Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   "Liu, Yi L" <yi.l.liu@intel.com>
To:     Jason Gunthorpe <jgg@nvidia.com>
CC:     "alex.williamson@redhat.com" <alex.williamson@redhat.com>,
        "hch@lst.de" <hch@lst.de>,
        "jasowang@redhat.com" <jasowang@redhat.com>,
        "joro@8bytes.org" <joro@8bytes.org>,
        "jean-philippe@linaro.org" <jean-philippe@linaro.org>,
        "Tian, Kevin" <kevin.tian@intel.com>,
        "parav@mellanox.com" <parav@mellanox.com>,
        "lkml@metux.net" <lkml@metux.net>,
        "pbonzini@redhat.com" <pbonzini@redhat.com>,
        "lushenming@huawei.com" <lushenming@huawei.com>,
        "eric.auger@redhat.com" <eric.auger@redhat.com>,
        "corbet@lwn.net" <corbet@lwn.net>,
        "Raj, Ashok" <ashok.raj@intel.com>,
        "yi.l.liu@linux.intel.com" <yi.l.liu@linux.intel.com>,
        "Tian, Jun J" <jun.j.tian@intel.com>, "Wu, Hao" <hao.wu@intel.com>,
        "Jiang, Dave" <dave.jiang@intel.com>,
        "jacob.jun.pan@linux.intel.com" <jacob.jun.pan@linux.intel.com>,
        "kwankhede@nvidia.com" <kwankhede@nvidia.com>,
        "robin.murphy@arm.com" <robin.murphy@arm.com>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>,
        "dwmw2@infradead.org" <dwmw2@infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "baolu.lu@linux.intel.com" <baolu.lu@linux.intel.com>,
        "david@gibson.dropbear.id.au" <david@gibson.dropbear.id.au>,
        "nicolinc@nvidia.com" <nicolinc@nvidia.com>
Subject: RE: [RFC 00/20] Introduce /dev/iommu for userspace I/O address space
 management
Thread-Topic: [RFC 00/20] Introduce /dev/iommu for userspace I/O address space
 management
Thread-Index: AQHXrSFkVs244O/dIkas8ZrIoCf5Fauug4UAgADkicA=
Date:   Wed, 22 Sep 2021 03:25:02 +0000
Message-ID: <PH0PR11MB565893BD99086EC51A8E8267C3A29@PH0PR11MB5658.namprd11.prod.outlook.com>
References: <20210919063848.1476776-1-yi.l.liu@intel.com>
 <20210921134508.GL327412@nvidia.com>
In-Reply-To: <20210921134508.GL327412@nvidia.com>
Accept-Language: en-US
Content-Language: en-US
dlp-reaction: no-action
dlp-version: 11.6.200.16
dlp-product: dlpe-windows
x-ms-exchange-antispam-messagedata-chunkcount: 1
x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?6irH3BN1PgmDbpYeGfF76KBthUk3FTT3O72e78i1yP8mCGQy0xOvjQW3sccL?=
 =?us-ascii?Q?l/OF1pLQPO/BVA0ixaktTL2KxeIbvOUgrVJQszr3CCZyqhlh9gEqThorxM+T?=
 =?us-ascii?Q?sdYYOaBYX4l6brGP/POnGJM6Q7TjXMAWLVgAXJ5l+QiY/1CwT53WbMGHUCyG?=
 =?us-ascii?Q?u9B+FT+3iW0xmfh3/MhMUJvTPqW5sMjB7Xdq3cU+74bDwExnW73leLVTXKK2?=
 =?us-ascii?Q?zdSY4/jf+KTfAPw8SLABqkr+obg6Y/qPP7kAgoYvlUJNftH8iVg5gyObBKdh?=
 =?us-ascii?Q?P0Z9WF51mblDYWrO8d0e6INbU3guZbHR9MjMLZSBN6/6PrA5YOXOCGOAYgwo?=
 =?us-ascii?Q?YETf8FSdNJmaPhP+THkudxnCjgICGk3v0xYyaq6FXDf53u8LCTnITfTC3tyz?=
 =?us-ascii?Q?N1aXKY5gH3h2UNNcCKIi+AKB1KhXPTGbtwXmKx7HrVpKbZ7joP3210gdE8At?=
 =?us-ascii?Q?acxEs1ERzE3X8ApOmB7kZeZjl24kkK0eva1bE58saxE6nIhmuw/utZqs/LYX?=
 =?us-ascii?Q?/f/UcZJRS0tResz27WpFZ+t8NXGG73avvrr3KFpRls/JOah3YLAPScVFa12K?=
 =?us-ascii?Q?feaXj2e0p8Ks+tyR6f/7WSoWeAigcrVDoq9msq/UlGwXsXJs0KkZ/yiLxB3N?=
 =?us-ascii?Q?jbZO39+U4NgwsrBB41C4v0tZ8Hx9eW1KGeoz+oTK46qtTXR2ux6D5/LvjbOK?=
 =?us-ascii?Q?HlbIitRSV3V+wg2cNksBu/YFhumATNocTRjn0qVTql2ng+OL+6KK/ZTmZcgJ?=
 =?us-ascii?Q?/5dG4p+QMFOas9o3yPoGXP64hSUrn/Zq30tMCaH8JpYs+LoP2mxOWnvGqigi?=
 =?us-ascii?Q?3d/5SMAhIEpkvIyqsW7JMf3iAFsl9sWYRP9nsWr3VnWzrumSqwKLjSJHs9J8?=
 =?us-ascii?Q?9eV19XITS8mdaGteUF2rFsOSRThUhxSXnzS8C7KlpK12JhGi+GItnVvU2gTy?=
 =?us-ascii?Q?fkPU8wLmEsQ7cYLcXvOQ1QGXUrf8Zy96k+g7wkZUeNzqL1yjC3min0kYeMXI?=
 =?us-ascii?Q?1oeEjhd4IS1HeKQ9nxEIYE1IXXjF0SApsvsbfJj+EMxNBY7MW4eb5sgVDSCy?=
 =?us-ascii?Q?O4eGjP4YvUoaMkR0A+bQj8ofdQFt3xmPNR4sXC/VCECq810Lcf/KXB5eoPQc?=
 =?us-ascii?Q?+FmcCtQyPlM5TOQJBfZ2Z7hXrTL0MT5Dhg9G6iyt4W7fGVw43SHBPd2jGNNe?=
 =?us-ascii?Q?l889JJSZXLDgsY6aEXA5D/SCwkmPLOspomXHJvpQ2Hj6OwuyMPb4cmin5SmM?=
 =?us-ascii?Q?Zy69fVwm0nU18MXRC5X7udb2n+JbXU86qTXgZ+kPmr5o1U042bqU90LwT/R4?=
 =?us-ascii?Q?MVOM/ujUsI4gMRgeztbw+g7l?=
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: PH0PR11MB5658.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 1565b33e-c5f1-46f1-6250-08d97d7890f6
X-MS-Exchange-CrossTenant-originalarrivaltime: 22 Sep 2021 03:25:02.9417
 (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: bHrpvyGZ9ljtqdPok6/POthXX3ZyJn4gqQ9vPLTEonnrnPi+Q2HAiSIVfJI9EQ+NvFqyvCcGYP+xrdCkNWdRDg==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR11MB5641
X-OriginatorOrg: intel.com
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Tuesday, September 21, 2021 9:45 PM
>=20
> On Sun, Sep 19, 2021 at 02:38:28PM +0800, Liu Yi L wrote:
> > Linux now includes multiple device-passthrough frameworks (e.g. VFIO
> and
> > vDPA) to manage secure device access from the userspace. One critical
> task
> > of those frameworks is to put the assigned device in a secure, IOMMU-
> > protected context so user-initiated DMAs are prevented from doing harm
> to
> > the rest of the system.
>=20
> Some bot will probably send this too, but it has compile warnings and
> needs to be rebased to 5.15-rc1

