Received-SPF: softfail (google.com: domain of transitioning linux-kernel-owner@vger.kernel.org does not designate 23.128.96.19 as permitted sender) client-ip=23.128.96.19;
Date:   Mon, 14 Mar 2022 18:49:28 -0300
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     Matthew Rosato <mjrosato@linux.ibm.com>
Cc:     linux-s390@vger.kernel.org, alex.williamson@redhat.com,
        cohuck@redhat.com, schnelle@linux.ibm.com, farman@linux.ibm.com,
        pmorel@linux.ibm.com, borntraeger@linux.ibm.com, hca@linux.ibm.com,
        gor@linux.ibm.com, gerald.schaefer@linux.ibm.com,
        agordeev@linux.ibm.com, svens@linux.ibm.com, frankja@linux.ibm.com,
        david@redhat.com, imbrenda@linux.ibm.com, vneethv@linux.ibm.com,
        oberpar@linux.ibm.com, freude@linux.ibm.com, thuth@redhat.com,
        pasic@linux.ibm.com, joro@8bytes.org, will@kernel.org,
        pbonzini@redhat.com, corbet@lwn.net, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
        linux-doc@vger.kernel.org
Subject: Re: [PATCH v4 29/32] vfio-pci/zdev: add DTSM to clp group capability
Message-ID: <20220314214928.GK11336@nvidia.com>
References: <20220314194451.58266-1-mjrosato@linux.ibm.com>
 <20220314194451.58266-30-mjrosato@linux.ibm.com>
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20220314194451.58266-30-mjrosato@linux.ibm.com>
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?JXLz8C8CDg2ibpjBeDUZAhe/RBRYjYSAYb9Yo7/F9FhA0/q6+6pbCX27QeZJ?=
 =?us-ascii?Q?sjXhbP3CrWGPBXx/JAcwQtwI27/K3J3NWUgQKMjqevp/NHN0RDwJTNi+XcY9?=
 =?us-ascii?Q?u6ko/wiYbNYmbfsRHF+RNpZdTYdb3w+szInjfNn1Rj6hv9XUX3LFmeIGqHtA?=
 =?us-ascii?Q?OmucCDHuLCxDLM+PS2naEpGeuiyNMa7PM7NP4JRsVlT1rlnYkJko2KcRHpFR?=
 =?us-ascii?Q?swexLSUMKJZ4aq4DkaO9LPTliFfLcNnoZO+3BoVesW4lcWnRB9mco7gGKqDj?=
 =?us-ascii?Q?BRmPlme1WmbBa8z9hl5F1NWM+6thUeC6m67sMVqUMuKOiV1FSaAHxnvSdMyn?=
 =?us-ascii?Q?WWJ465569o9W1L/C5oG8PpIPL4wM6wo2AFARon3vTk3jlg35D5D2xFJigGRy?=
 =?us-ascii?Q?eCGHGJBNWqEjBB4scsB/2AncdcdLpPiY1FCKKPj6Uh+ASDTj/LjS8R4ur2Ww?=
 =?us-ascii?Q?zoEG2QVCML4iceUwyminPFjIxydOGzAT2+v5kKzgPZZ96hbx/sZU4/kmbSXZ?=
 =?us-ascii?Q?dmBp2jDyh9ApSYguJBpjKQUoE9IwmGxFaH7JC0HUw99dU/Nl9EhsPZbCLCHI?=
 =?us-ascii?Q?cl/e8jgDNONAoqwmwD0c/IMD1jDxArJv2OhrpUg7zQrkabf+/sZkdaaROCyx?=
 =?us-ascii?Q?0VKwcyBIh84rdvUL9EV/vSfhXNBoY1SVdUmKcpdDtTrXDmm8i+6jxMWQ3Np1?=
 =?us-ascii?Q?UP5acGbBoVIr+9D6LsooNJYP/r1edc0gpZba4AEd0LTF3W2c1hpstr6uRODP?=
 =?us-ascii?Q?rA0GQEjQALAqjz2ot5OwZSPYp4x4NbhhXjRJCcRiN1A+mXO3htdzX8zl8YK8?=
 =?us-ascii?Q?O1W2c5VcUYKphjJoahuHCu54y7cAIwgDFOuE9oRthAjjbLfhVgIwIfhUFvTX?=
 =?us-ascii?Q?FvbFPC2Y3ma/MaHJui2Gf84ifLKakQs+ZBz6vrE4+G7yw2FCvns3JMUYTh59?=
 =?us-ascii?Q?mqj3PWIuw6Gj69YTX/O/5k72nBRNp4ArEqDLL9vzqmY1B6nx+BoadtHGwS3y?=
 =?us-ascii?Q?M8wuqm0fidPRl6cxv89W6YPczUe9/3KhQHP3CuZy5xj5KJ2EVpkSX6FmsYTe?=
 =?us-ascii?Q?yH/oKoGI46tUSGCh2lccIJl9liG9eFXUmhHfhUSiIVSGzWs069DIkwfN2QPm?=
 =?us-ascii?Q?Qms3VIwI/2lYjRHC/s0plU7O8MWuBky1PdSzin0pfOSUH1vWdn15PVzIxM5B?=
 =?us-ascii?Q?X5k5aQykIq4LVVtqiZpi5vpSA8LqfFS1gUJ77DGqdM1uQPqLL547fyaYrdSR?=
 =?us-ascii?Q?lnUy6Dgk2zQMEZXoYu07+k0p99xnB2gW+HJDYtQLnxX7QrGIW00qztAp+2hd?=
 =?us-ascii?Q?RJh8hxucWjmyB1WwswCqPnLUMaoENcBxAiQ+aAH7BMOeSdkmJh9MqAmVj78r?=
 =?us-ascii?Q?FaOF7jeSpIbw8VhnUhZwuOhFhJYOjgrlg4tHpzEINCjK60NvzLqYkifNk2UC?=
 =?us-ascii?Q?eR9qu0fVYTBn/RU3Gvnael4XWQgn+2JA?=
X-OriginatorOrg: Nvidia.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 7900b9f4-e3e0-461d-a170-08da06048412
X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB4192.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Mar 2022 21:49:29.3201
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: jLx/2rceEV40bH+wEiqgKMMldtrdLV1Z4ZGoEzWYxb/NSNFW6lJL0gcuAyr+dIpo
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY4PR12MB1174
X-Spam-Status: No, score=-3.5 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,
	DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,
	MAILING_LIST_MULTI,RDNS_NONE,SPF_HELO_NONE,T_SCC_BODY_TEXT_LINE
	autolearn=unavailable autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
	lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Mon, Mar 14, 2022 at 03:44:48PM -0400, Matthew Rosato wrote:
> The DTSM, or designation type supported mask, indicates what IOAT formats
> are available to the guest.  For an interpreted device, userspace will not
> know what format(s) the IOAT assist supports, so pass it via the
> capability chain.  Since the value belongs to the Query PCI Function Group
> clp, let's extend the existing capability with a new version.

Why is this on the VFIO device?

Maybe I don't quite understand it right, but the IOAT is the
'userspace page table'?

That is something that should be modeled as a nested iommu domain.

Querying the formats and any control logic for this should be on the
iommu side not built into VFIO.

Jason