From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.9 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 737E5C43461 for ; Fri, 4 Sep 2020 12:40:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3A9C12078E for ; Fri, 4 Sep 2020 12:40:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730263AbgIDMkm (ORCPT ); Fri, 4 Sep 2020 08:40:42 -0400 Received: from mx2.suse.de ([195.135.220.15]:56396 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730218AbgIDMk3 (ORCPT ); Fri, 4 Sep 2020 08:40:29 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 348C0ACB5; Fri, 4 Sep 2020 12:40:28 +0000 (UTC) Subject: Re: [PATCH v5 3/3] xen: add helpers to allocate unpopulated memory To: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= Cc: linux-kernel@vger.kernel.org, Oleksandr Andrushchenko , David Airlie , Daniel Vetter , Boris Ostrovsky , Stefano Stabellini , Dan Carpenter , Wei Liu , Yan Yankovskyi , dri-devel@lists.freedesktop.org, xen-devel@lists.xenproject.org, linux-mm@kvack.org, David Hildenbrand , Michal Hocko , Dan Williams References: <20200901083326.21264-1-roger.pau@citrix.com> <20200901083326.21264-4-roger.pau@citrix.com> <20200903163837.GM753@Air-de-Roger> <6fd73d30-5525-7f00-1e9c-d7bb96ea34a6@suse.com> <20200904084229.GN753@Air-de-Roger> From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= Message-ID: <41905296-c157-938b-4953-19af3435c085@suse.com> Date: Fri, 4 Sep 2020 14:40:26 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <20200904084229.GN753@Air-de-Roger> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04.09.20 10:42, Roger Pau Monné wrote: > On Fri, Sep 04, 2020 at 09:00:18AM +0200, Jürgen Groß wrote: >> On 03.09.20 18:38, Roger Pau Monné wrote: >>> On Thu, Sep 03, 2020 at 05:30:07PM +0200, Jürgen Groß wrote: >>>> On 01.09.20 10:33, Roger Pau Monne wrote: >>>>> To be used in order to create foreign mappings. This is based on the >>>>> ZONE_DEVICE facility which is used by persistent memory devices in >>>>> order to create struct pages and kernel virtual mappings for the IOMEM >>>>> areas of such devices. Note that on kernels without support for >>>>> ZONE_DEVICE Xen will fallback to use ballooned pages in order to >>>>> create foreign mappings. >>>>> >>>>> The newly added helpers use the same parameters as the existing >>>>> {alloc/free}_xenballooned_pages functions, which allows for in-place >>>>> replacement of the callers. Once a memory region has been added to be >>>>> used as scratch mapping space it will no longer be released, and pages >>>>> returned are kept in a linked list. This allows to have a buffer of >>>>> pages and prevents resorting to frequent additions and removals of >>>>> regions. >>>>> >>>>> If enabled (because ZONE_DEVICE is supported) the usage of the new >>>>> functionality untangles Xen balloon and RAM hotplug from the usage of >>>>> unpopulated physical memory ranges to map foreign pages, which is the >>>>> correct thing to do in order to avoid mappings of foreign pages depend >>>>> on memory hotplug. >>>>> >>>>> Note the driver is currently not enabled on Arm platforms because it >>>>> would interfere with the identity mapping required on some platforms. >>>>> >>>>> Signed-off-by: Roger Pau Monné >>>> >>>> Sorry, I just got a build error for x86 32-bit build: >>>> >>>> WARNING: unmet direct dependencies detected for ZONE_DEVICE >>>> Depends on [n]: MEMORY_HOTPLUG [=n] && MEMORY_HOTREMOVE [=n] && >>>> SPARSEMEM_VMEMMAP [=n] && ARCH_HAS_PTE_DEVMAP [=n] >>>> Selected by [y]: >>>> - XEN_UNPOPULATED_ALLOC [=y] && XEN [=y] && X86 [=y] >>>> GEN Makefile >>>> CC kernel/bounds.s >>>> CALL /home/gross/korg/src/scripts/atomic/check-atomics.sh >>>> UPD include/generated/bounds.h >>>> CC arch/x86/kernel/asm-offsets.s >>>> In file included from /home/gross/korg/src/include/linux/mmzone.h:19:0, >>>> from /home/gross/korg/src/include/linux/gfp.h:6, >>>> from /home/gross/korg/src/include/linux/slab.h:15, >>>> from /home/gross/korg/src/include/linux/crypto.h:19, >>>> from /home/gross/korg/src/arch/x86/kernel/asm-offsets.c:9: >>>> /home/gross/korg/src/include/linux/page-flags-layout.h:95:2: error: #error >>>> "Not enough bits in page flags" >>>> #error "Not enough bits in page flags" >>>> ^~~~~ >>>> make[2]: *** [/home/gross/korg/src/scripts/Makefile.build:114: >>>> arch/x86/kernel/asm-offsets.s] Error 1 >>>> make[1]: *** [/home/gross/korg/src/Makefile:1175: prepare0] Error 2 >>>> make[1]: Leaving directory '/home/gross/korg/x8632' >>>> make: *** [Makefile:185: __sub-make] Error 2 >>> >>> Sorry for this. I've tested a 32bit build but I think it was before >>> the last Kconfig changes. I'm a little unsure how to solve this, as >>> ZONE_DEVICE doesn't select the required options for it to run, but >>> rather depends on them to be available. >>> >>> You can trigger something similar on x86-64 by doing: >>> >>> $ make ARCH=x86_64 xen.config >>> Using .config as base >>> Merging ./kernel/configs/xen.config >>> Merging ./arch/x86/configs/xen.config >>> # >>> # merged configuration written to .config (needs make) >>> # >>> scripts/kconfig/conf --olddefconfig Kconfig >>> >>> WARNING: unmet direct dependencies detected for ZONE_DEVICE >>> Depends on [n]: MEMORY_HOTPLUG [=y] && MEMORY_HOTREMOVE [=n] && SPARSEMEM_VMEMMAP [=y] && ARCH_HAS_PTE_DEVMAP [=y] >>> Selected by [y]: >>> - XEN_UNPOPULATED_ALLOC [=y] && XEN [=y] && X86_64 [=y] >>> # >>> # configuration written to .config >>> # >>> >>> I think the only solution is to have XEN_UNPOPULATED_ALLOC depend on >>> ZONE_DEVICE rather than select it? >> >> Yes, I think so. >> >> I've folded that in and now build is fine. > > Thanks, I assume no further action is needed on my side. Right. Juergen