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=-5.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 74D43C33CB1 for ; Fri, 17 Jan 2020 12:14:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 49E6B2082F for ; Fri, 17 Jan 2020 12:14:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579263297; bh=d47gxuWmCSayfNRtGqrb+qmEhviKiKpxW6b00GdGhhA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=zy9UZ+3VGFLMgodyBw5+FdH+TB8QK5+KzkQ4jQnB22+iVqbTW6lLheX+AHu8MX0jH vZOQp1/YrHBkSl4dTc5wzNgSZWN2kcF/mAV2WbIdBV/G0ELNw8nX0+pKkxehToXyDg 56mlOFBYdgXXhhebZU9MYoQ1o7cL/sLdRw0cv4WA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726898AbgAQMO4 (ORCPT ); Fri, 17 Jan 2020 07:14:56 -0500 Received: from mail.kernel.org ([198.145.29.99]:41644 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726892AbgAQMO4 (ORCPT ); Fri, 17 Jan 2020 07:14:56 -0500 Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E0BB12073A; Fri, 17 Jan 2020 12:14:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579263295; bh=d47gxuWmCSayfNRtGqrb+qmEhviKiKpxW6b00GdGhhA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=c7iAkMi2OyjFfNHwdzi9yzKrCvbaxZZUcO7xT/HzFAL/6rZf971OGdHO6q2PAllrX oJOG+I3BSwCQfnEUUQybnhqwwCOp19eUgvNyFdMmxI45ZkdGfl7r6+L0+oio6vLIY3 NBBhdnfBZ6xI4fSVZPtpso/goGDz2BcX3IDn8ob8= Date: Fri, 17 Jan 2020 12:14:49 +0000 From: Will Deacon To: Hanjun Guo Cc: Lorenzo Pieralisi , Sudeep Holla , "Rafael J. Wysocki" , Pankaj Bansal , linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxarm@huawei.com, John Garry , Shameerali Kolothum Thodi , Ganapatrao Kulkarni , Ard Biesheuvel , Tyler Baicar , Catalin Marinas , Robin Murphy Subject: Re: [PATCH v2] ACPI/IORT: Fix 'Number of IDs' handling in iort_id_map() Message-ID: <20200117121448.GA8199@willie-the-truck> References: <1579004051-48797-1-git-send-email-guohanjun@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1579004051-48797-1-git-send-email-guohanjun@huawei.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Tue, Jan 14, 2020 at 08:14:11PM +0800, Hanjun Guo wrote: > The IORT specification [0] (Section 3, table 4, page 9) defines the > 'Number of IDs' as 'The number of IDs in the range minus one'. > > However, the IORT ID mapping function iort_id_map() treats the 'Number > of IDs' field as if it were the full IDs mapping count, with the > following check in place to detect out of boundary input IDs: > > InputID >= Input base + Number of IDs > > This check is flawed in that it considers the 'Number of IDs' field as > the full number of IDs mapping and disregards the 'minus one' from > the IDs count. > > The correct check in iort_id_map() should be implemented as: > > InputID > Input base + Number of IDs > > this implements the specification correctly but unfortunately it breaks > existing firmwares that erroneously set the 'Number of IDs' as the full > IDs mapping count rather than IDs mapping count minus one. > > e.g. > > PCI hostbridge mapping entry 1: > Input base: 0x1000 > ID Count: 0x100 > Output base: 0x1000 > Output reference: 0xC4 //ITS reference > > PCI hostbridge mapping entry 2: > Input base: 0x1100 > ID Count: 0x100 > Output base: 0x2000 > Output reference: 0xD4 //ITS reference > > Two mapping entries which the second entry's Input base = the first > entry's Input base + ID count, so for InputID 0x1100 and with the > correct InputID check in place in iort_id_map() the kernel would map > the InputID to ITS 0xC4 not 0xD4 as it would be expected. > > Therefore, to keep supporting existing flawed firmwares, introduce a > workaround that instructs the kernel to use the old InputID range check > logic in iort_id_map(), so that we can support both firmwares written > with the flawed 'Number of IDs' logic and the correct one as defined in > the specifications. > > [0]: http://infocenter.arm.com/help/topic/com.arm.doc.den0049d/DEN0049D_IO_Remapping_Table.pdf > > Reported-by: Pankaj Bansal > Link: https://lore.kernel.org/linux-acpi/20191215203303.29811-1-pankaj.bansal@nxp.com/ > Signed-off-by: Hanjun Guo > Signed-off-by: Lorenzo Pieralisi > Cc: Pankaj Bansal > Cc: Will Deacon > Cc: Sudeep Holla > Cc: Catalin Marinas > Cc: Robin Murphy > --- I'm a bit confused about the SoB chain here and which tree this is targetting. Lorenzo? Will