Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <4f9184c5-e6a2-08da-f44a-3000b6cdfe35@oracle.com>
Date:   Thu, 15 Jun 2023 08:49:18 +0100
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101
 Thunderbird/102.10.0
Subject: Re: [PATCH v4] iommu: Optimise PCI SAC address trick
To:     Jakub Kicinski <kuba@kernel.org>, Joerg Roedel <joro@8bytes.org>
Cc:     Robin Murphy <robin.murphy@arm.com>, will@kernel.org,
        iommu@lists.linux.dev, linux-kernel@vger.kernel.org,
        Linus Torvalds <torvalds@linux-foundation.org>
References: <b8502b115b915d2a3fabde367e099e39106686c8.1681392791.git.robin.murphy@arm.com>
 <ZDk83vpIarQ9jWa7@8bytes.org> <20230613105850.30172085@kernel.org>
Content-Language: en-US
From:   John Garry <john.g.garry@oracle.com>
Organization: Oracle Corporation
In-Reply-To: <20230613105850.30172085@kernel.org>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?SEpZQXNMSEFqbHN3aWJMODBvbXAvdlhYcmtZcEpTTVhNTVM2RnRMd0owSUR0?=
 =?utf-8?B?MGdmTW1ORElWb0ZDci95Z3FaREpUZnF4bENrVDl5emZMOGVBeTNSeW5oL0xn?=
 =?utf-8?B?QVVGR2NDTlkrOE9kVEU2dVdKWDZsNGF1eVJGOW5IcGFIN1BhUXhCcVZDNDBY?=
 =?utf-8?B?RFNjc01RdjQ2MkRBL0lrdlBIMjY4ZWVPWHgzWEZTV0J3RnZEcG54ZGNkVjg5?=
 =?utf-8?B?MVhGcGRnU0EwTElreFFaZ1pLM081S05VK2toeFk4NVczbFViQ2tZakRTMXZa?=
 =?utf-8?B?MnBKbWxpcmdUOEMwOUFLYjlndkkzNnFDRUcvWnkzVnZSRDkrRHRYak1aeERv?=
 =?utf-8?B?T0hDK3I4TGpMTTFyMkVESm5jdDl2WmM2YnBLTEpxWi94V2k3ZDNWbmp6MTdw?=
 =?utf-8?B?OU1xajIwZHNzMndEMmkxLzA2RzA5ejkwRWhWWWQrci85VnBBdnNUMHc0aDJ3?=
 =?utf-8?B?S3UzK1pKVmlNdFVBYXc1Snk0MG5RS3A3dHBjRXBaQWR5YjZ3TDkvTnIvQVRW?=
 =?utf-8?B?ZTNQTGxQOU9PVXBYcGlzSURMOTBaTDFkVkJmZFkxS1lxTWxIVTc5ZU9OdTNN?=
 =?utf-8?B?OXNaZzlwd3g1TUlvNCtiaVYvUnhkOVJmbmx6cWgyUkhoQmVINEVwazF5ZUFw?=
 =?utf-8?B?NDZEdFN2d3dYUnV2VjZyc3llTHpLMVBJZlNVUDJqWGN2ampvMUtoK0JkT2p2?=
 =?utf-8?B?WC8xcDA4ZjNyQWtzeHFsMkVBb3RPRWIycGlVdGhRSmlQNXJkZW1nTHQyRHU2?=
 =?utf-8?B?dHNyRlFja1laZTYxWFdEL3pJbGIzMWl4c3BFUFVJUm9jK2g4TS85ckZxbWp1?=
 =?utf-8?B?aDJXK0VkU05QQXhNUW1XNE42VEtIS1ltMXZFb1liaEhITmppKzl3T05pSEU1?=
 =?utf-8?B?SS8ybWRPcXpKR21DMmQ0QXo5dmdEeXk3UzdFT2pnZXF6YlNkbnFnQVdmSG1W?=
 =?utf-8?B?L2RvY2p2WC9jMlYxL1FsR2I5QWlTdTVpT05WenpWNHg5RkJkUllvaHo4UGs4?=
 =?utf-8?B?cEdBWFpxcjlzV0RNbVZJYk9LbTQ0QlRrNTJOMlR3eHpLUTg0NjFBbGppYU12?=
 =?utf-8?B?MFNhb0NNb2tXeG02Zjg4aGxGN3JVRm5jTFFabXRUUUJUQlMyaEFKZXlzc3hZ?=
 =?utf-8?B?UWp6eHl1cWZLMXBDdXlQSEZwT1ZSRTRvTnhRY01KbjVPUC9xV3J3dUUwTnUr?=
 =?utf-8?B?dHZHVEU5RjZvS3NUN3YzamRldlNMZVc0WWRQVGt4eEpNVGpBWHcxbjBPb1dN?=
 =?utf-8?B?TFdzUTlCMmlDWUYzWHp1by85N1VLL3kzU2t2dFlMVmYzUVV2eHozZlFhTEw5?=
