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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?4Fhlb2NkZLVMbBvTEButFOcItzHiJK0M3Ur0HyZQAflgJG7vKEZwQIykW+Cq?= =?us-ascii?Q?TJCqUL3QyF8TcFh9D6K0gCIFoIbZnUnqEgQ+af5dFLDPimXeRAJDsI/AoK1l?= =?us-ascii?Q?UHWNDlu6F1F1Y9QHnKkq3rFm+RNJlSQ7CO7kHpvZyY2fR9YquNSJylyDjrf/?= =?us-ascii?Q?1X6Q2N9ZKrhv8kai+ikSFflt7p4K2Y3izVlUG4v+39KsvLrWtTPcXJC96LMW?= =?us-ascii?Q?VJtPe9wCVUh8d5cGqryOMLRo/HJzErC3ka3CINvy752j7hhermuYFdUeAcMg?= =?us-ascii?Q?7QgZi6bT3OJ73aQoLZyreqngrxwhTqS4SDrdml+Nhal1E+2dkyP97wupG71B?= =?us-ascii?Q?RBE5NoWD3PTp0cLsYPsBap8AXIgjvLBxEx7Nb1etrmMdllIDNGVVtmqT/L0k?= =?us-ascii?Q?yqnGXsy5FIzQTipeDSiWYR5uQbyy/t53LZXjRqYZK76HR1zAviu0Gks+NkKU?= =?us-ascii?Q?0W4cg/cbVkgimHZK1LReqXuU8aL+layRHr5zugiBAJpTCITU3tuCymAMwnpw?= =?us-ascii?Q?zugsK0toxNX+buDCLBf2O4v67XfqekqAB6GN5UOl1dyMmhXEujiVimpNBqRM?= =?us-ascii?Q?k6DnJfrLwsvT1EK6hNytUnO7FdXAvNJEX87zF/a2n2zXbR15rezawRDx9zmF?= =?us-ascii?Q?xN0dXhIxonZNmdUBBQMxPIrFT48BQhxe0RNG32jyUzrUJxNsAVrHcfnYR+zv?= =?us-ascii?Q?1sTtaywQpNg3E7dEDKvJ/Pczn59nIFIy/ChpRjwYfYAyde5sGhhcYPxJLjlN?= =?us-ascii?Q?Y0Y9LEF3Vv7nnX3wjasJsBUSqprTxcpQAWYB+xJcm1jSu1SjSk9//s0Owejh?= =?us-ascii?Q?QFymfSo1/06HPqYs7eO98iFNnoTlCzxNX7hSwhFVZlpZAoKDivEpeeJHBtrn?= =?us-ascii?Q?S7iri1Q0wAhU0zRgTW4czBYUtXhdszZx51ujWAy4yCSMNrDY+nwOmFVFr/kz?= =?us-ascii?Q?jlfIZVfDiE0pFdGrdwgTjAEfVME7bSNtSMDi7El24dHl7PPbboPOmMA/ov5p?= =?us-ascii?Q?CAAU+oUzpx7v88vbZU7f2DCcB6jJ+HqT2oxIkVVo+xy2MiHND2/ZKs98TDYR?= =?us-ascii?Q?3e7n4E/O4KEvyst6M8KGTQmuN2J0xKk8oTlkIQBGggQkQ6ROaD8/MjjrdGuc?= =?us-ascii?Q?XlVbCxj0DoBExJ0UJaAIX61vDGYO8rUut9sbQDZLk8CDZwDV17hnvD299JAu?= =?us-ascii?Q?dYZz3bsOgAweQbxK7TEWHUp1kAFSBtO8gkAJ0tqFu0xv+xau6MGlR/MOlN00?= =?us-ascii?Q?WhzzfLBZgu1bjgLQ+iLVZ8en6k7y/dmsG3fd3NmDIq6j0BbA5HZ0sKMCJ/7l?= =?us-ascii?Q?Kf6Liacq8Z4B+IyIgD1ZU4e6UXAD3a03cfJvl6gMXtuyUruiICpvxHg00vK4?= =?us-ascii?Q?IVebE53vsnWMrTCqaVuDBwsubMT7woMlKD744dCHwDx03EPYrd6vZH+oAuiS?= =?us-ascii?Q?bBpyZ14fPHExyjaLwAiRscoRbDKjGhtWcftdGyzPSOyT46c5OJemaf8QAaF1?= =?us-ascii?Q?r1kAb4iptR+e6P6NC1v64htmr0OQOXitfdK6iFvkVOPx24zChFoHjW3EuOfb?= =?us-ascii?Q?+jU8PX7+AhoZ07aMy4mmN9EV2DPwWnY60a3AZJWQYvIQDtQLA1snW0NlcBDz?= =?us-ascii?Q?+ntVFeadjb96OH45HKk1EjvWgDIZmxgmPtgYCKKwSrmJv+G/DIQcsvcN4U0c?= =?us-ascii?Q?uulp3LpyroIwXuO3sigGQDPOadzmDjObkYHD9tdXcFk75ofr3hvUfx35o86n?= =?us-ascii?Q?MEa4F4wjdw=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 1c349c36-206f-4d60-87d8-08da1964e36d X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB4192.