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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 55E33C07E96 for ; Tue, 6 Jul 2021 15:39:32 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (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 F134B6139A for ; Tue, 6 Jul 2021 15:39:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F134B6139A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id AA75D40022; Tue, 6 Jul 2021 15:39:31 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Ro7m8JkIixmj; Tue, 6 Jul 2021 15:39:30 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [IPv6:2605:bc80:3010:104::8cd3:938]) by smtp2.osuosl.org (Postfix) with ESMTPS id 69961403D3; Tue, 6 Jul 2021 15:39:30 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 3DE5AC0010; Tue, 6 Jul 2021 15:39:30 +0000 (UTC) Received: from smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id 2A154C000E for ; Tue, 6 Jul 2021 15:39:29 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id 2403440589 for ; Tue, 6 Jul 2021 15:39:29 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 1dySfV4HOEWa for ; Tue, 6 Jul 2021 15:39:28 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp4.osuosl.org (Postfix) with ESMTP id DA66640585 for ; Tue, 6 Jul 2021 15:39:27 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D04E3106F; Tue, 6 Jul 2021 08:39:26 -0700 (PDT) Received: from [10.57.40.45] (unknown [10.57.40.45]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 793C53F73B; Tue, 6 Jul 2021 08:39:19 -0700 (PDT) Subject: Re: [PATCH v15 06/12] swiotlb: Use is_swiotlb_force_bounce for swiotlb data bouncing To: Christoph Hellwig References: <20210701074045.GA9436@willie-the-truck> <20210702135856.GB11132@willie-the-truck> <0f7bd903-e309-94a0-21d7-f0e8e9546018@arm.com> <20210705190352.GA19461@willie-the-truck> <20210706044848.GA13640@lst.de> <20210706132422.GA20327@willie-the-truck> <20210706140513.GA26498@lst.de> From: Robin Murphy Message-ID: Date: Tue, 6 Jul 2021 16:39:11 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210706140513.GA26498@lst.de> Content-Language: en-GB Cc: Jim Quinlan , heikki.krogerus@linux.intel.com, linux-devicetree , peterz@infradead.org, benh@kernel.crashing.org, joonas.lahtinen@linux.intel.com, dri-devel@lists.freedesktop.org, chris@chris-wilson.co.uk, grant.likely@arm.com, paulus@samba.org, Frank Rowand , mingo@kernel.org, Jianxiong Gao , Stefano Stabellini , Saravana Kannan , mpe@ellerman.id.au, "Rafael J . Wysocki" , Bartosz Golaszewski , bskeggs@redhat.com, linux-pci@vger.kernel.org, xen-devel@lists.xenproject.org, Thierry Reding , matthew.auld@intel.com, Nicolas Boichat , thomas.hellstrom@linux.intel.com, jgross@suse.com, Will Deacon , Konrad Rzeszutek Wilk , intel-gfx@lists.freedesktop.org, maarten.lankhorst@linux.intel.com, jani.nikula@linux.intel.com, Nathan Chancellor , Rob Herring , rodrigo.vivi@intel.com, Bjorn Helgaas , Claire Chang , Dan Williams , Andy Shevchenko , boris.ostrovsky@oracle.com, airlied@linux.ie, Greg KH , Randy Dunlap , Qian Cai , lkml , "list@263.net:IOMMU DRIVERS" , Daniel Vetter , xypron.glpk@gmx.de, Tom Lendacky , linuxppc-dev@lists.ozlabs.org, bauerman@linux.ibm.com X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On 2021-07-06 15:05, Christoph Hellwig wrote: > On Tue, Jul 06, 2021 at 03:01:04PM +0100, Robin Murphy wrote: >> FWIW I was pondering the question of whether to do something along those >> lines or just scrap the default assignment entirely, so since I hadn't got >> round to saying that I've gone ahead and hacked up the alternative >> (similarly untested) for comparison :) >> >> TBH I'm still not sure which one I prefer... > > Claire did implement something like your suggestion originally, but > I don't really like it as it doesn't scale for adding multiple global > pools, e.g. for the 64-bit addressable one for the various encrypted > secure guest schemes. Ah yes, that had slipped my mind, and it's a fair point indeed. Since we're not concerned with a minimal fix for backports anyway I'm more than happy to focus on Will's approach. Another thing is that that looks to take us a quiet step closer to the possibility of dynamically resizing a SWIOTLB pool, which is something that some of the hypervisor protection schemes looking to build on top of this series may want to explore at some point. Robin. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu