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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?vweFfnElvbXHBDMUDyjsmNuz75vS+IeJ23nxMF1ce8c5z9GyzkJeCLIsLSIh?= =?us-ascii?Q?InnLkSMt9tspJOfOIOozUKXh/Xhj6iibmbKyyOVWG1r6EfJx07/YuDjfBnaQ?= =?us-ascii?Q?QG0yErgs1HaClM5pMvqSs3IuYwjiwHscmQdS2PjkJFvqSQfofnlb3bnaCCfe?= =?us-ascii?Q?GnFL1dGJhj7RfSMDwhZOQzKIz5G9xA0H/ViPFt0J0l2Xuy7REUHZVp75OWgz?= =?us-ascii?Q?LItYUi7WIhwxVFUEMPkHAvJwlKZRVCdpN6IQArI0kdnUhSehpXdKUHcHfIET?= =?us-ascii?Q?c605ktmbYlwnYcgYKcA7d4fqDgKhdTblKCBoToB2NZhOQ2tNZb+dFCW4GpBM?= =?us-ascii?Q?05r59An7CGmg4vADrbsXOZeOX2sLBN4EpIpdPVjoPJ15euApxFhXuYcBoU9g?= =?us-ascii?Q?4rqciOstfRFC8FXeeqdtRcmxu4A0w8rVtvB+Qda/PwTgP7koqrG+NMurlEP7?= =?us-ascii?Q?8mr9TkTO5dBbtJsYXBK6KG58Z2ExeCiEkBpyqL7zlx4UnQWRlDyVK+TPhy0O?= =?us-ascii?Q?7pBLoNARAHePoo6W9gvL5PptzKauPujnCTBdE2PqAzGAziTKP5771c+ihche?= =?us-ascii?Q?c38KOs0XYN3ZzdnCiHh/lrt1F7KKEY2konFQSat9ffqnbSz6BCYFuW6GwrLV?= =?us-ascii?Q?Sk8un/QY3OeFabHGf4R8K8vW5NlxO8+RhEBYEosyXIPqpcqdXnxwNs7GmQCY?= =?us-ascii?Q?4wfAcm/8Iah+XjkO984QndTgIZj1nrU+BBmbp1pltgBqjuHiQk1j3kW4gRcF?= =?us-ascii?Q?hOj2M5VjHdJ65cwsWzbKGB5ZREhCMSCsLVIekd2V/5WEaQ1GfjCf6VkhYfy4?= =?us-ascii?Q?Mfk7zsAaUb9bAV0fFanEkul0HwscI57cRpRf8QviMJJREHotBUjGvp8O65Wv?= =?us-ascii?Q?DdrrSBeWfUY+TqGUl9fMSP9vw08kBojTDmZHhhfRTRt8c+BB7uITa+vOZJvj?= =?us-ascii?Q?eKlyFwc2To6R+NEL/yWJjEv9NgyvFt1WooHfS3c7CWhBOKNPy7RG7dEGv+HE?= =?us-ascii?Q?+7Ea6Dh/Q9I+SKXQ37ESkvPwpcHU7y0Rlnurxgc0uAxKlX/mIdw/mRQMa/aj?= =?us-ascii?Q?nvFZkXEB2rY2+uU9g993Z2izzGXbXSA1seI7U+wGOF8wzPiCErhK1j8rGBoj?= =?us-ascii?Q?u2/NBH1LAxgDyhYDoeAoWYuN5XgnYJIqG7+5ZO7z19GZKTbrjwIDr7guRoK2?= =?us-ascii?Q?OBuwoV0C9qgigm+y4j63zBEXk/JIt6qil469+GIV/lhVp9EboWbrMiruzJBh?= =?us-ascii?Q?Jj21knDs8XaehnKhbiue1+pExAgGtyNXdM9+HPwCDSFQbyCUG1e6ZN07BCCj?= =?us-ascii?Q?f48GZMtKJXHJCumpx+lzEAxx?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: 72df3fc7-eb2c-4948-b7d8-08d9638abb34 X-MS-Exchange-CrossTenant-AuthSource: CH2PR12MB4133.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Aug 2021 03:29:35.6714 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 1LoElluitC5lRWD9vh7TZQ595Ap9WWphGMwUVbHA5Iwww2mgjToXchFiTuNb0cwaS61fgTIg8pm52OvNOiAHxQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH2PR12MB4005 Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org On Thu, Aug 19, 2021 at 07:09:42PM +0200, Borislav Petkov wrote: > On Thu, Aug 19, 2021 at 09:58:31AM -0500, Michael Roth wrote: > > Not sure what you mean here. All the interfaces introduced here are used > > by acpi.c. There is another helper added later (efi_bp_find_vendor_table()) > > in "enable SEV-SNP-validated CPUID in #VC handler", since it's not used > > here by acpi.c. > > Maybe I got confused by the amount of changes in a single patch. I'll > try harder with your v5. :) > > > There is the aforementioned efi_bp_find_vendor_table() that does the > > simple iteration, but I wasn't sure how to build the "find one of these, > > but this one is preferred" logic into it in a reasonable way. > > Instead of efi_foreach_conf_entry() you simply do a bog-down simple > loop and each time you stop at a table, you examine it and overwrite > pointers, if you've found something better. > > With "overwrite pointers" I mean you cache the pointers to those conf > tables you iterate over and dig out so that you don't have to do it a > second time. That is, *if* you need them a second time. I believe you > call at least efi_bp_get_conf_table() twice... you get the idea. Sorry I'm still a little confused on how to determine "something better", since it's acpi.c that decides which GUID is preferred, whereas efi_find_vendor_table() is a library function with no outside knowledge other than its arguments, so to return the preferred pointer it would need both/multiple GUIDs passed in as arguments, wouldn't it? (or a callback) Another alternative is something like what drivers/firmware/efi/efi.c:common_tables does, where interesting table GUIDs are each associated with a pointer, and all the pointers can then be initialized with to the corresponding table address with a single pass. But would need to be careful to re-initialize those pointers when BSS gets cleared, or declare them in __section(".data"). Is that closer to what you were thinking? > > > I could just call it once for each of these GUIDs though. I was > > hesitant to do so since it's less efficient than existing code, but if > > it's worth it for the simplification then I'm all for it. > > Yeah, this is executed once during boot so I don't think you can make it > more efficient than a single iteration over the config table blobs. In v5, I've simplified things to just call efi_find_vendor_table() once for ACPI_20_TABLE_GUID, then once for ACPI_TABLE_GUID if that's not available. So definitely doesn't sound like what you are suggesting here, but does at least simplify code and gets rid of the efi_foreach* stuff. But happy to rework things if you had something else in mind. > > I hope that makes more sense. > > -- > Regards/Gruss, > Boris. > > https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpeople.kernel.org%2Ftglx%2Fnotes-about-netiquette&data=04%7C01%7Cmichael.roth%40amd.com%7C2a4304e70b5b4f2137f808d963340eec%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637649897546039774%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=GKDogD%2BOCN0swhmT4RZ2%2B3JmURF3e4qq%2FzgrxxFqJt0%3D&reserved=0