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 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 A0C5CC04FF3 for ; Mon, 24 May 2021 07:56:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8799B610CB for ; Mon, 24 May 2021 07:56:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232421AbhEXH5r (ORCPT ); Mon, 24 May 2021 03:57:47 -0400 Received: from ozlabs.org ([203.11.71.1]:59229 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232254AbhEXH5k (ORCPT ); Mon, 24 May 2021 03:57:40 -0400 Received: by ozlabs.org (Postfix, from userid 1007) id 4FpTzt3P3Mz9sPf; Mon, 24 May 2021 17:56:10 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gibson.dropbear.id.au; s=201602; t=1621842970; bh=C/hH2K1GEBPadXoSrKk7V2ObPasOjkp3z+Am5C3tgTM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=SlkI23zR6q71HmYnJJ3f9KWdOEkVnA6VgflwcXorCZ+xSlbOn80eH8qqkj1bGiDwr KC9B7UJXnzhSsKRs2ic63ipbacchSoGdi4E458+5M7iaEJIuB0k7HuIOJAPxbDK6pB dK2O+tSql9Eour4tx4hSxxkcAjj0iCOHwEc2IDJA= Date: Mon, 24 May 2021 17:56:05 +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: <20210429002149.GZ1370958@nvidia.com> <20210503160530.GL1370958@nvidia.com> <20210504181537.GC1370958@nvidia.com> <7e5c2276-ca1c-a8af-c15f-72a7c83c8bfa@ozlabs.ru> <20210505163902.GG1370958@nvidia.com> <20210513135030.GF1002214@nvidia.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="qdaYK/TYh/pdg5Us" Content-Disposition: inline In-Reply-To: <20210513135030.GF1002214@nvidia.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --qdaYK/TYh/pdg5Us Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, May 13, 2021 at 10:50:30AM -0300, Jason Gunthorpe wrote: > On Thu, May 13, 2021 at 04:07:07PM +1000, David Gibson wrote: > > 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 s= upported > > > > device which has a proprietary device firmware update tool which on= ly exists > > > > 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 = device. > > >=20 > > > That specific use case doesn't really need a vIOMMU though, does it? > >=20 > > 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. =20 >=20 > For very simple vIOMMUs this might be true, but this new features of nest= ing > PASID, migration, etc, etc all make the vIOMMU complicated and > emuluating it completely alot harder. Well, sure, emulating a complex vIOMMU is complex. But "very simple vIOMMUs" covers the vast majority of currently deployed hardware, and several are already emulated by qemu. > Stuffing a vfio-pci into a guest and creating a physical map using a > single IOASID is comparably trivial. Note that for PAPR (POWER guest) systems this is not an option: the PAPR platform *always* has a vIOMMU. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --qdaYK/TYh/pdg5Us Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEdfRlhq5hpmzETofcbDjKyiDZs5IFAmCrXBUACgkQbDjKyiDZ s5IBMw/6AomCVLmh/8hoxD3OLa7DsF2qksrpcbo5JXuotCrUKLd+NER23oRbTekN 8HQ/YKfUWhmFlGh9NeBcjjUjkm/ru1HFa3vbGfQIrVWxabmQX9vQSjKDc/qvQlKB ApOyT0PNJuHFy8rZNB7vrpd9zP9xhV1gKLk5nxmmPHeITxA2ZLrZSlfMkRhIG5vP 3xpnCB8KoycgXBsYbLCi50o11TxhVlYWoujMA/I69mLgfqFoxTy3+zz99RtEEnY9 Nqf3jnnpL+5tCu8gBZD2actRlu0jrnXU6nyYleOy89Sr2ZjrOM73cfrkrJjhuTa6 hdQVhb8XgS1HQPiELvT2WCVVQkfAG1ss0HcPi2Wt+JvVnxeQ4kNixS8ZNwh/X9/Q lMVqY0OsG8Gz38XftHA3oj20IyAKeVYfXkQJLougTadA3/ydrOELNB169PPHtggT qtgvOFogrmYKJyaGQaQvWIWmHd63OYqVxycbu2fimxeuM4kMxgU5ERWo6caXHLz+ bZfdkrRUW1vCGoMfjqpjG4OgDhnLwz4PUfy7tKdh6Ek4TGe0OUHYxcMcJI28AIii jnapbsmXzLYgsyHou+UYRwtLPrIOjOpRh3eDRzfRDtI1HQBWG1RBKkJdqUf1r5FW r45iEZaQ+AdySJsDkfCc7+SDhLx4AO8z6RuoKgukxPR6E5D8Z9c= =GQEt -----END PGP SIGNATURE----- --qdaYK/TYh/pdg5Us--