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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 4BF76C433E3 for ; Thu, 13 Aug 2020 10:02:38 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0F46320791 for ; Thu, 13 Aug 2020 10:02:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=citrix.com header.i=@citrix.com header.b="O3PyTlnI" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0F46320791 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=citrix.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A38536B000C; Thu, 13 Aug 2020 06:02:37 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9C1AB6B000D; Thu, 13 Aug 2020 06:02:37 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 862196B000E; Thu, 13 Aug 2020 06:02:37 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0108.hostedemail.com [216.40.44.108]) by kanga.kvack.org (Postfix) with ESMTP id 6896B6B000C for ; Thu, 13 Aug 2020 06:02:37 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 2484A8248068 for ; Thu, 13 Aug 2020 10:02:37 +0000 (UTC) X-FDA: 77145105954.02.rain44_54147b526ff3 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin02.hostedemail.com (Postfix) with ESMTP id E6D8D10097AC2 for ; Thu, 13 Aug 2020 10:02:36 +0000 (UTC) X-HE-Tag: rain44_54147b526ff3 X-Filterd-Recvd-Size: 4256 Received: from esa5.hc3370-68.iphmx.com (esa5.hc3370-68.iphmx.com [216.71.155.168]) by imf46.hostedemail.com (Postfix) with ESMTP for ; Thu, 13 Aug 2020 10:02:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=citrix.com; s=securemail; t=1597312955; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=kkFMyNBbOdtaKP3s0IKVuqUHyo7Vk4EymQC6D+Rwakc=; b=O3PyTlnIEqM2dhp5UuL47ygwNKVSq3ZUxCIl7nyEqAVLKHhxmv/vh3Fr X0kx5dzt3qtxI5TygjKZ0b09RmiAhGSrDs4TD4/hbZ4LThICmGdfWj2xE Ek+4AioawAlws5nxt4N1osWyrH/TSheaJdHtGRJ+6Xt3zi2LHoLzwNpFW U=; Authentication-Results: esa5.hc3370-68.iphmx.com; dkim=none (message not signed) header.i=none IronPort-SDR: wDtbUOGkC+v+QIiO9GW5InSj95+N5bZvHh0cz2sCfx8x8/0y/wKXIBeFTsdWA5IVAl9fHYeLN9 bkgatnmpc6dbgREHUynY40qpDjj/p707iFysIZlm+vriXLDuiKG2hWjEZM5lJMCBJKbBHnmRzT Ek4wVev1cfJou5ZUSJS2/wZJUJSBFN8IxZXcndS/Kdi0ZOoHWEwqy1VaqoDA1I5FfmKdrqia00 lv846+KFNsoIoemtWsa3un39WI8J3cPm1e5CBVfxjR5zuJsQM3Dozc/9+9CouCiP2ZBQIjfCnw Sa8= X-SBRS: 2.7 X-MesageID: 24601489 X-Ironport-Server: esa5.hc3370-68.iphmx.com X-Remote-IP: 162.221.158.21 X-Policy: $RELAYED X-IronPort-AV: E=Sophos;i="5.76,307,1592884800"; d="scan'208";a="24601489" Date: Thu, 13 Aug 2020 12:02:26 +0200 From: Roger Pau =?utf-8?B?TW9ubsOp?= To: Daniel Vetter CC: Christoph Hellwig , , Oleksandr Andrushchenko , David Airlie , Boris Ostrovsky , "Juergen Gross" , Stefano Stabellini , "Dan Carpenter" , Wei Liu , Yan Yankovskyi , , , , David Hildenbrand , Michal Hocko , Dan Williams Subject: Re: [PATCH v4 2/2] xen: add helpers to allocate unpopulated memory Message-ID: <20200813100226.GG975@Air-de-Roger> References: <20200811094447.31208-1-roger.pau@citrix.com> <20200811094447.31208-3-roger.pau@citrix.com> <20200813073337.GA16160@infradead.org> <20200813075420.GC975@Air-de-Roger> <20200813094946.GJ2352366@phenom.ffwll.local> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline In-Reply-To: <20200813094946.GJ2352366@phenom.ffwll.local> X-ClientProxiedBy: AMSPEX02CAS02.citrite.net (10.69.22.113) To AMSPEX02CL02.citrite.net (10.69.22.126) X-Rspamd-Queue-Id: E6D8D10097AC2 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Your email client seems to set 'Reply-to:' to point to everyone on the 'Cc:' field, but not yourself, which is kind of weird. I've manually fixed it on this reply by moving everyone to the 'Cc:' field and setting you on 'To:'. On Thu, Aug 13, 2020 at 11:49:46AM +0200, Daniel Vetter wrote: > On Thu, Aug 13, 2020 at 09:54:20AM +0200, Roger Pau Monn=C3=A9 wrote: > > On Thu, Aug 13, 2020 at 08:33:37AM +0100, Christoph Hellwig wrote: > > > On Tue, Aug 11, 2020 at 11:44:47AM +0200, Roger Pau Monne wrote: > > > > If enabled (because ZONE_DEVICE is supported) the usage of the ne= w > > > > functionality untangles Xen balloon and RAM hotplug from the usag= e of > > > > unpopulated physical memory ranges to map foreign pages, which is= the > > > > correct thing to do in order to avoid mappings of foreign pages d= epend > > > > on memory hotplug. > > >=20 > > > So please just select ZONE_DEVICE if this is so much better rather > > > than maintaining two variants. > >=20 > > We still need to other variant for Arm at least, so both need to be > > maintained anyway, even if we force ZONE_DEVICE on x86. >=20 > Why does arm not have ZONE_DEVICE? It's not that Arm doesn't have ZONE_DEVICE, it's just that the approach used here won't work correctly on an Arm Xen dom0 as-is. This is due to the usage of an identity second stage translation in order to workaround the lack of an IOMMU in some Arm boards. It can be made to work on Arm, but will likely require someone from the Arm side doing that. Roger.