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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 0BC6BC43387 for ; Thu, 20 Dec 2018 15:36:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C83B5218C3 for ; Thu, 20 Dec 2018 15:36:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="OBgO6UYP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731537AbeLTPgs (ORCPT ); Thu, 20 Dec 2018 10:36:48 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:42970 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731191AbeLTPgs (ORCPT ); Thu, 20 Dec 2018 10:36:48 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Transfer-Encoding :Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=aL191S3jRkuZn8xjEd4p6auxHNg7qsuIaEjoOzuvztQ=; b=OBgO6UYPjHPKU1wkC8UBZ5NRoU 1kp92d3/H7z1P9vbNE+JMe7whAWbD07o926aGPklwb+grm7zV5WtKYBmVjVzxGoKf+CU06tUSymyz f8qqC+ooRaj3OEw4Lr9AgmB8jVvUBEDK3/RH4Jg7gFnItx81nRRazxl47CQk7eNN9WnztDUTILIV6 BV26XjULGAMBMwQDFCu9MVS13dWTpWV6Wff0hdxdPxpETjyYiqO6lOq0nPNQYqBuS1OMRgRNC57vb gK5mIOc8nj/H8lskDZGtD/H39X7JbJiI3kcXBaGzX1hNxVpZVJBDITnwIFvkVMDrtz5ktSUqhmhDh rXxTQPIQ==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1ga0NS-0008Ce-4Y; Thu, 20 Dec 2018 15:36:46 +0000 Date: Thu, 20 Dec 2018 07:36:46 -0800 From: Christoph Hellwig To: Noralf =?iso-8859-1?Q?Tr=F8nnes?= Cc: Oleksandr Andrushchenko , xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, daniel.vetter@intel.com, jgross@suse.com, boris.ostrovsky@oracle.com, Oleksandr Andrushchenko Subject: Re: [PATCH] drm/xen-front: Make shmem backed display buffer coherent Message-ID: <20181220153646.GA22997@infradead.org> References: <20181127103252.20994-1-andr2000@gmail.com> <17640791-5306-f7e4-8588-dd39c14e975b@tronnes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <17640791-5306-f7e4-8588-dd39c14e975b@tronnes.org> User-Agent: Mutt/1.9.2 (2017-12-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 18, 2018 at 08:20:22PM +0100, Noralf Trønnes wrote: > > + if (!dma_map_sg(dev->dev, xen_obj->sgt->sgl, xen_obj->sgt->nents, > > + DMA_BIDIRECTIONAL)) { > > > Are you using the DMA streaming API as a way to flush the caches? This looks rather broken. Please send the whole patch series to the iommu list for proper review. > Does this mean that GFP_USER isn't making the buffer coherent? How could GFP_USER make memory coherent in any way?