Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753190AbYL3Qiv (ORCPT ); Tue, 30 Dec 2008 11:38:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751246AbYL3Qil (ORCPT ); Tue, 30 Dec 2008 11:38:41 -0500 Received: from mx2.redhat.com ([66.187.237.31]:46647 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750887AbYL3Qik (ORCPT ); Tue, 30 Dec 2008 11:38:40 -0500 Message-ID: <495A4E85.6070800@redhat.com> Date: Tue, 30 Dec 2008 18:38:29 +0200 From: Avi Kivity User-Agent: Thunderbird 2.0.0.18 (X11/20081119) MIME-Version: 1.0 To: Tony Battersby CC: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, David Woodhouse , "iommu@lists.linux-foundation.org" Subject: Re: [PATCH] [DMAR] Fix endless "Unknown DMAR structure type" loop References: <495A4A39.20903@cybernetics.com> In-Reply-To: <495A4A39.20903@cybernetics.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2882 Lines: 72 (copying relevant people) Tony Battersby wrote: > I have a SuperMicro C2SBX motherboard with BIOS revision 1.0b. With > vt-d enabled in the BIOS, Linux gets into an endless loop printing > "DMAR:Unknown DMAR structure type" when booting. Here is the DMAR ACPI > table: > > DMAR @ 0x7fe86dec > 0000: 44 4d 41 52 98 00 00 00 01 6f 49 6e 74 65 6c 20 DMAR.....oIntel > 0010: 4f 45 4d 44 4d 41 52 20 00 00 04 06 4c 4f 48 52 OEMDMAR ....LOHR > 0020: 01 00 00 00 23 00 00 00 00 00 00 00 00 00 00 00 ....#........... > 0030: 01 00 58 00 00 00 00 00 00 a0 e8 7f 00 00 00 00 ..X............. > 0040: ff ff ef 7f 00 00 00 00 01 08 00 00 00 00 1d 00 ................ > 0050: 01 08 00 00 00 00 1d 01 01 08 00 00 00 00 1d 02 ................ > 0060: 01 08 00 00 00 00 1d 07 01 08 00 00 00 00 1a 00 ................ > 0070: 01 08 00 00 00 00 1a 01 01 08 00 00 00 00 1a 02 ................ > 0080: 01 08 00 00 00 00 1a 07 01 08 00 00 00 00 1a 07 ................ > 0090: c0 00 68 00 04 10 66 60 ..h...f` > > Here are the messages printed by the kernel: > > DMAR:Host address width 36 > DMAR:RMRR base: 0x000000007fe8a000 end: 0x000000007fefffff > DMAR:Unknown DMAR structure type > DMAR:Unknown DMAR structure type > DMAR:Unknown DMAR structure type > ... > > Although I not very familiar with ACPI, to me it looks like > struct acpi_dmar_header::length == 0x0058 is incorrect, causing > parse_dmar_table() to look at an invalid offset on the next loop. This > offset happens to have struct acpi_dmar_header::length == 0x0000, which > prevents the loop from ever terminating. This patch checks for this > condition and bails out instead of looping forever. > > Signed-off-by: Tony Battersby > --- > > I previously sent this to linux-acpi on August 18, 2008, but got no > reply. Please apply this patch upstream (2.6.29 if possible). > > --- linux-2.6.28-git2/drivers/pci/dmar.c.orig 2008-12-24 18:26:37.000000000 -0500 > +++ linux-2.6.28-git2/drivers/pci/dmar.c 2008-12-30 11:01:17.000000000 -0500 > @@ -339,6 +339,14 @@ parse_dmar_table(void) > entry_header = (struct acpi_dmar_header *)(dmar + 1); > while (((unsigned long)entry_header) < > (((unsigned long)dmar) + dmar_tbl->length)) { > + /* Avoid looping forever on bad ACPI tables */ > + if (entry_header->length == 0) { > + printk(KERN_WARNING PREFIX > + "Invalid 0-length structure\n"); > + ret = -EINVAL; > + break; > + } > + > dmar_table_print_dmar_entry(entry_header); > > switch (entry_header->type) { > > > -- error compiling committee.c: too many arguments to function -- 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/