Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:18 as permitted sender) client-ip=2620:137:e000::1:18;
Date:   Mon, 21 Mar 2022 09:43:46 -0300
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     Jean-Philippe Brucker <jean-philippe@linaro.org>
Cc:     "Tian, Kevin" <kevin.tian@intel.com>,
        Lu Baolu <baolu.lu@linux.intel.com>,
        Joerg Roedel <joro@8bytes.org>,
        Christoph Hellwig <hch@infradead.org>,
        "Raj, Ashok" <ashok.raj@intel.com>, Will Deacon <will@kernel.org>,
        Robin Murphy <robin.murphy@arm.com>,
        Jean-Philippe Brucker <jean-philippe@linaro.com>,
        Eric Auger <eric.auger@redhat.com>,
        "Liu, Yi L" <yi.l.liu@intel.com>,
        "Pan, Jacob jun" <jacob.jun.pan@intel.com>,
        "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH RFC 10/11] iommu: Make IOPF handling framework generic
Message-ID: <20220321124346.GP11336@nvidia.com>
References: <20220320064030.2936936-1-baolu.lu@linux.intel.com>
 <20220320064030.2936936-11-baolu.lu@linux.intel.com>
 <BL1PR11MB5271DE11A868204D2E0D5B548C169@BL1PR11MB5271.namprd11.prod.outlook.com>
 <YjhkmDEGwF4EcM8R@myrica>
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <YjhkmDEGwF4EcM8R@myrica>
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?BbauTMU3bJxQFd6iCptuLkKAgDUlKzKgY8ZsV3mzOMsdSwev9aHac+pJefaX?=
 =?us-ascii?Q?g+cPXazp3pODoFU7uWQ0eAyVlJf7AJBG3qTQ7gE0PzASyeWxPvoKv6bgYhHo?=
 =?us-ascii?Q?myMGpvL8mTlxa9R04hE/NMk73JYcIV9cZXMZOThOXsZmD5Fc87TrC+lFO0iq?=
 =?us-ascii?Q?6JbytCJdHTjRKysVCiyBiqAhOguoIKDW9Tkz1IKJElHrC6WEJBTKGqvU+brM?=
 =?us-ascii?Q?RvZXTi1xGvpRGWNZe96KpnZ1V6x8WS22HvmtjgV5IMoQFJf9JqnjULPfM2qs?=
 =?us-ascii?Q?FRh66wxbuRxk+Y9cyIt3sMPVgKzltU2SjkiHhjxUeDrMmqpKuYbmfIJEil0D?=
 =?us-ascii?Q?6ur+iPdGhVeU/av5m6JFgFAa+aJBjU8hpxQL84gYRh8omnSqfc890Uf6Y0GV?=
 =?us-ascii?Q?v5TjAzUL7tp5N0QHBv6RKkNTLhI9rrrK/4ISiMgAkYjeLpHMATFqFTgm3MAL?=
 =?us-ascii?Q?8YLAFuyyqgtJu+s56VhE5560T2qJuph+DFjpcuwPhu+8oFdhwnj5+TmdVtaF?=
 =?us-ascii?Q?/5UJTJpwJjH9O0UpmpeD41rpEWfHittj/3ShgEp/mXetVz1nAy+36h+0imwc?=
 =?us-ascii?Q?pztv7hunCXApYjsxWWuh6ZOOnZGqnefjzMV/Yr/iecfGhyD7dHmlZEKQ5LMD?=
 =?us-ascii?Q?jTWEx7QK4pTlC+sbusSGWnRdiKaPluIcocZRZYsmLXA1n7dplUKEIQgvLRuD?=
 =?us-ascii?Q?aOEqYoXfeki0voODFV1nF+QKwqwr9iO7uIvRVUgu8yk1oXTz41HzpNQVPsmn?=
 =?us-ascii?Q?lN1os0nl0sekZnWm6abO9Id+ycaS7SnBZtEvr77EDT6RxeZIoXTwLzcYUtTR?=
 =?us-ascii?Q?GllMPYMUWX5vlL3dNqia55TbBeuHjBufizH3y2aVL2gWYqPizcekepBGmZQS?=
 =?us-ascii?Q?ZEZae5d1n0iEhbmi99rCBNjixcSpRSlHAcZ2V5MFcMy5Y53SbaiNzzUq0rXt?=
 =?us-ascii?Q?UY4lRzWhxVPMDOhs+g5xQ5CKDImBZDyIXRn/Nfdq5FMGDH+dBhT/vu/9xZyK?=
 =?us-ascii?Q?quGQAJSC3KVn6fmCBPHuuvRD6Rh71CEi9+RMeBhk/DasU4kxIhguskGtIFDf?=
 =?us-ascii?Q?agpk2+a4uNs+VVJvSzJnJwO06T0/Kpgm94WhXdbWpXbuZLfjsDNcJLWpluMW?=
 =?us-ascii?Q?L8asvBVfHX5G4+8ifVRTw74uzKUmwQYKFpcAtubR40Dnjb/fkH+jdaknC1mN?=
 =?us-ascii?Q?WBTCIk6DIRnYZxdrNhiQlegz6OPerM57E5G0kYpmsQ+ohNli5+ZoiT4qF50H?=
 =?us-ascii?Q?USCWVn8jVL5M+0Z8dpStW1cvY6/E4J041IgTf/heo2+0a3GGTNwNXGIRNWlu?=
 =?us-ascii?Q?wN1gsstaBWVBG9UkJEkicjZsA2C6OCw0KxkTzY+/VfnBIRTxVmvGA1d/6oPg?=
 =?us-ascii?Q?mUG/5rufWVTyQ1hOygtRPdJsbVJO2aDwW7vR2Ocygtw+N3MCbKfhEZQaiggq?=
 =?us-ascii?Q?Nt1imsCyRV8IQytfCAlaSR2Ui1nrihVm?=
X-OriginatorOrg: Nvidia.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 31829158-9103-452c-435a-08da0b387176
X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB4192.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 21 Mar 2022 12:43:47.7714
 (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: KfuWImIcTVdU3CB52SVn67Qc1GROdygrhCfxE0E6ouCzlPHqUPLwyphDd/SHfEDU
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR12MB3430
X-Spam-Status: No, score=-3.1 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 21, 2022 at 11:42:16AM +0000, Jean-Philippe Brucker wrote:

> I tend to disagree with that last part. The fault is caused by a specific
> device accessing shared page tables. We should keep that device
> information throughout the fault handling, so that we can report it to the
> driver when things go wrong. 

SVA faults should never be reported to drivers??

> A process can have multiple threads bound to different devices, they
> share the same mm so if the driver wanted to signal a misbehaving
> thread, similarly to a SEGV on the CPU side, it would need the
> device information to precisely report it to userspace.

I'm not sure I understand this - we can't match DMAs to executing
CPUs. On fault we fail the DMA and let the process keep running or
SIGSEGV the whole thread group.

Jason