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Peter Anvin" , "Peter Zijlstra" , , kernel test robot , Subject: Re: [PATCH] x86/fpu: set X86_FEATURE_OSXSAVE feature after enabling OSXSAVE in CR4 Message-ID: References: <20230823065747.92257-1-feng.tang@intel.com> <87r0nsddb5.ffs@tglx> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <87r0nsddb5.ffs@tglx> X-ClientProxiedBy: SG2PR01CA0153.apcprd01.prod.exchangelabs.com (2603:1096:4:8f::33) To MN0PR11MB6304.namprd11.prod.outlook.com (2603:10b6:208:3c0::7) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MN0PR11MB6304:EE_|DM6PR11MB4755:EE_ X-MS-Office365-Filtering-Correlation-Id: 4834a556-e3b2-4452-d2df-08dba49aceb1 X-LD-Processed: 46c98d88-e344-4ed4-8496-4ed7712e255d,ExtAddr X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:MN0PR11MB6304.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230031)(7916004)(366004)(136003)(396003)(39860400002)(376002)(346002)(451199024)(186009)(1800799009)(54906003)(33716001)(66946007)(66476007)(66556008)(316002)(6916009)(82960400001)(478600001)(26005)(44832011)(38100700002)(6666004)(41300700001)(86362001)(9686003)(6486002)(6512007)(2906002)(6506007)(8676002)(8936002)(4326008)(5660300002);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?3MJAktDjhb02XsiKqW524Y9pfvKxHfSVjF3bDlNfe8qkExYQdgfR5KWG8g+5?= =?us-ascii?Q?soI8zqC4ySEuwBj4H1DefkUDqt8DQzQA+QUGMEKypiElMXXUHlTyWkbiSGsA?= =?us-ascii?Q?jOC5zuu7JqLCWhLsOcXuW70p1mqkNwk0T0HllOuD5fFjV+x7L0WR+eUvzkQ+?= =?us-ascii?Q?nTM6cWGNvrUJNBj2GUkLVcwMZcA6qqigr+PWRRQcbhBqp/OjxTNO3hxqnUhv?= =?us-ascii?Q?MbYA1UVne/iD089WlWo3DrQ5k37ZFZ584BoJw4bcH0mOrZKPOKKGUnZVoyCR?= =?us-ascii?Q?fw16F5e51sMORh70e9wyYda9FHI7aJSuq3+OMuSQlxbG6KXn2cGig4ZzZDoZ?= =?us-ascii?Q?dKBmtEL6SUQbHnJlHYnxDheZBaaowkoCLpRqI/L0AnZqgDrywNHZoRSKUrWn?= =?us-ascii?Q?BkhdYo+E7jlZlfu1FVazGW++6ztDvCZ5CPhgVldO7B8Rck9q7upFjFsMv+mV?= =?us-ascii?Q?4pE50x0ivleVyDUnT7v+XpF8kho0qHHNjw9WtHb9VnyJHJG2ihQCJRZIUZYu?= =?us-ascii?Q?6kl8h8afc3RmSaF3dB3ZdVKwnkgR96FzhRwQthU0ljPVhyqObEg3/PPXGro+?= =?us-ascii?Q?wb4ywdWzToTPsGld+28YIYLz7vr1GpvwTvsJQ0bAWoZUQWwi2ucZmg4kYRaa?= =?us-ascii?Q?i/Yj6rlmoIqYhOhJEskaJN86ZwOZRqmu1HO2ju2VuDwR/5WghNlXUKrdpr82?= =?us-ascii?Q?fH156U0lW71x+JVExQQ2A7bfKmZZvkVg3O6U6VsR3e6P5CgaMxOFWrdwpt8F?= =?us-ascii?Q?Dg3NSdCkYhyfBt2Wn0KwijpEN3NnkD1qd1NU2cWWJRPy67LN0oqhTr/PZI0F?= =?us-ascii?Q?M1mK7za43uh0eJwEhyd6LACfsTlfnuK4ygb9O5oCkImBFRuW5fTqSOlxKK++?= =?us-ascii?Q?sYXkwY4vvaW/z2tPZC+1AfeIZz/StWTWWxSXeLMviLLIzQpRHPq08Qh+7a4g?