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Apr 2022 13:37:13.0470 (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: LvBiMn07iTwJX/OHMswiSrNyOZ6At7Y6FoKuTn9xlWoOlhYqLET0XpTd+UqKPrhe X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN6PR1201MB2481 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Apr 08, 2022 at 02:28:02PM +0100, Robin Murphy wrote: > > > One nit. Is it logistically more reasonable to put this patch before > > > changing VFIO to always set IOMMU_CACHE? > > > > For bisectability it has to be after > > > > iommu: Redefine IOMMU_CAP_CACHE_COHERENCY as the cap flag for IOMMU_CACHE > > > > Otherwise Intel iommu will stop working with VFIO > > > > The ordering is OK as is because no IOMMU that works with VFIO cares > > about IOMMU_CACHE. > > The Arm SMMU drivers do (without it even coherent traffic would be > downgraded to non-cacheable), but then they also handle > IOMMU_CAP_CACHE_COHERENCY nonsensically, and it happens to work out since > AFAIK there aren't (yet) any Arm-based systems where you can reasonably try > to use VFIO that don't also have hardware-coherent PCI. Thus I don't think > there's any risk of regression for us here. Right, I was unclear, I meant 'requires IOMMU_CACHE to be unset to work with VFIO' Jason 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 smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4CE67C43219 for ; Fri, 8 Apr 2022 13:37:19 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id DF4A341129; Fri, 8 Apr 2022 13:37:18 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id bZJxCTLE52tj; Fri, 8 Apr 2022 13:37:18 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [IPv6:2605:bc80:3010:104::8cd3:938]) by smtp2.osuosl.org (Postfix) with ESMTPS id AC383403C2; 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charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Fri, Apr 08, 2022 at 02:28:02PM +0100, Robin Murphy wrote: > > > One nit. Is it logistically more reasonable to put this patch before > > > changing VFIO to always set IOMMU_CACHE? > > > > For bisectability it has to be after > > > > iommu: Redefine IOMMU_CAP_CACHE_COHERENCY as the cap flag for IOMMU_CACHE > > > > Otherwise Intel iommu will stop working with VFIO > > > > The ordering is OK as is because no IOMMU that works with VFIO cares > > about IOMMU_CACHE. > > The Arm SMMU drivers do (without it even coherent traffic would be > downgraded to non-cacheable), but then they also handle > IOMMU_CAP_CACHE_COHERENCY nonsensically, and it happens to work out since > AFAIK there aren't (yet) any Arm-based systems where you can reasonably try > to use VFIO that don't also have hardware-coherent PCI. Thus I don't think > there's any risk of regression for us here. Right, I was unclear, I meant 'requires IOMMU_CACHE to be unset to work with VFIO' Jason _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu