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Peter Anvin" , Stanislav Spassov , Eric Biggers , Oleg Nesterov , Kees Cook Subject: Re: [PATCH v8 2/6] x86/fpu: Initialize guest FPU permissions from guest defaults Message-ID: References: <20250522151031.426788-1-chao.gao@intel.com> <20250522151031.426788-3-chao.gao@intel.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250522151031.426788-3-chao.gao@intel.com> X-ClientProxiedBy: PH8PR21CA0014.namprd21.prod.outlook.com (2603:10b6:510:2ce::28) To BL1PR12MB5995.namprd12.prod.outlook.com (2603:10b6:208:39b::20) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL1PR12MB5995:EE_|BN7PPF7C0ACC722:EE_ X-MS-Office365-Filtering-Correlation-Id: 7a392328-8989-4075-85b2-08dd9ef5cb45 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|366016|7416014|376014|7053199007; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?bM+3X607lnC+OnpDUF0F2N1fwi8JdcNNpFi3yvk/gqxxCJ5j0+4vJO6buBow?= =?us-ascii?Q?8snplzFzEUE9utWHUP7svaB7B7iGJR79ncnRm3jClBBO0Qq0zRnL4Gy3ZUKS?= =?us-ascii?Q?neDPBEAnxPGRCPy+ust00GukO6iTYZyedBYJoy2DQD7OqKU7tmAk4cCqKP+X?= =?us-ascii?Q?gmEgWUv+1DZ51AHdFU9bBt5w/TXq2GOgm/J1nf1eDh0CeY6bmjwap/iW+nPd?= =?us-ascii?Q?3nX8vwjGJASqSy1yIbb0xM61fz08Frr43pi6JLDGtUINPKkNj4mghAJQQQpP?= =?us-ascii?Q?sEc0L6RbLLndVNhEuP2KuOYzeexb27Dvcy4XeHp8bN+YvA9hOGrDpmLn3sY9?= =?us-ascii?Q?aSvAvz2h8MbzX5GuQCquwh7I4etVD/HgYIMpN5YbWuK92NBZYy2BjV9/zDyS?= =?us-ascii?Q?oW+a+OvL3O7/cjEQ3mcHhu3C6n/cagidXcCP1kZ87gGA2IoiQSzCgKa/RdC7?= =?us-ascii?Q?hTOL1x+LK4iKJEN+bePqePTEXHLhQs2p+REDWvCLWcAa/NTuiuKFG9D52mGK?= =?us-ascii?Q?jKod8hY+OuA20d3+R7Xj8UagaB+JChOfGJO0FgrxW4W5RawJne+MHNGt+5AN?= =?us-ascii?Q?1yK7wn8yAE/leIU2dMwm7iwX7dcRabNAo6vNPPRiIoLn2b+WuWaTz+CA4oab?= =?us-ascii?Q?0R7IIJ0WIVoLHK/588Z8jSitsAI439iIylH7mxZhx9V7YBYecb+DXdgm6upN?= =?us-ascii?Q?2aBrOrNuXvhOFWyutULYpsVtrTLfsM4MdTE7pqg9UncinjPnxiyzZs3awe8+?= =?us-ascii?Q?uCG0hF6Y765gzu+ELLyhRk+6KHkOxhESBLGxpuOJ73QmalU94L4woG24ip/y?= =?us-ascii?Q?V5c9Uxm3SiJdOHfzaTfALH5ZX7ID/O7xVx8yMuFO82HGH7X6//D3KK/ATLDk?= =?us-ascii?Q?oiMlqbmhRPC7wAAUiloBx6+13osD9m4MWRFgeP8UbXa1CTNFSBaNttor/D9e?= =?us-ascii?Q?aH/j4lnEvlcOf8JZ/j501en82sZEsTvWP98yXcKezqLNrZmmL262J4xhy/pm?= =?us-ascii?Q?YWtk51u5G82zJ/2vZz7h54XRSlRu5ojMR9k74/FkMPhosgZdvr9baLZKAN9h?= =?us-ascii?Q?p/MO/AEbTg2mcCgQ/0xqY8RbmBzZL/vi/C3V5jo//kvsj6u+H8k748I842g+?= =?us-ascii?Q?WI0XEPZCHRQRxEtt/ZlBZlDWDDFG2yU7Vse9ZCmbsYtiZfM+z3/9qiL/8ZKn?= =?us-ascii?Q?vJieyqUzd1faZhHipFvJlsLmZbIZlbw2wvGVNWa7FrbRJTz221ZBMZN1RZct?= =?us-ascii?Q?Z72CUL+mgLCWdGpVya3pz38IwFA6Xk9dvh7XkVZqpAYPWnRXK9hAbhB7sUxj?= =?us-ascii?Q?NcC5trt2mKKAYd5uzp8QSflMvoxQGLyh4lPaIkRVGxbdvkuUlfZ28tTySLRx?= =?us-ascii?Q?4G+hzG+II8l/4DH0rzi6dEMshJ87UwHYesYAE/lFZViACVcCRqHdqmOJbPi+?= =?us-ascii?Q?QuJuTtsdWfK8PZGwkaXsyBpObXEtXsNxwW0bqsEQ4IzBXn7lFYa4onh7Tn1J?= =?us-ascii?Q?gsFGQ5LIh5zXhFKBSeaXY05wzz9pPAh8K/q5w3wbm/RjnM0yOBzMJQr6IYD6?= =?us-ascii?Q?1PjxF7ku9Dhrckzb72R1X2Cw4wIs7Nn5HzRTqcoQ?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: 7a392328-8989-4075-85b2-08dd9ef5cb45 X-MS-Exchange-CrossTenant-AuthSource: BL1PR12MB5995.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 May 2025 21:14:27.2287 (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: j3T5GHI3ephFBfnrM4TroP7lOTGBhcQ21AyBKz5N3SIhYCNHmQYgyd4wKa6h5q1fU9SJwLg2afNjp/1ttXA7mA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN7PPF7C0ACC722 On Thu, May 22, 2025 at 08:10:05AM -0700, Chao Gao wrote: > Currently, fpu->guest_perm is copied from fpu->perm, which is derived from > fpu_kernel_cfg.default_features. > > Guest defaults were introduced to differentiate the features and sizes of > host and guest FPUs. Copying guest FPU permissions from the host will lead > to inconsistencies between the guest default features and permissions. > > Initialize guest FPU permissions from guest defaults instead of host > defaults. This ensures that any changes to guest default features are > automatically reflected in guest permissions, which in turn guarantees > that fpstate_realloc() allocates a correctly sized XSAVE buffer for guest > FPUs. > > Suggested-by: Chang S. Bae > Signed-off-by: Chao Gao > Reviewed-by: Rick Edgecombe Reviewed-by: John Allen