From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Gibson Subject: Re: [PATCH V4 05/18] iommu/ioasid: Redefine IOASID set and allocation APIs Date: Mon, 24 May 2021 17:56:05 +1000 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" Return-path: 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= Content-Disposition: inline In-Reply-To: <20210513135030.GF1002214-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> List-ID: 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-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org" , "cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Tejun Heo , Li Zefan , Johannes Weiner , Jean-Philippe Brucker , Jonathan Corbet , "Raj, Ashok" --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--