From:   "Tian, Kevin" <kevin.tian@intel.com>
To:     Thomas Gleixner <tglx@linutronix.de>,
        Jason Gunthorpe <jgg@nvidia.com>
CC:     "Jiang, Dave" <dave.jiang@intel.com>,
        Logan Gunthorpe <logang@deltatee.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Bjorn Helgaas <helgaas@kernel.org>,
        Marc Zygnier <maz@kernel.org>,
        Alex Williamson <alex.williamson@redhat.com>,
        "Dey, Megha" <megha.dey@intel.com>,
        "Raj, Ashok" <ashok.raj@intel.com>,
        "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jon Mason <jdmason@kudzu.us>, Allen Hubbe <allenbh@gmail.com>,
        "linux-ntb@googlegroups.com" <linux-ntb@googlegroups.com>,
        "linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
        Heiko Carstens <hca@linux.ibm.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        "x86@kernel.org" <x86@kernel.org>, Joerg Roedel <jroedel@suse.de>,
        "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>
Subject: RE: [patch 21/32] NTB/msi: Convert to msi_on_each_desc()
Thread-Topic: [patch 21/32] NTB/msi: Convert to msi_on_each_desc()
Thread-Index: AQHX4y1VNaiO68omHEet2J9DWrVARKwa1YEAgAAp0QCAABreAIAAIi2AgAE8MoCAAAd1gIAACyoAgAAPcQCAADDDAIAAp1uAgABn9QCAACTxgIAAAdGAgAAbd4CAAA94gIAABpSAgAt9SoCAADlJAIAAgb+AgABGMACAAAc8gIAAE+oAgAAmHACAAFJ4oIAAem8AgABqWwCAANPscA==
Date:   Sat, 11 Dec 2021 07:44:08 +0000
Message-ID: <BN9PR11MB527625E8A9BB854F3C0D19AE8C729@BN9PR11MB5276.namprd11.prod.outlook.com>
References: <f4cc305b-a329-6d27-9fca-b74ebc9fa0c1@intel.com>
 <878rx480fk.ffs@tglx>
 <BN9PR11MB52765F2EF8420C60FD5945D18C709@BN9PR11MB5276.namprd11.prod.outlook.com>
 <87sfv2yy19.ffs@tglx> <20211209162129.GS6385@nvidia.com>
 <878rwtzfh1.ffs@tglx> <20211209205835.GZ6385@nvidia.com>
 <8735n1zaz3.ffs@tglx> <87sfv1xq3b.ffs@tglx>
 <BN9PR11MB527619B099061B3814EB40408C719@BN9PR11MB5276.namprd11.prod.outlook.com>
 <20211210123938.GF6385@nvidia.com> <87fsr0xp31.ffs@tglx>
In-Reply-To: <87fsr0xp31.ffs@tglx>
Accept-Language: en-US
Content-Language: en-US
x-ms-exchange-antispam-messagedata-chunkcount: 1
x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?PslPlkTQDjU02BGCe/Eq0aMCXKc0S9/DhHx72OkBFzdkkGmaplHUUmlRfJVe?=
 =?us-ascii?Q?A4rk6YfsR6WD+O/rLAAlU7ksHOpLzGSxmvVp7vQgJeWTPyBbwm9Zr2GcjzKe?=
 =?us-ascii?Q?fMhIncYpeyxHca6K35UzX3SFQfgJpXdVeCxw+2ZvPHjXe/1lkhSheP/8qmae?=
 =?us-ascii?Q?jHPkW6+qAQjWO09BsyKMar2yglqvqb4L19cBpztszFOQ526prlFoJ0ejkChB?=
 =?us-ascii?Q?sJeAJ/UT4akLJjU4DRI5Q9BoXgiAXqYf6u/3brrZrQ2KApliAh3SMIEpxm6F?=
 =?us-ascii?Q?76mc5gedVaygayqIVkzMgBoZ25qPMalVn+xnREfD34ipny9TsmHmcb0pK4Kx?=
 =?us-ascii?Q?WIdU7oE1IaS0G3NPQ482fIw7g/NF9KBe6nNzWRe3Bh+JNanhQG+ktmjuXRFr?=
 =?us-ascii?Q?OLzdXBCyWMF7HSS7KhM/YOo3DjpGbyLIRgcPjtj4ceXzfS06tJWp8fOvsgyJ?=
 =?us-ascii?Q?AJbpj2ZwBnfMF3x96jEVddYhGZLAYPQF9v03JcA4XpS6QexdaC2aRJ+SGa0D?=
