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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 C2B43C433E0 for ; Tue, 7 Jul 2020 06:47:38 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (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 9766020675 for ; Tue, 7 Jul 2020 06:47:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9766020675 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id 3CCF8203EE; Tue, 7 Jul 2020 06:47:38 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 7ewNGWQfToaY; Tue, 7 Jul 2020 06:47:37 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by silver.osuosl.org (Postfix) with ESMTP id 7856A2037E; Tue, 7 Jul 2020 06:47:37 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 60063C0891; Tue, 7 Jul 2020 06:47:37 +0000 (UTC) Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) by lists.linuxfoundation.org (Postfix) with ESMTP id 76B6CC016F for ; Tue, 7 Jul 2020 06:47:35 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id 65C85893AF for ; Tue, 7 Jul 2020 06:47:35 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id YfvGM5YWprPM for ; Tue, 7 Jul 2020 06:47:34 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by hemlock.osuosl.org (Postfix) with ESMTPS id 39BDD88F41 for ; Tue, 7 Jul 2020 06:47:34 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id AD38268AFE; Tue, 7 Jul 2020 08:47:30 +0200 (CEST) Date: Tue, 7 Jul 2020 08:47:30 +0200 From: Christoph Hellwig To: Jonathan Lemon Subject: Re: [PATCH 1/4] dma-mapping: add a new dma_need_sync API Message-ID: <20200707064730.GA23602@lst.de> References: <20200629130359.2690853-1-hch@lst.de> <20200629130359.2690853-2-hch@lst.de> <20200706194227.vfhv5o4lporxjxmq@bsd-mbp.dhcp.thefacebook.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200706194227.vfhv5o4lporxjxmq@bsd-mbp.dhcp.thefacebook.com> User-Agent: Mutt/1.5.17 (2007-11-01) Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, bpf@vger.kernel.org, =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= , Christoph Hellwig , Magnus Karlsson 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-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Mon, Jul 06, 2020 at 12:42:27PM -0700, Jonathan Lemon wrote: > On Mon, Jun 29, 2020 at 03:03:56PM +0200, Christoph Hellwig wrote: > > Add a new API to check if calls to dma_sync_single_for_{device,cpu} are > > required for a given DMA streaming mapping. > > > > +:: > > + > > + bool > > + dma_need_sync(struct device *dev, dma_addr_t dma_addr); > > + > > +Returns %true if dma_sync_single_for_{device,cpu} calls are required to > > +transfer memory ownership. Returns %false if those calls can be skipped. > > Hi Christoph - > > Thie call above is for a specific dma_addr. For correctness, would I > need to check every addr, or can I assume that for a specific memory > type (pages returned from malloc), that the answer would be identical? You need to check every mapping. E.g. this API pairs with a dma_map_single/page call. For S/G mappings you'd need to call it for each entry, although if you have a use case for that we really should add a dma_sg_need_sync helper instea of open coding the scatterlist walk. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu