From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964808Ab1LPUGH (ORCPT ); Fri, 16 Dec 2011 15:06:07 -0500 Received: from cantor2.suse.de ([195.135.220.15]:45010 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932694Ab1LPTt6 (ORCPT ); Fri, 16 Dec 2011 14:49:58 -0500 X-Mailbox-Line: From gregkh@clark.kroah.org Fri Dec 16 11:46:00 2011 Message-Id: <20111216194600.542598387@clark.kroah.org> User-Agent: quilt/0.50-24.1 Date: Fri, 16 Dec 2011 11:45:37 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Ian Campbell , Konrad Rzeszutek Wilk Subject: [40/53] xen: only limit memory map to maximum reservation for domain 0. In-Reply-To: <20111216194613.GA18395@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ian Campbell commit d3db728125c4470a2d061ac10fa7395e18237263 upstream. d312ae878b6a "xen: use maximum reservation to limit amount of usable RAM" clamped the total amount of RAM to the current maximum reservation. This is correct for dom0 but is not correct for guest domains. In order to boot a guest "pre-ballooned" (e.g. with memory=1G but maxmem=2G) in order to allow for future memory expansion the guest must derive max_pfn from the e820 provided by the toolstack and not the current maximum reservation (which can reflect only the current maximum, not the guest lifetime max). The existing algorithm already behaves this correctly if we do not artificially limit the maximum number of pages for the guest case. For a guest booted with maxmem=512, memory=128 this results in: [ 0.000000] BIOS-provided physical RAM map: [ 0.000000] Xen: 0000000000000000 - 00000000000a0000 (usable) [ 0.000000] Xen: 00000000000a0000 - 0000000000100000 (reserved) -[ 0.000000] Xen: 0000000000100000 - 0000000008100000 (usable) -[ 0.000000] Xen: 0000000008100000 - 0000000020800000 (unusable) +[ 0.000000] Xen: 0000000000100000 - 0000000020800000 (usable) ... [ 0.000000] NX (Execute Disable) protection: active [ 0.000000] DMI not present or invalid. [ 0.000000] e820 update range: 0000000000000000 - 0000000000010000 (usable) ==> (reserved) [ 0.000000] e820 remove range: 00000000000a0000 - 0000000000100000 (usable) -[ 0.000000] last_pfn = 0x8100 max_arch_pfn = 0x1000000 +[ 0.000000] last_pfn = 0x20800 max_arch_pfn = 0x1000000 [ 0.000000] initial memory mapped : 0 - 027ff000 [ 0.000000] Base memory trampoline at [c009f000] 9f000 size 4096 -[ 0.000000] init_memory_mapping: 0000000000000000-0000000008100000 -[ 0.000000] 0000000000 - 0008100000 page 4k -[ 0.000000] kernel direct mapping tables up to 8100000 @ 27bb000-27ff000 +[ 0.000000] init_memory_mapping: 0000000000000000-0000000020800000 +[ 0.000000] 0000000000 - 0020800000 page 4k +[ 0.000000] kernel direct mapping tables up to 20800000 @ 26f8000-27ff000 [ 0.000000] xen: setting RW the range 27e8000 - 27ff000 [ 0.000000] 0MB HIGHMEM available. -[ 0.000000] 129MB LOWMEM available. -[ 0.000000] mapped low ram: 0 - 08100000 -[ 0.000000] low ram: 0 - 08100000 +[ 0.000000] 520MB LOWMEM available. +[ 0.000000] mapped low ram: 0 - 20800000 +[ 0.000000] low ram: 0 - 20800000 With this change "xl mem-set 512M" will successfully increase the guest RAM (by reducing the balloon). There is no change for dom0. Reported-and-Tested-by: George Shuklin Signed-off-by: Ian Campbell Reviewed-by: David Vrabel Signed-off-by: Konrad Rzeszutek Wilk Signed-off-by: Greg Kroah-Hartman --- arch/x86/xen/setup.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) --- a/arch/x86/xen/setup.c +++ b/arch/x86/xen/setup.c @@ -191,9 +191,21 @@ static unsigned long __init xen_get_max_ domid_t domid = DOMID_SELF; int ret; - ret = HYPERVISOR_memory_op(XENMEM_maximum_reservation, &domid); - if (ret > 0) - max_pages = ret; + /* + * For the initial domain we use the maximum reservation as + * the maximum page. + * + * For guest domains the current maximum reservation reflects + * the current maximum rather than the static maximum. In this + * case the e820 map provided to us will cover the static + * maximum region. + */ + if (xen_initial_domain()) { + ret = HYPERVISOR_memory_op(XENMEM_maximum_reservation, &domid); + if (ret > 0) + max_pages = ret; + } + return min(max_pages, MAX_DOMAIN_PAGES); }