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=-3.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 2E2CCC433FF for ; Mon, 5 Aug 2019 08:02:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 080652067D for ; Mon, 5 Aug 2019 08:02:00 +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="lJc/miCU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727763AbfHEIB6 (ORCPT ); Mon, 5 Aug 2019 04:01:58 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:49694 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726423AbfHEIB6 (ORCPT ); Mon, 5 Aug 2019 04:01:58 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Transfer-Encoding: MIME-Version:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=9C8BalNHtgcMpImxrnOhx7BfTEOVdkXTrjPSmrzHY1w=; b=lJc/miCU9VChJUuc3X35x4rbP UsPENE26leGH/y10sD6gJC6gfDd8wOyNBx6q8qCcYJdpzuy0LaNyfk6wo/ebbjq951Qu8+AdbM5sH yawOAdRIGDYeIoynYesWF5SN8ZmUHhW8xgMqta6RlXnV+OsRhmWioixd9/HPog9I1pdVALdfFPPxv 7fYv3+w6gurV55Nd880nPBrPBCtzAT9YulYKUsqb2GMCITJmJ3ppRgUyP8d5QbbSWwgW9p+R2B8y+ T4uvJJ9sbIdRDdnY2yUSsUszxZwcaUNdCBnGnOEgp8qVTR8dEj8c09HeJlLU6ZrYW8mdGX3rFDJB4 GUc+lIiuw==; Received: from [195.167.85.94] (helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1huXwC-0003Lv-6m; Mon, 05 Aug 2019 08:01:49 +0000 From: Christoph Hellwig To: iommu@lists.linux-foundation.org Cc: Shawn Anastasio , Michael Ellerman , Russell King , Catalin Marinas , Will Deacon , Robin Murphy , Paul Burton , James Hogan , linuxppc-dev@lists.ozlabs.org, linux-mips@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: fix default dma_mmap_* pgprot v2 Date: Mon, 5 Aug 2019 11:01:43 +0300 Message-Id: <20190805080145.5694-1-hch@lst.de> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 Hi all, As Shawn pointed out we've had issues with the dma mmap pgprots ever since the dma_common_mmap helper was added beyong the initial architectures - we default to uncached mappings, but for devices that are DMA coherent, or if the DMA_ATTR_NON_CONSISTENT is set (and supported) this can lead to aliasing of cache attributes. This patch fixes that. My explanation of why this hasn't been much of an issue is that the dma_mmap_ helpers aren't used widely and mostly just in architecture specific drivers. Changes since v1: - fix handling of DMA_ATTR_NON_CONSISTENT where it is a no-op (which is most architectures) - remove DMA_ATTR_WRITE_COMBINE on mips, as it seem dangerous as-is