Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:1 as permitted sender) client-ip=2620:137:e000::3:1;
Date:   Mon, 23 Oct 2023 10:23:05 -0300
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     Joao Martins <joao.m.martins@oracle.com>,
        Arnd Bergmann <arnd@kernel.org>,
        Kevin Tian <kevin.tian@intel.com>,
        Yishai Hadas <yishaih@nvidia.com>,
        Shameerali Kolothum Thodi 
        <shameerali.kolothum.thodi@huawei.com>,
        Alex Williamson <alex.williamson@redhat.com>,
        Brett Creeley <brett.creeley@amd.com>,
        oushixiong <oushixiong@kylinos.cn>, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] vfio: mlx5, pds: add IOMMU_SUPPORT dependency
Message-ID: <20231023132305.GT3952@nvidia.com>
References: <20231023115520.3530120-1-arnd@kernel.org>
 <20231023120418.GH691768@ziepe.ca>
 <a16758d6-964d-4e46-9074-4d155f9b3703@oracle.com>
 <b3f7ecb1-9484-426b-8692-98706f7ff6d4@app.fastmail.com>
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <b3f7ecb1-9484-426b-8692-98706f7ff6d4@app.fastmail.com>
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?ipfaSGVL0iUVNPnhBVocrh8xkmptMsVKxALONL1mfWX8/ei2Q/2zt/v3B5MJ?=
 =?us-ascii?Q?NasXtXLK0rR5F1Sx72+3fYPVvflJnMDuCqAt8b7hPWn5vqdnAmwNCixnCOlv?=
 =?us-ascii?Q?Yn1gd8f1Ht0lScWA5kDFfSZB4Itx7mEtoUS+azDYZyauGMXc6gpcQAdPB2sa?=
 =?us-ascii?Q?JeSNMMEd6vT7ZqX/0xqPFgoVCkoFwYLL8xABiFyD9VEHO1hEO/jxCcRE7+Q/?=
 =?us-ascii?Q?uAu5MpBwg9u3uWdHIDV8LLvWCvZ0RAOZZyTYbePMMIkftM2qwB5OuLz5tjSX?=
 =?us-ascii?Q?hR7NCxnYu2F5VQqL5we75OjmZvCVkQCU6VBuVx6jhv3ZyINYppNFPDOgTY1N?=
 =?us-ascii?Q?a/WSsB9QTyr/ZwFLK4ueqFZPmC9Et3Qnb6++G6BejvCBZ8RfKhbtMNrYB5rD?=
 =?us-ascii?Q?xBRgEhEBbow8u6LzCv8BKPnj4Ub8G4q5dyWipOnzqcbVxiB2aiHT2AMU40dj?=
 =?us-ascii?Q?//y/7eAaTspCTWDeLVaHET4cgjgjmvgB3fohns20/armHJQbZwW1e+mJSVMJ?=
 =?us-ascii?Q?pQTFc7sJ/2dBoTz/RRjFlhzNNSRVK8RpB09beOqgEAHWOC/TaVayjhgBySZl?=
 =?us-ascii?Q?cpHLk8tCqXWiCX65dEih4RpeulvmpDRlfXR1/DqL9oFnsuyD9GuE7Z6jnsY0?=
 =?us-ascii?Q?48l1nDx7IX+3sLS98tlv5qGy8bB2d2XDotso/pDYKOr4SHVqqMLFRQQAK3A0?=
 =?us-ascii?Q?5EWK94K+Cvx+RBH0yWFgQmBhTHtc62FdlERYtOVTM6x2f+WVfYvMp3gg82cR?=
 =?us-ascii?Q?5+Pc363KPwiLVjxo0OeZUYVMeF4U/IBkBHBVyVJPp53zqoy69kxpZB+tfASL?=
 =?us-ascii?Q?lL/ZttW5mmMF6+aDAnc0m1GjzQQXKEoCwYTSgxZujPD1bLnASlzBZu2W2QNL?=
 =?us-ascii?Q?P/q4BjG4YSia5FgSqw+uzZRRR/GBXckgU2F0zC187aDBH/NFfHLOaALTMV0X?=
 =?us-ascii?Q?Bkn4Aw55sMa1TnIj38l+mAl80PhDmQaHxnF44u2/HG8Pd01bA6+K8ZeM+Ttx?=
 =?us-ascii?Q?E3Fu0Eb++9pku+YKi0RM8sB03PxZ/Y1cbd0uvO4dYvwna1koMDCJvEhFOWT3?=
 =?us-ascii?Q?cju1wt0zqNhEsVu+oIhdopHSH2FEi2O6YsVkqdOH07lq/7d1+Gsmoh7LnWA3?=
 =?us-ascii?Q?sc0ZVE2+ro5wBWsh+w40/1JEkDeEwMsr/0gttM9yz8coxSaJTMU+6vM+G+UO?=
 =?us-ascii?Q?ir4wfCmGuvXu3o/vr47VPAsUrfQudJUii7Gcb0Cl3Qkxl0l82KQRHhpFGbQ1?=
 =?us-ascii?Q?pFrhxlebQxZuNw7NEeDMDdX2Zs0xXo+0ZpiItxOppS+7CSve7/AuyZkR7RBJ?=
 =?us-ascii?Q?HO8K4SrZ/ODzlPJwVU+9l+HqSOo8sikHMqNpr8WrBaGf342tJg/ForW0PfiG?=
 =?us-ascii?Q?Hu4y3hUwcEN7AEj8KeX9iHbQNsdo0mzWV52j2FBWI3xHibfDoa7QDyCrfFwI?=
 =?us-ascii?Q?QEg0NEvAPK+7rOYBGLeK0QRxWYzWTDSOgUtQ9TV27qkLaBFojMxX8YwsvMr8?=
 =?us-ascii?Q?f40N1Ri5E9l3xpbIh753CCcxtMw7P0gPi9mM326i07+I03I+yO1BEZf0tCgc?=
 =?us-ascii?Q?avFE0j57LQDu5reTclc=3D?=
X-OriginatorOrg: Nvidia.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 877930c3-5389-4819-4a9c-08dbd3cb31e8
X-MS-Exchange-CrossTenant-AuthSource: LV2PR12MB5869.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 Oct 2023 13:23:07.3630
 (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: GNwcKLJ0e939ZsXmddTSjnx1LOo1vaHFp6iI2l0ch/FRzLnoAIMOZKnyF+jFuhwG
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB5088
X-Spam-Status: No, score=-0.9 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED,
	DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,
	MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable
	autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on morse.vger.email
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (morse.vger.email [0.0.0.0]); Mon, 23 Oct 2023 06:25:52 -0700 (PDT)