 =?utf-8?B?MHhRMVdjNEZkYSs0SE94UzlxWDBzK1hWV2RvV0c2dkRkdlZZTXRIUUIzTEdP?=
 =?utf-8?B?WGF1Tkp2K2h5UGRuM2E3cUZHSXQ0cUxvTGo2dFRWY0tURmFiU0tvZjk0R09y?=
 =?utf-8?B?QldoVXJUa0VYUEFOQ1VSKzIybkN4TldjOGFlbEZqQUh3UUJVN1dCajZPcmNM?=
 =?utf-8?B?TjFVMFhQVzNOVzZkVTRTME5vVTBjbU03MUtGNWdkTFY0cFRrcTlQdnpYOWFO?=
 =?utf-8?B?ZVpuWUV1L1Y3SWt2UUYrMXI2Q0FUaC9NaGtPUEtvbXpnSVBFallWc215Q3BJ?=
 =?utf-8?B?Y0prTVFGeDBURU8xVExqMkd5KzdmcTNRVmwySzByY0pSYTlnellRTXJ4M3NB?=
 =?utf-8?B?RWhJYnFGeG9MdkR1Y21FVzN2R0t0R29WNytaZk5JQWdzd2NnanRMdjFSQWNH?=
 =?utf-8?B?S0Iybml6NTh2Y2hVeVhYdkQwN2ZhcFRCU0xCT1pIbDNlYzI0bk5SYnBTbzMy?=
 =?utf-8?B?NldOSHQ4cEZReXM0RDQxTGNWTTcwNzB0clVRaXpVS1JTZXFsQzZLWXV5eFk4?=
 =?utf-8?B?K20zV0lvMDJGSnNuUU5mNmdFODNIbzc4Y1lZTTVWeURhendtK05iR0lVMktN?=
 =?utf-8?B?b3grVzVWcTdVWG5seU54ZEtGRnJKQkJoTjNLUlBWNVNWVXk5ZlFueHc1WHNL?=
 =?utf-8?B?d1Q0R1VRZFAybHJDeDlpaktjdmhUSHpESmoxcldrclNFT0VyOWZPRVVhT2VS?=
 =?utf-8?B?cEZSak5iV3VoT0R2dDV5d0VDblA5RDhTdTJaZkh2ZXVIYjJiYXBDSlJYdXd3?=
 =?utf-8?B?dGQ4eUdQTXR6SEFEZ2NUUm9SZTA4SHA2SlRCQ0lMalRwYmZrWHNGaE5ydkg0?=
 =?utf-8?B?NUE9PQ==?=
X-MS-Exchange-AntiSpam-ExternalHop-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-ExternalHop-MessageData-0: =?utf-8?B?dkJUemxmN2R5OTQwaDByaEk3cnNhSTdWVENOcnFEMHp5azVaOFNUSVA3blE3?=
 =?utf-8?B?dktIK09Gdm0ySDVwZnRzS3h4TTBubzBKWGZHTmxwR0RDRmJpR1gwSkVJdlIv?=
 =?utf-8?B?WDJtbWw1UXpEcEdMVDFkbHUrcGloSEh6TjR4Q2lQSTUva3FQT1hoZ28zTG9o?=
 =?utf-8?B?YmR1eFhwRmlBa0Z2dXI5K1U5NS9WM0hTc01xQzFvWFBad3d5YVV5ODVNRStO?=
 =?utf-8?B?VnFyc1NPemVBTlNqVW8zaHBZMEgySS96cU01clJ3MEFmREw2Y3VnalZEbW1O?=
 =?utf-8?B?c0F6RnNMMW5wQm45bmZDb2tpVjJuaFY3Zm8zcmNOLy9ZdnpHTDRoVDVtOUxZ?=
 =?utf-8?B?cnRRbmNzUXkrd2d0NTlIWGlJd3BTWjE5d1c1bm9hYWU0eXFKd01nNUtNZmdZ?=
 =?utf-8?B?OW12MlJmSFJWNll3RDFuaFVxa2ZjU3RBWE1FcHdxL3U1dm9SMllLSi81VHBJ?=
 =?utf-8?B?ZllNYVRtcVhrWkxSRmdJdkNtak54WU9WRndFNCtkUzdzV0FqWmY0amFTYmlu?=
 =?utf-8?B?dlJLZFV4UkpRaVdlZ2xzTFlBVHBjbFo2YURBaGJZSS80VUJkSVNodnVSWmRj?=
 =?utf-8?B?Y2kvaUNUYldJdDVjZEFDbDNwKytFYXYvVjVLR0lzcWU4dVZoM3BaV2JBbXZ5?=
 =?utf-8?B?K1JPZmFGNlBvTXcrdGordzRRM3BHS0lpdWVLMmRXeEM3Z1JYRXpMWm1DUFR4?=
 =?utf-8?B?cUtLeTNXaDFDN0JHZWZvWHhnL2tLNVZ6NnZyZkJhMmtxYkZKNzRnYk9GSjdv?=
 =?utf-8?B?YXV5dlQ0SFl2aERXQkVIajIxelMvQnpveE9Felk1eTUvTGY4YTVQMVdxY1Nl?=
 =?utf-8?B?NEVuQnZ0Ti85T2dBRDhKaGh2b0ZaWDlzY3dybUtLeER6QlZFaWFac1lyZ3RT?=
 =?utf-8?B?U2ExeGk2cFNnZWJ5V1EzT0RvWk1Wb3RzdWFiNUtDS0FkbVlNRkxCbVBaVCt6?=
 =?utf-8?B?NFhCWWswbC9QRThmOGpOeWwwbmNwdnEzZk5kYk9FRHdyaG1ONUt1dVQxOHRH?=
 =?utf-8?B?U2JRNEd2Z05ITlZ5Yy9ZeWdydTNUOFZSQU1VSnNKOTZnY1d1NjlsNGI1UE9Q?=
