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charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Sat, Apr 02, 2022 at 07:12:12AM +0000, Tian, Kevin wrote: > That is one scenario of dma aliasing. Another is like Alex replied where > one device has an alias requestor ID due to PCI quirks. The alias RID > may or may not map to a real device but probably what we really care > here regarding to p2p are struct devices listed in the group. Those devices are just broken and not spec complaint. IMHO we can treat them as disabling ACS for their segment as well. > We may check following conditions to set the immutable flag when > a new group is created for a device in pci_device_group(): > > 1) ACS is enabled in the upstream path of the device; > 2) the device is single function or ACS is enabled on a multi-function device; > 3) the device type is PCI_EXP_TYPE_ENDPOINT (thus no hotplug); > 4) no 'dma aliasing' on this device; It makes sense to me Jason _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 76359C433EF for ; Sat, 2 Apr 2022 23:29:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231220AbiDBXbB (ORCPT ); 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?g5m0zTzAsUqpQ+VgkQb1TT8eILbJv378EXC2Y3wi2PF7dgKGun7ZD38Q4mdW?= =?us-ascii?Q?/FzE9OoSV4Bkr+7W8mXnsFbiQPJYidZ+ojbzK41OsBUguXcjK09SQxUEGxVA?= =?us-ascii?Q?xGs8QaCInvpL5MGYdUYaeRBA2Wj/i6wFmw737mn8+uxgWgGNuapWe/iVAD2z?= =?us-ascii?Q?p448F37dMSJdGVh2PGZFLh/I63nUSVYfZ7E+/2H8IQEDDDt+k9SqOsajZJ9Y?= =?us-ascii?Q?gzkPjlzn4aZh8AQyJAyugEd8AZ7MvTAP0iAUNo0tQoAaZifm0TFwl/lKhFu9?= =?us-ascii?Q?28OCAfZmH4Tuu1B1MffcBGbcPgt/9+YDHq4xDeRqFjAkQH+Sv4TSohKgQM+1?= =?us-ascii?Q?q5mkS+Lxs29CZGPjPwjpcFwOnjKmutBIwlUmGJ0+9sGwMZfgLfAZ6F8PwSEF?= =?us-ascii?Q?pHFBVrNeOM9b0zPzAZ9+4zWwNnus9nxX7fdpvqAAwIvTTzVo1H+KgZOuWud0?= =?us-ascii?Q?qq6J93B1FebYWvRFmriUJrjHP24BBe4c0YjhqBkWFfMwnRJBRcoJJqtt22Pl?= =?us-ascii?Q?keGhwGbuJ6QolaiCDIgRHkNoMWwQUarGk0bEK7nn1HJGP6OwKbl0or46bx0T?= =?us-ascii?Q?OZYGFQUJHIETUJ6ZWiNFaG7chWnK1tH8EShbL3XJRh+uhyAItSXwypmWNqd5?= =?us-ascii?Q?xbOtJcdvfYwfbBPkRxpAzAc58XwYx666/KtejcmWNzlhVQiHiTa2U8Piup0K?= =?us-ascii?Q?JSUNEGzT2vtfbpr798OQsj3+DGgdeFxxojqs0ze19B1KyKbIWIQze1JARMVm?= =?us-ascii?Q?tKMV/c993IO40JLq1WwsQ3h6FrUWsUWblm9DEcnfwP5E9p1Q/uTVeQGUlsUy?= =?us-ascii?Q?B7gubyPtVi9hsbNE+Ak44cms9u9+xA5iMstJl+50qBf0CmBvhSmTeTxEYZ60?= =?us-ascii?Q?gWPzPGg/ay2aoXd6PWr2K4bt1zYq9wi8pmQ1qIbhrsHO/HnYNhJghHerCuD/?= =?us-ascii?Q?zIppzQNwEWGoHnA9T2HIOe91U9Gx/mMLmqNPpvI+hJEBVuNTywcv6CLk9Uk2?= =?us-ascii?Q?5ITC/WmvKAjZPjqpaAm0UY9pMFD+NyZe5+sh/hJA8tjLZWcAJg9lRkGXyRmG?= =?us-ascii?Q?RoU2uK6MM2aVsIVa1MhPx3Y+5I+y7yWtWn3wr+WFqlmSvcm9kkCHvHsOveIQ?= =?us-ascii?Q?UqAlizlQNF7mVgx5aq2psUC33D9T/kZQ4G1p7rDkC7a8ne9bJBZva6XL4KZc?= =?us-ascii?Q?q9KQY1JEzujs8Izo+1eP4PcTKD9Fqgx9Wkoku6rcxOQVT3sk2HEuREd6qcwP?= =?us-ascii?Q?xmiyqNrsb4ZFvtBOs7H3myv5xqWVPo0SDRQ/k87X6K8d1ZC8VvUVlvezJOYH?= =?us-ascii?Q?wOZ4ZVqfnhUH1/qDTRMdKmrnYRKBy6Xr2AJ6UhzVhk2wRH9Rvm2u63It5acM?= =?us-ascii?Q?MsztEM6w6c2ve92pkI1dueSdbQEP/e++/Ar9nPA096lrEej20q2wnDXC/rQH?= =?us-ascii?Q?qujFMU+BNHeLcbtQJV4be/m7Zgfys6Pq7qFBeExL2JEIURuxwfEpHYzXb7fR?= =?us-ascii?Q?7XLO89lvELD8SNJ+roAQ2EAVn0azmH5P/bpgeyL4sArTkrEtHpdHTzeHsu1F?= =?us-ascii?Q?xQGnZyrGKgKY3OEElvjAWipHrQOTUjdCXz5j5Z0223uP9Y5VdasufQgPSelH?= =?us-ascii?Q?xs9FfzZZaVhqMyqNegfMzmYY/CvCOlKmmGy8ggHr1xTGKU+siEFStl1Y7Xed?= =?us-ascii?Q?qGHac6mG3irpCfUUiIuh5mHV1B54W1vd+Q09vAk+uHzn8/s90AZ3dJns7uuS?= =?us-ascii?Q?ETfUEFQQzA=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 9895d20c-971f-412e-adda-08da15009282 X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB4192.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 02 Apr 2022 23:29:03.0430 (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: rb3Qa7K9yxauneqzWHR2qNXLFCfkZwqmqQXIRA6T41P9jauB/Io+F/DoNW1M9r0W X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB4270 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Apr 02, 2022 at 07:12:12AM +0000, Tian, Kevin wrote: > That is one scenario of dma aliasing. Another is like Alex replied where > one device has an alias requestor ID due to PCI quirks. The alias RID > may or may not map to a real device but probably what we really care > here regarding to p2p are struct devices listed in the group. Those devices are just broken and not spec complaint. IMHO we can treat them as disabling ACS for their segment as well. > We may check following conditions to set the immutable flag when > a new group is created for a device in pci_device_group(): > > 1) ACS is enabled in the upstream path of the device; > 2) the device is single function or ACS is enabled on a multi-function device; > 3) the device type is PCI_EXP_TYPE_ENDPOINT (thus no hotplug); > 4) no 'dma aliasing' on this device; It makes sense to me Jason