On Mon, Oct 23, 2023 at 02:55:13PM +0200, Arnd Bergmann wrote:
> On Mon, Oct 23, 2023, at 14:37, Joao Martins wrote:
> > On 23/10/2023 13:04, Jason Gunthorpe wrote:
> >> On Mon, Oct 23, 2023 at 01:55:03PM +0200, Arnd Bergmann wrote:
> >
> > Right -- IOMMU drivers need really IOMMUFD (as its usage is driven by IOMMUFD),
> > whereby vfio pci drivers don't quite need the iommufd support, only the helper
> > code support, as the vfio UAPI drives VF own dirty tracking.
> >
> >> I think it means IOMMUFD_DRIVER should be lifted out of the
> >> IOMMU_SUPPORT block somehow. I guess just move it into the top of
> >> drivers/iommu/Kconfig?
> >
> > iommufd Kconfig is only included in the IOMMU_SUPPORT kconfig if clause; so
> > moving it out from the iommufd kconfig out into iommu kconfig should fix it.
> > Didn't realize that one can select IOMMU_API yet have IOMMU_SUPPORT unset/unmet.
> > I'll make the move in v6
> 
> Are there any useful configurations with IOMMU_API but
> not IOMMU_SUPPORT though? My first approach was actually

IOMMU_SUPPORT is just the menu option in kconfig, it doesn't actually
do anything functional as far as I can tell

But you can have IOMMU_API turned on without IOMMU_SUPPORT still on
power

I think the right thing is to combine IOMMU_SUPPORT and IOMMU_API into
the same thing.

Since VFIO already must depend on IOMMU_API it would be sufficient for
this problem too.

Jason