= =?us-ascii?Q?p10RAVCClrXKbBpeLdAtZ4KnfNmQNn3iUT21ueJKaWupNitaPwNp/3vP0xr6?= =?us-ascii?Q?990xVk/b+mHVVLaNogtX6BmcVQwmlEk94L/7j7+dhjFwVRmHeC6gMqJlPwLa?= =?us-ascii?Q?7Few+38j3S0m8wkA4Y6f1cDfsJwYLuUxfqDKEZ0zClxcYcMyASEBUdEvgx2V?= =?us-ascii?Q?qnQZh1DYSXHkj37r9Muala77aAp0IKKFK4IQX6Oi/su/kB044IlO4RXILiku?= =?us-ascii?Q?5eb5vMfQZdogA3AIp3HPiPmG3CR16t9JWRS339V18kWa+sSuZSZF8glZ0kjK?= =?us-ascii?Q?IJCdMEGU64zjNdy2hevgqVYAo1YwoTa5mifYhY15NodkzgOkRAeUfMiBcmoT?= =?us-ascii?Q?aYysz1O8tQ8N646Wg5OrloINU0wo6jIkvWQeziwSYdT6fqZYX0nKL1PTdPmd?= =?us-ascii?Q?jKzCwPFGBsC1NGt8PxUPbpuHFSI1vqONF+G9DQYMrvAxlQIxG6kHKNf2g97L?= =?us-ascii?Q?wu4MOAWAGGVDdfWItvhEyaG9D97VxharV9D2qZlDkM00xM2ymudy8rPJcTB3?= =?us-ascii?Q?1V6ZRXiuhPJtijylgdQiW+33WtoBmo2CudIqxRlv7tZE1EDK4XJg/OEbkpOq?= =?us-ascii?Q?JIu9iTLoBJWtDSJ2YVyDThZaaMlLRejJCltWD3mw?= X-MS-Exchange-CrossTenant-Network-Message-Id: 4834a556-e3b2-4452-d2df-08dba49aceb1 X-MS-Exchange-CrossTenant-AuthSource: MN0PR11MB6304.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Aug 2023 12:08:20.4957 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: rq/2W35QM2ccBIl+y+K83WteLDJoNEwaIDZvJPdApiWMQHEM74zvvmwFEI1hbm7WAE01Al9omj7Q7ai/682ggA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR11MB4755 X-OriginatorOrg: intel.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Thomas, On Thu, Aug 24, 2023 at 11:01:18AM +0200, Thomas Gleixner wrote: > On Wed, Aug 23 2023 at 14:57, Feng Tang wrote: > > diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c > > index 0bab497c9436..8ebea0d522d2 100644 > > --- a/arch/x86/kernel/fpu/xstate.c > > +++ b/arch/x86/kernel/fpu/xstate.c > > @@ -173,6 +173,9 @@ void fpu__init_cpu_xstate(void) > > > > cr4_set_bits(X86_CR4_OSXSAVE); > > > > + if (!boot_cpu_has(X86_FEATURE_OSXSAVE)) > > + setup_force_cpu_cap(X86_FEATURE_OSXSAVE); > > This is wrong in several aspects: > > 1) You force the feature bit _before_ XSAVE is completely > initialized. fpu__init_system_xstate() has error paths which > disable XSAVE. Yes, I missed the error path in BSP fpu initialization code. > 2) This conditional should have been a red flag for you simply > because fpu__init_cpu_xstate() is invoked on all CPUs not only > on the BSP. Indeed. when I worked on the patch, I even thought about ugly thing like: if (raw_smp_processor_id() == 0) setup_force_cpu_cap(X86_FEATURE_OSXSAVE); > I fixed it up and added a proper comment explaining it. Thanks for fixing it up and improving the comments! - Feng