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=unavailable 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 E6B27C28E83 for ; Fri, 4 Sep 2020 07:00:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C8A332067C for ; Fri, 4 Sep 2020 07:00:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726655AbgIDHAg (ORCPT ); Fri, 4 Sep 2020 03:00:36 -0400 Received: from mx2.suse.de ([195.135.220.15]:35444 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726089AbgIDHAU (ORCPT ); Fri, 4 Sep 2020 03:00:20 -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 10272AD5F; Fri, 4 Sep 2020 07:00:20 +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> From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= Message-ID: <6fd73d30-5525-7f00-1e9c-d7bb96ea34a6@suse.com> Date: Fri, 4 Sep 2020 09:00:18 +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: <20200903163837.GM753@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 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. Juergen