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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable 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 78347C64EAD for ; Tue, 9 Oct 2018 05:09:25 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (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 C85AF213A2 for ; Tue, 9 Oct 2018 05:09:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C85AF213A2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 42Tldb0JFTzF3Bm for ; Tue, 9 Oct 2018 16:09:23 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: lists.ozlabs.org; spf=permerror (mailfrom) smtp.mailfrom=kernel.crashing.org (client-ip=63.228.1.57; helo=gate.crashing.org; envelope-from=benh@kernel.crashing.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 42TlSk4FVfzF3Nf for ; Tue, 9 Oct 2018 16:01:42 +1100 (AEDT) Received: from localhost (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id w9951JY7002817; Tue, 9 Oct 2018 00:01:21 -0500 Message-ID: <8402ecc9c8ed9c69ad3e91eca4d07a5ab077b22d.camel@kernel.crashing.org> Subject: Re: [PATCH 5/5] dma-direct: always allow dma mask <= physiscal memory size From: Benjamin Herrenschmidt To: Alexander Duyck , Christoph Hellwig , Guenter Roeck Date: Tue, 09 Oct 2018 16:01:18 +1100 In-Reply-To: References: <20180927223539.28449-1-hch@lst.de> <20180927223539.28449-6-hch@lst.de> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 (3.28.5-1.fc28) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Greg KH , "open list:INTEL IOMMU \(VT-d\)" , "open list:LINUX FOR POWERPC \(32-BIT AND 64-BIT\)" , Robin Murphy , LKML Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Wed, 2018-10-03 at 16:10 -0700, Alexander Duyck wrote: > > - * Because 32-bit DMA masks are so common we expect every architecture > > - * to be able to satisfy them - either by not supporting more physical > > - * memory, or by providing a ZONE_DMA32. If neither is the case, the > > - * architecture needs to use an IOMMU instead of the direct mapping. > > - */ > > - if (mask < phys_to_dma(dev, DMA_BIT_MASK(32))) > > + u64 min_mask; > > + > > + if (IS_ENABLED(CONFIG_ZONE_DMA)) > > + min_mask = DMA_BIT_MASK(ARCH_ZONE_DMA_BITS); > > + else > > + min_mask = DMA_BIT_MASK(32); > > + > > + min_mask = min_t(u64, min_mask, (max_pfn - 1) << PAGE_SHIFT); > > + > > + if (mask >= phys_to_dma(dev, min_mask)) > > return 0; > > -#endif > > return 1; > > } > > So I believe I have run into the same issue that Guenter reported. On > an x86_64 system w/ Intel IOMMU. I wasn't able to complete boot and > all probe attempts for various devices were failing with -EIO errors. > > I believe the last mask check should be "if (mask < phys_to_dma(dev, > min_mask))" not a ">=" check. Right, that test is backwards. I needed to change it here too (powermac with the rest of the powerpc series). Cheers, Ben.