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,SPF_HELO_NONE,SPF_PASS, 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 0A18CC433E6 for ; Wed, 13 Jan 2021 18:33:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BF919233ED for ; Wed, 13 Jan 2021 18:33:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728429AbhAMSdJ (ORCPT ); Wed, 13 Jan 2021 13:33:09 -0500 Received: from verein.lst.de ([213.95.11.211]:33066 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728157AbhAMSdI (ORCPT ); Wed, 13 Jan 2021 13:33:08 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id A66E868B02; Wed, 13 Jan 2021 19:32:19 +0100 (CET) Date: Wed, 13 Jan 2021 19:32:18 +0100 From: Christoph Hellwig To: Robin Murphy Cc: Christoph Hellwig , Claire Chang , robh+dt@kernel.org, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, joro@8bytes.org, will@kernel.org, frowand.list@gmail.com, konrad.wilk@oracle.com, boris.ostrovsky@oracle.com, jgross@suse.com, sstabellini@kernel.org, m.szyprowski@samsung.com, grant.likely@arm.com, xypron.glpk@gmx.de, treding@nvidia.com, mingo@kernel.org, bauerman@linux.ibm.com, peterz@infradead.org, gregkh@linuxfoundation.org, saravanak@google.com, rafael.j.wysocki@intel.com, heikki.krogerus@linux.intel.com, andriy.shevchenko@linux.intel.com, rdunlap@infradead.org, dan.j.williams@intel.com, bgolaszewski@baylibre.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, iommu@lists.linux-foundation.org, xen-devel@lists.xenproject.org, tfiga@chromium.org, drinkcat@chromium.org Subject: Re: [RFC PATCH v3 4/6] swiotlb: Add restricted DMA alloc/free support. Message-ID: <20210113183218.GB19254@lst.de> References: <20210106034124.30560-1-tientzu@chromium.org> <20210106034124.30560-5-tientzu@chromium.org> <20210113124847.GC1383@lst.de> <82bb75bc-11e6-ac94-9d24-7c896e3aae98@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <82bb75bc-11e6-ac94-9d24-7c896e3aae98@arm.com> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 13, 2021 at 06:27:08PM +0000, Robin Murphy wrote: >> Can we hook in somewhat lower level in the dma-direct code so that all >> the remapping in dma-direct can be reused instead of duplicated? That >> also becomes important if we want to use non-remapping uncached support, >> e.g. on mips or x86, or the direct changing of the attributes that Will >> planned to look into for arm64. > > Indeed, AFAICS this ought to boil down to a direct equivalent of > __dma_direct_alloc_pages() - other than the address there should be no > conceptual difference between pages from the restricted pool and those from > the regular page allocator, so this probably deserves to be plumbed in as > an alternative to that. Yes, that's what I mean. You managed to word it much better, though.