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=-6.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 16E91C433DF for ; Thu, 20 Aug 2020 02:12:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DBE7720FC3 for ; Thu, 20 Aug 2020 02:12:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ellerman.id.au header.i=@ellerman.id.au header.b="pZigIs87" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726735AbgHTCMo (ORCPT ); Wed, 19 Aug 2020 22:12:44 -0400 Received: from bilbo.ozlabs.org ([203.11.71.1]:37319 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726578AbgHTCMm (ORCPT ); Wed, 19 Aug 2020 22:12:42 -0400 Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4BX7TM3wDzz9sRN; Thu, 20 Aug 2020 12:12:39 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ellerman.id.au; s=201909; t=1597889560; bh=gPdGSuMbBr6AKJw/++doCCfD8GkVb+j4pQ8PJ3xV49A=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=pZigIs87s/0HJCQu3CMeGxmU0e2JIr0P58tO7g3RDssIi9EJAWo6dG2xAEOeHDFUN H/U0C6GQyVs1FTXIqdcuIOi1g6VWt3esLh1358kQCRaPPn3HpgPcIfg7b0MqD4lPxa vaedp/MpmDiMZyRDSUDUTwoIyNc2WvONX4FWrm9ApXlgHzNAHzVOQ1LWJQ6aL7VIQv jYci3SYKpJhI7xoajLFJH8NrnUEgQdKBtqb/Gnjb6UVVuc40f9BgYZO2HAzBFkSGh8 Ym6AviUgzKcWLDdtvnZFf5y5fvG+orpGwMv3tCGcngvhsq4jMphAzi+hKg7TzFnQqq YO31FxQ3zKJzg== From: Michael Ellerman To: Christoph Hellwig , Thiago Jung Bauermann Cc: iommu@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Konrad Rzeszutek Wilk , Christoph Hellwig , Marek Szyprowski , Robin Murphy , Ram Pai , Satheesh Rajendran Subject: Re: [PATCH v3] powerpc/pseries/svm: Allocate SWIOTLB buffer anywhere in memory In-Reply-To: <20200819044351.GA19391@lst.de> References: <20200818221126.391073-1-bauerman@linux.ibm.com> <20200819044351.GA19391@lst.de> Date: Thu, 20 Aug 2020 12:12:35 +1000 Message-ID: <877dtuhxpo.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Christoph Hellwig writes: > 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). They're 80 columns AFAICS? cheers