactly to 1 << 32, thus zero, and produces the > following warning to dmesg: > > [ 6.396845] Truncating oversized swap area, only using 0k out of 2047996k > > Fix this by using unsigned long long instead. > > Reported-by: Dominique Leuenberger > Reported-by: Adrian Schroeter > Fixes: 17dbca119312 ("x86/speculation/l1tf: Add sysfs reporting for l1tf") > Fixes: 377eeaa8e11f ("x86/speculation/l1tf: Limit swap file size to MAX_PA/2") > Cc: stable@vger.kernel.org > Signed-off-by: Vlastimil Babka Looks good to me. I would probably use phys_addr_t which would be more descriptive but this is just minor thing. Acked-by: Michal Hocko > --- > arch/x86/include/asm/processor.h | 4 ++-- > arch/x86/mm/init.c | 4 ++-- > 2 files changed, 4 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h > index 682286aca881..a0a52274cb4a 100644 > --- a/arch/x86/include/asm/processor.h > +++ b/arch/x86/include/asm/processor.h > @@ -181,9 +181,9 @@ extern const struct seq_operations cpuinfo_op; > > extern void cpu_detect(struct cpuinfo_x86 *c); > > -static inline unsigned long l1tf_pfn_limit(void) > +static inline unsigned long long l1tf_pfn_limit(void) > { > - return BIT(boot_cpu_data.x86_phys_bits - 1 - PAGE_SHIFT) - 1; > + return BIT_ULL(boot_cpu_data.x86_phys_bits - 1 - PAGE_SHIFT) - 1; > } > > extern void early_cpu_init(void); > diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c > index acfab322fbe0..02de3d6065c4 100644 > --- a/arch/x86/mm/init.c > +++ b/arch/x86/mm/init.c > @@ -923,7 +923,7 @@ 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 l1tf_limit = l1tf_pfn_limit() + 1; > + unsigned long long l1tf_limit = l1tf_pfn_limit() + 1; > /* > * We encode swap offsets also with 3 bits below those for pfn > * which makes the usable limit higher. > @@ -931,7 +931,7 @@ unsigned long max_swapfile_size(void) > #if CONFIG_PGTABLE_LEVELS > 2 > l1tf_limit <<= PAGE_SHIFT - SWP_OFFSET_FIRST_BIT; > #endif > - pages = min_t(unsigned long, l1tf_limit, pages); > + pages = min_t(unsigned long long, l1tf_limit, pages); > } > return pages; > } > -- > 2.18.0 -- Michal Hocko SUSE Labs