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=-2.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 EB9E7C4361B for ; Mon, 7 Dec 2020 14:49:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BACCA23382 for ; Mon, 7 Dec 2020 14:49:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726778AbgLGOt0 (ORCPT ); Mon, 7 Dec 2020 09:49:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43204 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725822AbgLGOtW (ORCPT ); Mon, 7 Dec 2020 09:49:22 -0500 Received: from mail-ej1-x634.google.com (mail-ej1-x634.google.com [IPv6:2a00:1450:4864:20::634]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9D103C0613D0; Mon, 7 Dec 2020 06:48:41 -0800 (PST) Received: by mail-ej1-x634.google.com with SMTP id f23so19870125ejk.2; Mon, 07 Dec 2020 06:48:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=vvj+sguFIHCuvKw9HAkbiDDdNCIhXEC7IvjtKCPDPx0=; b=BZSpRRfIVSET+efV/b/fBEgdvRZsvtUl8nALoEPcJGcqxLa/Apn59UIRsV5hCVQemL 99P0WEtFrYVG/FWLP+j3PU8PLZ0A+rLUjy7w8jTWMhnB3TBMTTEZvLhBDyCVwll1ePFi 2CQy7NLTHKmomtC5JUX5+Zw0iPRp37rt0cFtdgIKQGRSaS9w/L8ow00DoCGLfFKkpOYm E3ut6ksre/YMS5F+Q7gPpu7QHGozz934R1gaIod0b4H6lgbPfX98QsgkjrcKVCOWarqi 9aJTzEX+RtTSGp+oMkSBKGThWdvHXAWbNt5qBDesfnYMayVBvM2lN4bzHmJIbEZB9DA7 QKQA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=vvj+sguFIHCuvKw9HAkbiDDdNCIhXEC7IvjtKCPDPx0=; b=BQ73q6UQ3dAgwUVw1jI7FaNBAgQJw0bsbmUHu9aO/I02Uy3MV5V/cwz2KRNiypaZJj Bhqe4d2ud0GbQ4/xK6dNUgAG5TMcwE3RxxwLB2ejfpkkmtQVpcuoEa033rwDfJjCkBEo FMm+q+kHWzwobWqqx5yQ/q0xUzZIqTnY9wxBojX31h11poNtmvCLzlUTxrF0LgO3ArPa NJudufNq+6UiPJkZU5nkL3gixRM6nUB7ehiimPJl4se/Ok3pAGi7pHTPXw3ZnOsrD69f qW6uCrEJbulk7/hUI2zucJbRw5C0nU6Uquc6FcFLO3iAmgKCI2QZ14RqVCSrsjUcprxD eEYA== X-Gm-Message-State: AOAM532OHBa4uRMG/UUTHBz2s7hfIeXCGP5s+HGLaYGjusH4NJ1b3Euu +WHqoor8Jixpc0BCaTR66EA= X-Google-Smtp-Source: ABdhPJwBNVQ7yrztLvoTTpW0NYHawkNrb81krpaZzFsMcLKRhBi7EqHEIkHJIZPB4baoYYek6nlVMA== X-Received: by 2002:a17:906:578e:: with SMTP id k14mr13885209ejq.90.1607352520379; Mon, 07 Dec 2020 06:48:40 -0800 (PST) Received: from localhost ([51.15.41.238]) by smtp.gmail.com with ESMTPSA id oq7sm2678535ejb.63.2020.12.07.06.48.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 07 Dec 2020 06:48:39 -0800 (PST) Date: Mon, 7 Dec 2020 14:48:38 +0000 From: Stefan Hajnoczi To: David Hildenbrand Cc: Peter Xu , Stefan Hajnoczi , Justin He , Alex Williamson , Cornelia Huck , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] vfio iommu type1: Bypass the vma permission check in vfio_pin_pages_remote() Message-ID: <20201207144838.GG203660@stefanha-x1.localdomain> References: <20201119142737.17574-1-justin.he@arm.com> <20201124181228.GA276043@xz-x1> <20201125155711.GA6489@xz-x1> <20201202143356.GK655829@stefanha-x1.localdomain> <20201202154511.GI3277@xz-x1> <20201203112002.GE689053@stefanha-x1.localdomain> <20201203154322.GH108496@xz-x1> <6a33e908-17ff-7a26-7341-4bcf7bbefe28@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="yZnyZsPjQYjG7xG7" Content-Disposition: inline In-Reply-To: <6a33e908-17ff-7a26-7341-4bcf7bbefe28@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --yZnyZsPjQYjG7xG7 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Thu, Dec 03, 2020 at 05:01:32PM +0100, David Hildenbrand wrote: > The real question is: do we even *need* DMA from vfio devices to > virtio-fs regions? If not (do guests rely on it? what does the spec > state?), just don't care about vfio at all and don't map anything. Can DMA to/from the virtio-fs DAX Window happen? Yes, the guest could do it although it's rare. Is it a great idea to combine VFIO and virtio-fs DAX? Maybe not. It involves pinning host page cache pages O_o. Stefan --yZnyZsPjQYjG7xG7 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAl/OQMUACgkQnKSrs4Gr c8jT2Af+JXkEPTuSerosjvKJgxGcKudB8C6f/Okm8J3Ylryh+5QznpspkUcnzDUe DokGkgjxcA6sqSsEMGqwSGLS3Ozshm9sUGRK4GAZsblxWDS9a5Es5A9SQvh117ip PED58xmoIHuFhoMIkzo/BrBvVzRFX/x4q7VEredEv23pAvlNWIRQm60DsgULcqiU 1EEbA+Hl8w0s4PYEYOw7suFUI3+lDB/0oOd9+YXl9UyV7guC7jaGJg+gQX7mVBi2 fnTlX/JeigsKT/DcwMFmlMtvw0emRYtfIOtubsT/k2eYM+5Az9OTzWqNF+33sJhe fGup4va8T0HHYPiOwaKu+QrFfwDgHw== =gJnL -----END PGP SIGNATURE----- --yZnyZsPjQYjG7xG7--