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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?8FJKPngCzI1i6xyLUxBvB0el/3PWdG8T1juhAEAqkJi0uFHNQhhRDvxv6a5N?= =?us-ascii?Q?zpZ6dV5vnvulD4nt5nrWGtIsdb8m0T+kCkk8Zh+CFoxQVzucI7f7Hrap7SS+?= =?us-ascii?Q?L7OhbjiJaUYHeKmVfvt+oIfnxjGOKEfDKho7R9dGpTv8CeHAiA0Wehkoij5t?= =?us-ascii?Q?zBludBsIE4Bw/PNe1SgPZtiuGzzSCSS3RGPVw4O1hqD8AHaYo1XyZYmNmEni?= =?us-ascii?Q?g1gQTXbnYHBlBuO5+fpFa3n/xbDzQ97R8mdT/Gktd3giCtSrii6/lMSe4XOm?= =?us-ascii?Q?oFNSBZN0uatXCZ2ojUTz2p39iQAER8DTL1YutugBHZjvozW3qdAaTzIoCdFE?= =?us-ascii?Q?9ms3wQkqiHdQo3LgSsLWP2j9kwU12nN+EsDygQmfu5GluB+hbEdKCAdLhs/5?= =?us-ascii?Q?EvMfzj41I6+RCAIzIr4IQcQLqlAeMsU88IOoguRnjxZUUv7AAxEtTllHM49C?= =?us-ascii?Q?W9JeBm7NrAQ+5NhWqTiQ47WaN2XUTBwnMM2B990+1K7ZOznCvTq7+E0Sogk/?= =?us-ascii?Q?lSesu8oD1fV+ANQumH98k7i8GCemVD8f8Sm/2Z/V5dyef1DAnIESzBvvRWV7?= =?us-ascii?Q?9H7Rpn7ECK69zbfuGdMhRtjV8Hy7vBZxYX60q6Q2Yd0Fpd0hRrvMJ00ImJMd?= =?us-ascii?Q?ABrk0vAUzlWlPE+nooqida7Jc8uLgtfBuG07avj5SuUJOLWKEFKyMcMRp04a?= =?us-ascii?Q?k30OFFT2iDoEDrEzanREpM0oqsvxzP4VVg54xLCR52YFSU+qyk5Yp8nnKD1x?= =?us-ascii?Q?7Rykj3mH45QCiBjtf7hwmEA6GOzhoXxCDnMypWgERt8rWmx0UYQsAYTF+TfN?= =?us-ascii?Q?29YldXoUh+DhUX18lNv4MDDZvI35/8yceyxB/1Ti/0gVqoO4H04Q4uNfcsZc?= =?us-ascii?Q?Rnh+phzpQKakrgrjuTfGPWaE/A5m6HldUmmIoI7OMGOywu1gdVY983drbqF8?= =?us-ascii?Q?e61v1htPr9SlOPqkFdFQ4IwrGIL6cqZzk8LvvZ8Oa45IQDq0zh8MUcufSvvf?= =?us-ascii?Q?BlRLid0/8VSggUC/idWhKnpAX+8yNUNvlCWdXwqPyJGBcpvoySrXtovqzyBc?= =?us-ascii?Q?GHcDZKmAaKgyFjGbOIKgN7iPAyiZzgf2XPP4EplsekleTs+NRTa0QNTgkatV?= =?us-ascii?Q?0iJdXCC0PxEE1sm7yxJJMe5pVSsAupxOx/24C0xByoHM3B57m3Y4bP+2yE9E?= =?us-ascii?Q?k7YIUIiRNS+Us6Qyio/R0WdlHZadQCl+i+bHG+t9AkCc3uYp+YIifD+e0YCL?= =?us-ascii?Q?i3nBTN90rfiCh4qqF3t405SW1caJrwDWa1sU77HaFbwhNCQEASs1TaPYggUQ?= =?us-ascii?Q?d804b4BYXk03iUjj4MLxTxc1yoh2hId7vA/AAreTTzHxb6zkjRLfjNG+Of+9?= =?us-ascii?Q?obvbgujL8BZRY2BlqlShW2Z2Id0xq7ZyVVzrEhtcdXeLtmm7Lw6fZolFM2zv?= =?us-ascii?Q?RvohhrCt7vdq72L8bsvMRr/M1RoPpfk/LSoHdXpEftumVWaOFlqhF0rN29PN?= =?us-ascii?Q?gEXox6A31wf+BEN+swaPUGbEbJ/Wyar7EYsuytl5VMLYC0m/XSN1TVRsywPl?= =?us-ascii?Q?+M9Ont5totWCc8XW/C2qyZTT1rzvFeT+pvTSslHy?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: e0d8f92d-33d4-4133-6fa6-08dc32e68e32 X-MS-Exchange-CrossTenant-AuthSource: LV2PR12MB5869.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 21 Feb 2024 14:08:19.0564 (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: vI9C7Y6xq3+DeU78fYUHpWeMUrHS38xJgWcHcKnH3gG65bek5WKnzS3n4cv9Yrud X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB6328 On Wed, Feb 21, 2024 at 01:49:23PM +0000, Will Deacon wrote: > Very roughly, yes, although I'd go further and just return a bitmap of > used qwords instead of tracking these bits. Basically, we could have some > #defines saying which qwords are used by which configs, I don't think this will work well for CD's EPD0 case.. static void arm_smmu_get_cd_used(const __le64 *ent, __le64 *used_bits) { used_bits[0] = cpu_to_le64(CTXDESC_CD_0_V); if (!(ent[0] & cpu_to_le64(CTXDESC_CD_0_V))) return; memset(used_bits, 0xFF, sizeof(struct arm_smmu_cd)); /* EPD0 means T0SZ/TG0/IR0/OR0/SH0/TTB0 are IGNORED */ if (ent[0] & cpu_to_le64(CTXDESC_CD_0_TCR_EPD0)) { used_bits[0] &= ~cpu_to_le64( CTXDESC_CD_0_TCR_T0SZ | CTXDESC_CD_0_TCR_TG0 | CTXDESC_CD_0_TCR_IRGN0 | CTXDESC_CD_0_TCR_ORGN0 | CTXDESC_CD_0_TCR_SH0); used_bits[1] &= ~cpu_to_le64(CTXDESC_CD_1_TTB0_MASK); } } > and then we can > simplify the algorithm while retaining the ability to reject updates > to qwords which we're not expecting. It is not much simplification. arm_smmu_entry_qword_diff() gets a bit shorter (not that it is complex anyhow) and other stuff gets worse. > > We'd have to really start doing really hacky things like remove the > > SHCFG as a used field entirely - but I think if you do that you break > > the entire logic of the design and also go backwards to having > > programming that only works if STEs are constructed in certain ways. > > I would actually like to remove SHCFG as a used field. If the encoding > was less whacky (i.e. if 0b00 always meant "use incoming"), then it would > be easy, but it shouldn't be too hard to work around that. But why? You throw away the entire logic of the design, go back to subtly coupling the two parts, and *for what*? Exactly what are we trying to achieve in return? You haven't explained why we are still discussing this afer 7 months. It really isn't worthwhile. Jason