 =?us-ascii?Q?9Bugk2qH7PCIcF6PjxUfieBIx8eJudLvk54FDiCcs7j+tgxMmsrKu1X6JnlS?=
 =?us-ascii?Q?7alXwRXAC2DrzRdsniCVBiCG5toKNeABFEgTtOs44IL5jShflP2K0XacmLr7?=
 =?us-ascii?Q?OxSXrV/yf1KOLbSlYqWaWUP00MB02YR9dZvzao4z7OIeXuDZnzfWIIAsNQGE?=
 =?us-ascii?Q?IYFK4l67387UlwBDB9yExsNnPSvSJSoiVgh++4kMFaPtYIDbnQbJIS8PpBo7?=
 =?us-ascii?Q?aiJiwBTQM68qQJGIxOheswVtRpjV0QD0UIeENisevP5O8MyJT9UH5il4BI6x?=
 =?us-ascii?Q?cnygsNRNqjD7FA0T4gXxMaYyUnN/Hsoxpqm0CWHCFlO8oirHvnOimSg9DD2E?=
 =?us-ascii?Q?Hid18qsKolU6EPBvBIQhQ/RO9kqzzmg6UNnjJHEcPuRclSj4VLeg9uLnOcu0?=
 =?us-ascii?Q?sUT0VuwG3BrxQglmIRwieVmUeudDTY6SpzfyhlDtuh1pPFV/alnVVTMcjN1j?=
 =?us-ascii?Q?Y/iaxzwVgOtPiWFSNDThdohhDsiIX8ZJlX6bXSlnKA7nDJtIRXs34vN5TNIX?=
 =?us-ascii?Q?1hn99n5cuTGzXTcu25CNeOjqii9gtrDFQrm96W910dhJfxYyHPs3xwAFeNrX?=
 =?us-ascii?Q?z5lLvz1w7ymSS2R2XqsAISC+htX0ivvMewQIzZrtLeYDXbpgmEc4DUV0/3my?=
 =?us-ascii?Q?bWbvVIxqSMXWnDEf0MBFcb7yPJW+UhGbcPGQHHfqXk0ULAz+VNlxKy9ZsuO4?=
 =?us-ascii?Q?N73V9Tq9JpI0aR3Vk6FkSlNP8GXvMW8Cv16lobov/sQuPrRpFs4HtB4qZdET?=
 =?us-ascii?Q?rce+lLIxVeijOELbSQP1SCQ1lmskl+OTX/hWWHqMzKhOMKOdarb2iTF7g0Z6?=
 =?us-ascii?Q?guD/6763Bc1A63I0pB09BovTshqUL6utkqV3dX3HqNaP1ESr++vTVDbh/j8o?=
 =?us-ascii?Q?p97x9V9nMDYAnT3FS0e0QBX9PH2LJedfcH6VSA7YUrdlLgs3DQ0XoBQlgSOI?=
 =?us-ascii?Q?cgaeWlgx/yZA81zJeCeGD98dbWp3Nahd3th0KP3foDac2tDT1j4xFhOIVU1j?=
 =?us-ascii?Q?hG/nJSwV1kquV4T3Y779s3ci0b20FidPfkW6IEXoW8sd9WjljYLwcbCBZkT3?=
 =?us-ascii?Q?Jw=3D=3D?=
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: BN9PR11MB5276.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 7d342c0f-91c8-497d-eb9d-08d9bc7a03d3
X-MS-Exchange-CrossTenant-originalarrivaltime: 11 Dec 2021 07:44:08.4284
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 46c98d88-e344-4ed4-8496-4ed7712e255d
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: OBVRhi4LfD/tQW8kiAxsEiyO4iK8narL/YKH0zkxNSVxodHoN+vbToDR0NxUqsP0hdeYfnB5mQxljrkPeAM22A==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN9PR11MB5355
X-OriginatorOrg: intel.com
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

> From: Thomas Gleixner <tglx@linutronix.de>
> Sent: Saturday, December 11, 2021 3:00 AM
>=20
> Jason,
>=20
> On Fri, Dec 10 2021 at 08:39, Jason Gunthorpe wrote:
>=20
> > On Fri, Dec 10, 2021 at 07:29:01AM +0000, Tian, Kevin wrote:
> >> >   5) It's not possible for the kernel to reliably detect whether it =
is
> >> >      running on bare metal or not. Yes we talked about heuristics, b=
ut
> >> >      that's something I really want to avoid.
> >>
> >> How would the hypercall mechanism avoid such heuristics?
> >
> > It is clever, we don't have an vIOMMU that supplies vIR today, so by
> > definition all guests are excluded and only bare metal works.
>=20
> Dammit. Now you spilled the beans. :)
>=20

Unfortunately we do have that today. Qemu supports IR for
both AMD and Intel vIOMMU.

Thanks
Kevin