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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 A5690C433ED for ; Thu, 13 May 2021 06:07:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 82172613E6 for ; Thu, 13 May 2021 06:07:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231329AbhEMGIm (ORCPT ); Thu, 13 May 2021 02:08:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44308 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230230AbhEMGIY (ORCPT ); Thu, 13 May 2021 02:08:24 -0400 Received: from ozlabs.org (bilbo.ozlabs.org [IPv6:2401:3900:2:1::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 115D2C061574; Wed, 12 May 2021 23:07:15 -0700 (PDT) Received: by ozlabs.org (Postfix, from userid 1007) id 4Fgh5D6YwQz9sWl; Thu, 13 May 2021 16:07:12 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gibson.dropbear.id.au; s=201602; t=1620886032; bh=EDbwQxFNCJJrrEgHzT5gGi+1oWXpdmyJr1eJ+NUQ4bM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=kWqsHMbOiAyxwLod+Rqt4KhSwB2oo0bV5TchI5WxvF3IL2lqztrJrQv615kgKUDnS rvOjRZCfVWenSYZrOWPrRga+vGFG2OWEIfQgUnlH6IFYpycIGoxJyhVRhtXU4RZ9Gc 02pKAkrH9LTvDiy9LdpyASoaGfwW0N2RNDDTSEfE= Date: Thu, 13 May 2021 16:07:07 +1000 From: David Gibson To: Jason Gunthorpe Cc: Alexey Kardashevskiy , Alex Williamson , "Liu, Yi L" , Jacob Pan , Auger Eric , Jean-Philippe Brucker , "Tian, Kevin" , LKML , Joerg Roedel , Lu Baolu , David Woodhouse , "iommu@lists.linux-foundation.org" , "cgroups@vger.kernel.org" , Tejun Heo , Li Zefan , Johannes Weiner , Jean-Philippe Brucker , Jonathan Corbet , "Raj, Ashok" , "Wu, Hao" , "Jiang, Dave" Subject: Re: [PATCH V4 05/18] iommu/ioasid: Redefine IOASID set and allocation APIs Message-ID: References: <20210427172432.GE1370958@nvidia.com> <20210429002149.GZ1370958@nvidia.com> <20210503160530.GL1370958@nvidia.com> <20210504181537.GC1370958@nvidia.com> <7e5c2276-ca1c-a8af-c15f-72a7c83c8bfa@ozlabs.ru> <20210505163902.GG1370958@nvidia.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="/Mf++rjztzZShRAS" Content-Disposition: inline In-Reply-To: <20210505163902.GG1370958@nvidia.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --/Mf++rjztzZShRAS Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, May 05, 2021 at 01:39:02PM -0300, Jason Gunthorpe wrote: > On Wed, May 05, 2021 at 02:28:53PM +1000, Alexey Kardashevskiy wrote: >=20 > > This is a good feature in general when let's say there is a linux suppo= rted > > device which has a proprietary device firmware update tool which only e= xists > > as an x86 binary and your hardware is not x86 - running qemu + vfio in = full > > emulation would provide a way to run the tool to update a physical devi= ce. >=20 > That specific use case doesn't really need a vIOMMU though, does it? Possibly not, but the mechanics needed to do vIOMMU on different host IOMMU aren't really different from what you need for a no-vIOMMU guest. With a vIOMMU you need to map guest IOVA space into the host IOVA space. With no no-vIOMMU you need to map guest physical addresses into the host IOVA space. In either case the GPA/gIOVA to userspace and userspace to HPA mappings are basically arbitrary. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. 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