 =?utf-8?B?T29aTjVsUXhkMkYzUWtJNTEwOHUrKzRqcXVKOG1GdHMxYXliRU5zOG12ME9V?=
 =?utf-8?B?WCtxS0FlUUVDZnNIL0cyanU2NUtHL2cvOWxQbTdtTk9DQ2wxaEkreEVneUlk?=
 =?utf-8?B?TktHWm5XL3FWUWVmQzJXREZCMTVBaExZRjI3K1ZHdFdwc0xodVppc3NrNGhu?=
 =?utf-8?Q?kKMFp7NOsLbIdnU?=
X-OriginatorOrg: oracle.com
X-MS-Exchange-CrossTenant-Network-Message-Id: bdbb2cec-a7bb-4c46-b872-08db6d7509c1
X-MS-Exchange-CrossTenant-AuthSource: DM6PR10MB4313.namprd10.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Jun 2023 07:49:24.7256
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: 2U+0BbRIXIWJs4qBmA7zRz2YlXuysgEORyskNrMu+9GSV54OdTlJzYTJhwZVdge26096eapXSic8f0CYW45C9w==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY8PR10MB6801
X-Proofpoint-Virus-Version: vendor=baseguard
 engine=ICAP:2.0.254,Aquarius:18.0.957,Hydra:6.0.573,FMLib:17.11.176.26
 definitions=2023-06-15_04,2023-06-14_02,2023-05-22_02
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 malwarescore=0
 suspectscore=0 mlxlogscore=763 mlxscore=0 phishscore=0 spamscore=0
 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1
 engine=8.12.0-2305260000 definitions=main-2306150065
X-Proofpoint-ORIG-GUID: 36WqDo0S0qOaovU3_ghjSfg8UGUER_m_
X-Proofpoint-GUID: 36WqDo0S0qOaovU3_ghjSfg8UGUER_m_
X-Spam-Status: No, score=-2.9 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NICE_REPLY_A,RCVD_IN_DNSWL_LOW,
        RCVD_IN_MSPIKE_H5,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_NONE,
        T_SCC_BODY_TEXT_LINE autolearn=ham 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 13/06/2023 18:58, Jakub Kicinski wrote:
> On Fri, 14 Apr 2023 13:45:34 +0200 Joerg Roedel wrote:
>> Thanks for working on this, I think this is good to go. But given the
>> issues we had with last attempt I'd like to have this in linux-next for
>> a few weeks before sending it upstream. Therefore I will defer this
>> patch and merge it early in the next cycle.
> Is this patch queued up? I don't see it in linux-next and we keep
> hitting this issue in production. After a few NIC reconfigurations
> IOMMU starts consuming 90+% of CPU time.
> 

Since we're at rc6 time and a cautious approach was wanted to merge this 
change, I doubt that this will be merged for this cycle. That's quite 
unfortunate.

Please note what I mentioned earlier about using dma_opt_mapping_size(). 
This API is used by some block storage drivers to avoid your same 
problem, by clamping max_sectors_kb at this size - see sysfs-block Doc 
for info there. Maybe it can be used similarly for network drivers.

Thanks,
John