From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754546AbbICMZp (ORCPT ); Thu, 3 Sep 2015 08:25:45 -0400 Received: from mx2.suse.de ([195.135.220.15]:49348 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752636AbbICMZo (ORCPT ); Thu, 3 Sep 2015 08:25:44 -0400 Subject: Re: [PATCH] xen/p2m: fix extra memory regions accounting To: Roger Pau Monne , linux-kernel@vger.kernel.org References: <1441281916-38284-1-git-send-email-roger.pau@citrix.com> Cc: Konrad Rzeszutek Wilk , Boris Ostrovsky , David Vrabel , xen-devel@lists.xenproject.org From: Juergen Gross Message-ID: <55E83C46.8010701@suse.com> Date: Thu, 3 Sep 2015 14:25:42 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <1441281916-38284-1-git-send-email-roger.pau@citrix.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/03/2015 02:05 PM, Roger Pau Monne wrote: > On systems with memory maps with ranges that don't end at page boundaries, > like: > > [...] > (XEN) 0000000000100000 - 00000000dfdf9c00 (usable) > (XEN) 00000000dfdf9c00 - 00000000dfe4bc00 (ACPI NVS) > [...] > > xen_add_extra_mem will create a protected range that ends up at 0xdfdf9c00, > but the function used to check if a memory address is inside of a protected > range works with pfns, which means that an attempt to map 0xdfdf9c00 will be > refused because the check is performed against 0xdfdf9000 instead of > 0xdfdf9c00. > > In order to fix this, make sure that the ranges that are added to the > xen_extra_mem array are aligned to page boundaries. > > Signed-off-by: Roger Pau Monné > Cc: Konrad Rzeszutek Wilk > Cc: Boris Ostrovsky > Cc: David Vrabel > Cc: Juergen Gross > Cc: xen-devel@lists.xenproject.org > --- > AFAICT this patch needs to be backported to 3.19, 4.0, 4.1 and 4.2. > --- > arch/x86/xen/setup.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c > index 55f388e..dcf5865 100644 > --- a/arch/x86/xen/setup.c > +++ b/arch/x86/xen/setup.c > @@ -68,6 +68,9 @@ static void __init xen_add_extra_mem(phys_addr_t start, phys_addr_t size) > { > int i; > > + start = PAGE_ALIGN(start); > + size &= PAGE_MASK; This is not correct. If start wasn't page aligned and size was, you'll add one additional page to xen_extra_mem. > + > for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) { > /* Add new region. */ > if (xen_extra_mem[i].size == 0) { > @@ -92,6 +95,9 @@ static void __init xen_del_extra_mem(phys_addr_t start, phys_addr_t size) > int i; > phys_addr_t start_r, size_r; > > + start = PAGE_ALIGN(start); > + size &= PAGE_MASK; Not really needed, as xen_del_extra_mem() is called with aligned values only. OTOH it does no harm, as long as you correct size as above. > + > for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) { > start_r = xen_extra_mem[i].start; > size_r = xen_extra_mem[i].size; > Juergen