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=-8.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,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 C936BC433DF for ; Wed, 19 Aug 2020 04:46:36 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 808F120738 for ; Wed, 19 Aug 2020 04:46:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 808F120738 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4BWZxQ2Yn2zDqtN for ; Wed, 19 Aug 2020 14:46:34 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=lst.de (client-ip=213.95.11.211; helo=verein.lst.de; envelope-from=hch@lst.de; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=lst.de Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4BWZtQ1FWyzDqD2 for ; Wed, 19 Aug 2020 14:43:57 +1000 (AEST) Received: by verein.lst.de (Postfix, from userid 2407) id D70DE68AFE; Wed, 19 Aug 2020 06:43:51 +0200 (CEST) Date: Wed, 19 Aug 2020 06:43:51 +0200 From: Christoph Hellwig To: Thiago Jung Bauermann Subject: Re: [PATCH v3] powerpc/pseries/svm: Allocate SWIOTLB buffer anywhere in memory Message-ID: <20200819044351.GA19391@lst.de> References: <20200818221126.391073-1-bauerman@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200818221126.391073-1-bauerman@linux.ibm.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Konrad Rzeszutek Wilk , Robin Murphy , Ram Pai , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Satheesh Rajendran , linuxppc-dev@lists.ozlabs.org, Christoph Hellwig , Marek Szyprowski Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Tue, Aug 18, 2020 at 07:11:26PM -0300, Thiago Jung Bauermann wrote: > POWER secure guests (i.e., guests which use the Protection Execution > Facility) need to use SWIOTLB to be able to do I/O with the hypervisor, but > they don't need the SWIOTLB memory to be in low addresses since the > hypervisor doesn't have any addressing limitation. > > This solves a SWIOTLB initialization problem we are seeing in secure guests > with 128 GB of RAM: they are configured with 4 GB of crashkernel reserved > memory, which leaves no space for SWIOTLB in low addresses. > > To do this, we use mostly the same code as swiotlb_init(), but allocate the > buffer using memblock_alloc() instead of memblock_alloc_low(). > > Signed-off-by: Thiago Jung Bauermann Looks fine to me (except for the pointlessly long comment lines, but I've been told that's the powerpc way).