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=-6.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED 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 982D6C00449 for ; Wed, 3 Oct 2018 23:10:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4EF5F213A2 for ; Wed, 3 Oct 2018 23:10:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="aAS3H7iR" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4EF5F213A2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727183AbeJDGBW (ORCPT ); Thu, 4 Oct 2018 02:01:22 -0400 Received: from mail-it1-f195.google.com ([209.85.166.195]:36135 "EHLO mail-it1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726198AbeJDGBV (ORCPT ); Thu, 4 Oct 2018 02:01:21 -0400 Received: by mail-it1-f195.google.com with SMTP id c85-v6so11466153itd.1 for ; Wed, 03 Oct 2018 16:10:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=WkneyoPSzQoLcAs/axE/9Wn7NDHDcegu/815uCyWtMQ=; b=aAS3H7iR7tKCn18Bu+R32muRHNGmesECifoN6+HaBzwzWou8RvaJKS5mvdhzMIP50o 3yBpvLrKH1OBDLET7sSFa3XI+zP37X9cskU3e6dfd6anZTptDHDLbQ+HIey2iu/93dvS Ui0s3EsCBaTLwQ/FzIcdINEVUnxqHNCnAo13e1ur0jl9DL1EasnhqEppccKEHMudUSxM JdcefefdmeAvHgKKdygewMnQxkLcTdd8MaK/7g04fW2f4KN4EAyGAvC8MnS3hbUtiC08 p61jtfmN0EeN+oIFyrasdH5vtC8FtRqf0S5Sr4pbsYKIIfeTu1ATQJYrVoc7X1vxG2RV 3cOA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=WkneyoPSzQoLcAs/axE/9Wn7NDHDcegu/815uCyWtMQ=; b=CT7eZXNwQ1CZaKlYXEtnTEgA1gGTBn/UjSKc9DcBYRKOM3D3BqP1SxbI5KgyNk+tpR ghN+7EXnFoPSC9Mx7M3GqptT1Vonupc2LjimkyvCp4Mpg/qxyO51bzjNGHcvqlZIjNNN Cck2UpBjzEL858cXA2IZI7N8BE8fosVp/OGbmyGqMdqTpksxAiWXnOMnXQkbSSS1Ffjk tT748QB1/3+yKX+THiMvWTmKJXdoxYpAt9VlHKLOG0hAUvVsjd7xbp+NKD+GdjZWDq8A eQRguWQGRRIRPH9NsxmkrGIMgpZOhw7OOTkj54VjMMGepqB0cmPj7q8fT5A2LZPXaN/9 18uA== X-Gm-Message-State: ABuFfoiMAqDtGGS90VZYaR0QAsfHa4Kj66TYO7DCLBzx4VH3PTbfX3jB hK3y65nDm0/qhJTxYB/L0LrUDS6Sp67eJ6dQe5o= X-Google-Smtp-Source: ACcGV61yJGqdImxFUQ185ncRCzs26khJfftTvba1wTU1tDyNNhtXksshLE/PMTxBzPFSN0y2EGlBjQoQF4a5iZfz1x0= X-Received: by 2002:a02:3d8e:: with SMTP id n136-v6mr3010705jan.87.1538608253265; Wed, 03 Oct 2018 16:10:53 -0700 (PDT) MIME-Version: 1.0 References: <20180927223539.28449-1-hch@lst.de> <20180927223539.28449-6-hch@lst.de> In-Reply-To: <20180927223539.28449-6-hch@lst.de> From: Alexander Duyck Date: Wed, 3 Oct 2018 16:10:42 -0700 Message-ID: Subject: Re: [PATCH 5/5] dma-direct: always allow dma mask <= physiscal memory size To: Christoph Hellwig , Guenter Roeck Cc: "open list:INTEL IOMMU (VT-d)" , Benjamin Herrenschmidt , Robin Murphy , LKML , Greg KH , "open list:LINUX FOR POWERPC (32-BIT AND 64-BIT)" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 27, 2018 at 3:38 PM Christoph Hellwig wrote: > > This way an architecture with less than 4G of RAM can support dma_mask > smaller than 32-bit without a ZONE_DMA. Apparently that is a common > case on powerpc. > > Signed-off-by: Christoph Hellwig > Reviewed-by: Robin Murphy > --- > kernel/dma/direct.c | 28 ++++++++++++++++------------ > 1 file changed, 16 insertions(+), 12 deletions(-) > > diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c > index 60c433b880e0..170bd322a94a 100644 > --- a/kernel/dma/direct.c > +++ b/kernel/dma/direct.c > @@ -284,21 +284,25 @@ int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents, > return nents; > } > > +/* > + * 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. > + */ > int dma_direct_supported(struct device *dev, u64 mask) > { > -#ifdef CONFIG_ZONE_DMA > - if (mask < phys_to_dma(dev, DMA_BIT_MASK(ARCH_ZONE_DMA_BITS))) > - return 0; > -#else > - /* > - * 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. - Alex