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 ECC90C433E2 for ; Thu, 3 Sep 2020 15:30:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CAB7421527 for ; Thu, 3 Sep 2020 15:30:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728473AbgICPaM (ORCPT ); Thu, 3 Sep 2020 11:30:12 -0400 Received: from mx2.suse.de ([195.135.220.15]:58750 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728145AbgICPaK (ORCPT ); Thu, 3 Sep 2020 11:30:10 -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 CE5D6AD60; Thu, 3 Sep 2020 15:30:09 +0000 (UTC) Subject: Re: [PATCH v5 3/3] xen: add helpers to allocate unpopulated memory To: Roger Pau Monne , linux-kernel@vger.kernel.org Cc: 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> From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= Message-ID: Date: Thu, 3 Sep 2020 17:30:07 +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: <20200901083326.21264-4-roger.pau@citrix.com> 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 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 Juergen