Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752061AbbFXIae (ORCPT ); Wed, 24 Jun 2015 04:30:34 -0400 Received: from mail-wi0-f172.google.com ([209.85.212.172]:35037 "EHLO mail-wi0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751174AbbFXIaZ (ORCPT ); Wed, 24 Jun 2015 04:30:25 -0400 Date: Wed, 24 Jun 2015 10:30:19 +0200 From: Ingo Molnar To: Jiang Liu Cc: "Rafael J . Wysocki" , Bjorn Helgaas , Boszormenyi Zoltan , Len Brown , LKML , linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org, "x86 @ kernel . org" Subject: Re: [Bugfix v2] PCI, ACPI: Fix regressions caused by resource_size_t overflow with 32bit kernel Message-ID: <20150624083019.GA26672@gmail.com> References: <1435131817-28167-1-git-send-email-jiang.liu@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1435131817-28167-1-git-send-email-jiang.liu@linux.intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2053 Lines: 47 * Jiang Liu wrote: > Since commit 593669c2ac0f ("x86/PCI/ACPI: Use common ACPI resource interfaces to > simplify implementation"), x86 PCI ACPI host bridge driver validates ACPI > resources by first converting an ACPI resource to a 'struct resource' structure > and then applying checks against the converted resource structure. The 'start' > and 'end' fields in 'struct resource' are defined to be type of resource_size_t, > which may be 32 bits or 64 bits depending on CONFIG_PHYS_ADDR_T_64BIT. > > This may cause incorrect resource validation results with 32 bit kernels because > 64bit ACPI resource descriptors may get truncated when converting to 32bit > 'start' and 'end' fields in 'struct resource'. And eventually affects PCI > resource allocation subsystem and causes some PCI devices unusable. s/causes some PCI devices unusuable. makes some PCI devices unusuable. Also, this description is still pretty vague. What exactly happened? Did some PCI devices not show up during bootup? Or did they hang? Or did something else happen? This is _by far_ the most important part of the changelog and determines whether a patch gets backported or not. Why does a usable regression description have to be coaxed out of you like pulling teeth?? > So enhance the ACPI resource parsing interfaces to ignore ACPI resource > descriptors with address/offset observe 4G when running in 32bit mode. This > reverts to the behavior before commit 593669c2ac0f. > > This issue was triggered on a platform running 32bit kernel with an ACPI > resource descriptor with address range [0x400000000-0xfffffffff]. Please refer > to https://lkml.org/lkml/2015/6/19/277 for more information. s/32bit/32-bit s/64bit/64-bit s/32 bit/32-bit s/64 bit/64-bit Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/