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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E3D55C433F5 for ; Tue, 9 Nov 2021 14:39:31 +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 8FBE561177 for ; Tue, 9 Nov 2021 14:39:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 8FBE561177 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 54695401BD; Tue, 9 Nov 2021 14:39:31 +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 jL20YhPBbpbK; Tue, 9 Nov 2021 14:39:30 +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 07E2A40286; Tue, 9 Nov 2021 14:39:29 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id D7913C0012; Tue, 9 Nov 2021 14:39:29 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 98545C000E for ; Tue, 9 Nov 2021 14:39:28 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 7B42080BB6 for ; Tue, 9 Nov 2021 14:39:28 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id kCXFeInpAWo3 for ; Tue, 9 Nov 2021 14:39:27 +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 smtp1.osuosl.org (Postfix) with ESMTP id E2AE180BB5 for ; Tue, 9 Nov 2021 14:39:27 +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 2A2A92B; Tue, 9 Nov 2021 06:39:27 -0800 (PST) Received: from [10.57.81.233] (unknown [10.57.81.233]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 90E9B3F800; Tue, 9 Nov 2021 06:39:26 -0800 (PST) Message-ID: <986642d1-c3f2-6c8a-ad26-459355c47bb6@arm.com> Date: Tue, 9 Nov 2021 14:39:21 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:91.0) Gecko/20100101 Thunderbird/91.3.0 Subject: Re: [PATCH 05/10] dma-direct: factor out a helper for DMA_ATTR_NO_KERNEL_MAPPING allocations Content-Language: en-GB To: Christoph Hellwig References: <20211021090611.488281-1-hch@lst.de> <20211021090611.488281-6-hch@lst.de> <20211109142532.GD23489@lst.de> From: Robin Murphy In-Reply-To: <20211109142532.GD23489@lst.de> Cc: iommu@lists.linux-foundation.org, David Rientjes 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 2021-11-09 14:25, Christoph Hellwig wrote: > On Thu, Nov 04, 2021 at 12:36:16PM +0000, Robin Murphy wrote: >>> - *dma_handle = phys_to_dma_direct(dev, page_to_phys(page)); >>> - /* return the page pointer as the opaque cookie */ >>> - return page; >>> - } >>> + !force_dma_unencrypted(dev) && !is_swiotlb_for_alloc(dev)) >> >> Hmm, does force_dma_unencrypted() actually matter if the caller doesn't >> want to access the buffer itself? Presumably any subsequent mmap() to >> userspace would still do the right thing? > > Well, force_dma_unencrypted is a bit misnamed I think. It is mostly > used to force bounce buffering for protected guest schemes. Ah, that'll be what that small nagging doubt was at the time :) Furthermore, implicit in the fact that the only comment I had was just musing on the existing code being moved, feel free to have a Reviewed-by: Robin Murphy for the refactor as-is. Cheers, Robin. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu