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=-0.9 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS 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 55F7AC65BAE for ; Thu, 13 Dec 2018 19:56:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1C61F20870 for ; Thu, 13 Dec 2018 19:56:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=intel-com.20150623.gappssmtp.com header.i=@intel-com.20150623.gappssmtp.com header.b="l3m2rX27" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1C61F20870 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.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 S1729198AbeLMT4A (ORCPT ); Thu, 13 Dec 2018 14:56:00 -0500 Received: from mail-it1-f195.google.com ([209.85.166.195]:54892 "EHLO mail-it1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727951AbeLMT4A (ORCPT ); Thu, 13 Dec 2018 14:56:00 -0500 Received: by mail-it1-f195.google.com with SMTP id i145so5529747ita.4; Thu, 13 Dec 2018 11:55:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=TsKo232A90Q/y11IqC0AmQfyKdijRKOvwm3OJEXsKlg=; b=l3m2rX27q6sVM+8YWa0xbbDWX6k5XCv7TWdyvaoN7/fnNVmTY070aKfgCNcc0/+fS2 cPGlM4kSq6eOIheixxHuzV+ni80lHnr9r42oF0/AYrmckzdV9caFcED57E3hl6GVfK8f bKedDZg3Xx49m6d0ZyBbu348ffBa3SspIZuvHfxOE5hueAUNP99icNDYHQTSKlie9xZL 1MVGaPT4kxlShQDLWdOic0D/wKESM0uPE3An5B5szOshGNWwRL/DVfzAn/TPquYnThnn 3Drq7ARpAgmaGkFdg1LkuI40cGL83CizPhYFUFkjrYanrGvZ34Ke5IRY0xakeEZazTC4 mdOw== 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=TsKo232A90Q/y11IqC0AmQfyKdijRKOvwm3OJEXsKlg=; b=eUcRz3YT3Z/5g0UKbm3QuiUZ4gaH1ejCuyO81FwGD7PTrCuE4SNQm5ZzhS+YtJ1k6g KJqFF6B04hg7YCCjtlzl/5V7IFzi94Einn4+MjeIvP2auWFbkrxENLel5+8E927ETCwz FithsSz2lyAmFffcdreIjFcuteS18S6sAH7O5hLo62oQ6aIjUCVKi1TmImOapGVHsotw 59ynCmvgctOysqR9H2NOtVHeQAATL1zZVoEzEzxZ0hx4wgNG/fHcYWr7fbSWQx9FjQ2D 2ZQWhwPAsseKPnWNJ+cRJwYaH7mO3ggwrWOBs9mBCRIEE5Es6Hmtc9W//aYLDdLkJ3GA w3xQ== X-Gm-Message-State: AA+aEWYritsoG9hhiB+9/MCBwaJqlhPoSvbIgJctz2GACyJ14sxnhLf/ 4qmGgNNfRTisqTECIjzLiVXNnp9w7YGvkF8O8NE= X-Google-Smtp-Source: AFSGD/Wby55pQNi6tcE/0ISvmvqBhzPOn+PvbcS3I6bSbkklVrOLaCMeJ6kZCqEs3kbE3W4bc/nnHrlQeo5La3iY614= X-Received: by 2002:a24:4648:: with SMTP id j69mr693247itb.56.1544730959317; Thu, 13 Dec 2018 11:55:59 -0800 (PST) MIME-Version: 1.0 References: <20181210171318.16998-1-vgoyal@redhat.com> <20181210171318.16998-16-vgoyal@redhat.com> In-Reply-To: <20181210171318.16998-16-vgoyal@redhat.com> From: Dan Williams Date: Thu, 13 Dec 2018 11:55:47 -0800 Message-ID: Subject: Re: [PATCH 15/52] fuse: map virtio_fs DAX window BAR To: vgoyal@redhat.com Cc: linux-fsdevel , Linux Kernel Mailing List , KVM list , Miklos Szeredi , stefanha@redhat.com, dgilbert@redhat.com, sweil@redhat.com, swhiteho@redhat.com 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 Mon, Dec 10, 2018 at 9:22 AM Vivek Goyal wrote: > > From: Stefan Hajnoczi > > Experimental QEMU code introduces an MMIO BAR for mapping portions of > files in the virtio-fs device. Map this BAR so that FUSE DAX can access > file contents from the host page cache. FUSE DAX sounds terrifying, can you explain a bit more about what this is? > The DAX window is accessed by the fs/dax.c infrastructure and must have > struct pages (at least on x86). Use devm_memremap_pages() to map the > DAX window PCI BAR and allocate struct page. PCI BAR space is not cache coherent, what prevents these pages from being used in paths that would do: object = page_address(pfn_to_page(virtio_fs_pfn)); ...?