Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.35 as permitted sender) client-ip=23.128.96.35;
Date:   Tue, 26 Sep 2023 13:29:20 -0300
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     "Tian, Kevin" <kevin.tian@intel.com>
Cc:     Robin Murphy <robin.murphy@arm.com>,
        Baolu Lu <baolu.lu@linux.intel.com>,
        "Liu, Yi L" <yi.l.liu@intel.com>,
        "joro@8bytes.org" <joro@8bytes.org>,
        "alex.williamson@redhat.com" <alex.williamson@redhat.com>,
        "cohuck@redhat.com" <cohuck@redhat.com>,
        "eric.auger@redhat.com" <eric.auger@redhat.com>,
        "nicolinc@nvidia.com" <nicolinc@nvidia.com>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "mjrosato@linux.ibm.com" <mjrosato@linux.ibm.com>,
        "chao.p.peng@linux.intel.com" <chao.p.peng@linux.intel.com>,
        "yi.y.sun@linux.intel.com" <yi.y.sun@linux.intel.com>,
        "peterx@redhat.com" <peterx@redhat.com>,
        "jasowang@redhat.com" <jasowang@redhat.com>,
        "shameerali.kolothum.thodi@huawei.com" 
        <shameerali.kolothum.thodi@huawei.com>,
        "lulu@redhat.com" <lulu@redhat.com>,
        "suravee.suthikulpanit@amd.com" <suravee.suthikulpanit@amd.com>,
        "iommu@lists.linux.dev" <iommu@lists.linux.dev>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-kselftest@vger.kernel.org" <linux-kselftest@vger.kernel.org>,
        "Duan, Zhenzhong" <zhenzhong.duan@intel.com>,
        "Martins, Joao" <joao.m.martins@oracle.com>
Subject: Re: [PATCH v4 01/17] iommu: Add hwpt_type with user_data for
 domain_alloc_user op
Message-ID: <20230926162920.GQ13733@nvidia.com>
References: <20230921075138.124099-1-yi.l.liu@intel.com>
 <20230921075138.124099-2-yi.l.liu@intel.com>
 <0d37a1b1-e7ef-fa73-d17c-629cd254ae75@linux.intel.com>
 <20230921164447.GQ13733@nvidia.com>
 <dcde6757-8d14-6460-c75e-c30d69219e4b@arm.com>
 <BN9PR11MB52765B3F127EE04E4A79C7778CC3A@BN9PR11MB5276.namprd11.prod.outlook.com>
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <BN9PR11MB52765B3F127EE04E4A79C7778CC3A@BN9PR11MB5276.namprd11.prod.outlook.com>
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?jVlEflHhPcVV8eihy8SrU6I0V7NCqVFSEe98VoKrtfMOXzd23oyly1iWQq8H?=
 =?us-ascii?Q?ept4pxa3uX2wbnCEtsXICDbrPrd10kEI0GArE8z/7w7RxgpxUipoqaDC4nEh?=
 =?us-ascii?Q?4DhMciPVZiSsCPbnGkB4NLMNCwEi6uHLauMgtozwM6VXk18glt09YZQbmO0h?=
 =?us-ascii?Q?0v0h8fM2AOSS1s6+E6jAlnDIb454nigRRb0S9Ky1m/y5LJE/HWJ62dmoCBff?=
 =?us-ascii?Q?+7p1qpsjZ+tNt5gOkJ5XA8em2AUUNapGu93o+589QRNmurUodBIXsROxvNKq?=
 =?us-ascii?Q?rUHu22aiR/Ks/wtg6f/s1feoIT1bx3xJC9C/BRHTsNpZmqB+3P8iDLVRmMP7?=
 =?us-ascii?Q?mQWUN8QpK47rMs0Vkc9pmb55z+nd4UY2EqXmYzw5NzCL0WyQWIu/GDc+zMG6?=
 =?us-ascii?Q?RAiVS0rjh++sLJRPfmqD9GtikqxAQBEIjxVNFQYn1tFgi6i+2r0dyo27zcq4?=
 =?us-ascii?Q?tEdlD32hJz6Ng5NiXQ3NBq0xb8957Ia6qhzNEyLkBKh0/WwzK1AMv9JcDGAa?=
 =?us-ascii?Q?sCsmD04vq+gUFNMo4pDSyOcS1QnwUC8VEadVg28OIYtqCRqiiJ4/BTunEgHU?=
 =?us-ascii?Q?cnIhNu4fypFNQjlqOQ4o5zHobJ0cHjxaEwjetxRJ8IfGx7KbbjM9RJWlwHPS?=
 =?us-ascii?Q?MnBnGDYqGO0aOQ7cI4WAEVDA+Bkm4IJLwwbf7zCgEq/QdDOEpsRQYmNmbmjq?=
 =?us-ascii?Q?S+8K44vgU0Yvr0e/p3Bty/qkDTXzhfEx/lzmj/MdsOu0q8fJmY4qCH49/hnG?=
 =?us-ascii?Q?b8AlOy7jLXoDp7SVaCURvTZhY48HV6WQ1hjsZqC/Kqd3WT103K2Shki40645?=
 =?us-ascii?Q?MfbHEsFIQSjssvzwauYdhYwKS3MAqSi6/P3qUVMsBTA9bzFEi0QBJgrpyzBW?=
 =?us-ascii?Q?C5A4foLXWkm+gwSZ61k812SGq5nVXWynu3wlD6OlBWq+wkpEVlkNXkD/pkqJ?=
 =?us-ascii?Q?EBgF8otf3rKuiIbMxnYDQlt4qf4Ozeoc28P3qfiLc/dEPw0TePFOex1u2zVr?=
 =?us-ascii?Q?u8j6H2XUoBvVlhjAVTKgEQQKjuEjQYC57RFKr6IrRsvZTB8qUrrf+BPjGIVH?=
 =?us-ascii?Q?sn5BvWVeWsQP8patnYstzvXoAK+WBwoqWAm6wmDiJXERPeLD4/MRWaqPHuF7?=
 =?us-ascii?Q?OWfmd1fXDWXW9g/jY2wGPAutG84MV8/af7beYTWwMT5tQOxWLH6AR7fx5EWL?=
 =?us-ascii?Q?+jMo3s9EdA4qFn8+LrSJNppUcdPquRzHSCC8KB4xTb5nXDIrHgv8oKSjlYDu?=
 =?us-ascii?Q?iCCUiNP1686F5ZkgI07Yo+DkirNPrZbTdK3ALwoePB0nY5RtcTPcCePpkLkm?=
 =?us-ascii?Q?pDPmOFHxtI9GfCNccB1D07DyKBAwHrvx3d8wRAB4Ru88V1JtHn6J0qolX1n6?=
 =?us-ascii?Q?swwRwzxd+9mtwfkg8MRmcVz9zVW+m0M0hSnnsD+KW9ylVf6uWkvTx26+MXH9?=
 =?us-ascii?Q?0OHEu4ob7A1mlUlcm/tDS6rU7/HHJj2sPjvfwSUNNKrAEdZJhBMfBrG9jU3H?=
 =?us-ascii?Q?ZMChC1rzFCjMqv0eTp+u5I8LvPBNO+HATroRu8dMiuJwsfZOxpGmRm/GkjMM?=
 =?us-ascii?Q?hs/lcIOPpFfBZ4JOxwyz+XKkDiHBWq5IJUpMVoaf?=
X-OriginatorOrg: Nvidia.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 1e5e7933-ab80-4249-0d92-08dbbeadbcd0
X-MS-Exchange-CrossTenant-AuthSource: LV2PR12MB5869.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 26 Sep 2023 16:29:21.1288
 (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: aSiqyPE3midtuK9TwP54pNLYZWdWancUMQiaYwFf9KtBNY0e64vAf2UW4Vbm7QIP
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH0PR12MB5369
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 groat.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 (groat.vger.email [0.0.0.0]); Tue, 26 Sep 2023 09:29:52 -0700 (PDT)

