From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932630Ab2EXKdb (ORCPT ); Thu, 24 May 2012 06:33:31 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60605 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754713Ab2EXKda (ORCPT ); Thu, 24 May 2012 06:33:30 -0400 Message-ID: <4FBE0E75.8080503@redhat.com> Date: Thu, 24 May 2012 13:33:25 +0300 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:12.0) Gecko/20120430 Thunderbird/12.0.1 MIME-Version: 1.0 To: Gleb Natapov CC: Xiao Guangrong , Marcelo Tosatti , LKML , KVM Subject: Re: [PATCH v2] KVM: introduce readonly memory region References: <4FBDFE52.5090902@linux.vnet.ibm.com> <20120524095938.GX10209@redhat.com> In-Reply-To: <20120524095938.GX10209@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/24/2012 12:59 PM, Gleb Natapov wrote: > On Thu, May 24, 2012 at 05:24:34PM +0800, Xiao Guangrong wrote: >> In current code, if we map a readonly memory space from host to guest >> and the page is not currently mapped in the host, we will get a fault-pfn >> and async is not allowed, then the vm will crash >> >> Address Avi's idea, we introduce readonly memory region to map ROM/ROMD >> to the guest >> > As far as I can tell this implements only ROMD. i.e write access to read > only slot will generate IO exit. Which userspace can then ignore. The question is whether writes to ROM are frequent, and whether the performance in that case matters. -- error compiling committee.c: too many arguments to function