From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966733AbcLWAsJ (ORCPT ); Thu, 22 Dec 2016 19:48:09 -0500 Received: from mail.kernel.org ([198.145.29.136]:59942 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966602AbcLWAsF (ORCPT ); Thu, 22 Dec 2016 19:48:05 -0500 Date: Thu, 22 Dec 2016 18:48:01 -0600 From: Bjorn Helgaas To: "Raj, Ashok" Cc: Joerg Roedel , linux-pci@vger.kernel.org, iommu@lists.linux-foundation.org, David Woodhouse , linux-kernel@vger.kernel.org, rwright@hpe.com Subject: Re: possible dmar_init_reserved_ranges() error Message-ID: <20161223004801.GA1096@bhelgaas-glaptop.roam.corp.google.com> References: <20161219212044.GA21774@bhelgaas-glaptop.roam.corp.google.com> <20161222162713.GF17255@8bytes.org> <20161222202803.GA16855@bhelgaas-glaptop.roam.corp.google.com> <20161222233238.GA20861@otc-nc-03> <20161222234508.GA20924@otc-nc-03> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161222234508.GA20924@otc-nc-03> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Ashok, On Thu, Dec 22, 2016 at 03:45:08PM -0800, Raj, Ashok wrote: > Hi Bjorn > > None in the platform group say they know about this. So i'm fairly sure > we don't do that on Intel hardware (x86). I'm pretty sure there was once an x86 prototype for which PCI bus addresses were not identical to CPU physical addresses, but I have no idea whether it shipped that way. Even if such a system never shipped, the x86 arch code supports _TRA, and there's no reason to make the unnecessary assumption in this code that _TRA is always zero. If we didn't want to use pcibios_resource_to_bus() here for some reason, we should at least add a comment about why we think it's OK to use a CPU physical address as an IOVA. Bjorn