On Tue, Sep 26, 2023 at 06:37:55AM +0000, Tian, Kevin wrote:
> > From: Robin Murphy <robin.murphy@arm.com>
> > Sent: Friday, September 22, 2023 5:48 PM
> > 
> > I could go on enjoying myself, but basically yeah, "default" can't be a
> > type in itself (at best it would be a meta-type which could be
> > requested, such that it resolves to some real type to actually
> > allocate), so a good name should reflect what the type functionally
> > *means* to the user. IIUC the important distinction is that it's an
> > abstract kernel-owned pagetable for the user to indirectly control via
> > the API, rather than one it owns and writes directly (and thus has to be
> > in a specific agreed format).
> > 
> 
> IOMMU_HWPT_TYPE_KERNEL then?
> 
> IOMMU_HWPT_TYPE_GENERIC also doesn't sound a straight word.

At the end of the day this enum is the type tag for:

 struct iommu_hwpt_alloc {
 	__u32 size;
 	__u32 pt_id;
 	__u32 out_hwpt_id;
 	__u32 __reserved;
+	__u32 hwpt_type;
+	__u32 data_len;
+	__aligned_u64 data_uptr;
 };

That pointer.

IOMMU_HWPT_ALLOC_DATA_NONE = 0
IOMMU_HWPT_ALLOC_DATA_INTEL_VTD
IOMMU_HWPT_ALLOC_DATA_ARM_SMMUV3

etc?

DATA_NONE requires data_len == 0

Jason