From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758661Ab0JUWsB (ORCPT ); Thu, 21 Oct 2010 18:48:01 -0400 Received: from terminus.zytor.com ([198.137.202.10]:53610 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752206Ab0JUWsA (ORCPT ); Thu, 21 Oct 2010 18:48:00 -0400 Message-ID: <4CC0C318.90401@zytor.com> Date: Thu, 21 Oct 2010 15:47:52 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.9) Gecko/20100921 Fedora/3.1.4-1.fc13 Thunderbird/3.1.4 MIME-Version: 1.0 To: Jeremy Fitzhardinge CC: the arch/x86 maintainers , "Xen-devel@lists.xensource.com" , Linux Kernel Mailing List , Konrad Rzeszutek Wilk Subject: Re: [PATCH] x86: define arch_vm_get_page_prot to set _PAGE_IOMAP on VM_IO vmas References: <4CC0C14E.5080205@goop.org> In-Reply-To: <4CC0C14E.5080205@goop.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/21/2010 03:40 PM, Jeremy Fitzhardinge wrote: > > Set _PAGE_IOMAP in ptes mapping a VM_IO vma. This says that the mapping > is of a real piece of physical hardware, and not just system memory. > > Xen, in particular, uses to this to inhibit the normal pfn->mfn conversion > that would normally happen - in other words, treat the address directly > as a machine physical address without converting it from pseudo-physical. > > [ Impact: make VM_IO mappings map the right thing under Xen ] > > Signed-off-by: Jeremy Fitzhardinge > Am I the only one who thinks this seems extremely odd that the guest is trusted to make this distinction? -hpa