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, HEADER_FROM_DIFFERENT_DOMAINS,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 590B8C282C2 for ; Thu, 7 Feb 2019 20:47:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 239BA2081B for ; Thu, 7 Feb 2019 20:47:35 +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="a3w+mGLw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727487AbfBGUrd (ORCPT ); Thu, 7 Feb 2019 15:47:33 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:37226 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726691AbfBGUrd (ORCPT ); Thu, 7 Feb 2019 15:47:33 -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-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding: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=bEHNsOwIgj2itCnyGzcvVjHB+SGmRzUaNDbsBFafgJY=; b=a3w+mGLwkOd/LnmT1Kr17k8Ac iiSGnFoBQOvfQLItyqgAN5qfcm7xBZ1vMohHj+l/Mb86wTUG5ei8jRwOKQQr19RHICdtX+XBgnSPm ngWzQav+9byDRbJdC2L4Qt9dIA8BaiScsgkiNmCNFItcDrxdFfUL52noO6o/1wn/uMzK7HUaLlWpu +xc6VTs+Hb9K7rp9XlNqEH0fSbhdA65dTkFojxq87skezQMas/XHUvr3wXBm0xyO0mMNUqsB7deR1 hv7BMXw4MXdmqNRRb0lxu2L+R8nxalxpbbSjt9wzmoLAHETncwDBKhlTMSEA3l9iJ3vDvY4yGYgoV XgrmgX6dA==; Received: from dvhart by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1grqa3-00060N-Hd; Thu, 07 Feb 2019 20:47:31 +0000 Date: Thu, 7 Feb 2019 12:47:30 -0800 From: Darren Hart To: Christoph Hellwig Cc: stuart.w.hayes@gmail.com, andy@infradead.org, platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org, Mario_Limonciello@dell.com Subject: Re: [PATCH] dell_rbu: stop abusing the DMA API Message-ID: <20190207204730.GA21530@wrath> References: <20190129073409.7247-1-hch@lst.de> <20190201231559.GC105752@fedora.eng.vmware.com> <20190202171659.GA3324@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190202171659.GA3324@lst.de> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Feb 02, 2019 at 06:16:59PM +0100, Christoph Hellwig wrote: > On Fri, Feb 01, 2019 at 03:15:59PM -0800, Darren Hart wrote: > > On Tue, Jan 29, 2019 at 08:34:09AM +0100, Christoph Hellwig wrote: > > > For some odd reason dell_rbu actually seems to want the physical and > > > not a bus address for the allocated buffer. Lets assume that actually > > > is correct given that it is BIOS-related and that is a good source > > > of insanity. In that case we should not use dma_alloc_coherent with > > > a NULL device to allocate memory, but use GFP_DMA32 to stay under > > > the 32-bit BIOS limit. > > > > + Mario re bios related physical address - is Christoph's assumption > > correct? > > > > Christoph, did you observe a failure? If so, we should probably also > > tag for stable. > > No, I've been auditing for DMA API (ab-)users that don't pass a > struct device. Generally the fix was to just pass a struct device > that is easily available. But dell_rbu doesn't actually seem to > be a "device" in the traditional sense, and the way it uses the > DMA API is really, really odd - it first does a virt_to_phys on > memory allocated from the page allocator (so works with physical > addresses in that case) and the retries with a dma_alloc_coherent > with a NULL argument, which in no way is guaranteed to you give > you something else, although for the current x86 implementation > will give you the equivalent of a GFP_DMA32 page allocator allocation > plus virt_to_phys. > Thanks Christoph, merged to for-next. -- Darren Hart VMware Open Source Technology Center