thanks Jason, will fix the warnings. yeah, I was using 5.14 in the test, wi=
ll
rebase to 5.15-rc# in next version.

Regards,
Yi Liu

> drivers/iommu/iommufd/iommufd.c:269:6: warning: variable 'ret' is used
> uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized=
]
>         if (refcount_read(&ioas->refs) > 1) {
>             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/iommu/iommufd/iommufd.c:277:9: note: uninitialized use occurs
> here
>         return ret;
>                ^~~
> drivers/iommu/iommufd/iommufd.c:269:2: note: remove the 'if' if its
> condition is always true
>         if (refcount_read(&ioas->refs) > 1) {
>         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/iommu/iommufd/iommufd.c:253:17: note: initialize the variable 're=
t'
> to silence this warning
>         int ioasid, ret;
>                        ^
>                         =3D 0
> drivers/iommu/iommufd/iommufd.c:727:7: warning: variable 'ret' is used
> uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
>                 if (idev->dev =3D=3D dev || idev->dev_cookie =3D=3D dev_c=
ookie) {
>                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/iommu/iommufd/iommufd.c:767:17: note: uninitialized use occurs
> here
>         return ERR_PTR(ret);
>                        ^~~
> drivers/iommu/iommufd/iommufd.c:727:3: note: remove the 'if' if its
> condition is always false
>                 if (idev->dev =3D=3D dev || idev->dev_cookie =3D=3D dev_c=
ookie) {
>=20
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/iommu/iommufd/iommufd.c:727:7: warning: variable 'ret' is used
> uninitialized whenever '||' condition is true [-Wsometimes-uninitialized]
>                 if (idev->dev =3D=3D dev || idev->dev_cookie =3D=3D dev_c=
ookie) {
>                     ^~~~~~~~~~~~~~~~
> drivers/iommu/iommufd/iommufd.c:767:17: note: uninitialized use occurs
> here
>         return ERR_PTR(ret);
>                        ^~~
> drivers/iommu/iommufd/iommufd.c:727:7: note: remove the '||' if its
> condition is always false
>                 if (idev->dev =3D=3D dev || idev->dev_cookie =3D=3D dev_c=
ookie) {
>                     ^~~~~~~~~~~~~~~~~~~
> drivers/iommu/iommufd/iommufd.c:717:9: note: initialize the variable 'ret=
'
> to silence this warning
>         int ret;
>                ^
>                 =3D 0
>=20
> Jason